common: compile libconsumer, libust-consumer, libkernel-consumer as C++
authorSimon Marchi <simon.marchi@efficios.com>
Fri, 3 Sep 2021 21:31:29 +0000 (17:31 -0400)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Thu, 18 Nov 2021 00:01:01 +0000 (19:01 -0500)
Change-Id: I6d51a069b360121152286a674d551fd5e80bfe2f
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
28 files changed:
src/common/consumer/Makefile.am
src/common/consumer/consumer-metadata-cache.c [deleted file]
src/common/consumer/consumer-metadata-cache.cpp [new file with mode: 0644]
src/common/consumer/consumer-metadata-cache.h
src/common/consumer/consumer-stream.c [deleted file]
src/common/consumer/consumer-stream.cpp [new file with mode: 0644]
src/common/consumer/consumer-stream.h
src/common/consumer/consumer-timer.c [deleted file]
src/common/consumer/consumer-timer.cpp [new file with mode: 0644]
src/common/consumer/consumer.c [deleted file]
src/common/consumer/consumer.cpp [new file with mode: 0644]
src/common/consumer/consumer.h
src/common/consumer/metadata-bucket.c [deleted file]
src/common/consumer/metadata-bucket.cpp [new file with mode: 0644]
src/common/consumer/metadata-bucket.h
src/common/kernel-consumer/Makefile.am
src/common/kernel-consumer/kernel-consumer.c [deleted file]
src/common/kernel-consumer/kernel-consumer.cpp [new file with mode: 0644]
src/common/kernel-consumer/kernel-consumer.h
src/common/ust-consumer/Makefile.am
src/common/ust-consumer/ust-consumer.c [deleted file]
src/common/ust-consumer/ust-consumer.cpp [new file with mode: 0644]
src/common/ust-consumer/ust-consumer.h
tests/regression/tools/notification/Makefile.am
tests/regression/tools/notification/consumer_testpoints.c [deleted file]
tests/regression/tools/notification/consumer_testpoints.cpp [new file with mode: 0644]
tests/regression/tools/notification/sessiond_testpoints.c [deleted file]
tests/regression/tools/notification/sessiond_testpoints.cpp [new file with mode: 0644]

index 55e47b2101dcae6ac7ef0c4eab260689c601ba98..ba3ecf1da3834879d9053d409cfee063d57e53d2 100644 (file)
@@ -5,9 +5,15 @@ noinst_LTLIBRARIES = libconsumer.la
 noinst_HEADERS = consumer-metadata-cache.h consumer-timer.h \
                 consumer-testpoint.h
 
-libconsumer_la_SOURCES = consumer.c consumer.h consumer-metadata-cache.c \
-                         consumer-timer.c consumer-stream.c consumer-stream.h \
-                         metadata-bucket.c metadata-bucket.h
+libconsumer_la_SOURCES = \
+       consumer.cpp \
+       consumer.h \
+       consumer-metadata-cache.cpp \
+       consumer-stream.cpp \
+       consumer-stream.h \
+       consumer-timer.cpp \
+       metadata-bucket.cpp \
+       metadata-bucket.h
 
 libconsumer_la_LIBADD = \
                $(top_builddir)/src/common/sessiond-comm/libsessiond-comm.la \
diff --git a/src/common/consumer/consumer-metadata-cache.c b/src/common/consumer/consumer-metadata-cache.c
deleted file mode 100644 (file)
index 8ef2848..0000000
+++ /dev/null
@@ -1,245 +0,0 @@
-/*
- * Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
- * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#define _LGPL_SOURCE
-#include <pthread.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include <inttypes.h>
-
-#include <common/common.h>
-#include <common/utils.h>
-#include <common/sessiond-comm/sessiond-comm.h>
-#include <common/ust-consumer/ust-consumer.h>
-#include <common/consumer/consumer.h>
-
-#include "consumer-metadata-cache.h"
-
-enum metadata_cache_update_version_status {
-       METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED,
-       METADATA_CACHE_UPDATE_STATUS_VERSION_NOT_UPDATED,
-};
-
-extern struct lttng_consumer_global_data the_consumer_data;
-
-/*
- * Reset the metadata cache.
- */
-static
-void metadata_cache_reset(struct consumer_metadata_cache *cache)
-{
-       const int ret = lttng_dynamic_buffer_set_size(&cache->contents, 0);
-
-       LTTNG_ASSERT(ret == 0);
-}
-
-/*
- * Check if the metadata cache version changed.
- * If it did, reset the metadata cache.
- * The metadata cache lock MUST be held.
- */
-static enum metadata_cache_update_version_status metadata_cache_update_version(
-               struct consumer_metadata_cache *cache, uint64_t version)
-{
-       enum metadata_cache_update_version_status status;
-
-       if (cache->version == version) {
-               status = METADATA_CACHE_UPDATE_STATUS_VERSION_NOT_UPDATED;
-               goto end;
-       }
-
-       DBG("Metadata cache version update to %" PRIu64, version);
-       cache->version = version;
-       status = METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED;
-
-end:
-       return status;
-}
-
-/*
- * Write metadata to the cache, extend the cache if necessary. We support
- * overlapping updates, but they need to be contiguous. Send the
- * contiguous metadata in cache to the ring buffer. The metadata cache
- * lock MUST be acquired to write in the cache.
- *
- * See `enum consumer_metadata_cache_write_status` for the meaning of the
- * various returned status codes.
- */
-enum consumer_metadata_cache_write_status
-consumer_metadata_cache_write(struct consumer_metadata_cache *cache,
-               unsigned int offset, unsigned int len, uint64_t version,
-               const char *data)
-{
-       int ret = 0;
-       enum consumer_metadata_cache_write_status status;
-       bool cache_is_invalidated = false;
-       uint64_t original_size;
-
-       LTTNG_ASSERT(cache);
-       ASSERT_LOCKED(cache->lock);
-       original_size = cache->contents.size;
-
-       if (metadata_cache_update_version(cache, version) ==
-                       METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED) {
-               metadata_cache_reset(cache);
-               cache_is_invalidated = true;
-       }
-
-       DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
-       if (offset + len > cache->contents.size) {
-               ret = lttng_dynamic_buffer_set_size(
-                               &cache->contents, offset + len);
-               if (ret) {
-                       ERR("Extending metadata cache");
-                       status = CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR;
-                       goto end;
-               }
-       }
-
-       memcpy(cache->contents.data + offset, data, len);
-
-       if (cache_is_invalidated) {
-               status = CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED;
-       } else if (cache->contents.size > original_size) {
-               status = CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT;
-       } else {
-               status = CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE;
-               LTTNG_ASSERT(cache->contents.size == original_size);
-       }
-
-end:
-       return status;
-}
-
-/*
- * Create the metadata cache, original allocated size: max_sb_size
- *
- * Return 0 on success, a negative value on error.
- */
-int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
-{
-       int ret;
-
-       LTTNG_ASSERT(channel);
-
-       channel->metadata_cache = zmalloc(
-                       sizeof(struct consumer_metadata_cache));
-       if (!channel->metadata_cache) {
-               PERROR("zmalloc metadata cache struct");
-               ret = -1;
-               goto end;
-       }
-       ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
-       if (ret != 0) {
-               PERROR("mutex init");
-               goto end_free_cache;
-       }
-
-       lttng_dynamic_buffer_init(&channel->metadata_cache->contents);
-       ret = lttng_dynamic_buffer_set_capacity(
-                       &channel->metadata_cache->contents,
-                       DEFAULT_METADATA_CACHE_SIZE);
-       if (ret) {
-               PERROR("Failed to pre-allocate metadata cache storage of %d bytes on creation",
-                               DEFAULT_METADATA_CACHE_SIZE);
-               ret = -1;
-               goto end_free_mutex;
-       }
-
-       DBG("Allocated metadata cache: current capacity = %zu",
-                       lttng_dynamic_buffer_get_capacity_left(
-                                       &channel->metadata_cache->contents));
-
-       ret = 0;
-       goto end;
-
-end_free_mutex:
-       pthread_mutex_destroy(&channel->metadata_cache->lock);
-end_free_cache:
-       free(channel->metadata_cache);
-end:
-       return ret;
-}
-
-/*
- * Destroy and free the metadata cache
- */
-void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
-{
-       if (!channel || !channel->metadata_cache) {
-               return;
-       }
-
-       DBG("Destroying metadata cache");
-
-       pthread_mutex_destroy(&channel->metadata_cache->lock);
-       lttng_dynamic_buffer_reset(&channel->metadata_cache->contents);
-       free(channel->metadata_cache);
-}
-
-/*
- * Check if the cache is flushed up to the offset passed in parameter.
- *
- * Return 0 if everything has been flushed, 1 if there is data not flushed.
- */
-int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
-               uint64_t offset, int timer)
-{
-       int ret = 0;
-       struct lttng_consumer_stream *metadata_stream;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(channel->metadata_cache);
-
-       /*
-        * If not called from a timer handler, we have to take the
-        * channel lock to be mutually exclusive with channel teardown.
-        * Timer handler does not need to take this lock because it is
-        * already synchronized by timer stop (and, more importantly,
-        * taking this lock in a timer handler would cause a deadlock).
-        */
-       if (!timer) {
-               pthread_mutex_lock(&channel->lock);
-       }
-       pthread_mutex_lock(&channel->timer_lock);
-       metadata_stream = channel->metadata_stream;
-       if (!metadata_stream) {
-               /*
-                * Having no metadata stream means the channel is being destroyed so there
-                * is no cache to flush anymore.
-                */
-               ret = 0;
-               goto end_unlock_channel;
-       }
-
-       pthread_mutex_lock(&metadata_stream->lock);
-       pthread_mutex_lock(&channel->metadata_cache->lock);
-
-       if (metadata_stream->ust_metadata_pushed >= offset) {
-               ret = 0;
-       } else if (channel->metadata_stream->endpoint_status !=
-                       CONSUMER_ENDPOINT_ACTIVE) {
-               /* An inactive endpoint means we don't have to flush anymore. */
-               ret = 0;
-       } else {
-               /* Still not completely flushed. */
-               ret = 1;
-       }
-
-       pthread_mutex_unlock(&channel->metadata_cache->lock);
-       pthread_mutex_unlock(&metadata_stream->lock);
-end_unlock_channel:
-       pthread_mutex_unlock(&channel->timer_lock);
-       if (!timer) {
-               pthread_mutex_unlock(&channel->lock);
-       }
-
-       return ret;
-}
diff --git a/src/common/consumer/consumer-metadata-cache.cpp b/src/common/consumer/consumer-metadata-cache.cpp
new file mode 100644 (file)
index 0000000..fdda6be
--- /dev/null
@@ -0,0 +1,245 @@
+/*
+ * Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
+ * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#define _LGPL_SOURCE
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <inttypes.h>
+
+#include <common/common.h>
+#include <common/utils.h>
+#include <common/sessiond-comm/sessiond-comm.h>
+#include <common/ust-consumer/ust-consumer.h>
+#include <common/consumer/consumer.h>
+
+#include "consumer-metadata-cache.h"
+
+enum metadata_cache_update_version_status {
+       METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED,
+       METADATA_CACHE_UPDATE_STATUS_VERSION_NOT_UPDATED,
+};
+
+extern struct lttng_consumer_global_data the_consumer_data;
+
+/*
+ * Reset the metadata cache.
+ */
+static
+void metadata_cache_reset(struct consumer_metadata_cache *cache)
+{
+       const int ret = lttng_dynamic_buffer_set_size(&cache->contents, 0);
+
+       LTTNG_ASSERT(ret == 0);
+}
+
+/*
+ * Check if the metadata cache version changed.
+ * If it did, reset the metadata cache.
+ * The metadata cache lock MUST be held.
+ */
+static enum metadata_cache_update_version_status metadata_cache_update_version(
+               struct consumer_metadata_cache *cache, uint64_t version)
+{
+       enum metadata_cache_update_version_status status;
+
+       if (cache->version == version) {
+               status = METADATA_CACHE_UPDATE_STATUS_VERSION_NOT_UPDATED;
+               goto end;
+       }
+
+       DBG("Metadata cache version update to %" PRIu64, version);
+       cache->version = version;
+       status = METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED;
+
+end:
+       return status;
+}
+
+/*
+ * Write metadata to the cache, extend the cache if necessary. We support
+ * overlapping updates, but they need to be contiguous. Send the
+ * contiguous metadata in cache to the ring buffer. The metadata cache
+ * lock MUST be acquired to write in the cache.
+ *
+ * See `enum consumer_metadata_cache_write_status` for the meaning of the
+ * various returned status codes.
+ */
+enum consumer_metadata_cache_write_status
+consumer_metadata_cache_write(struct consumer_metadata_cache *cache,
+               unsigned int offset, unsigned int len, uint64_t version,
+               const char *data)
+{
+       int ret = 0;
+       enum consumer_metadata_cache_write_status status;
+       bool cache_is_invalidated = false;
+       uint64_t original_size;
+
+       LTTNG_ASSERT(cache);
+       ASSERT_LOCKED(cache->lock);
+       original_size = cache->contents.size;
+
+       if (metadata_cache_update_version(cache, version) ==
+                       METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED) {
+               metadata_cache_reset(cache);
+               cache_is_invalidated = true;
+       }
+
+       DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
+       if (offset + len > cache->contents.size) {
+               ret = lttng_dynamic_buffer_set_size(
+                               &cache->contents, offset + len);
+               if (ret) {
+                       ERR("Extending metadata cache");
+                       status = CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR;
+                       goto end;
+               }
+       }
+
+       memcpy(cache->contents.data + offset, data, len);
+
+       if (cache_is_invalidated) {
+               status = CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED;
+       } else if (cache->contents.size > original_size) {
+               status = CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT;
+       } else {
+               status = CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE;
+               LTTNG_ASSERT(cache->contents.size == original_size);
+       }
+
+end:
+       return status;
+}
+
+/*
+ * Create the metadata cache, original allocated size: max_sb_size
+ *
+ * Return 0 on success, a negative value on error.
+ */
+int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
+{
+       int ret;
+
+       LTTNG_ASSERT(channel);
+
+       channel->metadata_cache = (consumer_metadata_cache *) zmalloc(
+                       sizeof(struct consumer_metadata_cache));
+       if (!channel->metadata_cache) {
+               PERROR("zmalloc metadata cache struct");
+               ret = -1;
+               goto end;
+       }
+       ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
+       if (ret != 0) {
+               PERROR("mutex init");
+               goto end_free_cache;
+       }
+
+       lttng_dynamic_buffer_init(&channel->metadata_cache->contents);
+       ret = lttng_dynamic_buffer_set_capacity(
+                       &channel->metadata_cache->contents,
+                       DEFAULT_METADATA_CACHE_SIZE);
+       if (ret) {
+               PERROR("Failed to pre-allocate metadata cache storage of %d bytes on creation",
+                               DEFAULT_METADATA_CACHE_SIZE);
+               ret = -1;
+               goto end_free_mutex;
+       }
+
+       DBG("Allocated metadata cache: current capacity = %zu",
+                       lttng_dynamic_buffer_get_capacity_left(
+                                       &channel->metadata_cache->contents));
+
+       ret = 0;
+       goto end;
+
+end_free_mutex:
+       pthread_mutex_destroy(&channel->metadata_cache->lock);
+end_free_cache:
+       free(channel->metadata_cache);
+end:
+       return ret;
+}
+
+/*
+ * Destroy and free the metadata cache
+ */
+void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
+{
+       if (!channel || !channel->metadata_cache) {
+               return;
+       }
+
+       DBG("Destroying metadata cache");
+
+       pthread_mutex_destroy(&channel->metadata_cache->lock);
+       lttng_dynamic_buffer_reset(&channel->metadata_cache->contents);
+       free(channel->metadata_cache);
+}
+
+/*
+ * Check if the cache is flushed up to the offset passed in parameter.
+ *
+ * Return 0 if everything has been flushed, 1 if there is data not flushed.
+ */
+int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
+               uint64_t offset, int timer)
+{
+       int ret = 0;
+       struct lttng_consumer_stream *metadata_stream;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(channel->metadata_cache);
+
+       /*
+        * If not called from a timer handler, we have to take the
+        * channel lock to be mutually exclusive with channel teardown.
+        * Timer handler does not need to take this lock because it is
+        * already synchronized by timer stop (and, more importantly,
+        * taking this lock in a timer handler would cause a deadlock).
+        */
+       if (!timer) {
+               pthread_mutex_lock(&channel->lock);
+       }
+       pthread_mutex_lock(&channel->timer_lock);
+       metadata_stream = channel->metadata_stream;
+       if (!metadata_stream) {
+               /*
+                * Having no metadata stream means the channel is being destroyed so there
+                * is no cache to flush anymore.
+                */
+               ret = 0;
+               goto end_unlock_channel;
+       }
+
+       pthread_mutex_lock(&metadata_stream->lock);
+       pthread_mutex_lock(&channel->metadata_cache->lock);
+
+       if (metadata_stream->ust_metadata_pushed >= offset) {
+               ret = 0;
+       } else if (channel->metadata_stream->endpoint_status !=
+                       CONSUMER_ENDPOINT_ACTIVE) {
+               /* An inactive endpoint means we don't have to flush anymore. */
+               ret = 0;
+       } else {
+               /* Still not completely flushed. */
+               ret = 1;
+       }
+
+       pthread_mutex_unlock(&channel->metadata_cache->lock);
+       pthread_mutex_unlock(&metadata_stream->lock);
+end_unlock_channel:
+       pthread_mutex_unlock(&channel->timer_lock);
+       if (!timer) {
+               pthread_mutex_unlock(&channel->lock);
+       }
+
+       return ret;
+}
index b8f4efadc4c5ec59913cb75ea1644882fab2331b..4f8bb763fefdd1a893c01f5bd70f1fa9148866df 100644 (file)
 #include <common/consumer/consumer.h>
 #include <common/dynamic-buffer.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 enum consumer_metadata_cache_write_status {
        CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR = -1,
        /*
@@ -59,4 +63,8 @@ void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel);
 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
                uint64_t offset, int timer);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* CONSUMER_METADATA_CACHE_H */
diff --git a/src/common/consumer/consumer-stream.c b/src/common/consumer/consumer-stream.c
deleted file mode 100644 (file)
index be19c1b..0000000
+++ /dev/null
@@ -1,1329 +0,0 @@
-/*
- * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
- * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#define _LGPL_SOURCE
-#include <inttypes.h>
-#include <sys/mman.h>
-#include <unistd.h>
-
-#include <common/common.h>
-#include <common/index/index.h>
-#include <common/kernel-consumer/kernel-consumer.h>
-#include <common/relayd/relayd.h>
-#include <common/ust-consumer/ust-consumer.h>
-#include <common/utils.h>
-#include <common/consumer/consumer.h>
-#include <common/consumer/consumer-timer.h>
-#include <common/consumer/metadata-bucket.h>
-#include <common/kernel-ctl/kernel-ctl.h>
-
-#include "consumer-stream.h"
-
-/*
- * RCU call to free stream. MUST only be used with call_rcu().
- */
-static void free_stream_rcu(struct rcu_head *head)
-{
-       struct lttng_ht_node_u64 *node =
-               caa_container_of(head, struct lttng_ht_node_u64, head);
-       struct lttng_consumer_stream *stream =
-               caa_container_of(node, struct lttng_consumer_stream, node);
-
-       pthread_mutex_destroy(&stream->lock);
-       free(stream);
-}
-
-static void consumer_stream_data_lock_all(struct lttng_consumer_stream *stream)
-{
-       pthread_mutex_lock(&stream->chan->lock);
-       pthread_mutex_lock(&stream->lock);
-}
-
-static void consumer_stream_data_unlock_all(struct lttng_consumer_stream *stream)
-{
-       pthread_mutex_unlock(&stream->lock);
-       pthread_mutex_unlock(&stream->chan->lock);
-}
-
-static void consumer_stream_metadata_lock_all(struct lttng_consumer_stream *stream)
-{
-       consumer_stream_data_lock_all(stream);
-       pthread_mutex_lock(&stream->metadata_rdv_lock);
-}
-
-static void consumer_stream_metadata_unlock_all(struct lttng_consumer_stream *stream)
-{
-       pthread_mutex_unlock(&stream->metadata_rdv_lock);
-       consumer_stream_data_unlock_all(stream);
-}
-
-/* Only used for data streams. */
-static int consumer_stream_update_stats(struct lttng_consumer_stream *stream,
-               const struct stream_subbuffer *subbuf)
-{
-       int ret = 0;
-       uint64_t sequence_number;
-       const uint64_t discarded_events = subbuf->info.data.events_discarded;
-
-       if (!subbuf->info.data.sequence_number.is_set) {
-               /* Command not supported by the tracer. */
-               sequence_number = -1ULL;
-               stream->sequence_number_unavailable = true;
-       } else {
-               sequence_number = subbuf->info.data.sequence_number.value;
-       }
-
-       /*
-        * Start the sequence when we extract the first packet in case we don't
-        * start at 0 (for example if a consumer is not connected to the
-        * session immediately after the beginning).
-        */
-       if (stream->last_sequence_number == -1ULL) {
-               stream->last_sequence_number = sequence_number;
-       } else if (sequence_number > stream->last_sequence_number) {
-               stream->chan->lost_packets += sequence_number -
-                               stream->last_sequence_number - 1;
-       } else {
-               /* seq <= last_sequence_number */
-               ERR("Sequence number inconsistent : prev = %" PRIu64
-                   ", current = %" PRIu64,
-                               stream->last_sequence_number, sequence_number);
-               ret = -1;
-               goto end;
-       }
-       stream->last_sequence_number = sequence_number;
-
-       if (discarded_events < stream->last_discarded_events) {
-               /*
-                * Overflow has occurred. We assume only one wrap-around
-                * has occurred.
-                */
-               stream->chan->discarded_events +=
-                               (1ULL << (CAA_BITS_PER_LONG - 1)) -
-                               stream->last_discarded_events +
-                               discarded_events;
-       } else {
-               stream->chan->discarded_events += discarded_events -
-                                                 stream->last_discarded_events;
-       }
-       stream->last_discarded_events = discarded_events;
-       ret = 0;
-
-end:
-       return ret;
-}
-
-static
-void ctf_packet_index_populate(struct ctf_packet_index *index,
-               off_t offset, const struct stream_subbuffer *subbuffer)
-{
-       *index = (typeof(*index)){
-               .offset = htobe64(offset),
-               .packet_size = htobe64(subbuffer->info.data.packet_size),
-               .content_size = htobe64(subbuffer->info.data.content_size),
-               .timestamp_begin = htobe64(
-                               subbuffer->info.data.timestamp_begin),
-               .timestamp_end = htobe64(
-                               subbuffer->info.data.timestamp_end),
-               .events_discarded = htobe64(
-                               subbuffer->info.data.events_discarded),
-               .stream_id = htobe64(subbuffer->info.data.stream_id),
-               .stream_instance_id = htobe64(
-                               subbuffer->info.data.stream_instance_id.is_set ?
-                               subbuffer->info.data.stream_instance_id.value : -1ULL),
-               .packet_seq_num = htobe64(
-                               subbuffer->info.data.sequence_number.is_set ?
-                               subbuffer->info.data.sequence_number.value : -1ULL),
-       };
-}
-
-static ssize_t consumer_stream_consume_mmap(
-               struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *stream,
-               const struct stream_subbuffer *subbuffer)
-{
-       const unsigned long padding_size =
-                       subbuffer->info.data.padded_subbuf_size -
-                       subbuffer->info.data.subbuf_size;
-       const ssize_t written_bytes = lttng_consumer_on_read_subbuffer_mmap(
-                       stream, &subbuffer->buffer.buffer, padding_size);
-
-       if (stream->net_seq_idx == -1ULL) {
-               /*
-                * When writing on disk, check that only the subbuffer (no
-                * padding) was written to disk.
-                */
-               if (written_bytes != subbuffer->info.data.padded_subbuf_size) {
-                       DBG("Failed to write the entire padded subbuffer on disk (written_bytes: %zd, padded subbuffer size %lu)",
-                                       written_bytes,
-                                       subbuffer->info.data.padded_subbuf_size);
-               }
-       } else {
-               /*
-                * When streaming over the network, check that the entire
-                * subbuffer including padding was successfully written.
-                */
-               if (written_bytes != subbuffer->info.data.subbuf_size) {
-                       DBG("Failed to write only the subbuffer over the network (written_bytes: %zd, subbuffer size %lu)",
-                                       written_bytes,
-                                       subbuffer->info.data.subbuf_size);
-               }
-       }
-
-       /*
-        * If `lttng_consumer_on_read_subbuffer_mmap()` returned an error, pass
-        * it along to the caller, else return zero.
-        */
-       if (written_bytes < 0) {
-               ERR("Error reading mmap subbuffer: %zd", written_bytes);
-       }
-
-       return written_bytes;
-}
-
-static ssize_t consumer_stream_consume_splice(
-               struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *stream,
-               const struct stream_subbuffer *subbuffer)
-{
-       const ssize_t written_bytes = lttng_consumer_on_read_subbuffer_splice(
-                       ctx, stream, subbuffer->info.data.padded_subbuf_size, 0);
-
-       if (written_bytes != subbuffer->info.data.padded_subbuf_size) {
-               DBG("Failed to write the entire padded subbuffer (written_bytes: %zd, padded subbuffer size %lu)",
-                               written_bytes,
-                               subbuffer->info.data.padded_subbuf_size);
-       }
-
-       /*
-        * If `lttng_consumer_on_read_subbuffer_splice()` returned an error,
-        * pass it along to the caller, else return zero.
-        */
-       if (written_bytes < 0) {
-               ERR("Error reading splice subbuffer: %zd", written_bytes);
-       }
-
-       return written_bytes;
-}
-
-static int consumer_stream_send_index(
-               struct lttng_consumer_stream *stream,
-               const struct stream_subbuffer *subbuffer,
-               struct lttng_consumer_local_data *ctx)
-{
-       off_t packet_offset = 0;
-       struct ctf_packet_index index = {};
-
-       /*
-        * This is called after consuming the sub-buffer; substract the
-        * effect this sub-buffer from the offset.
-        */
-       if (stream->net_seq_idx == (uint64_t) -1ULL) {
-               packet_offset = stream->out_fd_offset -
-                               subbuffer->info.data.padded_subbuf_size;
-       }
-
-       ctf_packet_index_populate(&index, packet_offset, subbuffer);
-       return consumer_stream_write_index(stream, &index);
-}
-
-/*
- * Actually do the metadata sync using the given metadata stream.
- *
- * Return 0 on success else a negative value. ENODATA can be returned also
- * indicating that there is no metadata available for that stream.
- */
-static int do_sync_metadata(struct lttng_consumer_stream *metadata,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret;
-       enum sync_metadata_status status;
-
-       LTTNG_ASSERT(metadata);
-       LTTNG_ASSERT(metadata->metadata_flag);
-       LTTNG_ASSERT(ctx);
-
-       /*
-        * In UST, since we have to write the metadata from the cache packet
-        * by packet, we might need to start this procedure multiple times
-        * until all the metadata from the cache has been extracted.
-        */
-       do {
-               /*
-                * Steps :
-                * - Lock the metadata stream
-                * - Check if metadata stream node was deleted before locking.
-                *   - if yes, release and return success
-                * - Check if new metadata is ready (flush + snapshot pos)
-                * - If nothing : release and return.
-                * - Lock the metadata_rdv_lock
-                * - Unlock the metadata stream
-                * - cond_wait on metadata_rdv to wait the wakeup from the
-                *   metadata thread
-                * - Unlock the metadata_rdv_lock
-                */
-               pthread_mutex_lock(&metadata->lock);
-
-               /*
-                * There is a possibility that we were able to acquire a reference on the
-                * stream from the RCU hash table but between then and now, the node might
-                * have been deleted just before the lock is acquired. Thus, after locking,
-                * we make sure the metadata node has not been deleted which means that the
-                * buffers are closed.
-                *
-                * In that case, there is no need to sync the metadata hence returning a
-                * success return code.
-                */
-               ret = cds_lfht_is_node_deleted(&metadata->node.node);
-               if (ret) {
-                       ret = 0;
-                       goto end_unlock_mutex;
-               }
-
-               switch (ctx->type) {
-               case LTTNG_CONSUMER_KERNEL:
-                       /*
-                        * Empty the metadata cache and flush the current stream.
-                        */
-                       status = lttng_kconsumer_sync_metadata(metadata);
-                       break;
-               case LTTNG_CONSUMER32_UST:
-               case LTTNG_CONSUMER64_UST:
-                       /*
-                        * Ask the sessiond if we have new metadata waiting and update the
-                        * consumer metadata cache.
-                        */
-                       status = lttng_ustconsumer_sync_metadata(ctx, metadata);
-                       break;
-               default:
-                       abort();
-               }
-
-               switch (status) {
-               case SYNC_METADATA_STATUS_NEW_DATA:
-                       break;
-               case SYNC_METADATA_STATUS_NO_DATA:
-                       ret = 0;
-                       goto end_unlock_mutex;
-               case SYNC_METADATA_STATUS_ERROR:
-                       ret = -1;
-                       goto end_unlock_mutex;
-               default:
-                       abort();
-               }
-
-               /*
-                * At this point, new metadata have been flushed, so we wait on the
-                * rendez-vous point for the metadata thread to wake us up when it
-                * finishes consuming the metadata and continue execution.
-                */
-
-               pthread_mutex_lock(&metadata->metadata_rdv_lock);
-
-               /*
-                * Release metadata stream lock so the metadata thread can process it.
-                */
-               pthread_mutex_unlock(&metadata->lock);
-
-               /*
-                * Wait on the rendez-vous point. Once woken up, it means the metadata was
-                * consumed and thus synchronization is achieved.
-                */
-               pthread_cond_wait(&metadata->metadata_rdv, &metadata->metadata_rdv_lock);
-               pthread_mutex_unlock(&metadata->metadata_rdv_lock);
-       } while (status == SYNC_METADATA_STATUS_NEW_DATA);
-
-       /* Success */
-       return 0;
-
-end_unlock_mutex:
-       pthread_mutex_unlock(&metadata->lock);
-       return ret;
-}
-
-/*
- * Synchronize the metadata using a given session ID. A successful acquisition
- * of a metadata stream will trigger a request to the session daemon and a
- * snapshot so the metadata thread can consume it.
- *
- * This function call is a rendez-vous point between the metadata thread and
- * the data thread.
- *
- * Return 0 on success or else a negative value.
- */
-int consumer_stream_sync_metadata(struct lttng_consumer_local_data *ctx,
-               uint64_t session_id)
-{
-       int ret;
-       struct lttng_consumer_stream *stream = NULL;
-       struct lttng_ht_iter iter;
-       struct lttng_ht *ht;
-
-       LTTNG_ASSERT(ctx);
-
-       /* Ease our life a bit. */
-       ht = the_consumer_data.stream_list_ht;
-
-       rcu_read_lock();
-
-       /* Search the metadata associated with the session id of the given stream. */
-
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&session_id, lttng_ht_seed), ht->match_fct,
-                       &session_id, &iter.iter, stream, node_session_id.node) {
-               if (!stream->metadata_flag) {
-                       continue;
-               }
-
-               ret = do_sync_metadata(stream, ctx);
-               if (ret < 0) {
-                       goto end;
-               }
-       }
-
-       /*
-        * Force return code to 0 (success) since ret might be ENODATA for instance
-        * which is not an error but rather that we should come back.
-        */
-       ret = 0;
-
-end:
-       rcu_read_unlock();
-       return ret;
-}
-
-static int consumer_stream_sync_metadata_index(
-               struct lttng_consumer_stream *stream,
-               const struct stream_subbuffer *subbuffer,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret;
-
-       /* Block until all the metadata is sent. */
-       pthread_mutex_lock(&stream->metadata_timer_lock);
-       LTTNG_ASSERT(!stream->missed_metadata_flush);
-       stream->waiting_on_metadata = true;
-       pthread_mutex_unlock(&stream->metadata_timer_lock);
-
-       ret = consumer_stream_sync_metadata(ctx, stream->session_id);
-
-       pthread_mutex_lock(&stream->metadata_timer_lock);
-       stream->waiting_on_metadata = false;
-       if (stream->missed_metadata_flush) {
-               stream->missed_metadata_flush = false;
-               pthread_mutex_unlock(&stream->metadata_timer_lock);
-               (void) stream->read_subbuffer_ops.send_live_beacon(stream);
-       } else {
-               pthread_mutex_unlock(&stream->metadata_timer_lock);
-       }
-       if (ret < 0) {
-               goto end;
-       }
-
-       ret = consumer_stream_send_index(stream, subbuffer, ctx);
-end:
-       return ret;
-}
-
-/*
- * Check if the local version of the metadata stream matches with the version
- * of the metadata stream in the kernel. If it was updated, set the reset flag
- * on the stream.
- */
-static
-int metadata_stream_check_version(struct lttng_consumer_stream *stream,
-       const struct stream_subbuffer *subbuffer)
-{
-       if (stream->metadata_version == subbuffer->info.metadata.version) {
-               goto end;
-       }
-
-       DBG("New metadata version detected");
-       consumer_stream_metadata_set_version(stream,
-                       subbuffer->info.metadata.version);
-
-       if (stream->read_subbuffer_ops.reset_metadata) {
-               stream->read_subbuffer_ops.reset_metadata(stream);
-       }
-
-end:
-       return 0;
-}
-
-static
-bool stream_is_rotating_to_null_chunk(
-               const struct lttng_consumer_stream *stream)
-{
-       bool rotating_to_null_chunk = false;
-
-       if (stream->rotate_position == -1ULL) {
-               /* No rotation ongoing. */
-               goto end;
-       }
-
-       if (stream->trace_chunk == stream->chan->trace_chunk ||
-                       !stream->chan->trace_chunk) {
-               rotating_to_null_chunk = true;
-       }
-end:
-       return rotating_to_null_chunk;
-}
-
-enum consumer_stream_open_packet_status consumer_stream_open_packet(
-               struct lttng_consumer_stream *stream)
-{
-       int ret;
-       enum consumer_stream_open_packet_status status;
-       unsigned long produced_pos_before, produced_pos_after;
-
-       ret = lttng_consumer_sample_snapshot_positions(stream);
-       if (ret < 0) {
-               ERR("Failed to snapshot positions before post-rotation empty packet flush: stream id = %" PRIu64
-                               ", channel name = %s, session id = %" PRIu64,
-                               stream->key, stream->chan->name,
-                               stream->chan->session_id);
-               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = lttng_consumer_get_produced_snapshot(
-                       stream, &produced_pos_before);
-       if (ret < 0) {
-               ERR("Failed to read produced position before post-rotation empty packet flush: stream id = %" PRIu64
-                               ", channel name = %s, session id = %" PRIu64,
-                               stream->key, stream->chan->name,
-                               stream->chan->session_id);
-               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = consumer_stream_flush_buffer(stream, 0);
-       if (ret) {
-               ERR("Failed to flush an empty packet at rotation point: stream id = %" PRIu64
-                               ", channel name = %s, session id = %" PRIu64,
-                               stream->key, stream->chan->name,
-                               stream->chan->session_id);
-               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = lttng_consumer_sample_snapshot_positions(stream);
-       if (ret < 0) {
-               ERR("Failed to snapshot positions after post-rotation empty packet flush: stream id = %" PRIu64
-                               ", channel name = %s, session id = %" PRIu64,
-                               stream->key, stream->chan->name,
-                               stream->chan->session_id);
-               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = lttng_consumer_get_produced_snapshot(stream, &produced_pos_after);
-       if (ret < 0) {
-               ERR("Failed to read produced position after post-rotation empty packet flush: stream id = %" PRIu64
-                               ", channel name = %s, session id = %" PRIu64,
-                               stream->key, stream->chan->name,
-                               stream->chan->session_id);
-               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
-               goto end;
-       }
-
-       /*
-        * Determine if the flush had an effect by comparing the produced
-        * positons before and after the flush.
-        */
-       status = produced_pos_before != produced_pos_after ?
-                       CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED :
-                       CONSUMER_STREAM_OPEN_PACKET_STATUS_NO_SPACE;
-       if (status == CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED) {
-               stream->opened_packet_in_current_trace_chunk = true;
-       }
-
-end:
-       return status;
-}
-
-/*
- * An attempt to open a new packet is performed after a rotation completes to
- * get a begin timestamp as close as possible to the rotation point.
- *
- * However, that initial attempt at opening a packet can fail due to a full
- * ring-buffer. In that case, a second attempt is performed after consuming
- * a packet since that will have freed enough space in the ring-buffer.
- */
-static
-int post_consume_open_new_packet(struct lttng_consumer_stream *stream,
-               const struct stream_subbuffer *subbuffer,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret = 0;
-
-       if (!stream->opened_packet_in_current_trace_chunk &&
-                       stream->trace_chunk &&
-                       !stream_is_rotating_to_null_chunk(stream)) {
-               const enum consumer_stream_open_packet_status status =
-                               consumer_stream_open_packet(stream);
-
-               switch (status) {
-               case CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED:
-                       DBG("Opened a packet after consuming a packet rotation: stream id = %" PRIu64
-                                       ", channel name = %s, session id = %" PRIu64,
-                                       stream->key, stream->chan->name,
-                                       stream->chan->session_id);
-                       stream->opened_packet_in_current_trace_chunk = true;
-                       break;
-               case CONSUMER_STREAM_OPEN_PACKET_STATUS_NO_SPACE:
-                       /*
-                        * Can't open a packet as there is no space left.
-                        * This means that new events were produced, resulting
-                        * in a packet being opened, which is what we want
-                        * anyhow.
-                        */
-                       DBG("No space left to open a packet after consuming a packet: stream id = %" PRIu64
-                                       ", channel name = %s, session id = %" PRIu64,
-                                       stream->key, stream->chan->name,
-                                       stream->chan->session_id);
-                       stream->opened_packet_in_current_trace_chunk = true;
-                       break;
-               case CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR:
-                       /* Logged by callee. */
-                       ret = -1;
-                       goto end;
-               default:
-                       abort();
-               }
-
-               stream->opened_packet_in_current_trace_chunk = true;
-       }
-
-end:
-       return ret;
-}
-
-struct lttng_consumer_stream *consumer_stream_create(
-               struct lttng_consumer_channel *channel,
-               uint64_t channel_key,
-               uint64_t stream_key,
-               const char *channel_name,
-               uint64_t relayd_id,
-               uint64_t session_id,
-               struct lttng_trace_chunk *trace_chunk,
-               int cpu,
-               int *alloc_ret,
-               enum consumer_channel_type type,
-               unsigned int monitor)
-{
-       int ret;
-       struct lttng_consumer_stream *stream;
-
-       stream = zmalloc(sizeof(*stream));
-       if (stream == NULL) {
-               PERROR("malloc struct lttng_consumer_stream");
-               ret = -ENOMEM;
-               goto end;
-       }
-
-       rcu_read_lock();
-
-       if (trace_chunk && !lttng_trace_chunk_get(trace_chunk)) {
-               ERR("Failed to acquire trace chunk reference during the creation of a stream");
-               ret = -1;
-               goto error;
-       }
-
-       stream->chan = channel;
-       stream->key = stream_key;
-       stream->trace_chunk = trace_chunk;
-       stream->out_fd = -1;
-       stream->out_fd_offset = 0;
-       stream->output_written = 0;
-       stream->net_seq_idx = relayd_id;
-       stream->session_id = session_id;
-       stream->monitor = monitor;
-       stream->endpoint_status = CONSUMER_ENDPOINT_ACTIVE;
-       stream->index_file = NULL;
-       stream->last_sequence_number = -1ULL;
-       stream->rotate_position = -1ULL;
-       /* Buffer is created with an open packet. */
-       stream->opened_packet_in_current_trace_chunk = true;
-       pthread_mutex_init(&stream->lock, NULL);
-       pthread_mutex_init(&stream->metadata_timer_lock, NULL);
-
-       /* If channel is the metadata, flag this stream as metadata. */
-       if (type == CONSUMER_CHANNEL_TYPE_METADATA) {
-               stream->metadata_flag = 1;
-               /* Metadata is flat out. */
-               strncpy(stream->name, DEFAULT_METADATA_NAME, sizeof(stream->name));
-               /* Live rendez-vous point. */
-               pthread_cond_init(&stream->metadata_rdv, NULL);
-               pthread_mutex_init(&stream->metadata_rdv_lock, NULL);
-       } else {
-               /* Format stream name to <channel_name>_<cpu_number> */
-               ret = snprintf(stream->name, sizeof(stream->name), "%s_%d",
-                               channel_name, cpu);
-               if (ret < 0) {
-                       PERROR("snprintf stream name");
-                       goto error;
-               }
-       }
-
-       switch (channel->output) {
-       case CONSUMER_CHANNEL_SPLICE:
-               stream->output = LTTNG_EVENT_SPLICE;
-               ret = utils_create_pipe(stream->splice_pipe);
-               if (ret < 0) {
-                       goto error;
-               }
-               break;
-       case CONSUMER_CHANNEL_MMAP:
-               stream->output = LTTNG_EVENT_MMAP;
-               break;
-       default:
-               abort();
-       }
-
-       /* Key is always the wait_fd for streams. */
-       lttng_ht_node_init_u64(&stream->node, stream->key);
-
-       /* Init node per channel id key */
-       lttng_ht_node_init_u64(&stream->node_channel_id, channel_key);
-
-       /* Init session id node with the stream session id */
-       lttng_ht_node_init_u64(&stream->node_session_id, stream->session_id);
-
-       DBG3("Allocated stream %s (key %" PRIu64 ", chan_key %" PRIu64
-                       " relayd_id %" PRIu64 ", session_id %" PRIu64,
-                       stream->name, stream->key, channel_key,
-                       stream->net_seq_idx, stream->session_id);
-
-       rcu_read_unlock();
-
-       lttng_dynamic_array_init(&stream->read_subbuffer_ops.post_consume_cbs,
-                       sizeof(post_consume_cb), NULL);
-
-       if (type == CONSUMER_CHANNEL_TYPE_METADATA) {
-               stream->read_subbuffer_ops.lock =
-                               consumer_stream_metadata_lock_all;
-               stream->read_subbuffer_ops.unlock =
-                               consumer_stream_metadata_unlock_all;
-               stream->read_subbuffer_ops.pre_consume_subbuffer =
-                               metadata_stream_check_version;
-       } else {
-               const post_consume_cb post_consume_index_op = channel->is_live ?
-                               consumer_stream_sync_metadata_index :
-                               consumer_stream_send_index;
-
-               ret = lttng_dynamic_array_add_element(
-                               &stream->read_subbuffer_ops.post_consume_cbs,
-                               &post_consume_index_op);
-               if (ret) {
-                       PERROR("Failed to add `send index` callback to stream's post consumption callbacks");
-                       goto error;
-               }
-
-               ret = lttng_dynamic_array_add_element(
-                               &stream->read_subbuffer_ops.post_consume_cbs,
-                               &(post_consume_cb) { post_consume_open_new_packet });
-               if (ret) {
-                       PERROR("Failed to add `open new packet` callback to stream's post consumption callbacks");
-                       goto error;
-               }
-
-               stream->read_subbuffer_ops.lock = consumer_stream_data_lock_all;
-               stream->read_subbuffer_ops.unlock =
-                               consumer_stream_data_unlock_all;
-               stream->read_subbuffer_ops.pre_consume_subbuffer =
-                               consumer_stream_update_stats;
-       }
-
-       if (channel->output == CONSUMER_CHANNEL_MMAP) {
-               stream->read_subbuffer_ops.consume_subbuffer =
-                               consumer_stream_consume_mmap;
-       } else {
-               stream->read_subbuffer_ops.consume_subbuffer =
-                               consumer_stream_consume_splice;
-       }
-
-       return stream;
-
-error:
-       rcu_read_unlock();
-       lttng_trace_chunk_put(stream->trace_chunk);
-       lttng_dynamic_array_reset(&stream->read_subbuffer_ops.post_consume_cbs);
-       free(stream);
-end:
-       if (alloc_ret) {
-               *alloc_ret = ret;
-       }
-       return NULL;
-}
-
-/*
- * Close stream on the relayd side. This call can destroy a relayd if the
- * conditions are met.
- *
- * A RCU read side lock MUST be acquired if the relayd object was looked up in
- * a hash table before calling this.
- */
-void consumer_stream_relayd_close(struct lttng_consumer_stream *stream,
-               struct consumer_relayd_sock_pair *relayd)
-{
-       int ret;
-
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(relayd);
-
-       if (stream->sent_to_relayd) {
-               uatomic_dec(&relayd->refcount);
-               LTTNG_ASSERT(uatomic_read(&relayd->refcount) >= 0);
-       }
-
-       /* Closing streams requires to lock the control socket. */
-       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-       ret = relayd_send_close_stream(&relayd->control_sock,
-                       stream->relayd_stream_id,
-                       stream->next_net_seq_num - 1);
-       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-       if (ret < 0) {
-               ERR("Relayd send close stream failed. Cleaning up relayd %" PRIu64 ".", relayd->net_seq_idx);
-               lttng_consumer_cleanup_relayd(relayd);
-       }
-
-       /* Both conditions are met, we destroy the relayd. */
-       if (uatomic_read(&relayd->refcount) == 0 &&
-                       uatomic_read(&relayd->destroy_flag)) {
-               consumer_destroy_relayd(relayd);
-       }
-       stream->net_seq_idx = (uint64_t) -1ULL;
-       stream->sent_to_relayd = 0;
-}
-
-/*
- * Close stream's file descriptors and, if needed, close stream also on the
- * relayd side.
- *
- * The consumer data lock MUST be acquired.
- * The stream lock MUST be acquired.
- */
-void consumer_stream_close(struct lttng_consumer_stream *stream)
-{
-       int ret;
-       struct consumer_relayd_sock_pair *relayd;
-
-       LTTNG_ASSERT(stream);
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               if (stream->mmap_base != NULL) {
-                       ret = munmap(stream->mmap_base, stream->mmap_len);
-                       if (ret != 0) {
-                               PERROR("munmap");
-                       }
-               }
-
-               if (stream->wait_fd >= 0) {
-                       ret = close(stream->wait_fd);
-                       if (ret) {
-                               PERROR("close");
-                       }
-                       stream->wait_fd = -1;
-               }
-               if (stream->chan->output == CONSUMER_CHANNEL_SPLICE) {
-                       utils_close_pipe(stream->splice_pipe);
-               }
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-       {
-               /*
-                * Special case for the metadata since the wait fd is an internal pipe
-                * polled in the metadata thread.
-                */
-               if (stream->metadata_flag && stream->chan->monitor) {
-                       int rpipe = stream->ust_metadata_poll_pipe[0];
-
-                       /*
-                        * This will stop the channel timer if one and close the write side
-                        * of the metadata poll pipe.
-                        */
-                       lttng_ustconsumer_close_metadata(stream->chan);
-                       if (rpipe >= 0) {
-                               ret = close(rpipe);
-                               if (ret < 0) {
-                                       PERROR("closing metadata pipe read side");
-                               }
-                               stream->ust_metadata_poll_pipe[0] = -1;
-                       }
-               }
-               break;
-       }
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-       }
-
-       /* Close output fd. Could be a socket or local file at this point. */
-       if (stream->out_fd >= 0) {
-               ret = close(stream->out_fd);
-               if (ret) {
-                       PERROR("close");
-               }
-               stream->out_fd = -1;
-       }
-
-       if (stream->index_file) {
-               lttng_index_file_put(stream->index_file);
-               stream->index_file = NULL;
-       }
-
-       lttng_trace_chunk_put(stream->trace_chunk);
-       stream->trace_chunk = NULL;
-
-       /* Check and cleanup relayd if needed. */
-       rcu_read_lock();
-       relayd = consumer_find_relayd(stream->net_seq_idx);
-       if (relayd != NULL) {
-               consumer_stream_relayd_close(stream, relayd);
-       }
-       rcu_read_unlock();
-}
-
-/*
- * Delete the stream from all possible hash tables.
- *
- * The consumer data lock MUST be acquired.
- * The stream lock MUST be acquired.
- */
-void consumer_stream_delete(struct lttng_consumer_stream *stream,
-               struct lttng_ht *ht)
-{
-       int ret;
-       struct lttng_ht_iter iter;
-
-       LTTNG_ASSERT(stream);
-       /* Should NEVER be called not in monitor mode. */
-       LTTNG_ASSERT(stream->chan->monitor);
-
-       rcu_read_lock();
-
-       if (ht) {
-               iter.iter.node = &stream->node.node;
-               ret = lttng_ht_del(ht, &iter);
-               LTTNG_ASSERT(!ret);
-       }
-
-       /* Delete from stream per channel ID hash table. */
-       iter.iter.node = &stream->node_channel_id.node;
-       /*
-        * The returned value is of no importance. Even if the node is NOT in the
-        * hash table, we continue since we may have been called by a code path
-        * that did not add the stream to a (all) hash table. Same goes for the
-        * next call ht del call.
-        */
-       (void) lttng_ht_del(the_consumer_data.stream_per_chan_id_ht, &iter);
-
-       /* Delete from the global stream list. */
-       iter.iter.node = &stream->node_session_id.node;
-       /* See the previous ht del on why we ignore the returned value. */
-       (void) lttng_ht_del(the_consumer_data.stream_list_ht, &iter);
-
-       rcu_read_unlock();
-
-       if (!stream->metadata_flag) {
-               /* Decrement the stream count of the global consumer data. */
-               LTTNG_ASSERT(the_consumer_data.stream_count > 0);
-               the_consumer_data.stream_count--;
-       }
-}
-
-/*
- * Free the given stream within a RCU call.
- */
-void consumer_stream_free(struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-
-       metadata_bucket_destroy(stream->metadata_bucket);
-       call_rcu(&stream->node.head, free_stream_rcu);
-}
-
-/*
- * Destroy the stream's buffers of the tracer.
- */
-void consumer_stream_destroy_buffers(struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               lttng_ustconsumer_del_stream(stream);
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-       }
-}
-
-/*
- * Destroy and close a already created stream.
- */
-static void destroy_close_stream(struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-
-       DBG("Consumer stream destroy monitored key: %" PRIu64, stream->key);
-
-       /* Destroy tracer buffers of the stream. */
-       consumer_stream_destroy_buffers(stream);
-       /* Close down everything including the relayd if one. */
-       consumer_stream_close(stream);
-}
-
-/*
- * Decrement the stream's channel refcount and if down to 0, return the channel
- * pointer so it can be destroyed by the caller or NULL if not.
- */
-static struct lttng_consumer_channel *unref_channel(
-               struct lttng_consumer_stream *stream)
-{
-       struct lttng_consumer_channel *free_chan = NULL;
-
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->chan);
-
-       /* Update refcount of channel and see if we need to destroy it. */
-       if (!uatomic_sub_return(&stream->chan->refcount, 1)
-                       && !uatomic_read(&stream->chan->nb_init_stream_left)) {
-               free_chan = stream->chan;
-       }
-
-       return free_chan;
-}
-
-/*
- * Destroy a stream completely. This will delete, close and free the stream.
- * Once return, the stream is NO longer usable. Its channel may get destroyed
- * if conditions are met for a monitored stream.
- *
- * This MUST be called WITHOUT the consumer data and stream lock acquired if
- * the stream is in _monitor_ mode else it does not matter.
- */
-void consumer_stream_destroy(struct lttng_consumer_stream *stream,
-               struct lttng_ht *ht)
-{
-       LTTNG_ASSERT(stream);
-
-       /* Stream is in monitor mode. */
-       if (stream->monitor) {
-               struct lttng_consumer_channel *free_chan = NULL;
-
-               /*
-                * This means that the stream was successfully removed from the streams
-                * list of the channel and sent to the right thread managing this
-                * stream thus being globally visible.
-                */
-               if (stream->globally_visible) {
-                       pthread_mutex_lock(&the_consumer_data.lock);
-                       pthread_mutex_lock(&stream->chan->lock);
-                       pthread_mutex_lock(&stream->lock);
-                       /* Remove every reference of the stream in the consumer. */
-                       consumer_stream_delete(stream, ht);
-
-                       destroy_close_stream(stream);
-
-                       /* Update channel's refcount of the stream. */
-                       free_chan = unref_channel(stream);
-
-                       /* Indicates that the consumer data state MUST be updated after this. */
-                       the_consumer_data.need_update = 1;
-
-                       pthread_mutex_unlock(&stream->lock);
-                       pthread_mutex_unlock(&stream->chan->lock);
-                       pthread_mutex_unlock(&the_consumer_data.lock);
-               } else {
-                       /*
-                        * If the stream is not visible globally, this needs to be done
-                        * outside of the consumer data lock section.
-                        */
-                       free_chan = unref_channel(stream);
-               }
-
-               if (free_chan) {
-                       consumer_del_channel(free_chan);
-               }
-       } else {
-               destroy_close_stream(stream);
-       }
-
-       /* Free stream within a RCU call. */
-       lttng_trace_chunk_put(stream->trace_chunk);
-       stream->trace_chunk = NULL;
-       lttng_dynamic_array_reset(&stream->read_subbuffer_ops.post_consume_cbs);
-       consumer_stream_free(stream);
-}
-
-/*
- * Write index of a specific stream either on the relayd or local disk.
- *
- * Return 0 on success or else a negative value.
- */
-int consumer_stream_write_index(struct lttng_consumer_stream *stream,
-               struct ctf_packet_index *element)
-{
-       int ret;
-
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(element);
-
-       rcu_read_lock();
-       if (stream->net_seq_idx != (uint64_t) -1ULL) {
-               struct consumer_relayd_sock_pair *relayd;
-               relayd = consumer_find_relayd(stream->net_seq_idx);
-               if (relayd) {
-                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-                       ret = relayd_send_index(&relayd->control_sock, element,
-                               stream->relayd_stream_id, stream->next_net_seq_num - 1);
-                       if (ret < 0) {
-                               /*
-                                * Communication error with lttng-relayd,
-                                * perform cleanup now
-                                */
-                               ERR("Relayd send index failed. Cleaning up relayd %" PRIu64 ".", relayd->net_seq_idx);
-                               lttng_consumer_cleanup_relayd(relayd);
-                               ret = -1;
-                       }
-                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-               } else {
-                       ERR("Stream %" PRIu64 " relayd ID %" PRIu64 " unknown. Can't write index.",
-                                       stream->key, stream->net_seq_idx);
-                       ret = -1;
-               }
-       } else {
-               if (lttng_index_file_write(stream->index_file, element)) {
-                       ret = -1;
-               } else {
-                       ret = 0;
-               }
-       }
-       if (ret < 0) {
-               goto error;
-       }
-
-error:
-       rcu_read_unlock();
-       return ret;
-}
-
-int consumer_stream_create_output_files(struct lttng_consumer_stream *stream,
-               bool create_index)
-{
-       int ret;
-       enum lttng_trace_chunk_status chunk_status;
-       const int flags = O_WRONLY | O_CREAT | O_TRUNC;
-       const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
-       char stream_path[LTTNG_PATH_MAX];
-
-       ASSERT_LOCKED(stream->lock);
-       LTTNG_ASSERT(stream->trace_chunk);
-
-       ret = utils_stream_file_path(stream->chan->pathname, stream->name,
-                       stream->chan->tracefile_size,
-                       stream->tracefile_count_current, NULL,
-                       stream_path, sizeof(stream_path));
-       if (ret < 0) {
-               goto end;
-       }
-
-       if (stream->out_fd >= 0) {
-               ret = close(stream->out_fd);
-               if (ret < 0) {
-                       PERROR("Failed to close stream file \"%s\"",
-                                       stream->name);
-                       goto end;
-               }
-               stream->out_fd = -1;
-       }
-
-       DBG("Opening stream output file \"%s\"", stream_path);
-       chunk_status = lttng_trace_chunk_open_file(stream->trace_chunk, stream_path,
-                       flags, mode, &stream->out_fd, false);
-       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
-               ERR("Failed to open stream file \"%s\"", stream->name);
-               ret = -1;
-               goto end;
-       }
-
-       if (!stream->metadata_flag && (create_index || stream->index_file)) {
-               if (stream->index_file) {
-                       lttng_index_file_put(stream->index_file);
-               }
-               chunk_status = lttng_index_file_create_from_trace_chunk(
-                               stream->trace_chunk,
-                               stream->chan->pathname,
-                               stream->name,
-                               stream->chan->tracefile_size,
-                               stream->tracefile_count_current,
-                               CTF_INDEX_MAJOR, CTF_INDEX_MINOR,
-                               false, &stream->index_file);
-               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
-                       ret = -1;
-                       goto end;
-               }
-       }
-
-       /* Reset current size because we just perform a rotation. */
-       stream->tracefile_size_current = 0;
-       stream->out_fd_offset = 0;
-end:
-       return ret;
-}
-
-int consumer_stream_rotate_output_files(struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       stream->tracefile_count_current++;
-       if (stream->chan->tracefile_count > 0) {
-               stream->tracefile_count_current %=
-                               stream->chan->tracefile_count;
-       }
-
-       DBG("Rotating output files of stream \"%s\"", stream->name);
-       ret = consumer_stream_create_output_files(stream, true);
-       if (ret) {
-               goto end;
-       }
-
-end:
-       return ret;
-}
-
-bool consumer_stream_is_deleted(struct lttng_consumer_stream *stream)
-{
-       /*
-        * This function does not take a const stream since
-        * cds_lfht_is_node_deleted was not const before liburcu 0.12.
-        */
-       LTTNG_ASSERT(stream);
-       return cds_lfht_is_node_deleted(&stream->node.node);
-}
-
-static ssize_t metadata_bucket_flush(
-               const struct stream_subbuffer *buffer, void *data)
-{
-       ssize_t ret;
-       struct lttng_consumer_stream *stream = data;
-
-       ret = consumer_stream_consume_mmap(NULL, stream, buffer);
-       if (ret < 0) {
-               goto end;
-       }
-end:
-       return ret;
-}
-
-static ssize_t metadata_bucket_consume(
-               struct lttng_consumer_local_data *unused,
-               struct lttng_consumer_stream *stream,
-               const struct stream_subbuffer *subbuffer)
-{
-       ssize_t ret;
-       enum metadata_bucket_status status;
-
-       status = metadata_bucket_fill(stream->metadata_bucket, subbuffer);
-       switch (status) {
-       case METADATA_BUCKET_STATUS_OK:
-               /* Return consumed size. */
-               ret = subbuffer->buffer.buffer.size;
-               break;
-       default:
-               ret = -1;
-       }
-
-       return ret;
-}
-
-int consumer_stream_enable_metadata_bucketization(
-               struct lttng_consumer_stream *stream)
-{
-       int ret = 0;
-
-       LTTNG_ASSERT(stream->metadata_flag);
-       LTTNG_ASSERT(!stream->metadata_bucket);
-       LTTNG_ASSERT(stream->chan->output == CONSUMER_CHANNEL_MMAP);
-
-       stream->metadata_bucket = metadata_bucket_create(
-                       metadata_bucket_flush, stream);
-       if (!stream->metadata_bucket) {
-               ret = -1;
-               goto end;
-       }
-
-       stream->read_subbuffer_ops.consume_subbuffer = metadata_bucket_consume;
-end:
-       return ret;
-}
-
-void consumer_stream_metadata_set_version(
-               struct lttng_consumer_stream *stream, uint64_t new_version)
-{
-       LTTNG_ASSERT(new_version > stream->metadata_version);
-       stream->metadata_version = new_version;
-       stream->reset_metadata_flag = 1;
-
-       if (stream->metadata_bucket) {
-               metadata_bucket_reset(stream->metadata_bucket);
-       }
-}
-
-int consumer_stream_flush_buffer(struct lttng_consumer_stream *stream,
-               bool producer_active)
-{
-       int ret = 0;
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               if (producer_active) {
-                       ret = kernctl_buffer_flush(stream->wait_fd);
-                       if (ret < 0) {
-                               ERR("Failed to flush kernel stream");
-                               goto end;
-                       }
-               } else {
-                       ret = kernctl_buffer_flush_empty(stream->wait_fd);
-                       if (ret < 0) {
-                               /*
-                                * Doing a buffer flush which does not take into
-                                * account empty packets. This is not perfect,
-                                * but required as a fall-back when
-                                * "flush_empty" is not implemented by
-                                * lttng-modules.
-                                */
-                               ret = kernctl_buffer_flush(stream->wait_fd);
-                               if (ret < 0) {
-                                       ERR("Failed to flush kernel stream");
-                                       goto end;
-                               }
-                       }
-               }
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               ret = lttng_ustconsumer_flush_buffer(stream, (int) producer_active);
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-       }
-
-end:
-       return ret;
-}
diff --git a/src/common/consumer/consumer-stream.cpp b/src/common/consumer/consumer-stream.cpp
new file mode 100644 (file)
index 0000000..fbaf4ae
--- /dev/null
@@ -0,0 +1,1331 @@
+/*
+ * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#define _LGPL_SOURCE
+#include <inttypes.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include <common/common.h>
+#include <common/index/index.h>
+#include <common/kernel-consumer/kernel-consumer.h>
+#include <common/relayd/relayd.h>
+#include <common/ust-consumer/ust-consumer.h>
+#include <common/utils.h>
+#include <common/consumer/consumer.h>
+#include <common/consumer/consumer-timer.h>
+#include <common/consumer/metadata-bucket.h>
+#include <common/kernel-ctl/kernel-ctl.h>
+
+#include "consumer-stream.h"
+
+/*
+ * RCU call to free stream. MUST only be used with call_rcu().
+ */
+static void free_stream_rcu(struct rcu_head *head)
+{
+       struct lttng_ht_node_u64 *node =
+               caa_container_of(head, struct lttng_ht_node_u64, head);
+       struct lttng_consumer_stream *stream =
+               caa_container_of(node, struct lttng_consumer_stream, node);
+
+       pthread_mutex_destroy(&stream->lock);
+       free(stream);
+}
+
+static void consumer_stream_data_lock_all(struct lttng_consumer_stream *stream)
+{
+       pthread_mutex_lock(&stream->chan->lock);
+       pthread_mutex_lock(&stream->lock);
+}
+
+static void consumer_stream_data_unlock_all(struct lttng_consumer_stream *stream)
+{
+       pthread_mutex_unlock(&stream->lock);
+       pthread_mutex_unlock(&stream->chan->lock);
+}
+
+static void consumer_stream_metadata_lock_all(struct lttng_consumer_stream *stream)
+{
+       consumer_stream_data_lock_all(stream);
+       pthread_mutex_lock(&stream->metadata_rdv_lock);
+}
+
+static void consumer_stream_metadata_unlock_all(struct lttng_consumer_stream *stream)
+{
+       pthread_mutex_unlock(&stream->metadata_rdv_lock);
+       consumer_stream_data_unlock_all(stream);
+}
+
+/* Only used for data streams. */
+static int consumer_stream_update_stats(struct lttng_consumer_stream *stream,
+               const struct stream_subbuffer *subbuf)
+{
+       int ret = 0;
+       uint64_t sequence_number;
+       const uint64_t discarded_events = subbuf->info.data.events_discarded;
+
+       if (!subbuf->info.data.sequence_number.is_set) {
+               /* Command not supported by the tracer. */
+               sequence_number = -1ULL;
+               stream->sequence_number_unavailable = true;
+       } else {
+               sequence_number = subbuf->info.data.sequence_number.value;
+       }
+
+       /*
+        * Start the sequence when we extract the first packet in case we don't
+        * start at 0 (for example if a consumer is not connected to the
+        * session immediately after the beginning).
+        */
+       if (stream->last_sequence_number == -1ULL) {
+               stream->last_sequence_number = sequence_number;
+       } else if (sequence_number > stream->last_sequence_number) {
+               stream->chan->lost_packets += sequence_number -
+                               stream->last_sequence_number - 1;
+       } else {
+               /* seq <= last_sequence_number */
+               ERR("Sequence number inconsistent : prev = %" PRIu64
+                   ", current = %" PRIu64,
+                               stream->last_sequence_number, sequence_number);
+               ret = -1;
+               goto end;
+       }
+       stream->last_sequence_number = sequence_number;
+
+       if (discarded_events < stream->last_discarded_events) {
+               /*
+                * Overflow has occurred. We assume only one wrap-around
+                * has occurred.
+                */
+               stream->chan->discarded_events +=
+                               (1ULL << (CAA_BITS_PER_LONG - 1)) -
+                               stream->last_discarded_events +
+                               discarded_events;
+       } else {
+               stream->chan->discarded_events += discarded_events -
+                                                 stream->last_discarded_events;
+       }
+       stream->last_discarded_events = discarded_events;
+       ret = 0;
+
+end:
+       return ret;
+}
+
+static
+void ctf_packet_index_populate(struct ctf_packet_index *index,
+               off_t offset, const struct stream_subbuffer *subbuffer)
+{
+       *index = (typeof(*index)){
+               .offset = htobe64(offset),
+               .packet_size = htobe64(subbuffer->info.data.packet_size),
+               .content_size = htobe64(subbuffer->info.data.content_size),
+               .timestamp_begin = htobe64(
+                               subbuffer->info.data.timestamp_begin),
+               .timestamp_end = htobe64(
+                               subbuffer->info.data.timestamp_end),
+               .events_discarded = htobe64(
+                               subbuffer->info.data.events_discarded),
+               .stream_id = htobe64(subbuffer->info.data.stream_id),
+               .stream_instance_id = htobe64(
+                               subbuffer->info.data.stream_instance_id.is_set ?
+                               subbuffer->info.data.stream_instance_id.value : -1ULL),
+               .packet_seq_num = htobe64(
+                               subbuffer->info.data.sequence_number.is_set ?
+                               subbuffer->info.data.sequence_number.value : -1ULL),
+       };
+}
+
+static ssize_t consumer_stream_consume_mmap(
+               struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_stream *stream,
+               const struct stream_subbuffer *subbuffer)
+{
+       const unsigned long padding_size =
+                       subbuffer->info.data.padded_subbuf_size -
+                       subbuffer->info.data.subbuf_size;
+       const ssize_t written_bytes = lttng_consumer_on_read_subbuffer_mmap(
+                       stream, &subbuffer->buffer.buffer, padding_size);
+
+       if (stream->net_seq_idx == -1ULL) {
+               /*
+                * When writing on disk, check that only the subbuffer (no
+                * padding) was written to disk.
+                */
+               if (written_bytes != subbuffer->info.data.padded_subbuf_size) {
+                       DBG("Failed to write the entire padded subbuffer on disk (written_bytes: %zd, padded subbuffer size %lu)",
+                                       written_bytes,
+                                       subbuffer->info.data.padded_subbuf_size);
+               }
+       } else {
+               /*
+                * When streaming over the network, check that the entire
+                * subbuffer including padding was successfully written.
+                */
+               if (written_bytes != subbuffer->info.data.subbuf_size) {
+                       DBG("Failed to write only the subbuffer over the network (written_bytes: %zd, subbuffer size %lu)",
+                                       written_bytes,
+                                       subbuffer->info.data.subbuf_size);
+               }
+       }
+
+       /*
+        * If `lttng_consumer_on_read_subbuffer_mmap()` returned an error, pass
+        * it along to the caller, else return zero.
+        */
+       if (written_bytes < 0) {
+               ERR("Error reading mmap subbuffer: %zd", written_bytes);
+       }
+
+       return written_bytes;
+}
+
+static ssize_t consumer_stream_consume_splice(
+               struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_stream *stream,
+               const struct stream_subbuffer *subbuffer)
+{
+       const ssize_t written_bytes = lttng_consumer_on_read_subbuffer_splice(
+                       ctx, stream, subbuffer->info.data.padded_subbuf_size, 0);
+
+       if (written_bytes != subbuffer->info.data.padded_subbuf_size) {
+               DBG("Failed to write the entire padded subbuffer (written_bytes: %zd, padded subbuffer size %lu)",
+                               written_bytes,
+                               subbuffer->info.data.padded_subbuf_size);
+       }
+
+       /*
+        * If `lttng_consumer_on_read_subbuffer_splice()` returned an error,
+        * pass it along to the caller, else return zero.
+        */
+       if (written_bytes < 0) {
+               ERR("Error reading splice subbuffer: %zd", written_bytes);
+       }
+
+       return written_bytes;
+}
+
+static int consumer_stream_send_index(
+               struct lttng_consumer_stream *stream,
+               const struct stream_subbuffer *subbuffer,
+               struct lttng_consumer_local_data *ctx)
+{
+       off_t packet_offset = 0;
+       struct ctf_packet_index index = {};
+
+       /*
+        * This is called after consuming the sub-buffer; substract the
+        * effect this sub-buffer from the offset.
+        */
+       if (stream->net_seq_idx == (uint64_t) -1ULL) {
+               packet_offset = stream->out_fd_offset -
+                               subbuffer->info.data.padded_subbuf_size;
+       }
+
+       ctf_packet_index_populate(&index, packet_offset, subbuffer);
+       return consumer_stream_write_index(stream, &index);
+}
+
+/*
+ * Actually do the metadata sync using the given metadata stream.
+ *
+ * Return 0 on success else a negative value. ENODATA can be returned also
+ * indicating that there is no metadata available for that stream.
+ */
+static int do_sync_metadata(struct lttng_consumer_stream *metadata,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+       enum sync_metadata_status status;
+
+       LTTNG_ASSERT(metadata);
+       LTTNG_ASSERT(metadata->metadata_flag);
+       LTTNG_ASSERT(ctx);
+
+       /*
+        * In UST, since we have to write the metadata from the cache packet
+        * by packet, we might need to start this procedure multiple times
+        * until all the metadata from the cache has been extracted.
+        */
+       do {
+               /*
+                * Steps :
+                * - Lock the metadata stream
+                * - Check if metadata stream node was deleted before locking.
+                *   - if yes, release and return success
+                * - Check if new metadata is ready (flush + snapshot pos)
+                * - If nothing : release and return.
+                * - Lock the metadata_rdv_lock
+                * - Unlock the metadata stream
+                * - cond_wait on metadata_rdv to wait the wakeup from the
+                *   metadata thread
+                * - Unlock the metadata_rdv_lock
+                */
+               pthread_mutex_lock(&metadata->lock);
+
+               /*
+                * There is a possibility that we were able to acquire a reference on the
+                * stream from the RCU hash table but between then and now, the node might
+                * have been deleted just before the lock is acquired. Thus, after locking,
+                * we make sure the metadata node has not been deleted which means that the
+                * buffers are closed.
+                *
+                * In that case, there is no need to sync the metadata hence returning a
+                * success return code.
+                */
+               ret = cds_lfht_is_node_deleted(&metadata->node.node);
+               if (ret) {
+                       ret = 0;
+                       goto end_unlock_mutex;
+               }
+
+               switch (ctx->type) {
+               case LTTNG_CONSUMER_KERNEL:
+                       /*
+                        * Empty the metadata cache and flush the current stream.
+                        */
+                       status = lttng_kconsumer_sync_metadata(metadata);
+                       break;
+               case LTTNG_CONSUMER32_UST:
+               case LTTNG_CONSUMER64_UST:
+                       /*
+                        * Ask the sessiond if we have new metadata waiting and update the
+                        * consumer metadata cache.
+                        */
+                       status = lttng_ustconsumer_sync_metadata(ctx, metadata);
+                       break;
+               default:
+                       abort();
+               }
+
+               switch (status) {
+               case SYNC_METADATA_STATUS_NEW_DATA:
+                       break;
+               case SYNC_METADATA_STATUS_NO_DATA:
+                       ret = 0;
+                       goto end_unlock_mutex;
+               case SYNC_METADATA_STATUS_ERROR:
+                       ret = -1;
+                       goto end_unlock_mutex;
+               default:
+                       abort();
+               }
+
+               /*
+                * At this point, new metadata have been flushed, so we wait on the
+                * rendez-vous point for the metadata thread to wake us up when it
+                * finishes consuming the metadata and continue execution.
+                */
+
+               pthread_mutex_lock(&metadata->metadata_rdv_lock);
+
+               /*
+                * Release metadata stream lock so the metadata thread can process it.
+                */
+               pthread_mutex_unlock(&metadata->lock);
+
+               /*
+                * Wait on the rendez-vous point. Once woken up, it means the metadata was
+                * consumed and thus synchronization is achieved.
+                */
+               pthread_cond_wait(&metadata->metadata_rdv, &metadata->metadata_rdv_lock);
+               pthread_mutex_unlock(&metadata->metadata_rdv_lock);
+       } while (status == SYNC_METADATA_STATUS_NEW_DATA);
+
+       /* Success */
+       return 0;
+
+end_unlock_mutex:
+       pthread_mutex_unlock(&metadata->lock);
+       return ret;
+}
+
+/*
+ * Synchronize the metadata using a given session ID. A successful acquisition
+ * of a metadata stream will trigger a request to the session daemon and a
+ * snapshot so the metadata thread can consume it.
+ *
+ * This function call is a rendez-vous point between the metadata thread and
+ * the data thread.
+ *
+ * Return 0 on success or else a negative value.
+ */
+int consumer_stream_sync_metadata(struct lttng_consumer_local_data *ctx,
+               uint64_t session_id)
+{
+       int ret;
+       struct lttng_consumer_stream *stream = NULL;
+       struct lttng_ht_iter iter;
+       struct lttng_ht *ht;
+
+       LTTNG_ASSERT(ctx);
+
+       /* Ease our life a bit. */
+       ht = the_consumer_data.stream_list_ht;
+
+       rcu_read_lock();
+
+       /* Search the metadata associated with the session id of the given stream. */
+
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&session_id, lttng_ht_seed), ht->match_fct,
+                       &session_id, &iter.iter, stream, node_session_id.node) {
+               if (!stream->metadata_flag) {
+                       continue;
+               }
+
+               ret = do_sync_metadata(stream, ctx);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+
+       /*
+        * Force return code to 0 (success) since ret might be ENODATA for instance
+        * which is not an error but rather that we should come back.
+        */
+       ret = 0;
+
+end:
+       rcu_read_unlock();
+       return ret;
+}
+
+static int consumer_stream_sync_metadata_index(
+               struct lttng_consumer_stream *stream,
+               const struct stream_subbuffer *subbuffer,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+
+       /* Block until all the metadata is sent. */
+       pthread_mutex_lock(&stream->metadata_timer_lock);
+       LTTNG_ASSERT(!stream->missed_metadata_flush);
+       stream->waiting_on_metadata = true;
+       pthread_mutex_unlock(&stream->metadata_timer_lock);
+
+       ret = consumer_stream_sync_metadata(ctx, stream->session_id);
+
+       pthread_mutex_lock(&stream->metadata_timer_lock);
+       stream->waiting_on_metadata = false;
+       if (stream->missed_metadata_flush) {
+               stream->missed_metadata_flush = false;
+               pthread_mutex_unlock(&stream->metadata_timer_lock);
+               (void) stream->read_subbuffer_ops.send_live_beacon(stream);
+       } else {
+               pthread_mutex_unlock(&stream->metadata_timer_lock);
+       }
+       if (ret < 0) {
+               goto end;
+       }
+
+       ret = consumer_stream_send_index(stream, subbuffer, ctx);
+end:
+       return ret;
+}
+
+/*
+ * Check if the local version of the metadata stream matches with the version
+ * of the metadata stream in the kernel. If it was updated, set the reset flag
+ * on the stream.
+ */
+static
+int metadata_stream_check_version(struct lttng_consumer_stream *stream,
+       const struct stream_subbuffer *subbuffer)
+{
+       if (stream->metadata_version == subbuffer->info.metadata.version) {
+               goto end;
+       }
+
+       DBG("New metadata version detected");
+       consumer_stream_metadata_set_version(stream,
+                       subbuffer->info.metadata.version);
+
+       if (stream->read_subbuffer_ops.reset_metadata) {
+               stream->read_subbuffer_ops.reset_metadata(stream);
+       }
+
+end:
+       return 0;
+}
+
+static
+bool stream_is_rotating_to_null_chunk(
+               const struct lttng_consumer_stream *stream)
+{
+       bool rotating_to_null_chunk = false;
+
+       if (stream->rotate_position == -1ULL) {
+               /* No rotation ongoing. */
+               goto end;
+       }
+
+       if (stream->trace_chunk == stream->chan->trace_chunk ||
+                       !stream->chan->trace_chunk) {
+               rotating_to_null_chunk = true;
+       }
+end:
+       return rotating_to_null_chunk;
+}
+
+enum consumer_stream_open_packet_status consumer_stream_open_packet(
+               struct lttng_consumer_stream *stream)
+{
+       int ret;
+       enum consumer_stream_open_packet_status status;
+       unsigned long produced_pos_before, produced_pos_after;
+
+       ret = lttng_consumer_sample_snapshot_positions(stream);
+       if (ret < 0) {
+               ERR("Failed to snapshot positions before post-rotation empty packet flush: stream id = %" PRIu64
+                               ", channel name = %s, session id = %" PRIu64,
+                               stream->key, stream->chan->name,
+                               stream->chan->session_id);
+               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = lttng_consumer_get_produced_snapshot(
+                       stream, &produced_pos_before);
+       if (ret < 0) {
+               ERR("Failed to read produced position before post-rotation empty packet flush: stream id = %" PRIu64
+                               ", channel name = %s, session id = %" PRIu64,
+                               stream->key, stream->chan->name,
+                               stream->chan->session_id);
+               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = consumer_stream_flush_buffer(stream, 0);
+       if (ret) {
+               ERR("Failed to flush an empty packet at rotation point: stream id = %" PRIu64
+                               ", channel name = %s, session id = %" PRIu64,
+                               stream->key, stream->chan->name,
+                               stream->chan->session_id);
+               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = lttng_consumer_sample_snapshot_positions(stream);
+       if (ret < 0) {
+               ERR("Failed to snapshot positions after post-rotation empty packet flush: stream id = %" PRIu64
+                               ", channel name = %s, session id = %" PRIu64,
+                               stream->key, stream->chan->name,
+                               stream->chan->session_id);
+               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = lttng_consumer_get_produced_snapshot(stream, &produced_pos_after);
+       if (ret < 0) {
+               ERR("Failed to read produced position after post-rotation empty packet flush: stream id = %" PRIu64
+                               ", channel name = %s, session id = %" PRIu64,
+                               stream->key, stream->chan->name,
+                               stream->chan->session_id);
+               status = CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR;
+               goto end;
+       }
+
+       /*
+        * Determine if the flush had an effect by comparing the produced
+        * positons before and after the flush.
+        */
+       status = produced_pos_before != produced_pos_after ?
+                       CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED :
+                       CONSUMER_STREAM_OPEN_PACKET_STATUS_NO_SPACE;
+       if (status == CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED) {
+               stream->opened_packet_in_current_trace_chunk = true;
+       }
+
+end:
+       return status;
+}
+
+/*
+ * An attempt to open a new packet is performed after a rotation completes to
+ * get a begin timestamp as close as possible to the rotation point.
+ *
+ * However, that initial attempt at opening a packet can fail due to a full
+ * ring-buffer. In that case, a second attempt is performed after consuming
+ * a packet since that will have freed enough space in the ring-buffer.
+ */
+static
+int post_consume_open_new_packet(struct lttng_consumer_stream *stream,
+               const struct stream_subbuffer *subbuffer,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret = 0;
+
+       if (!stream->opened_packet_in_current_trace_chunk &&
+                       stream->trace_chunk &&
+                       !stream_is_rotating_to_null_chunk(stream)) {
+               const enum consumer_stream_open_packet_status status =
+                               consumer_stream_open_packet(stream);
+
+               switch (status) {
+               case CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED:
+                       DBG("Opened a packet after consuming a packet rotation: stream id = %" PRIu64
+                                       ", channel name = %s, session id = %" PRIu64,
+                                       stream->key, stream->chan->name,
+                                       stream->chan->session_id);
+                       stream->opened_packet_in_current_trace_chunk = true;
+                       break;
+               case CONSUMER_STREAM_OPEN_PACKET_STATUS_NO_SPACE:
+                       /*
+                        * Can't open a packet as there is no space left.
+                        * This means that new events were produced, resulting
+                        * in a packet being opened, which is what we want
+                        * anyhow.
+                        */
+                       DBG("No space left to open a packet after consuming a packet: stream id = %" PRIu64
+                                       ", channel name = %s, session id = %" PRIu64,
+                                       stream->key, stream->chan->name,
+                                       stream->chan->session_id);
+                       stream->opened_packet_in_current_trace_chunk = true;
+                       break;
+               case CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR:
+                       /* Logged by callee. */
+                       ret = -1;
+                       goto end;
+               default:
+                       abort();
+               }
+
+               stream->opened_packet_in_current_trace_chunk = true;
+       }
+
+end:
+       return ret;
+}
+
+struct lttng_consumer_stream *consumer_stream_create(
+               struct lttng_consumer_channel *channel,
+               uint64_t channel_key,
+               uint64_t stream_key,
+               const char *channel_name,
+               uint64_t relayd_id,
+               uint64_t session_id,
+               struct lttng_trace_chunk *trace_chunk,
+               int cpu,
+               int *alloc_ret,
+               enum consumer_channel_type type,
+               unsigned int monitor)
+{
+       int ret;
+       struct lttng_consumer_stream *stream;
+
+       stream = (lttng_consumer_stream *) zmalloc(sizeof(*stream));
+       if (stream == NULL) {
+               PERROR("malloc struct lttng_consumer_stream");
+               ret = -ENOMEM;
+               goto end;
+       }
+
+       rcu_read_lock();
+
+       if (trace_chunk && !lttng_trace_chunk_get(trace_chunk)) {
+               ERR("Failed to acquire trace chunk reference during the creation of a stream");
+               ret = -1;
+               goto error;
+       }
+
+       stream->chan = channel;
+       stream->key = stream_key;
+       stream->trace_chunk = trace_chunk;
+       stream->out_fd = -1;
+       stream->out_fd_offset = 0;
+       stream->output_written = 0;
+       stream->net_seq_idx = relayd_id;
+       stream->session_id = session_id;
+       stream->monitor = monitor;
+       stream->endpoint_status = CONSUMER_ENDPOINT_ACTIVE;
+       stream->index_file = NULL;
+       stream->last_sequence_number = -1ULL;
+       stream->rotate_position = -1ULL;
+       /* Buffer is created with an open packet. */
+       stream->opened_packet_in_current_trace_chunk = true;
+       pthread_mutex_init(&stream->lock, NULL);
+       pthread_mutex_init(&stream->metadata_timer_lock, NULL);
+
+       /* If channel is the metadata, flag this stream as metadata. */
+       if (type == CONSUMER_CHANNEL_TYPE_METADATA) {
+               stream->metadata_flag = 1;
+               /* Metadata is flat out. */
+               strncpy(stream->name, DEFAULT_METADATA_NAME, sizeof(stream->name));
+               /* Live rendez-vous point. */
+               pthread_cond_init(&stream->metadata_rdv, NULL);
+               pthread_mutex_init(&stream->metadata_rdv_lock, NULL);
+       } else {
+               /* Format stream name to <channel_name>_<cpu_number> */
+               ret = snprintf(stream->name, sizeof(stream->name), "%s_%d",
+                               channel_name, cpu);
+               if (ret < 0) {
+                       PERROR("snprintf stream name");
+                       goto error;
+               }
+       }
+
+       switch (channel->output) {
+       case CONSUMER_CHANNEL_SPLICE:
+               stream->output = LTTNG_EVENT_SPLICE;
+               ret = utils_create_pipe(stream->splice_pipe);
+               if (ret < 0) {
+                       goto error;
+               }
+               break;
+       case CONSUMER_CHANNEL_MMAP:
+               stream->output = LTTNG_EVENT_MMAP;
+               break;
+       default:
+               abort();
+       }
+
+       /* Key is always the wait_fd for streams. */
+       lttng_ht_node_init_u64(&stream->node, stream->key);
+
+       /* Init node per channel id key */
+       lttng_ht_node_init_u64(&stream->node_channel_id, channel_key);
+
+       /* Init session id node with the stream session id */
+       lttng_ht_node_init_u64(&stream->node_session_id, stream->session_id);
+
+       DBG3("Allocated stream %s (key %" PRIu64 ", chan_key %" PRIu64
+                       " relayd_id %" PRIu64 ", session_id %" PRIu64,
+                       stream->name, stream->key, channel_key,
+                       stream->net_seq_idx, stream->session_id);
+
+       rcu_read_unlock();
+
+       lttng_dynamic_array_init(&stream->read_subbuffer_ops.post_consume_cbs,
+                       sizeof(post_consume_cb), NULL);
+
+       if (type == CONSUMER_CHANNEL_TYPE_METADATA) {
+               stream->read_subbuffer_ops.lock =
+                               consumer_stream_metadata_lock_all;
+               stream->read_subbuffer_ops.unlock =
+                               consumer_stream_metadata_unlock_all;
+               stream->read_subbuffer_ops.pre_consume_subbuffer =
+                               metadata_stream_check_version;
+       } else {
+               const post_consume_cb post_consume_index_op = channel->is_live ?
+                               consumer_stream_sync_metadata_index :
+                               consumer_stream_send_index;
+               const post_consume_cb post_consume_open_new_packet_ =
+                               post_consume_open_new_packet;
+
+               ret = lttng_dynamic_array_add_element(
+                               &stream->read_subbuffer_ops.post_consume_cbs,
+                               &post_consume_index_op);
+               if (ret) {
+                       PERROR("Failed to add `send index` callback to stream's post consumption callbacks");
+                       goto error;
+               }
+
+               ret = lttng_dynamic_array_add_element(
+                               &stream->read_subbuffer_ops.post_consume_cbs,
+                               &post_consume_open_new_packet_);
+               if (ret) {
+                       PERROR("Failed to add `open new packet` callback to stream's post consumption callbacks");
+                       goto error;
+               }
+
+               stream->read_subbuffer_ops.lock = consumer_stream_data_lock_all;
+               stream->read_subbuffer_ops.unlock =
+                               consumer_stream_data_unlock_all;
+               stream->read_subbuffer_ops.pre_consume_subbuffer =
+                               consumer_stream_update_stats;
+       }
+
+       if (channel->output == CONSUMER_CHANNEL_MMAP) {
+               stream->read_subbuffer_ops.consume_subbuffer =
+                               consumer_stream_consume_mmap;
+       } else {
+               stream->read_subbuffer_ops.consume_subbuffer =
+                               consumer_stream_consume_splice;
+       }
+
+       return stream;
+
+error:
+       rcu_read_unlock();
+       lttng_trace_chunk_put(stream->trace_chunk);
+       lttng_dynamic_array_reset(&stream->read_subbuffer_ops.post_consume_cbs);
+       free(stream);
+end:
+       if (alloc_ret) {
+               *alloc_ret = ret;
+       }
+       return NULL;
+}
+
+/*
+ * Close stream on the relayd side. This call can destroy a relayd if the
+ * conditions are met.
+ *
+ * A RCU read side lock MUST be acquired if the relayd object was looked up in
+ * a hash table before calling this.
+ */
+void consumer_stream_relayd_close(struct lttng_consumer_stream *stream,
+               struct consumer_relayd_sock_pair *relayd)
+{
+       int ret;
+
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(relayd);
+
+       if (stream->sent_to_relayd) {
+               uatomic_dec(&relayd->refcount);
+               LTTNG_ASSERT(uatomic_read(&relayd->refcount) >= 0);
+       }
+
+       /* Closing streams requires to lock the control socket. */
+       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+       ret = relayd_send_close_stream(&relayd->control_sock,
+                       stream->relayd_stream_id,
+                       stream->next_net_seq_num - 1);
+       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+       if (ret < 0) {
+               ERR("Relayd send close stream failed. Cleaning up relayd %" PRIu64 ".", relayd->net_seq_idx);
+               lttng_consumer_cleanup_relayd(relayd);
+       }
+
+       /* Both conditions are met, we destroy the relayd. */
+       if (uatomic_read(&relayd->refcount) == 0 &&
+                       uatomic_read(&relayd->destroy_flag)) {
+               consumer_destroy_relayd(relayd);
+       }
+       stream->net_seq_idx = (uint64_t) -1ULL;
+       stream->sent_to_relayd = 0;
+}
+
+/*
+ * Close stream's file descriptors and, if needed, close stream also on the
+ * relayd side.
+ *
+ * The consumer data lock MUST be acquired.
+ * The stream lock MUST be acquired.
+ */
+void consumer_stream_close(struct lttng_consumer_stream *stream)
+{
+       int ret;
+       struct consumer_relayd_sock_pair *relayd;
+
+       LTTNG_ASSERT(stream);
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               if (stream->mmap_base != NULL) {
+                       ret = munmap(stream->mmap_base, stream->mmap_len);
+                       if (ret != 0) {
+                               PERROR("munmap");
+                       }
+               }
+
+               if (stream->wait_fd >= 0) {
+                       ret = close(stream->wait_fd);
+                       if (ret) {
+                               PERROR("close");
+                       }
+                       stream->wait_fd = -1;
+               }
+               if (stream->chan->output == CONSUMER_CHANNEL_SPLICE) {
+                       utils_close_pipe(stream->splice_pipe);
+               }
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+       {
+               /*
+                * Special case for the metadata since the wait fd is an internal pipe
+                * polled in the metadata thread.
+                */
+               if (stream->metadata_flag && stream->chan->monitor) {
+                       int rpipe = stream->ust_metadata_poll_pipe[0];
+
+                       /*
+                        * This will stop the channel timer if one and close the write side
+                        * of the metadata poll pipe.
+                        */
+                       lttng_ustconsumer_close_metadata(stream->chan);
+                       if (rpipe >= 0) {
+                               ret = close(rpipe);
+                               if (ret < 0) {
+                                       PERROR("closing metadata pipe read side");
+                               }
+                               stream->ust_metadata_poll_pipe[0] = -1;
+                       }
+               }
+               break;
+       }
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+       }
+
+       /* Close output fd. Could be a socket or local file at this point. */
+       if (stream->out_fd >= 0) {
+               ret = close(stream->out_fd);
+               if (ret) {
+                       PERROR("close");
+               }
+               stream->out_fd = -1;
+       }
+
+       if (stream->index_file) {
+               lttng_index_file_put(stream->index_file);
+               stream->index_file = NULL;
+       }
+
+       lttng_trace_chunk_put(stream->trace_chunk);
+       stream->trace_chunk = NULL;
+
+       /* Check and cleanup relayd if needed. */
+       rcu_read_lock();
+       relayd = consumer_find_relayd(stream->net_seq_idx);
+       if (relayd != NULL) {
+               consumer_stream_relayd_close(stream, relayd);
+       }
+       rcu_read_unlock();
+}
+
+/*
+ * Delete the stream from all possible hash tables.
+ *
+ * The consumer data lock MUST be acquired.
+ * The stream lock MUST be acquired.
+ */
+void consumer_stream_delete(struct lttng_consumer_stream *stream,
+               struct lttng_ht *ht)
+{
+       int ret;
+       struct lttng_ht_iter iter;
+
+       LTTNG_ASSERT(stream);
+       /* Should NEVER be called not in monitor mode. */
+       LTTNG_ASSERT(stream->chan->monitor);
+
+       rcu_read_lock();
+
+       if (ht) {
+               iter.iter.node = &stream->node.node;
+               ret = lttng_ht_del(ht, &iter);
+               LTTNG_ASSERT(!ret);
+       }
+
+       /* Delete from stream per channel ID hash table. */
+       iter.iter.node = &stream->node_channel_id.node;
+       /*
+        * The returned value is of no importance. Even if the node is NOT in the
+        * hash table, we continue since we may have been called by a code path
+        * that did not add the stream to a (all) hash table. Same goes for the
+        * next call ht del call.
+        */
+       (void) lttng_ht_del(the_consumer_data.stream_per_chan_id_ht, &iter);
+
+       /* Delete from the global stream list. */
+       iter.iter.node = &stream->node_session_id.node;
+       /* See the previous ht del on why we ignore the returned value. */
+       (void) lttng_ht_del(the_consumer_data.stream_list_ht, &iter);
+
+       rcu_read_unlock();
+
+       if (!stream->metadata_flag) {
+               /* Decrement the stream count of the global consumer data. */
+               LTTNG_ASSERT(the_consumer_data.stream_count > 0);
+               the_consumer_data.stream_count--;
+       }
+}
+
+/*
+ * Free the given stream within a RCU call.
+ */
+void consumer_stream_free(struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+
+       metadata_bucket_destroy(stream->metadata_bucket);
+       call_rcu(&stream->node.head, free_stream_rcu);
+}
+
+/*
+ * Destroy the stream's buffers of the tracer.
+ */
+void consumer_stream_destroy_buffers(struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               lttng_ustconsumer_del_stream(stream);
+               break;
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+       }
+}
+
+/*
+ * Destroy and close a already created stream.
+ */
+static void destroy_close_stream(struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+
+       DBG("Consumer stream destroy monitored key: %" PRIu64, stream->key);
+
+       /* Destroy tracer buffers of the stream. */
+       consumer_stream_destroy_buffers(stream);
+       /* Close down everything including the relayd if one. */
+       consumer_stream_close(stream);
+}
+
+/*
+ * Decrement the stream's channel refcount and if down to 0, return the channel
+ * pointer so it can be destroyed by the caller or NULL if not.
+ */
+static struct lttng_consumer_channel *unref_channel(
+               struct lttng_consumer_stream *stream)
+{
+       struct lttng_consumer_channel *free_chan = NULL;
+
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->chan);
+
+       /* Update refcount of channel and see if we need to destroy it. */
+       if (!uatomic_sub_return(&stream->chan->refcount, 1)
+                       && !uatomic_read(&stream->chan->nb_init_stream_left)) {
+               free_chan = stream->chan;
+       }
+
+       return free_chan;
+}
+
+/*
+ * Destroy a stream completely. This will delete, close and free the stream.
+ * Once return, the stream is NO longer usable. Its channel may get destroyed
+ * if conditions are met for a monitored stream.
+ *
+ * This MUST be called WITHOUT the consumer data and stream lock acquired if
+ * the stream is in _monitor_ mode else it does not matter.
+ */
+void consumer_stream_destroy(struct lttng_consumer_stream *stream,
+               struct lttng_ht *ht)
+{
+       LTTNG_ASSERT(stream);
+
+       /* Stream is in monitor mode. */
+       if (stream->monitor) {
+               struct lttng_consumer_channel *free_chan = NULL;
+
+               /*
+                * This means that the stream was successfully removed from the streams
+                * list of the channel and sent to the right thread managing this
+                * stream thus being globally visible.
+                */
+               if (stream->globally_visible) {
+                       pthread_mutex_lock(&the_consumer_data.lock);
+                       pthread_mutex_lock(&stream->chan->lock);
+                       pthread_mutex_lock(&stream->lock);
+                       /* Remove every reference of the stream in the consumer. */
+                       consumer_stream_delete(stream, ht);
+
+                       destroy_close_stream(stream);
+
+                       /* Update channel's refcount of the stream. */
+                       free_chan = unref_channel(stream);
+
+                       /* Indicates that the consumer data state MUST be updated after this. */
+                       the_consumer_data.need_update = 1;
+
+                       pthread_mutex_unlock(&stream->lock);
+                       pthread_mutex_unlock(&stream->chan->lock);
+                       pthread_mutex_unlock(&the_consumer_data.lock);
+               } else {
+                       /*
+                        * If the stream is not visible globally, this needs to be done
+                        * outside of the consumer data lock section.
+                        */
+                       free_chan = unref_channel(stream);
+               }
+
+               if (free_chan) {
+                       consumer_del_channel(free_chan);
+               }
+       } else {
+               destroy_close_stream(stream);
+       }
+
+       /* Free stream within a RCU call. */
+       lttng_trace_chunk_put(stream->trace_chunk);
+       stream->trace_chunk = NULL;
+       lttng_dynamic_array_reset(&stream->read_subbuffer_ops.post_consume_cbs);
+       consumer_stream_free(stream);
+}
+
+/*
+ * Write index of a specific stream either on the relayd or local disk.
+ *
+ * Return 0 on success or else a negative value.
+ */
+int consumer_stream_write_index(struct lttng_consumer_stream *stream,
+               struct ctf_packet_index *element)
+{
+       int ret;
+
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(element);
+
+       rcu_read_lock();
+       if (stream->net_seq_idx != (uint64_t) -1ULL) {
+               struct consumer_relayd_sock_pair *relayd;
+               relayd = consumer_find_relayd(stream->net_seq_idx);
+               if (relayd) {
+                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+                       ret = relayd_send_index(&relayd->control_sock, element,
+                               stream->relayd_stream_id, stream->next_net_seq_num - 1);
+                       if (ret < 0) {
+                               /*
+                                * Communication error with lttng-relayd,
+                                * perform cleanup now
+                                */
+                               ERR("Relayd send index failed. Cleaning up relayd %" PRIu64 ".", relayd->net_seq_idx);
+                               lttng_consumer_cleanup_relayd(relayd);
+                               ret = -1;
+                       }
+                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+               } else {
+                       ERR("Stream %" PRIu64 " relayd ID %" PRIu64 " unknown. Can't write index.",
+                                       stream->key, stream->net_seq_idx);
+                       ret = -1;
+               }
+       } else {
+               if (lttng_index_file_write(stream->index_file, element)) {
+                       ret = -1;
+               } else {
+                       ret = 0;
+               }
+       }
+       if (ret < 0) {
+               goto error;
+       }
+
+error:
+       rcu_read_unlock();
+       return ret;
+}
+
+int consumer_stream_create_output_files(struct lttng_consumer_stream *stream,
+               bool create_index)
+{
+       int ret;
+       enum lttng_trace_chunk_status chunk_status;
+       const int flags = O_WRONLY | O_CREAT | O_TRUNC;
+       const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
+       char stream_path[LTTNG_PATH_MAX];
+
+       ASSERT_LOCKED(stream->lock);
+       LTTNG_ASSERT(stream->trace_chunk);
+
+       ret = utils_stream_file_path(stream->chan->pathname, stream->name,
+                       stream->chan->tracefile_size,
+                       stream->tracefile_count_current, NULL,
+                       stream_path, sizeof(stream_path));
+       if (ret < 0) {
+               goto end;
+       }
+
+       if (stream->out_fd >= 0) {
+               ret = close(stream->out_fd);
+               if (ret < 0) {
+                       PERROR("Failed to close stream file \"%s\"",
+                                       stream->name);
+                       goto end;
+               }
+               stream->out_fd = -1;
+       }
+
+       DBG("Opening stream output file \"%s\"", stream_path);
+       chunk_status = lttng_trace_chunk_open_file(stream->trace_chunk, stream_path,
+                       flags, mode, &stream->out_fd, false);
+       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+               ERR("Failed to open stream file \"%s\"", stream->name);
+               ret = -1;
+               goto end;
+       }
+
+       if (!stream->metadata_flag && (create_index || stream->index_file)) {
+               if (stream->index_file) {
+                       lttng_index_file_put(stream->index_file);
+               }
+               chunk_status = lttng_index_file_create_from_trace_chunk(
+                               stream->trace_chunk,
+                               stream->chan->pathname,
+                               stream->name,
+                               stream->chan->tracefile_size,
+                               stream->tracefile_count_current,
+                               CTF_INDEX_MAJOR, CTF_INDEX_MINOR,
+                               false, &stream->index_file);
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ret = -1;
+                       goto end;
+               }
+       }
+
+       /* Reset current size because we just perform a rotation. */
+       stream->tracefile_size_current = 0;
+       stream->out_fd_offset = 0;
+end:
+       return ret;
+}
+
+int consumer_stream_rotate_output_files(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       stream->tracefile_count_current++;
+       if (stream->chan->tracefile_count > 0) {
+               stream->tracefile_count_current %=
+                               stream->chan->tracefile_count;
+       }
+
+       DBG("Rotating output files of stream \"%s\"", stream->name);
+       ret = consumer_stream_create_output_files(stream, true);
+       if (ret) {
+               goto end;
+       }
+
+end:
+       return ret;
+}
+
+bool consumer_stream_is_deleted(struct lttng_consumer_stream *stream)
+{
+       /*
+        * This function does not take a const stream since
+        * cds_lfht_is_node_deleted was not const before liburcu 0.12.
+        */
+       LTTNG_ASSERT(stream);
+       return cds_lfht_is_node_deleted(&stream->node.node);
+}
+
+static ssize_t metadata_bucket_flush(
+               const struct stream_subbuffer *buffer, void *data)
+{
+       ssize_t ret;
+       struct lttng_consumer_stream *stream = (lttng_consumer_stream *) data;
+
+       ret = consumer_stream_consume_mmap(NULL, stream, buffer);
+       if (ret < 0) {
+               goto end;
+       }
+end:
+       return ret;
+}
+
+static ssize_t metadata_bucket_consume(
+               struct lttng_consumer_local_data *unused,
+               struct lttng_consumer_stream *stream,
+               const struct stream_subbuffer *subbuffer)
+{
+       ssize_t ret;
+       enum metadata_bucket_status status;
+
+       status = metadata_bucket_fill(stream->metadata_bucket, subbuffer);
+       switch (status) {
+       case METADATA_BUCKET_STATUS_OK:
+               /* Return consumed size. */
+               ret = subbuffer->buffer.buffer.size;
+               break;
+       default:
+               ret = -1;
+       }
+
+       return ret;
+}
+
+int consumer_stream_enable_metadata_bucketization(
+               struct lttng_consumer_stream *stream)
+{
+       int ret = 0;
+
+       LTTNG_ASSERT(stream->metadata_flag);
+       LTTNG_ASSERT(!stream->metadata_bucket);
+       LTTNG_ASSERT(stream->chan->output == CONSUMER_CHANNEL_MMAP);
+
+       stream->metadata_bucket = metadata_bucket_create(
+                       metadata_bucket_flush, stream);
+       if (!stream->metadata_bucket) {
+               ret = -1;
+               goto end;
+       }
+
+       stream->read_subbuffer_ops.consume_subbuffer = metadata_bucket_consume;
+end:
+       return ret;
+}
+
+void consumer_stream_metadata_set_version(
+               struct lttng_consumer_stream *stream, uint64_t new_version)
+{
+       LTTNG_ASSERT(new_version > stream->metadata_version);
+       stream->metadata_version = new_version;
+       stream->reset_metadata_flag = 1;
+
+       if (stream->metadata_bucket) {
+               metadata_bucket_reset(stream->metadata_bucket);
+       }
+}
+
+int consumer_stream_flush_buffer(struct lttng_consumer_stream *stream,
+               bool producer_active)
+{
+       int ret = 0;
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               if (producer_active) {
+                       ret = kernctl_buffer_flush(stream->wait_fd);
+                       if (ret < 0) {
+                               ERR("Failed to flush kernel stream");
+                               goto end;
+                       }
+               } else {
+                       ret = kernctl_buffer_flush_empty(stream->wait_fd);
+                       if (ret < 0) {
+                               /*
+                                * Doing a buffer flush which does not take into
+                                * account empty packets. This is not perfect,
+                                * but required as a fall-back when
+                                * "flush_empty" is not implemented by
+                                * lttng-modules.
+                                */
+                               ret = kernctl_buffer_flush(stream->wait_fd);
+                               if (ret < 0) {
+                                       ERR("Failed to flush kernel stream");
+                                       goto end;
+                               }
+                       }
+               }
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               ret = lttng_ustconsumer_flush_buffer(stream, (int) producer_active);
+               break;
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+       }
+
+end:
+       return ret;
+}
index c9af63cd83841c10a542e015aba3d6c3eb5fd69d..af0690a25a0920e3e4c9cb4638c38724aa94b351 100644 (file)
 
 #include "consumer.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 enum consumer_stream_open_packet_status {
        CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED,
        CONSUMER_STREAM_OPEN_PACKET_STATUS_NO_SPACE,
@@ -166,4 +170,8 @@ enum consumer_stream_open_packet_status consumer_stream_open_packet(
 int consumer_stream_flush_buffer(struct lttng_consumer_stream *stream,
                bool producer_active);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* LTTNG_CONSUMER_STREAM_H */
diff --git a/src/common/consumer/consumer-timer.c b/src/common/consumer/consumer-timer.c
deleted file mode 100644 (file)
index 6d2e6b2..0000000
+++ /dev/null
@@ -1,803 +0,0 @@
-/*
- * Copyright (C) 2012 Julien Desfossez <julien.desfossez@efficios.com>
- * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#define _LGPL_SOURCE
-#include <inttypes.h>
-#include <signal.h>
-
-#include <bin/lttng-consumerd/health-consumerd.h>
-#include <common/common.h>
-#include <common/compat/endian.h>
-#include <common/kernel-ctl/kernel-ctl.h>
-#include <common/kernel-consumer/kernel-consumer.h>
-#include <common/consumer/consumer-stream.h>
-#include <common/consumer/consumer-timer.h>
-#include <common/consumer/consumer-testpoint.h>
-#include <common/ust-consumer/ust-consumer.h>
-
-typedef int (*sample_positions_cb)(struct lttng_consumer_stream *stream);
-typedef int (*get_consumed_cb)(struct lttng_consumer_stream *stream,
-               unsigned long *consumed);
-typedef int (*get_produced_cb)(struct lttng_consumer_stream *stream,
-               unsigned long *produced);
-typedef int (*flush_index_cb)(struct lttng_consumer_stream *stream);
-
-static struct timer_signal_data timer_signal = {
-       .tid = 0,
-       .setup_done = 0,
-       .qs_done = 0,
-       .lock = PTHREAD_MUTEX_INITIALIZER,
-};
-
-/*
- * Set custom signal mask to current thread.
- */
-static void setmask(sigset_t *mask)
-{
-       int ret;
-
-       ret = sigemptyset(mask);
-       if (ret) {
-               PERROR("sigemptyset");
-       }
-       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_SWITCH);
-       if (ret) {
-               PERROR("sigaddset switch");
-       }
-       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_TEARDOWN);
-       if (ret) {
-               PERROR("sigaddset teardown");
-       }
-       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_LIVE);
-       if (ret) {
-               PERROR("sigaddset live");
-       }
-       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_MONITOR);
-       if (ret) {
-               PERROR("sigaddset monitor");
-       }
-       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_EXIT);
-       if (ret) {
-               PERROR("sigaddset exit");
-       }
-}
-
-static int the_channel_monitor_pipe = -1;
-
-/*
- * Execute action on a timer switch.
- *
- * Beware: metadata_switch_timer() should *never* take a mutex also held
- * while consumer_timer_switch_stop() is called. It would result in
- * deadlocks.
- */
-static void metadata_switch_timer(struct lttng_consumer_local_data *ctx,
-               siginfo_t *si)
-{
-       int ret;
-       struct lttng_consumer_channel *channel;
-
-       channel = si->si_value.sival_ptr;
-       LTTNG_ASSERT(channel);
-
-       if (channel->switch_timer_error) {
-               return;
-       }
-
-       DBG("Switch timer for channel %" PRIu64, channel->key);
-       switch (ctx->type) {
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               /*
-                * Locks taken by lttng_ustconsumer_request_metadata():
-                * - metadata_socket_lock
-                *   - Calling lttng_ustconsumer_recv_metadata():
-                *     - channel->metadata_cache->lock
-                *     - Calling consumer_metadata_cache_flushed():
-                *       - channel->timer_lock
-                *         - channel->metadata_cache->lock
-                *
-                * Ensure that neither consumer_data.lock nor
-                * channel->lock are taken within this function, since
-                * they are held while consumer_timer_switch_stop() is
-                * called.
-                */
-               ret = lttng_ustconsumer_request_metadata(ctx, channel, 1, 1);
-               if (ret < 0) {
-                       channel->switch_timer_error = 1;
-               }
-               break;
-       case LTTNG_CONSUMER_KERNEL:
-       case LTTNG_CONSUMER_UNKNOWN:
-               abort();
-               break;
-       }
-}
-
-static int send_empty_index(struct lttng_consumer_stream *stream, uint64_t ts,
-               uint64_t stream_id)
-{
-       int ret;
-       struct ctf_packet_index index;
-
-       memset(&index, 0, sizeof(index));
-       index.stream_id = htobe64(stream_id);
-       index.timestamp_end = htobe64(ts);
-       ret = consumer_stream_write_index(stream, &index);
-       if (ret < 0) {
-               goto error;
-       }
-
-error:
-       return ret;
-}
-
-int consumer_flush_kernel_index(struct lttng_consumer_stream *stream)
-{
-       uint64_t ts, stream_id;
-       int ret;
-
-       ret = kernctl_get_current_timestamp(stream->wait_fd, &ts);
-       if (ret < 0) {
-               ERR("Failed to get the current timestamp");
-               goto end;
-       }
-       ret = kernctl_buffer_flush(stream->wait_fd);
-       if (ret < 0) {
-               ERR("Failed to flush kernel stream");
-               goto end;
-       }
-       ret = kernctl_snapshot(stream->wait_fd);
-       if (ret < 0) {
-               if (ret != -EAGAIN && ret != -ENODATA) {
-                       PERROR("live timer kernel snapshot");
-                       ret = -1;
-                       goto end;
-               }
-               ret = kernctl_get_stream_id(stream->wait_fd, &stream_id);
-               if (ret < 0) {
-                       PERROR("kernctl_get_stream_id");
-                       goto end;
-               }
-               DBG("Stream %" PRIu64 " empty, sending beacon", stream->key);
-               ret = send_empty_index(stream, ts, stream_id);
-               if (ret < 0) {
-                       goto end;
-               }
-       }
-       ret = 0;
-end:
-       return ret;
-}
-
-static int check_stream(struct lttng_consumer_stream *stream,
-               flush_index_cb flush_index)
-{
-       int ret;
-
-       /*
-        * While holding the stream mutex, try to take a snapshot, if it
-        * succeeds, it means that data is ready to be sent, just let the data
-        * thread handle that. Otherwise, if the snapshot returns EAGAIN, it
-        * means that there is no data to read after the flush, so we can
-        * safely send the empty index.
-        *
-        * Doing a trylock and checking if waiting on metadata if
-        * trylock fails. Bail out of the stream is indeed waiting for
-        * metadata to be pushed. Busy wait on trylock otherwise.
-        */
-       for (;;) {
-               ret = pthread_mutex_trylock(&stream->lock);
-               switch (ret) {
-               case 0:
-                       break;  /* We have the lock. */
-               case EBUSY:
-                       pthread_mutex_lock(&stream->metadata_timer_lock);
-                       if (stream->waiting_on_metadata) {
-                               ret = 0;
-                               stream->missed_metadata_flush = true;
-                               pthread_mutex_unlock(&stream->metadata_timer_lock);
-                               goto end;       /* Bail out. */
-                       }
-                       pthread_mutex_unlock(&stream->metadata_timer_lock);
-                       /* Try again. */
-                       caa_cpu_relax();
-                       continue;
-               default:
-                       ERR("Unexpected pthread_mutex_trylock error %d", ret);
-                       ret = -1;
-                       goto end;
-               }
-               break;
-       }
-       ret = flush_index(stream);
-       pthread_mutex_unlock(&stream->lock);
-end:
-       return ret;
-}
-
-int consumer_flush_ust_index(struct lttng_consumer_stream *stream)
-{
-       uint64_t ts, stream_id;
-       int ret;
-
-       ret = cds_lfht_is_node_deleted(&stream->node.node);
-       if (ret) {
-               goto end;
-       }
-
-       ret = lttng_ustconsumer_get_current_timestamp(stream, &ts);
-       if (ret < 0) {
-               ERR("Failed to get the current timestamp");
-               goto end;
-       }
-       ret = lttng_ustconsumer_flush_buffer(stream, 1);
-       if (ret < 0) {
-               ERR("Failed to flush buffer while flushing index");
-               goto end;
-       }
-       ret = lttng_ustconsumer_take_snapshot(stream);
-       if (ret < 0) {
-               if (ret != -EAGAIN) {
-                       ERR("Taking UST snapshot");
-                       ret = -1;
-                       goto end;
-               }
-               ret = lttng_ustconsumer_get_stream_id(stream, &stream_id);
-               if (ret < 0) {
-                       PERROR("lttng_ust_ctl_get_stream_id");
-                       goto end;
-               }
-               DBG("Stream %" PRIu64 " empty, sending beacon", stream->key);
-               ret = send_empty_index(stream, ts, stream_id);
-               if (ret < 0) {
-                       goto end;
-               }
-       }
-       ret = 0;
-end:
-       return ret;
-}
-
-/*
- * Execute action on a live timer
- */
-static void live_timer(struct lttng_consumer_local_data *ctx,
-               siginfo_t *si)
-{
-       int ret;
-       struct lttng_consumer_channel *channel;
-       struct lttng_consumer_stream *stream;
-       struct lttng_ht_iter iter;
-       const struct lttng_ht *ht = the_consumer_data.stream_per_chan_id_ht;
-       const flush_index_cb flush_index =
-                       ctx->type == LTTNG_CONSUMER_KERNEL ?
-                                       consumer_flush_kernel_index :
-                                       consumer_flush_ust_index;
-
-       channel = si->si_value.sival_ptr;
-       LTTNG_ASSERT(channel);
-
-       if (channel->switch_timer_error) {
-               goto error;
-       }
-
-       DBG("Live timer for channel %" PRIu64, channel->key);
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&channel->key, lttng_ht_seed),
-                       ht->match_fct, &channel->key, &iter.iter,
-                       stream, node_channel_id.node) {
-               ret = check_stream(stream, flush_index);
-               if (ret < 0) {
-                       goto error_unlock;
-               }
-       }
-
-error_unlock:
-       rcu_read_unlock();
-
-error:
-       return;
-}
-
-static
-void consumer_timer_signal_thread_qs(unsigned int signr)
-{
-       sigset_t pending_set;
-       int ret;
-
-       /*
-        * We need to be the only thread interacting with the thread
-        * that manages signals for teardown synchronization.
-        */
-       pthread_mutex_lock(&timer_signal.lock);
-
-       /* Ensure we don't have any signal queued for this channel. */
-       for (;;) {
-               ret = sigemptyset(&pending_set);
-               if (ret == -1) {
-                       PERROR("sigemptyset");
-               }
-               ret = sigpending(&pending_set);
-               if (ret == -1) {
-                       PERROR("sigpending");
-               }
-               if (!sigismember(&pending_set, signr)) {
-                       break;
-               }
-               caa_cpu_relax();
-       }
-
-       /*
-        * From this point, no new signal handler will be fired that would try to
-        * access "chan". However, we still need to wait for any currently
-        * executing handler to complete.
-        */
-       cmm_smp_mb();
-       CMM_STORE_SHARED(timer_signal.qs_done, 0);
-       cmm_smp_mb();
-
-       /*
-        * Kill with LTTNG_CONSUMER_SIG_TEARDOWN, so signal management thread wakes
-        * up.
-        */
-       kill(getpid(), LTTNG_CONSUMER_SIG_TEARDOWN);
-
-       while (!CMM_LOAD_SHARED(timer_signal.qs_done)) {
-               caa_cpu_relax();
-       }
-       cmm_smp_mb();
-
-       pthread_mutex_unlock(&timer_signal.lock);
-}
-
-/*
- * Start a timer channel timer which will fire at a given interval
- * (timer_interval_us)and fire a given signal (signal).
- *
- * Returns a negative value on error, 0 if a timer was created, and
- * a positive value if no timer was created (not an error).
- */
-static
-int consumer_channel_timer_start(timer_t *timer_id,
-               struct lttng_consumer_channel *channel,
-               unsigned int timer_interval_us, int signal)
-{
-       int ret = 0, delete_ret;
-       struct sigevent sev = {};
-       struct itimerspec its;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(channel->key);
-
-       if (timer_interval_us == 0) {
-               /* No creation needed; not an error. */
-               ret = 1;
-               goto end;
-       }
-
-       sev.sigev_notify = SIGEV_SIGNAL;
-       sev.sigev_signo = signal;
-       sev.sigev_value.sival_ptr = channel;
-       ret = timer_create(CLOCKID, &sev, timer_id);
-       if (ret == -1) {
-               PERROR("timer_create");
-               goto end;
-       }
-
-       its.it_value.tv_sec = timer_interval_us / 1000000;
-       its.it_value.tv_nsec = (timer_interval_us % 1000000) * 1000;
-       its.it_interval.tv_sec = its.it_value.tv_sec;
-       its.it_interval.tv_nsec = its.it_value.tv_nsec;
-
-       ret = timer_settime(*timer_id, 0, &its, NULL);
-       if (ret == -1) {
-               PERROR("timer_settime");
-               goto error_destroy_timer;
-       }
-end:
-       return ret;
-error_destroy_timer:
-       delete_ret = timer_delete(*timer_id);
-       if (delete_ret == -1) {
-               PERROR("timer_delete");
-       }
-       goto end;
-}
-
-static
-int consumer_channel_timer_stop(timer_t *timer_id, int signal)
-{
-       int ret = 0;
-
-       ret = timer_delete(*timer_id);
-       if (ret == -1) {
-               PERROR("timer_delete");
-               goto end;
-       }
-
-       consumer_timer_signal_thread_qs(signal);
-       *timer_id = 0;
-end:
-       return ret;
-}
-
-/*
- * Set the channel's switch timer.
- */
-void consumer_timer_switch_start(struct lttng_consumer_channel *channel,
-               unsigned int switch_timer_interval_us)
-{
-       int ret;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(channel->key);
-
-       ret = consumer_channel_timer_start(&channel->switch_timer, channel,
-                       switch_timer_interval_us, LTTNG_CONSUMER_SIG_SWITCH);
-
-       channel->switch_timer_enabled = !!(ret == 0);
-}
-
-/*
- * Stop and delete the channel's switch timer.
- */
-void consumer_timer_switch_stop(struct lttng_consumer_channel *channel)
-{
-       int ret;
-
-       LTTNG_ASSERT(channel);
-
-       ret = consumer_channel_timer_stop(&channel->switch_timer,
-                       LTTNG_CONSUMER_SIG_SWITCH);
-       if (ret == -1) {
-               ERR("Failed to stop switch timer");
-       }
-
-       channel->switch_timer_enabled = 0;
-}
-
-/*
- * Set the channel's live timer.
- */
-void consumer_timer_live_start(struct lttng_consumer_channel *channel,
-               unsigned int live_timer_interval_us)
-{
-       int ret;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(channel->key);
-
-       ret = consumer_channel_timer_start(&channel->live_timer, channel,
-                       live_timer_interval_us, LTTNG_CONSUMER_SIG_LIVE);
-
-       channel->live_timer_enabled = !!(ret == 0);
-}
-
-/*
- * Stop and delete the channel's live timer.
- */
-void consumer_timer_live_stop(struct lttng_consumer_channel *channel)
-{
-       int ret;
-
-       LTTNG_ASSERT(channel);
-
-       ret = consumer_channel_timer_stop(&channel->live_timer,
-                       LTTNG_CONSUMER_SIG_LIVE);
-       if (ret == -1) {
-               ERR("Failed to stop live timer");
-       }
-
-       channel->live_timer_enabled = 0;
-}
-
-/*
- * Set the channel's monitoring timer.
- *
- * Returns a negative value on error, 0 if a timer was created, and
- * a positive value if no timer was created (not an error).
- */
-int consumer_timer_monitor_start(struct lttng_consumer_channel *channel,
-               unsigned int monitor_timer_interval_us)
-{
-       int ret;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(channel->key);
-       LTTNG_ASSERT(!channel->monitor_timer_enabled);
-
-       ret = consumer_channel_timer_start(&channel->monitor_timer, channel,
-                       monitor_timer_interval_us, LTTNG_CONSUMER_SIG_MONITOR);
-       channel->monitor_timer_enabled = !!(ret == 0);
-       return ret;
-}
-
-/*
- * Stop and delete the channel's monitoring timer.
- */
-int consumer_timer_monitor_stop(struct lttng_consumer_channel *channel)
-{
-       int ret;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(channel->monitor_timer_enabled);
-
-       ret = consumer_channel_timer_stop(&channel->monitor_timer,
-                       LTTNG_CONSUMER_SIG_MONITOR);
-       if (ret == -1) {
-               ERR("Failed to stop live timer");
-               goto end;
-       }
-
-       channel->monitor_timer_enabled = 0;
-end:
-       return ret;
-}
-
-/*
- * Block the RT signals for the entire process. It must be called from the
- * consumer main before creating the threads
- */
-int consumer_signal_init(void)
-{
-       int ret;
-       sigset_t mask;
-
-       /* Block signal for entire process, so only our thread processes it. */
-       setmask(&mask);
-       ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
-       if (ret) {
-               errno = ret;
-               PERROR("pthread_sigmask");
-               return -1;
-       }
-       return 0;
-}
-
-static
-int sample_channel_positions(struct lttng_consumer_channel *channel,
-               uint64_t *_highest_use, uint64_t *_lowest_use, uint64_t *_total_consumed,
-               sample_positions_cb sample, get_consumed_cb get_consumed,
-               get_produced_cb get_produced)
-{
-       int ret = 0;
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_stream *stream;
-       bool empty_channel = true;
-       uint64_t high = 0, low = UINT64_MAX;
-       struct lttng_ht *ht = the_consumer_data.stream_per_chan_id_ht;
-
-       *_total_consumed = 0;
-
-       rcu_read_lock();
-
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&channel->key, lttng_ht_seed),
-                       ht->match_fct, &channel->key,
-                       &iter.iter, stream, node_channel_id.node) {
-               unsigned long produced, consumed, usage;
-
-               empty_channel = false;
-
-               pthread_mutex_lock(&stream->lock);
-               if (cds_lfht_is_node_deleted(&stream->node.node)) {
-                       goto next;
-               }
-
-               ret = sample(stream);
-               if (ret) {
-                       ERR("Failed to take buffer position snapshot in monitor timer (ret = %d)", ret);
-                       pthread_mutex_unlock(&stream->lock);
-                       goto end;
-               }
-               ret = get_consumed(stream, &consumed);
-               if (ret) {
-                       ERR("Failed to get buffer consumed position in monitor timer");
-                       pthread_mutex_unlock(&stream->lock);
-                       goto end;
-               }
-               ret = get_produced(stream, &produced);
-               if (ret) {
-                       ERR("Failed to get buffer produced position in monitor timer");
-                       pthread_mutex_unlock(&stream->lock);
-                       goto end;
-               }
-
-               usage = produced - consumed;
-               high = (usage > high) ? usage : high;
-               low = (usage < low) ? usage : low;
-
-               /*
-                * We don't use consumed here for 2 reasons:
-                *  - output_written takes into account the padding written in the
-                *    tracefiles when we stop the session;
-                *  - the consumed position is not the accurate representation of what
-                *    was extracted from a buffer in overwrite mode.
-                */
-               *_total_consumed += stream->output_written;
-       next:
-               pthread_mutex_unlock(&stream->lock);
-       }
-
-       *_highest_use = high;
-       *_lowest_use = low;
-end:
-       rcu_read_unlock();
-       if (empty_channel) {
-               ret = -1;
-       }
-       return ret;
-}
-
-/*
- * Execute action on a monitor timer.
- */
-static
-void monitor_timer(struct lttng_consumer_channel *channel)
-{
-       int ret;
-       int channel_monitor_pipe =
-                       consumer_timer_thread_get_channel_monitor_pipe();
-       struct lttcomm_consumer_channel_monitor_msg msg = {
-               .key = channel->key,
-       };
-       sample_positions_cb sample;
-       get_consumed_cb get_consumed;
-       get_produced_cb get_produced;
-       uint64_t lowest = 0, highest = 0, total_consumed = 0;
-
-       LTTNG_ASSERT(channel);
-
-       if (channel_monitor_pipe < 0) {
-               return;
-       }
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               sample = lttng_kconsumer_sample_snapshot_positions;
-               get_consumed = lttng_kconsumer_get_consumed_snapshot;
-               get_produced = lttng_kconsumer_get_produced_snapshot;
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               sample = lttng_ustconsumer_sample_snapshot_positions;
-               get_consumed = lttng_ustconsumer_get_consumed_snapshot;
-               get_produced = lttng_ustconsumer_get_produced_snapshot;
-               break;
-       default:
-               abort();
-       }
-
-       ret = sample_channel_positions(channel, &highest, &lowest,
-                       &total_consumed, sample, get_consumed, get_produced);
-       if (ret) {
-               return;
-       }
-       msg.highest = highest;
-       msg.lowest = lowest;
-       msg.total_consumed = total_consumed;
-
-       /*
-        * Writes performed here are assumed to be atomic which is only
-        * guaranteed for sizes < than PIPE_BUF.
-        */
-       LTTNG_ASSERT(sizeof(msg) <= PIPE_BUF);
-
-       do {
-               ret = write(channel_monitor_pipe, &msg, sizeof(msg));
-       } while (ret == -1 && errno == EINTR);
-       if (ret == -1) {
-               if (errno == EAGAIN) {
-                       /* Not an error, the sample is merely dropped. */
-                       DBG("Channel monitor pipe is full; dropping sample for channel key = %"PRIu64,
-                                       channel->key);
-               } else {
-                       PERROR("write to the channel monitor pipe");
-               }
-       } else {
-               DBG("Sent channel monitoring sample for channel key %" PRIu64
-                               ", (highest = %" PRIu64 ", lowest = %"PRIu64")",
-                               channel->key, msg.highest, msg.lowest);
-       }
-}
-
-int consumer_timer_thread_get_channel_monitor_pipe(void)
-{
-       return uatomic_read(&the_channel_monitor_pipe);
-}
-
-int consumer_timer_thread_set_channel_monitor_pipe(int fd)
-{
-       int ret;
-
-       ret = uatomic_cmpxchg(&the_channel_monitor_pipe, -1, fd);
-       if (ret != -1) {
-               ret = -1;
-               goto end;
-       }
-       ret = 0;
-end:
-       return ret;
-}
-
-/*
- * This thread is the sighandler for signals LTTNG_CONSUMER_SIG_SWITCH,
- * LTTNG_CONSUMER_SIG_TEARDOWN, LTTNG_CONSUMER_SIG_LIVE, and
- * LTTNG_CONSUMER_SIG_MONITOR, LTTNG_CONSUMER_SIG_EXIT.
- */
-void *consumer_timer_thread(void *data)
-{
-       int signr;
-       sigset_t mask;
-       siginfo_t info;
-       struct lttng_consumer_local_data *ctx = data;
-
-       rcu_register_thread();
-
-       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_METADATA_TIMER);
-
-       if (testpoint(consumerd_thread_metadata_timer)) {
-               goto error_testpoint;
-       }
-
-       health_code_update();
-
-       /* Only self thread will receive signal mask. */
-       setmask(&mask);
-       CMM_STORE_SHARED(timer_signal.tid, pthread_self());
-
-       while (1) {
-               health_code_update();
-
-               health_poll_entry();
-               signr = sigwaitinfo(&mask, &info);
-               health_poll_exit();
-
-               /*
-                * NOTE: cascading conditions are used instead of a switch case
-                * since the use of SIGRTMIN in the definition of the signals'
-                * values prevents the reduction to an integer constant.
-                */
-               if (signr == -1) {
-                       if (errno != EINTR) {
-                               PERROR("sigwaitinfo");
-                       }
-                       continue;
-               } else if (signr == LTTNG_CONSUMER_SIG_SWITCH) {
-                       metadata_switch_timer(ctx, &info);
-               } else if (signr == LTTNG_CONSUMER_SIG_TEARDOWN) {
-                       cmm_smp_mb();
-                       CMM_STORE_SHARED(timer_signal.qs_done, 1);
-                       cmm_smp_mb();
-                       DBG("Signal timer metadata thread teardown");
-               } else if (signr == LTTNG_CONSUMER_SIG_LIVE) {
-                       live_timer(ctx, &info);
-               } else if (signr == LTTNG_CONSUMER_SIG_MONITOR) {
-                       struct lttng_consumer_channel *channel;
-
-                       channel = info.si_value.sival_ptr;
-                       monitor_timer(channel);
-               } else if (signr == LTTNG_CONSUMER_SIG_EXIT) {
-                       LTTNG_ASSERT(CMM_LOAD_SHARED(consumer_quit));
-                       goto end;
-               } else {
-                       ERR("Unexpected signal %d\n", info.si_signo);
-               }
-       }
-
-error_testpoint:
-       /* Only reached in testpoint error */
-       health_error();
-end:
-       health_unregister(health_consumerd);
-       rcu_unregister_thread();
-       return NULL;
-}
diff --git a/src/common/consumer/consumer-timer.cpp b/src/common/consumer/consumer-timer.cpp
new file mode 100644 (file)
index 0000000..f6cb60c
--- /dev/null
@@ -0,0 +1,803 @@
+/*
+ * Copyright (C) 2012 Julien Desfossez <julien.desfossez@efficios.com>
+ * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#define _LGPL_SOURCE
+#include <inttypes.h>
+#include <signal.h>
+
+#include <bin/lttng-consumerd/health-consumerd.h>
+#include <common/common.h>
+#include <common/compat/endian.h>
+#include <common/kernel-ctl/kernel-ctl.h>
+#include <common/kernel-consumer/kernel-consumer.h>
+#include <common/consumer/consumer-stream.h>
+#include <common/consumer/consumer-timer.h>
+#include <common/consumer/consumer-testpoint.h>
+#include <common/ust-consumer/ust-consumer.h>
+
+typedef int (*sample_positions_cb)(struct lttng_consumer_stream *stream);
+typedef int (*get_consumed_cb)(struct lttng_consumer_stream *stream,
+               unsigned long *consumed);
+typedef int (*get_produced_cb)(struct lttng_consumer_stream *stream,
+               unsigned long *produced);
+typedef int (*flush_index_cb)(struct lttng_consumer_stream *stream);
+
+static struct timer_signal_data timer_signal = {
+       .tid = 0,
+       .setup_done = 0,
+       .qs_done = 0,
+       .lock = PTHREAD_MUTEX_INITIALIZER,
+};
+
+/*
+ * Set custom signal mask to current thread.
+ */
+static void setmask(sigset_t *mask)
+{
+       int ret;
+
+       ret = sigemptyset(mask);
+       if (ret) {
+               PERROR("sigemptyset");
+       }
+       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_SWITCH);
+       if (ret) {
+               PERROR("sigaddset switch");
+       }
+       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_TEARDOWN);
+       if (ret) {
+               PERROR("sigaddset teardown");
+       }
+       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_LIVE);
+       if (ret) {
+               PERROR("sigaddset live");
+       }
+       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_MONITOR);
+       if (ret) {
+               PERROR("sigaddset monitor");
+       }
+       ret = sigaddset(mask, LTTNG_CONSUMER_SIG_EXIT);
+       if (ret) {
+               PERROR("sigaddset exit");
+       }
+}
+
+static int the_channel_monitor_pipe = -1;
+
+/*
+ * Execute action on a timer switch.
+ *
+ * Beware: metadata_switch_timer() should *never* take a mutex also held
+ * while consumer_timer_switch_stop() is called. It would result in
+ * deadlocks.
+ */
+static void metadata_switch_timer(struct lttng_consumer_local_data *ctx,
+               siginfo_t *si)
+{
+       int ret;
+       struct lttng_consumer_channel *channel;
+
+       channel = (lttng_consumer_channel *) si->si_value.sival_ptr;
+       LTTNG_ASSERT(channel);
+
+       if (channel->switch_timer_error) {
+               return;
+       }
+
+       DBG("Switch timer for channel %" PRIu64, channel->key);
+       switch (ctx->type) {
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               /*
+                * Locks taken by lttng_ustconsumer_request_metadata():
+                * - metadata_socket_lock
+                *   - Calling lttng_ustconsumer_recv_metadata():
+                *     - channel->metadata_cache->lock
+                *     - Calling consumer_metadata_cache_flushed():
+                *       - channel->timer_lock
+                *         - channel->metadata_cache->lock
+                *
+                * Ensure that neither consumer_data.lock nor
+                * channel->lock are taken within this function, since
+                * they are held while consumer_timer_switch_stop() is
+                * called.
+                */
+               ret = lttng_ustconsumer_request_metadata(ctx, channel, 1, 1);
+               if (ret < 0) {
+                       channel->switch_timer_error = 1;
+               }
+               break;
+       case LTTNG_CONSUMER_KERNEL:
+       case LTTNG_CONSUMER_UNKNOWN:
+               abort();
+               break;
+       }
+}
+
+static int send_empty_index(struct lttng_consumer_stream *stream, uint64_t ts,
+               uint64_t stream_id)
+{
+       int ret;
+       struct ctf_packet_index index;
+
+       memset(&index, 0, sizeof(index));
+       index.stream_id = htobe64(stream_id);
+       index.timestamp_end = htobe64(ts);
+       ret = consumer_stream_write_index(stream, &index);
+       if (ret < 0) {
+               goto error;
+       }
+
+error:
+       return ret;
+}
+
+int consumer_flush_kernel_index(struct lttng_consumer_stream *stream)
+{
+       uint64_t ts, stream_id;
+       int ret;
+
+       ret = kernctl_get_current_timestamp(stream->wait_fd, &ts);
+       if (ret < 0) {
+               ERR("Failed to get the current timestamp");
+               goto end;
+       }
+       ret = kernctl_buffer_flush(stream->wait_fd);
+       if (ret < 0) {
+               ERR("Failed to flush kernel stream");
+               goto end;
+       }
+       ret = kernctl_snapshot(stream->wait_fd);
+       if (ret < 0) {
+               if (ret != -EAGAIN && ret != -ENODATA) {
+                       PERROR("live timer kernel snapshot");
+                       ret = -1;
+                       goto end;
+               }
+               ret = kernctl_get_stream_id(stream->wait_fd, &stream_id);
+               if (ret < 0) {
+                       PERROR("kernctl_get_stream_id");
+                       goto end;
+               }
+               DBG("Stream %" PRIu64 " empty, sending beacon", stream->key);
+               ret = send_empty_index(stream, ts, stream_id);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+       ret = 0;
+end:
+       return ret;
+}
+
+static int check_stream(struct lttng_consumer_stream *stream,
+               flush_index_cb flush_index)
+{
+       int ret;
+
+       /*
+        * While holding the stream mutex, try to take a snapshot, if it
+        * succeeds, it means that data is ready to be sent, just let the data
+        * thread handle that. Otherwise, if the snapshot returns EAGAIN, it
+        * means that there is no data to read after the flush, so we can
+        * safely send the empty index.
+        *
+        * Doing a trylock and checking if waiting on metadata if
+        * trylock fails. Bail out of the stream is indeed waiting for
+        * metadata to be pushed. Busy wait on trylock otherwise.
+        */
+       for (;;) {
+               ret = pthread_mutex_trylock(&stream->lock);
+               switch (ret) {
+               case 0:
+                       break;  /* We have the lock. */
+               case EBUSY:
+                       pthread_mutex_lock(&stream->metadata_timer_lock);
+                       if (stream->waiting_on_metadata) {
+                               ret = 0;
+                               stream->missed_metadata_flush = true;
+                               pthread_mutex_unlock(&stream->metadata_timer_lock);
+                               goto end;       /* Bail out. */
+                       }
+                       pthread_mutex_unlock(&stream->metadata_timer_lock);
+                       /* Try again. */
+                       caa_cpu_relax();
+                       continue;
+               default:
+                       ERR("Unexpected pthread_mutex_trylock error %d", ret);
+                       ret = -1;
+                       goto end;
+               }
+               break;
+       }
+       ret = flush_index(stream);
+       pthread_mutex_unlock(&stream->lock);
+end:
+       return ret;
+}
+
+int consumer_flush_ust_index(struct lttng_consumer_stream *stream)
+{
+       uint64_t ts, stream_id;
+       int ret;
+
+       ret = cds_lfht_is_node_deleted(&stream->node.node);
+       if (ret) {
+               goto end;
+       }
+
+       ret = lttng_ustconsumer_get_current_timestamp(stream, &ts);
+       if (ret < 0) {
+               ERR("Failed to get the current timestamp");
+               goto end;
+       }
+       ret = lttng_ustconsumer_flush_buffer(stream, 1);
+       if (ret < 0) {
+               ERR("Failed to flush buffer while flushing index");
+               goto end;
+       }
+       ret = lttng_ustconsumer_take_snapshot(stream);
+       if (ret < 0) {
+               if (ret != -EAGAIN) {
+                       ERR("Taking UST snapshot");
+                       ret = -1;
+                       goto end;
+               }
+               ret = lttng_ustconsumer_get_stream_id(stream, &stream_id);
+               if (ret < 0) {
+                       PERROR("lttng_ust_ctl_get_stream_id");
+                       goto end;
+               }
+               DBG("Stream %" PRIu64 " empty, sending beacon", stream->key);
+               ret = send_empty_index(stream, ts, stream_id);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+       ret = 0;
+end:
+       return ret;
+}
+
+/*
+ * Execute action on a live timer
+ */
+static void live_timer(struct lttng_consumer_local_data *ctx,
+               siginfo_t *si)
+{
+       int ret;
+       struct lttng_consumer_channel *channel;
+       struct lttng_consumer_stream *stream;
+       struct lttng_ht_iter iter;
+       const struct lttng_ht *ht = the_consumer_data.stream_per_chan_id_ht;
+       const flush_index_cb flush_index =
+                       ctx->type == LTTNG_CONSUMER_KERNEL ?
+                                       consumer_flush_kernel_index :
+                                       consumer_flush_ust_index;
+
+       channel = (lttng_consumer_channel *) si->si_value.sival_ptr;
+       LTTNG_ASSERT(channel);
+
+       if (channel->switch_timer_error) {
+               goto error;
+       }
+
+       DBG("Live timer for channel %" PRIu64, channel->key);
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&channel->key, lttng_ht_seed),
+                       ht->match_fct, &channel->key, &iter.iter,
+                       stream, node_channel_id.node) {
+               ret = check_stream(stream, flush_index);
+               if (ret < 0) {
+                       goto error_unlock;
+               }
+       }
+
+error_unlock:
+       rcu_read_unlock();
+
+error:
+       return;
+}
+
+static
+void consumer_timer_signal_thread_qs(unsigned int signr)
+{
+       sigset_t pending_set;
+       int ret;
+
+       /*
+        * We need to be the only thread interacting with the thread
+        * that manages signals for teardown synchronization.
+        */
+       pthread_mutex_lock(&timer_signal.lock);
+
+       /* Ensure we don't have any signal queued for this channel. */
+       for (;;) {
+               ret = sigemptyset(&pending_set);
+               if (ret == -1) {
+                       PERROR("sigemptyset");
+               }
+               ret = sigpending(&pending_set);
+               if (ret == -1) {
+                       PERROR("sigpending");
+               }
+               if (!sigismember(&pending_set, signr)) {
+                       break;
+               }
+               caa_cpu_relax();
+       }
+
+       /*
+        * From this point, no new signal handler will be fired that would try to
+        * access "chan". However, we still need to wait for any currently
+        * executing handler to complete.
+        */
+       cmm_smp_mb();
+       CMM_STORE_SHARED(timer_signal.qs_done, 0);
+       cmm_smp_mb();
+
+       /*
+        * Kill with LTTNG_CONSUMER_SIG_TEARDOWN, so signal management thread wakes
+        * up.
+        */
+       kill(getpid(), LTTNG_CONSUMER_SIG_TEARDOWN);
+
+       while (!CMM_LOAD_SHARED(timer_signal.qs_done)) {
+               caa_cpu_relax();
+       }
+       cmm_smp_mb();
+
+       pthread_mutex_unlock(&timer_signal.lock);
+}
+
+/*
+ * Start a timer channel timer which will fire at a given interval
+ * (timer_interval_us)and fire a given signal (signal).
+ *
+ * Returns a negative value on error, 0 if a timer was created, and
+ * a positive value if no timer was created (not an error).
+ */
+static
+int consumer_channel_timer_start(timer_t *timer_id,
+               struct lttng_consumer_channel *channel,
+               unsigned int timer_interval_us, int signal)
+{
+       int ret = 0, delete_ret;
+       struct sigevent sev = {};
+       struct itimerspec its;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(channel->key);
+
+       if (timer_interval_us == 0) {
+               /* No creation needed; not an error. */
+               ret = 1;
+               goto end;
+       }
+
+       sev.sigev_notify = SIGEV_SIGNAL;
+       sev.sigev_signo = signal;
+       sev.sigev_value.sival_ptr = channel;
+       ret = timer_create(CLOCKID, &sev, timer_id);
+       if (ret == -1) {
+               PERROR("timer_create");
+               goto end;
+       }
+
+       its.it_value.tv_sec = timer_interval_us / 1000000;
+       its.it_value.tv_nsec = (timer_interval_us % 1000000) * 1000;
+       its.it_interval.tv_sec = its.it_value.tv_sec;
+       its.it_interval.tv_nsec = its.it_value.tv_nsec;
+
+       ret = timer_settime(*timer_id, 0, &its, NULL);
+       if (ret == -1) {
+               PERROR("timer_settime");
+               goto error_destroy_timer;
+       }
+end:
+       return ret;
+error_destroy_timer:
+       delete_ret = timer_delete(*timer_id);
+       if (delete_ret == -1) {
+               PERROR("timer_delete");
+       }
+       goto end;
+}
+
+static
+int consumer_channel_timer_stop(timer_t *timer_id, int signal)
+{
+       int ret = 0;
+
+       ret = timer_delete(*timer_id);
+       if (ret == -1) {
+               PERROR("timer_delete");
+               goto end;
+       }
+
+       consumer_timer_signal_thread_qs(signal);
+       *timer_id = 0;
+end:
+       return ret;
+}
+
+/*
+ * Set the channel's switch timer.
+ */
+void consumer_timer_switch_start(struct lttng_consumer_channel *channel,
+               unsigned int switch_timer_interval_us)
+{
+       int ret;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(channel->key);
+
+       ret = consumer_channel_timer_start(&channel->switch_timer, channel,
+                       switch_timer_interval_us, LTTNG_CONSUMER_SIG_SWITCH);
+
+       channel->switch_timer_enabled = !!(ret == 0);
+}
+
+/*
+ * Stop and delete the channel's switch timer.
+ */
+void consumer_timer_switch_stop(struct lttng_consumer_channel *channel)
+{
+       int ret;
+
+       LTTNG_ASSERT(channel);
+
+       ret = consumer_channel_timer_stop(&channel->switch_timer,
+                       LTTNG_CONSUMER_SIG_SWITCH);
+       if (ret == -1) {
+               ERR("Failed to stop switch timer");
+       }
+
+       channel->switch_timer_enabled = 0;
+}
+
+/*
+ * Set the channel's live timer.
+ */
+void consumer_timer_live_start(struct lttng_consumer_channel *channel,
+               unsigned int live_timer_interval_us)
+{
+       int ret;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(channel->key);
+
+       ret = consumer_channel_timer_start(&channel->live_timer, channel,
+                       live_timer_interval_us, LTTNG_CONSUMER_SIG_LIVE);
+
+       channel->live_timer_enabled = !!(ret == 0);
+}
+
+/*
+ * Stop and delete the channel's live timer.
+ */
+void consumer_timer_live_stop(struct lttng_consumer_channel *channel)
+{
+       int ret;
+
+       LTTNG_ASSERT(channel);
+
+       ret = consumer_channel_timer_stop(&channel->live_timer,
+                       LTTNG_CONSUMER_SIG_LIVE);
+       if (ret == -1) {
+               ERR("Failed to stop live timer");
+       }
+
+       channel->live_timer_enabled = 0;
+}
+
+/*
+ * Set the channel's monitoring timer.
+ *
+ * Returns a negative value on error, 0 if a timer was created, and
+ * a positive value if no timer was created (not an error).
+ */
+int consumer_timer_monitor_start(struct lttng_consumer_channel *channel,
+               unsigned int monitor_timer_interval_us)
+{
+       int ret;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(channel->key);
+       LTTNG_ASSERT(!channel->monitor_timer_enabled);
+
+       ret = consumer_channel_timer_start(&channel->monitor_timer, channel,
+                       monitor_timer_interval_us, LTTNG_CONSUMER_SIG_MONITOR);
+       channel->monitor_timer_enabled = !!(ret == 0);
+       return ret;
+}
+
+/*
+ * Stop and delete the channel's monitoring timer.
+ */
+int consumer_timer_monitor_stop(struct lttng_consumer_channel *channel)
+{
+       int ret;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(channel->monitor_timer_enabled);
+
+       ret = consumer_channel_timer_stop(&channel->monitor_timer,
+                       LTTNG_CONSUMER_SIG_MONITOR);
+       if (ret == -1) {
+               ERR("Failed to stop live timer");
+               goto end;
+       }
+
+       channel->monitor_timer_enabled = 0;
+end:
+       return ret;
+}
+
+/*
+ * Block the RT signals for the entire process. It must be called from the
+ * consumer main before creating the threads
+ */
+int consumer_signal_init(void)
+{
+       int ret;
+       sigset_t mask;
+
+       /* Block signal for entire process, so only our thread processes it. */
+       setmask(&mask);
+       ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_sigmask");
+               return -1;
+       }
+       return 0;
+}
+
+static
+int sample_channel_positions(struct lttng_consumer_channel *channel,
+               uint64_t *_highest_use, uint64_t *_lowest_use, uint64_t *_total_consumed,
+               sample_positions_cb sample, get_consumed_cb get_consumed,
+               get_produced_cb get_produced)
+{
+       int ret = 0;
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+       bool empty_channel = true;
+       uint64_t high = 0, low = UINT64_MAX;
+       struct lttng_ht *ht = the_consumer_data.stream_per_chan_id_ht;
+
+       *_total_consumed = 0;
+
+       rcu_read_lock();
+
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&channel->key, lttng_ht_seed),
+                       ht->match_fct, &channel->key,
+                       &iter.iter, stream, node_channel_id.node) {
+               unsigned long produced, consumed, usage;
+
+               empty_channel = false;
+
+               pthread_mutex_lock(&stream->lock);
+               if (cds_lfht_is_node_deleted(&stream->node.node)) {
+                       goto next;
+               }
+
+               ret = sample(stream);
+               if (ret) {
+                       ERR("Failed to take buffer position snapshot in monitor timer (ret = %d)", ret);
+                       pthread_mutex_unlock(&stream->lock);
+                       goto end;
+               }
+               ret = get_consumed(stream, &consumed);
+               if (ret) {
+                       ERR("Failed to get buffer consumed position in monitor timer");
+                       pthread_mutex_unlock(&stream->lock);
+                       goto end;
+               }
+               ret = get_produced(stream, &produced);
+               if (ret) {
+                       ERR("Failed to get buffer produced position in monitor timer");
+                       pthread_mutex_unlock(&stream->lock);
+                       goto end;
+               }
+
+               usage = produced - consumed;
+               high = (usage > high) ? usage : high;
+               low = (usage < low) ? usage : low;
+
+               /*
+                * We don't use consumed here for 2 reasons:
+                *  - output_written takes into account the padding written in the
+                *    tracefiles when we stop the session;
+                *  - the consumed position is not the accurate representation of what
+                *    was extracted from a buffer in overwrite mode.
+                */
+               *_total_consumed += stream->output_written;
+       next:
+               pthread_mutex_unlock(&stream->lock);
+       }
+
+       *_highest_use = high;
+       *_lowest_use = low;
+end:
+       rcu_read_unlock();
+       if (empty_channel) {
+               ret = -1;
+       }
+       return ret;
+}
+
+/*
+ * Execute action on a monitor timer.
+ */
+static
+void monitor_timer(struct lttng_consumer_channel *channel)
+{
+       int ret;
+       int channel_monitor_pipe =
+                       consumer_timer_thread_get_channel_monitor_pipe();
+       struct lttcomm_consumer_channel_monitor_msg msg = {
+               .key = channel->key,
+       };
+       sample_positions_cb sample;
+       get_consumed_cb get_consumed;
+       get_produced_cb get_produced;
+       uint64_t lowest = 0, highest = 0, total_consumed = 0;
+
+       LTTNG_ASSERT(channel);
+
+       if (channel_monitor_pipe < 0) {
+               return;
+       }
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               sample = lttng_kconsumer_sample_snapshot_positions;
+               get_consumed = lttng_kconsumer_get_consumed_snapshot;
+               get_produced = lttng_kconsumer_get_produced_snapshot;
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               sample = lttng_ustconsumer_sample_snapshot_positions;
+               get_consumed = lttng_ustconsumer_get_consumed_snapshot;
+               get_produced = lttng_ustconsumer_get_produced_snapshot;
+               break;
+       default:
+               abort();
+       }
+
+       ret = sample_channel_positions(channel, &highest, &lowest,
+                       &total_consumed, sample, get_consumed, get_produced);
+       if (ret) {
+               return;
+       }
+       msg.highest = highest;
+       msg.lowest = lowest;
+       msg.total_consumed = total_consumed;
+
+       /*
+        * Writes performed here are assumed to be atomic which is only
+        * guaranteed for sizes < than PIPE_BUF.
+        */
+       LTTNG_ASSERT(sizeof(msg) <= PIPE_BUF);
+
+       do {
+               ret = write(channel_monitor_pipe, &msg, sizeof(msg));
+       } while (ret == -1 && errno == EINTR);
+       if (ret == -1) {
+               if (errno == EAGAIN) {
+                       /* Not an error, the sample is merely dropped. */
+                       DBG("Channel monitor pipe is full; dropping sample for channel key = %" PRIu64,
+                                       channel->key);
+               } else {
+                       PERROR("write to the channel monitor pipe");
+               }
+       } else {
+               DBG("Sent channel monitoring sample for channel key %" PRIu64
+                               ", (highest = %" PRIu64 ", lowest = %" PRIu64 ")",
+                               channel->key, msg.highest, msg.lowest);
+       }
+}
+
+int consumer_timer_thread_get_channel_monitor_pipe(void)
+{
+       return uatomic_read(&the_channel_monitor_pipe);
+}
+
+int consumer_timer_thread_set_channel_monitor_pipe(int fd)
+{
+       int ret;
+
+       ret = uatomic_cmpxchg(&the_channel_monitor_pipe, -1, fd);
+       if (ret != -1) {
+               ret = -1;
+               goto end;
+       }
+       ret = 0;
+end:
+       return ret;
+}
+
+/*
+ * This thread is the sighandler for signals LTTNG_CONSUMER_SIG_SWITCH,
+ * LTTNG_CONSUMER_SIG_TEARDOWN, LTTNG_CONSUMER_SIG_LIVE, and
+ * LTTNG_CONSUMER_SIG_MONITOR, LTTNG_CONSUMER_SIG_EXIT.
+ */
+void *consumer_timer_thread(void *data)
+{
+       int signr;
+       sigset_t mask;
+       siginfo_t info;
+       struct lttng_consumer_local_data *ctx = (lttng_consumer_local_data *) data;
+
+       rcu_register_thread();
+
+       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_METADATA_TIMER);
+
+       if (testpoint(consumerd_thread_metadata_timer)) {
+               goto error_testpoint;
+       }
+
+       health_code_update();
+
+       /* Only self thread will receive signal mask. */
+       setmask(&mask);
+       CMM_STORE_SHARED(timer_signal.tid, pthread_self());
+
+       while (1) {
+               health_code_update();
+
+               health_poll_entry();
+               signr = sigwaitinfo(&mask, &info);
+               health_poll_exit();
+
+               /*
+                * NOTE: cascading conditions are used instead of a switch case
+                * since the use of SIGRTMIN in the definition of the signals'
+                * values prevents the reduction to an integer constant.
+                */
+               if (signr == -1) {
+                       if (errno != EINTR) {
+                               PERROR("sigwaitinfo");
+                       }
+                       continue;
+               } else if (signr == LTTNG_CONSUMER_SIG_SWITCH) {
+                       metadata_switch_timer(ctx, &info);
+               } else if (signr == LTTNG_CONSUMER_SIG_TEARDOWN) {
+                       cmm_smp_mb();
+                       CMM_STORE_SHARED(timer_signal.qs_done, 1);
+                       cmm_smp_mb();
+                       DBG("Signal timer metadata thread teardown");
+               } else if (signr == LTTNG_CONSUMER_SIG_LIVE) {
+                       live_timer(ctx, &info);
+               } else if (signr == LTTNG_CONSUMER_SIG_MONITOR) {
+                       struct lttng_consumer_channel *channel;
+
+                       channel = (lttng_consumer_channel *) info.si_value.sival_ptr;
+                       monitor_timer(channel);
+               } else if (signr == LTTNG_CONSUMER_SIG_EXIT) {
+                       LTTNG_ASSERT(CMM_LOAD_SHARED(consumer_quit));
+                       goto end;
+               } else {
+                       ERR("Unexpected signal %d\n", info.si_signo);
+               }
+       }
+
+error_testpoint:
+       /* Only reached in testpoint error */
+       health_error();
+end:
+       health_unregister(health_consumerd);
+       rcu_unregister_thread();
+       return NULL;
+}
diff --git a/src/common/consumer/consumer.c b/src/common/consumer/consumer.c
deleted file mode 100644 (file)
index 84fdbca..0000000
+++ /dev/null
@@ -1,5259 +0,0 @@
-/*
- * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
- * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#include "common/index/ctf-index.h"
-#define _LGPL_SOURCE
-#include <poll.h>
-#include <pthread.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/mman.h>
-#include <sys/socket.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include <inttypes.h>
-#include <signal.h>
-
-#include <bin/lttng-consumerd/health-consumerd.h>
-#include <common/common.h>
-#include <common/utils.h>
-#include <common/time.h>
-#include <common/compat/poll.h>
-#include <common/compat/endian.h>
-#include <common/index/index.h>
-#include <common/kernel-ctl/kernel-ctl.h>
-#include <common/sessiond-comm/relayd.h>
-#include <common/sessiond-comm/sessiond-comm.h>
-#include <common/kernel-consumer/kernel-consumer.h>
-#include <common/relayd/relayd.h>
-#include <common/ust-consumer/ust-consumer.h>
-#include <common/consumer/consumer-timer.h>
-#include <common/consumer/consumer.h>
-#include <common/consumer/consumer-stream.h>
-#include <common/consumer/consumer-testpoint.h>
-#include <common/align.h>
-#include <common/consumer/consumer-metadata-cache.h>
-#include <common/trace-chunk.h>
-#include <common/trace-chunk-registry.h>
-#include <common/string-utils/format.h>
-#include <common/dynamic-array.h>
-
-struct lttng_consumer_global_data the_consumer_data = {
-               .stream_count = 0,
-               .need_update = 1,
-               .type = LTTNG_CONSUMER_UNKNOWN,
-};
-
-enum consumer_channel_action {
-       CONSUMER_CHANNEL_ADD,
-       CONSUMER_CHANNEL_DEL,
-       CONSUMER_CHANNEL_QUIT,
-};
-
-struct consumer_channel_msg {
-       enum consumer_channel_action action;
-       struct lttng_consumer_channel *chan;    /* add */
-       uint64_t key;                           /* del */
-};
-
-/* Flag used to temporarily pause data consumption from testpoints. */
-int data_consumption_paused;
-
-/*
- * Flag to inform the polling thread to quit when all fd hung up. Updated by
- * the consumer_thread_receive_fds when it notices that all fds has hung up.
- * Also updated by the signal handler (consumer_should_exit()). Read by the
- * polling threads.
- */
-int consumer_quit;
-
-/*
- * Global hash table containing respectively metadata and data streams. The
- * stream element in this ht should only be updated by the metadata poll thread
- * for the metadata and the data poll thread for the data.
- */
-static struct lttng_ht *metadata_ht;
-static struct lttng_ht *data_ht;
-
-static const char *get_consumer_domain(void)
-{
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               return DEFAULT_KERNEL_TRACE_DIR;
-       case LTTNG_CONSUMER64_UST:
-               /* Fall-through. */
-       case LTTNG_CONSUMER32_UST:
-               return DEFAULT_UST_TRACE_DIR;
-       default:
-               abort();
-       }
-}
-
-/*
- * Notify a thread lttng pipe to poll back again. This usually means that some
- * global state has changed so we just send back the thread in a poll wait
- * call.
- */
-static void notify_thread_lttng_pipe(struct lttng_pipe *pipe)
-{
-       struct lttng_consumer_stream *null_stream = NULL;
-
-       LTTNG_ASSERT(pipe);
-
-       (void) lttng_pipe_write(pipe, &null_stream, sizeof(null_stream));
-}
-
-static void notify_health_quit_pipe(int *pipe)
-{
-       ssize_t ret;
-
-       ret = lttng_write(pipe[1], "4", 1);
-       if (ret < 1) {
-               PERROR("write consumer health quit");
-       }
-}
-
-static void notify_channel_pipe(struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_channel *chan,
-               uint64_t key,
-               enum consumer_channel_action action)
-{
-       struct consumer_channel_msg msg;
-       ssize_t ret;
-
-       memset(&msg, 0, sizeof(msg));
-
-       msg.action = action;
-       msg.chan = chan;
-       msg.key = key;
-       ret = lttng_write(ctx->consumer_channel_pipe[1], &msg, sizeof(msg));
-       if (ret < sizeof(msg)) {
-               PERROR("notify_channel_pipe write error");
-       }
-}
-
-void notify_thread_del_channel(struct lttng_consumer_local_data *ctx,
-               uint64_t key)
-{
-       notify_channel_pipe(ctx, NULL, key, CONSUMER_CHANNEL_DEL);
-}
-
-static int read_channel_pipe(struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_channel **chan,
-               uint64_t *key,
-               enum consumer_channel_action *action)
-{
-       struct consumer_channel_msg msg;
-       ssize_t ret;
-
-       ret = lttng_read(ctx->consumer_channel_pipe[0], &msg, sizeof(msg));
-       if (ret < sizeof(msg)) {
-               ret = -1;
-               goto error;
-       }
-       *action = msg.action;
-       *chan = msg.chan;
-       *key = msg.key;
-error:
-       return (int) ret;
-}
-
-/*
- * Cleanup the stream list of a channel. Those streams are not yet globally
- * visible
- */
-static void clean_channel_stream_list(struct lttng_consumer_channel *channel)
-{
-       struct lttng_consumer_stream *stream, *stmp;
-
-       LTTNG_ASSERT(channel);
-
-       /* Delete streams that might have been left in the stream list. */
-       cds_list_for_each_entry_safe(stream, stmp, &channel->streams.head,
-                       send_node) {
-               cds_list_del(&stream->send_node);
-               /*
-                * Once a stream is added to this list, the buffers were created so we
-                * have a guarantee that this call will succeed. Setting the monitor
-                * mode to 0 so we don't lock nor try to delete the stream from the
-                * global hash table.
-                */
-               stream->monitor = 0;
-               consumer_stream_destroy(stream, NULL);
-       }
-}
-
-/*
- * Find a stream. The consumer_data.lock must be locked during this
- * call.
- */
-static struct lttng_consumer_stream *find_stream(uint64_t key,
-               struct lttng_ht *ht)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_ht_node_u64 *node;
-       struct lttng_consumer_stream *stream = NULL;
-
-       LTTNG_ASSERT(ht);
-
-       /* -1ULL keys are lookup failures */
-       if (key == (uint64_t) -1ULL) {
-               return NULL;
-       }
-
-       rcu_read_lock();
-
-       lttng_ht_lookup(ht, &key, &iter);
-       node = lttng_ht_iter_get_node_u64(&iter);
-       if (node != NULL) {
-               stream = caa_container_of(node, struct lttng_consumer_stream, node);
-       }
-
-       rcu_read_unlock();
-
-       return stream;
-}
-
-static void steal_stream_key(uint64_t key, struct lttng_ht *ht)
-{
-       struct lttng_consumer_stream *stream;
-
-       rcu_read_lock();
-       stream = find_stream(key, ht);
-       if (stream) {
-               stream->key = (uint64_t) -1ULL;
-               /*
-                * We don't want the lookup to match, but we still need
-                * to iterate on this stream when iterating over the hash table. Just
-                * change the node key.
-                */
-               stream->node.key = (uint64_t) -1ULL;
-       }
-       rcu_read_unlock();
-}
-
-/*
- * Return a channel object for the given key.
- *
- * RCU read side lock MUST be acquired before calling this function and
- * protects the channel ptr.
- */
-struct lttng_consumer_channel *consumer_find_channel(uint64_t key)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_ht_node_u64 *node;
-       struct lttng_consumer_channel *channel = NULL;
-
-       /* -1ULL keys are lookup failures */
-       if (key == (uint64_t) -1ULL) {
-               return NULL;
-       }
-
-       lttng_ht_lookup(the_consumer_data.channel_ht, &key, &iter);
-       node = lttng_ht_iter_get_node_u64(&iter);
-       if (node != NULL) {
-               channel = caa_container_of(node, struct lttng_consumer_channel, node);
-       }
-
-       return channel;
-}
-
-/*
- * There is a possibility that the consumer does not have enough time between
- * the close of the channel on the session daemon and the cleanup in here thus
- * once we have a channel add with an existing key, we know for sure that this
- * channel will eventually get cleaned up by all streams being closed.
- *
- * This function just nullifies the already existing channel key.
- */
-static void steal_channel_key(uint64_t key)
-{
-       struct lttng_consumer_channel *channel;
-
-       rcu_read_lock();
-       channel = consumer_find_channel(key);
-       if (channel) {
-               channel->key = (uint64_t) -1ULL;
-               /*
-                * We don't want the lookup to match, but we still need to iterate on
-                * this channel when iterating over the hash table. Just change the
-                * node key.
-                */
-               channel->node.key = (uint64_t) -1ULL;
-       }
-       rcu_read_unlock();
-}
-
-static void free_channel_rcu(struct rcu_head *head)
-{
-       struct lttng_ht_node_u64 *node =
-               caa_container_of(head, struct lttng_ht_node_u64, head);
-       struct lttng_consumer_channel *channel =
-               caa_container_of(node, struct lttng_consumer_channel, node);
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               lttng_ustconsumer_free_channel(channel);
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-       }
-       free(channel);
-}
-
-/*
- * RCU protected relayd socket pair free.
- */
-static void free_relayd_rcu(struct rcu_head *head)
-{
-       struct lttng_ht_node_u64 *node =
-               caa_container_of(head, struct lttng_ht_node_u64, head);
-       struct consumer_relayd_sock_pair *relayd =
-               caa_container_of(node, struct consumer_relayd_sock_pair, node);
-
-       /*
-        * Close all sockets. This is done in the call RCU since we don't want the
-        * socket fds to be reassigned thus potentially creating bad state of the
-        * relayd object.
-        *
-        * We do not have to lock the control socket mutex here since at this stage
-        * there is no one referencing to this relayd object.
-        */
-       (void) relayd_close(&relayd->control_sock);
-       (void) relayd_close(&relayd->data_sock);
-
-       pthread_mutex_destroy(&relayd->ctrl_sock_mutex);
-       free(relayd);
-}
-
-/*
- * Destroy and free relayd socket pair object.
- */
-void consumer_destroy_relayd(struct consumer_relayd_sock_pair *relayd)
-{
-       int ret;
-       struct lttng_ht_iter iter;
-
-       if (relayd == NULL) {
-               return;
-       }
-
-       DBG("Consumer destroy and close relayd socket pair");
-
-       iter.iter.node = &relayd->node.node;
-       ret = lttng_ht_del(the_consumer_data.relayd_ht, &iter);
-       if (ret != 0) {
-               /* We assume the relayd is being or is destroyed */
-               return;
-       }
-
-       /* RCU free() call */
-       call_rcu(&relayd->node.head, free_relayd_rcu);
-}
-
-/*
- * Remove a channel from the global list protected by a mutex. This function is
- * also responsible for freeing its data structures.
- */
-void consumer_del_channel(struct lttng_consumer_channel *channel)
-{
-       struct lttng_ht_iter iter;
-
-       DBG("Consumer delete channel key %" PRIu64, channel->key);
-
-       pthread_mutex_lock(&the_consumer_data.lock);
-       pthread_mutex_lock(&channel->lock);
-
-       /* Destroy streams that might have been left in the stream list. */
-       clean_channel_stream_list(channel);
-
-       if (channel->live_timer_enabled == 1) {
-               consumer_timer_live_stop(channel);
-       }
-       if (channel->monitor_timer_enabled == 1) {
-               consumer_timer_monitor_stop(channel);
-       }
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               lttng_ustconsumer_del_channel(channel);
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-               goto end;
-       }
-
-       lttng_trace_chunk_put(channel->trace_chunk);
-       channel->trace_chunk = NULL;
-
-       if (channel->is_published) {
-               int ret;
-
-               rcu_read_lock();
-               iter.iter.node = &channel->node.node;
-               ret = lttng_ht_del(the_consumer_data.channel_ht, &iter);
-               LTTNG_ASSERT(!ret);
-
-               iter.iter.node = &channel->channels_by_session_id_ht_node.node;
-               ret = lttng_ht_del(the_consumer_data.channels_by_session_id_ht,
-                               &iter);
-               LTTNG_ASSERT(!ret);
-               rcu_read_unlock();
-       }
-
-       channel->is_deleted = true;
-       call_rcu(&channel->node.head, free_channel_rcu);
-end:
-       pthread_mutex_unlock(&channel->lock);
-       pthread_mutex_unlock(&the_consumer_data.lock);
-}
-
-/*
- * Iterate over the relayd hash table and destroy each element. Finally,
- * destroy the whole hash table.
- */
-static void cleanup_relayd_ht(void)
-{
-       struct lttng_ht_iter iter;
-       struct consumer_relayd_sock_pair *relayd;
-
-       rcu_read_lock();
-
-       cds_lfht_for_each_entry(the_consumer_data.relayd_ht->ht, &iter.iter,
-                       relayd, node.node) {
-               consumer_destroy_relayd(relayd);
-       }
-
-       rcu_read_unlock();
-
-       lttng_ht_destroy(the_consumer_data.relayd_ht);
-}
-
-/*
- * Update the end point status of all streams having the given network sequence
- * index (relayd index).
- *
- * It's atomically set without having the stream mutex locked which is fine
- * because we handle the write/read race with a pipe wakeup for each thread.
- */
-static void update_endpoint_status_by_netidx(uint64_t net_seq_idx,
-               enum consumer_endpoint_status status)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_stream *stream;
-
-       DBG("Consumer set delete flag on stream by idx %" PRIu64, net_seq_idx);
-
-       rcu_read_lock();
-
-       /* Let's begin with metadata */
-       cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream, node.node) {
-               if (stream->net_seq_idx == net_seq_idx) {
-                       uatomic_set(&stream->endpoint_status, status);
-                       DBG("Delete flag set to metadata stream %d", stream->wait_fd);
-               }
-       }
-
-       /* Follow up by the data streams */
-       cds_lfht_for_each_entry(data_ht->ht, &iter.iter, stream, node.node) {
-               if (stream->net_seq_idx == net_seq_idx) {
-                       uatomic_set(&stream->endpoint_status, status);
-                       DBG("Delete flag set to data stream %d", stream->wait_fd);
-               }
-       }
-       rcu_read_unlock();
-}
-
-/*
- * Cleanup a relayd object by flagging every associated streams for deletion,
- * destroying the object meaning removing it from the relayd hash table,
- * closing the sockets and freeing the memory in a RCU call.
- *
- * If a local data context is available, notify the threads that the streams'
- * state have changed.
- */
-void lttng_consumer_cleanup_relayd(struct consumer_relayd_sock_pair *relayd)
-{
-       uint64_t netidx;
-
-       LTTNG_ASSERT(relayd);
-
-       DBG("Cleaning up relayd object ID %"PRIu64, relayd->net_seq_idx);
-
-       /* Save the net sequence index before destroying the object */
-       netidx = relayd->net_seq_idx;
-
-       /*
-        * Delete the relayd from the relayd hash table, close the sockets and free
-        * the object in a RCU call.
-        */
-       consumer_destroy_relayd(relayd);
-
-       /* Set inactive endpoint to all streams */
-       update_endpoint_status_by_netidx(netidx, CONSUMER_ENDPOINT_INACTIVE);
-
-       /*
-        * With a local data context, notify the threads that the streams' state
-        * have changed. The write() action on the pipe acts as an "implicit"
-        * memory barrier ordering the updates of the end point status from the
-        * read of this status which happens AFTER receiving this notify.
-        */
-       notify_thread_lttng_pipe(relayd->ctx->consumer_data_pipe);
-       notify_thread_lttng_pipe(relayd->ctx->consumer_metadata_pipe);
-}
-
-/*
- * Flag a relayd socket pair for destruction. Destroy it if the refcount
- * reaches zero.
- *
- * RCU read side lock MUST be aquired before calling this function.
- */
-void consumer_flag_relayd_for_destroy(struct consumer_relayd_sock_pair *relayd)
-{
-       LTTNG_ASSERT(relayd);
-
-       /* Set destroy flag for this object */
-       uatomic_set(&relayd->destroy_flag, 1);
-
-       /* Destroy the relayd if refcount is 0 */
-       if (uatomic_read(&relayd->refcount) == 0) {
-               consumer_destroy_relayd(relayd);
-       }
-}
-
-/*
- * Completly destroy stream from every visiable data structure and the given
- * hash table if one.
- *
- * One this call returns, the stream object is not longer usable nor visible.
- */
-void consumer_del_stream(struct lttng_consumer_stream *stream,
-               struct lttng_ht *ht)
-{
-       consumer_stream_destroy(stream, ht);
-}
-
-/*
- * XXX naming of del vs destroy is all mixed up.
- */
-void consumer_del_stream_for_data(struct lttng_consumer_stream *stream)
-{
-       consumer_stream_destroy(stream, data_ht);
-}
-
-void consumer_del_stream_for_metadata(struct lttng_consumer_stream *stream)
-{
-       consumer_stream_destroy(stream, metadata_ht);
-}
-
-void consumer_stream_update_channel_attributes(
-               struct lttng_consumer_stream *stream,
-               struct lttng_consumer_channel *channel)
-{
-       stream->channel_read_only_attributes.tracefile_size =
-                       channel->tracefile_size;
-}
-
-/*
- * Add a stream to the global list protected by a mutex.
- */
-void consumer_add_data_stream(struct lttng_consumer_stream *stream)
-{
-       struct lttng_ht *ht = data_ht;
-
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(ht);
-
-       DBG3("Adding consumer stream %" PRIu64, stream->key);
-
-       pthread_mutex_lock(&the_consumer_data.lock);
-       pthread_mutex_lock(&stream->chan->lock);
-       pthread_mutex_lock(&stream->chan->timer_lock);
-       pthread_mutex_lock(&stream->lock);
-       rcu_read_lock();
-
-       /* Steal stream identifier to avoid having streams with the same key */
-       steal_stream_key(stream->key, ht);
-
-       lttng_ht_add_unique_u64(ht, &stream->node);
-
-       lttng_ht_add_u64(the_consumer_data.stream_per_chan_id_ht,
-                       &stream->node_channel_id);
-
-       /*
-        * Add stream to the stream_list_ht of the consumer data. No need to steal
-        * the key since the HT does not use it and we allow to add redundant keys
-        * into this table.
-        */
-       lttng_ht_add_u64(the_consumer_data.stream_list_ht,
-                       &stream->node_session_id);
-
-       /*
-        * When nb_init_stream_left reaches 0, we don't need to trigger any action
-        * in terms of destroying the associated channel, because the action that
-        * causes the count to become 0 also causes a stream to be added. The
-        * channel deletion will thus be triggered by the following removal of this
-        * stream.
-        */
-       if (uatomic_read(&stream->chan->nb_init_stream_left) > 0) {
-               /* Increment refcount before decrementing nb_init_stream_left */
-               cmm_smp_wmb();
-               uatomic_dec(&stream->chan->nb_init_stream_left);
-       }
-
-       /* Update consumer data once the node is inserted. */
-       the_consumer_data.stream_count++;
-       the_consumer_data.need_update = 1;
-
-       rcu_read_unlock();
-       pthread_mutex_unlock(&stream->lock);
-       pthread_mutex_unlock(&stream->chan->timer_lock);
-       pthread_mutex_unlock(&stream->chan->lock);
-       pthread_mutex_unlock(&the_consumer_data.lock);
-}
-
-/*
- * Add relayd socket to global consumer data hashtable. RCU read side lock MUST
- * be acquired before calling this.
- */
-static int add_relayd(struct consumer_relayd_sock_pair *relayd)
-{
-       int ret = 0;
-       struct lttng_ht_node_u64 *node;
-       struct lttng_ht_iter iter;
-
-       LTTNG_ASSERT(relayd);
-
-       lttng_ht_lookup(the_consumer_data.relayd_ht, &relayd->net_seq_idx,
-                       &iter);
-       node = lttng_ht_iter_get_node_u64(&iter);
-       if (node != NULL) {
-               goto end;
-       }
-       lttng_ht_add_unique_u64(the_consumer_data.relayd_ht, &relayd->node);
-
-end:
-       return ret;
-}
-
-/*
- * Allocate and return a consumer relayd socket.
- */
-static struct consumer_relayd_sock_pair *consumer_allocate_relayd_sock_pair(
-               uint64_t net_seq_idx)
-{
-       struct consumer_relayd_sock_pair *obj = NULL;
-
-       /* net sequence index of -1 is a failure */
-       if (net_seq_idx == (uint64_t) -1ULL) {
-               goto error;
-       }
-
-       obj = zmalloc(sizeof(struct consumer_relayd_sock_pair));
-       if (obj == NULL) {
-               PERROR("zmalloc relayd sock");
-               goto error;
-       }
-
-       obj->net_seq_idx = net_seq_idx;
-       obj->refcount = 0;
-       obj->destroy_flag = 0;
-       obj->control_sock.sock.fd = -1;
-       obj->data_sock.sock.fd = -1;
-       lttng_ht_node_init_u64(&obj->node, obj->net_seq_idx);
-       pthread_mutex_init(&obj->ctrl_sock_mutex, NULL);
-
-error:
-       return obj;
-}
-
-/*
- * Find a relayd socket pair in the global consumer data.
- *
- * Return the object if found else NULL.
- * RCU read-side lock must be held across this call and while using the
- * returned object.
- */
-struct consumer_relayd_sock_pair *consumer_find_relayd(uint64_t key)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_ht_node_u64 *node;
-       struct consumer_relayd_sock_pair *relayd = NULL;
-
-       /* Negative keys are lookup failures */
-       if (key == (uint64_t) -1ULL) {
-               goto error;
-       }
-
-       lttng_ht_lookup(the_consumer_data.relayd_ht, &key, &iter);
-       node = lttng_ht_iter_get_node_u64(&iter);
-       if (node != NULL) {
-               relayd = caa_container_of(node, struct consumer_relayd_sock_pair, node);
-       }
-
-error:
-       return relayd;
-}
-
-/*
- * Find a relayd and send the stream
- *
- * Returns 0 on success, < 0 on error
- */
-int consumer_send_relayd_stream(struct lttng_consumer_stream *stream,
-               char *path)
-{
-       int ret = 0;
-       struct consumer_relayd_sock_pair *relayd;
-
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->net_seq_idx != -1ULL);
-       LTTNG_ASSERT(path);
-
-       /* The stream is not metadata. Get relayd reference if exists. */
-       rcu_read_lock();
-       relayd = consumer_find_relayd(stream->net_seq_idx);
-       if (relayd != NULL) {
-               /* Add stream on the relayd */
-               pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-               ret = relayd_add_stream(&relayd->control_sock, stream->name,
-                               get_consumer_domain(), path, &stream->relayd_stream_id,
-                               stream->chan->tracefile_size,
-                               stream->chan->tracefile_count,
-                               stream->trace_chunk);
-               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-               if (ret < 0) {
-                       ERR("Relayd add stream failed. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
-                       lttng_consumer_cleanup_relayd(relayd);
-                       goto end;
-               }
-
-               uatomic_inc(&relayd->refcount);
-               stream->sent_to_relayd = 1;
-       } else {
-               ERR("Stream %" PRIu64 " relayd ID %" PRIu64 " unknown. Can't send it.",
-                               stream->key, stream->net_seq_idx);
-               ret = -1;
-               goto end;
-       }
-
-       DBG("Stream %s with key %" PRIu64 " sent to relayd id %" PRIu64,
-                       stream->name, stream->key, stream->net_seq_idx);
-
-end:
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Find a relayd and send the streams sent message
- *
- * Returns 0 on success, < 0 on error
- */
-int consumer_send_relayd_streams_sent(uint64_t net_seq_idx)
-{
-       int ret = 0;
-       struct consumer_relayd_sock_pair *relayd;
-
-       LTTNG_ASSERT(net_seq_idx != -1ULL);
-
-       /* The stream is not metadata. Get relayd reference if exists. */
-       rcu_read_lock();
-       relayd = consumer_find_relayd(net_seq_idx);
-       if (relayd != NULL) {
-               /* Add stream on the relayd */
-               pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-               ret = relayd_streams_sent(&relayd->control_sock);
-               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-               if (ret < 0) {
-                       ERR("Relayd streams sent failed. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
-                       lttng_consumer_cleanup_relayd(relayd);
-                       goto end;
-               }
-       } else {
-               ERR("Relayd ID %" PRIu64 " unknown. Can't send streams_sent.",
-                               net_seq_idx);
-               ret = -1;
-               goto end;
-       }
-
-       ret = 0;
-       DBG("All streams sent relayd id %" PRIu64, net_seq_idx);
-
-end:
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Find a relayd and close the stream
- */
-void close_relayd_stream(struct lttng_consumer_stream *stream)
-{
-       struct consumer_relayd_sock_pair *relayd;
-
-       /* The stream is not metadata. Get relayd reference if exists. */
-       rcu_read_lock();
-       relayd = consumer_find_relayd(stream->net_seq_idx);
-       if (relayd) {
-               consumer_stream_relayd_close(stream, relayd);
-       }
-       rcu_read_unlock();
-}
-
-/*
- * Handle stream for relayd transmission if the stream applies for network
- * streaming where the net sequence index is set.
- *
- * Return destination file descriptor or negative value on error.
- */
-static int write_relayd_stream_header(struct lttng_consumer_stream *stream,
-               size_t data_size, unsigned long padding,
-               struct consumer_relayd_sock_pair *relayd)
-{
-       int outfd = -1, ret;
-       struct lttcomm_relayd_data_hdr data_hdr;
-
-       /* Safety net */
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(relayd);
-
-       /* Reset data header */
-       memset(&data_hdr, 0, sizeof(data_hdr));
-
-       if (stream->metadata_flag) {
-               /* Caller MUST acquire the relayd control socket lock */
-               ret = relayd_send_metadata(&relayd->control_sock, data_size);
-               if (ret < 0) {
-                       goto error;
-               }
-
-               /* Metadata are always sent on the control socket. */
-               outfd = relayd->control_sock.sock.fd;
-       } else {
-               /* Set header with stream information */
-               data_hdr.stream_id = htobe64(stream->relayd_stream_id);
-               data_hdr.data_size = htobe32(data_size);
-               data_hdr.padding_size = htobe32(padding);
-
-               /*
-                * Note that net_seq_num below is assigned with the *current* value of
-                * next_net_seq_num and only after that the next_net_seq_num will be
-                * increment. This is why when issuing a command on the relayd using
-                * this next value, 1 should always be substracted in order to compare
-                * the last seen sequence number on the relayd side to the last sent.
-                */
-               data_hdr.net_seq_num = htobe64(stream->next_net_seq_num);
-               /* Other fields are zeroed previously */
-
-               ret = relayd_send_data_hdr(&relayd->data_sock, &data_hdr,
-                               sizeof(data_hdr));
-               if (ret < 0) {
-                       goto error;
-               }
-
-               ++stream->next_net_seq_num;
-
-               /* Set to go on data socket */
-               outfd = relayd->data_sock.sock.fd;
-       }
-
-error:
-       return outfd;
-}
-
-/*
- * Write a character on the metadata poll pipe to wake the metadata thread.
- * Returns 0 on success, -1 on error.
- */
-int consumer_metadata_wakeup_pipe(const struct lttng_consumer_channel *channel)
-{
-       int ret = 0;
-
-       DBG("Waking up metadata poll thread (writing to pipe): channel name = '%s'",
-                       channel->name);
-       if (channel->monitor && channel->metadata_stream) {
-               const char dummy = 'c';
-               const ssize_t write_ret = lttng_write(
-                               channel->metadata_stream->ust_metadata_poll_pipe[1],
-                               &dummy, 1);
-
-               if (write_ret < 1) {
-                       if (errno == EWOULDBLOCK) {
-                               /*
-                                * This is fine, the metadata poll thread
-                                * is having a hard time keeping-up, but
-                                * it will eventually wake-up and consume
-                                * the available data.
-                                */
-                               ret = 0;
-                       } else {
-                               PERROR("Failed to write to UST metadata pipe while attempting to wake-up the metadata poll thread");
-                               ret = -1;
-                               goto end;
-                       }
-               }
-       }
-
-end:
-       return ret;
-}
-
-/*
- * Trigger a dump of the metadata content. Following/during the succesful
- * completion of this call, the metadata poll thread will start receiving
- * metadata packets to consume.
- *
- * The caller must hold the channel and stream locks.
- */
-static
-int consumer_metadata_stream_dump(struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       ASSERT_LOCKED(stream->chan->lock);
-       ASSERT_LOCKED(stream->lock);
-       LTTNG_ASSERT(stream->metadata_flag);
-       LTTNG_ASSERT(stream->chan->trace_chunk);
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               /*
-                * Reset the position of what has been read from the
-                * metadata cache to 0 so we can dump it again.
-                */
-               ret = kernctl_metadata_cache_dump(stream->wait_fd);
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               /*
-                * Reset the position pushed from the metadata cache so it
-                * will write from the beginning on the next push.
-                */
-               stream->ust_metadata_pushed = 0;
-               ret = consumer_metadata_wakeup_pipe(stream->chan);
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-       }
-       if (ret < 0) {
-               ERR("Failed to dump the metadata cache");
-       }
-       return ret;
-}
-
-static
-int lttng_consumer_channel_set_trace_chunk(
-               struct lttng_consumer_channel *channel,
-               struct lttng_trace_chunk *new_trace_chunk)
-{
-       pthread_mutex_lock(&channel->lock);
-       if (channel->is_deleted) {
-               /*
-                * The channel has been logically deleted and should no longer
-                * be used. It has released its reference to its current trace
-                * chunk and should not acquire a new one.
-                *
-                * Return success as there is nothing for the caller to do.
-                */
-               goto end;
-       }
-
-       /*
-        * The acquisition of the reference cannot fail (barring
-        * a severe internal error) since a reference to the published
-        * chunk is already held by the caller.
-        */
-       if (new_trace_chunk) {
-               const bool acquired_reference = lttng_trace_chunk_get(
-                               new_trace_chunk);
-
-               LTTNG_ASSERT(acquired_reference);
-       }
-
-       lttng_trace_chunk_put(channel->trace_chunk);
-       channel->trace_chunk = new_trace_chunk;
-end:
-       pthread_mutex_unlock(&channel->lock);
-       return 0;
-}
-
-/*
- * Allocate and return a new lttng_consumer_channel object using the given key
- * to initialize the hash table node.
- *
- * On error, return NULL.
- */
-struct lttng_consumer_channel *consumer_allocate_channel(uint64_t key,
-               uint64_t session_id,
-               const uint64_t *chunk_id,
-               const char *pathname,
-               const char *name,
-               uint64_t relayd_id,
-               enum lttng_event_output output,
-               uint64_t tracefile_size,
-               uint64_t tracefile_count,
-               uint64_t session_id_per_pid,
-               unsigned int monitor,
-               unsigned int live_timer_interval,
-               bool is_in_live_session,
-               const char *root_shm_path,
-               const char *shm_path)
-{
-       struct lttng_consumer_channel *channel = NULL;
-       struct lttng_trace_chunk *trace_chunk = NULL;
-
-       if (chunk_id) {
-               trace_chunk = lttng_trace_chunk_registry_find_chunk(
-                               the_consumer_data.chunk_registry, session_id,
-                               *chunk_id);
-               if (!trace_chunk) {
-                       ERR("Failed to find trace chunk reference during creation of channel");
-                       goto end;
-               }
-       }
-
-       channel = zmalloc(sizeof(*channel));
-       if (channel == NULL) {
-               PERROR("malloc struct lttng_consumer_channel");
-               goto end;
-       }
-
-       channel->key = key;
-       channel->refcount = 0;
-       channel->session_id = session_id;
-       channel->session_id_per_pid = session_id_per_pid;
-       channel->relayd_id = relayd_id;
-       channel->tracefile_size = tracefile_size;
-       channel->tracefile_count = tracefile_count;
-       channel->monitor = monitor;
-       channel->live_timer_interval = live_timer_interval;
-       channel->is_live = is_in_live_session;
-       pthread_mutex_init(&channel->lock, NULL);
-       pthread_mutex_init(&channel->timer_lock, NULL);
-
-       switch (output) {
-       case LTTNG_EVENT_SPLICE:
-               channel->output = CONSUMER_CHANNEL_SPLICE;
-               break;
-       case LTTNG_EVENT_MMAP:
-               channel->output = CONSUMER_CHANNEL_MMAP;
-               break;
-       default:
-               abort();
-               free(channel);
-               channel = NULL;
-               goto end;
-       }
-
-       /*
-        * In monitor mode, the streams associated with the channel will be put in
-        * a special list ONLY owned by this channel. So, the refcount is set to 1
-        * here meaning that the channel itself has streams that are referenced.
-        *
-        * On a channel deletion, once the channel is no longer visible, the
-        * refcount is decremented and checked for a zero value to delete it. With
-        * streams in no monitor mode, it will now be safe to destroy the channel.
-        */
-       if (!channel->monitor) {
-               channel->refcount = 1;
-       }
-
-       strncpy(channel->pathname, pathname, sizeof(channel->pathname));
-       channel->pathname[sizeof(channel->pathname) - 1] = '\0';
-
-       strncpy(channel->name, name, sizeof(channel->name));
-       channel->name[sizeof(channel->name) - 1] = '\0';
-
-       if (root_shm_path) {
-               strncpy(channel->root_shm_path, root_shm_path, sizeof(channel->root_shm_path));
-               channel->root_shm_path[sizeof(channel->root_shm_path) - 1] = '\0';
-       }
-       if (shm_path) {
-               strncpy(channel->shm_path, shm_path, sizeof(channel->shm_path));
-               channel->shm_path[sizeof(channel->shm_path) - 1] = '\0';
-       }
-
-       lttng_ht_node_init_u64(&channel->node, channel->key);
-       lttng_ht_node_init_u64(&channel->channels_by_session_id_ht_node,
-                       channel->session_id);
-
-       channel->wait_fd = -1;
-       CDS_INIT_LIST_HEAD(&channel->streams.head);
-
-       if (trace_chunk) {
-               int ret = lttng_consumer_channel_set_trace_chunk(channel,
-                               trace_chunk);
-               if (ret) {
-                       goto error;
-               }
-       }
-
-       DBG("Allocated channel (key %" PRIu64 ")", channel->key);
-
-end:
-       lttng_trace_chunk_put(trace_chunk);
-       return channel;
-error:
-       consumer_del_channel(channel);
-       channel = NULL;
-       goto end;
-}
-
-/*
- * Add a channel to the global list protected by a mutex.
- *
- * Always return 0 indicating success.
- */
-int consumer_add_channel(struct lttng_consumer_channel *channel,
-               struct lttng_consumer_local_data *ctx)
-{
-       pthread_mutex_lock(&the_consumer_data.lock);
-       pthread_mutex_lock(&channel->lock);
-       pthread_mutex_lock(&channel->timer_lock);
-
-       /*
-        * This gives us a guarantee that the channel we are about to add to the
-        * channel hash table will be unique. See this function comment on the why
-        * we need to steel the channel key at this stage.
-        */
-       steal_channel_key(channel->key);
-
-       rcu_read_lock();
-       lttng_ht_add_unique_u64(the_consumer_data.channel_ht, &channel->node);
-       lttng_ht_add_u64(the_consumer_data.channels_by_session_id_ht,
-                       &channel->channels_by_session_id_ht_node);
-       rcu_read_unlock();
-       channel->is_published = true;
-
-       pthread_mutex_unlock(&channel->timer_lock);
-       pthread_mutex_unlock(&channel->lock);
-       pthread_mutex_unlock(&the_consumer_data.lock);
-
-       if (channel->wait_fd != -1 && channel->type == CONSUMER_CHANNEL_TYPE_DATA) {
-               notify_channel_pipe(ctx, channel, -1, CONSUMER_CHANNEL_ADD);
-       }
-
-       return 0;
-}
-
-/*
- * Allocate the pollfd structure and the local view of the out fds to avoid
- * doing a lookup in the linked list and concurrency issues when writing is
- * needed. Called with consumer_data.lock held.
- *
- * Returns the number of fds in the structures.
- */
-static int update_poll_array(struct lttng_consumer_local_data *ctx,
-               struct pollfd **pollfd, struct lttng_consumer_stream **local_stream,
-               struct lttng_ht *ht, int *nb_inactive_fd)
-{
-       int i = 0;
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_stream *stream;
-
-       LTTNG_ASSERT(ctx);
-       LTTNG_ASSERT(ht);
-       LTTNG_ASSERT(pollfd);
-       LTTNG_ASSERT(local_stream);
-
-       DBG("Updating poll fd array");
-       *nb_inactive_fd = 0;
-       rcu_read_lock();
-       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
-               /*
-                * Only active streams with an active end point can be added to the
-                * poll set and local stream storage of the thread.
-                *
-                * There is a potential race here for endpoint_status to be updated
-                * just after the check. However, this is OK since the stream(s) will
-                * be deleted once the thread is notified that the end point state has
-                * changed where this function will be called back again.
-                *
-                * We track the number of inactive FDs because they still need to be
-                * closed by the polling thread after a wakeup on the data_pipe or
-                * metadata_pipe.
-                */
-               if (stream->endpoint_status == CONSUMER_ENDPOINT_INACTIVE) {
-                       (*nb_inactive_fd)++;
-                       continue;
-               }
-               /*
-                * This clobbers way too much the debug output. Uncomment that if you
-                * need it for debugging purposes.
-                */
-               (*pollfd)[i].fd = stream->wait_fd;
-               (*pollfd)[i].events = POLLIN | POLLPRI;
-               local_stream[i] = stream;
-               i++;
-       }
-       rcu_read_unlock();
-
-       /*
-        * Insert the consumer_data_pipe at the end of the array and don't
-        * increment i so nb_fd is the number of real FD.
-        */
-       (*pollfd)[i].fd = lttng_pipe_get_readfd(ctx->consumer_data_pipe);
-       (*pollfd)[i].events = POLLIN | POLLPRI;
-
-       (*pollfd)[i + 1].fd = lttng_pipe_get_readfd(ctx->consumer_wakeup_pipe);
-       (*pollfd)[i + 1].events = POLLIN | POLLPRI;
-       return i;
-}
-
-/*
- * Poll on the should_quit pipe and the command socket return -1 on
- * error, 1 if should exit, 0 if data is available on the command socket
- */
-int lttng_consumer_poll_socket(struct pollfd *consumer_sockpoll)
-{
-       int num_rdy;
-
-restart:
-       num_rdy = poll(consumer_sockpoll, 2, -1);
-       if (num_rdy == -1) {
-               /*
-                * Restart interrupted system call.
-                */
-               if (errno == EINTR) {
-                       goto restart;
-               }
-               PERROR("Poll error");
-               return -1;
-       }
-       if (consumer_sockpoll[0].revents & (POLLIN | POLLPRI)) {
-               DBG("consumer_should_quit wake up");
-               return 1;
-       }
-       return 0;
-}
-
-/*
- * Set the error socket.
- */
-void lttng_consumer_set_error_sock(struct lttng_consumer_local_data *ctx,
-               int sock)
-{
-       ctx->consumer_error_socket = sock;
-}
-
-/*
- * Set the command socket path.
- */
-void lttng_consumer_set_command_sock_path(
-               struct lttng_consumer_local_data *ctx, char *sock)
-{
-       ctx->consumer_command_sock_path = sock;
-}
-
-/*
- * Send return code to the session daemon.
- * If the socket is not defined, we return 0, it is not a fatal error
- */
-int lttng_consumer_send_error(struct lttng_consumer_local_data *ctx, int cmd)
-{
-       if (ctx->consumer_error_socket > 0) {
-               return lttcomm_send_unix_sock(ctx->consumer_error_socket, &cmd,
-                               sizeof(enum lttcomm_sessiond_command));
-       }
-
-       return 0;
-}
-
-/*
- * Close all the tracefiles and stream fds and MUST be called when all
- * instances are destroyed i.e. when all threads were joined and are ended.
- */
-void lttng_consumer_cleanup(void)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_channel *channel;
-       unsigned int trace_chunks_left;
-
-       rcu_read_lock();
-
-       cds_lfht_for_each_entry(the_consumer_data.channel_ht->ht, &iter.iter,
-                       channel, node.node) {
-               consumer_del_channel(channel);
-       }
-
-       rcu_read_unlock();
-
-       lttng_ht_destroy(the_consumer_data.channel_ht);
-       lttng_ht_destroy(the_consumer_data.channels_by_session_id_ht);
-
-       cleanup_relayd_ht();
-
-       lttng_ht_destroy(the_consumer_data.stream_per_chan_id_ht);
-
-       /*
-        * This HT contains streams that are freed by either the metadata thread or
-        * the data thread so we do *nothing* on the hash table and simply destroy
-        * it.
-        */
-       lttng_ht_destroy(the_consumer_data.stream_list_ht);
-
-       /*
-        * Trace chunks in the registry may still exist if the session
-        * daemon has encountered an internal error and could not
-        * tear down its sessions and/or trace chunks properly.
-        *
-        * Release the session daemon's implicit reference to any remaining
-        * trace chunk and print an error if any trace chunk was found. Note
-        * that there are _no_ legitimate cases for trace chunks to be left,
-        * it is a leak. However, it can happen following a crash of the
-        * session daemon and not emptying the registry would cause an assertion
-        * to hit.
-        */
-       trace_chunks_left = lttng_trace_chunk_registry_put_each_chunk(
-                       the_consumer_data.chunk_registry);
-       if (trace_chunks_left) {
-               ERR("%u trace chunks are leaked by lttng-consumerd. "
-                               "This can be caused by an internal error of the session daemon.",
-                               trace_chunks_left);
-       }
-       /* Run all callbacks freeing each chunk. */
-       rcu_barrier();
-       lttng_trace_chunk_registry_destroy(the_consumer_data.chunk_registry);
-}
-
-/*
- * Called from signal handler.
- */
-void lttng_consumer_should_exit(struct lttng_consumer_local_data *ctx)
-{
-       ssize_t ret;
-
-       CMM_STORE_SHARED(consumer_quit, 1);
-       ret = lttng_write(ctx->consumer_should_quit[1], "4", 1);
-       if (ret < 1) {
-               PERROR("write consumer quit");
-       }
-
-       DBG("Consumer flag that it should quit");
-}
-
-
-/*
- * Flush pending writes to trace output disk file.
- */
-static
-void lttng_consumer_sync_trace_file(struct lttng_consumer_stream *stream,
-               off_t orig_offset)
-{
-       int ret;
-       int outfd = stream->out_fd;
-
-       /*
-        * This does a blocking write-and-wait on any page that belongs to the
-        * subbuffer prior to the one we just wrote.
-        * Don't care about error values, as these are just hints and ways to
-        * limit the amount of page cache used.
-        */
-       if (orig_offset < stream->max_sb_size) {
-               return;
-       }
-       lttng_sync_file_range(outfd, orig_offset - stream->max_sb_size,
-                       stream->max_sb_size,
-                       SYNC_FILE_RANGE_WAIT_BEFORE
-                       | SYNC_FILE_RANGE_WRITE
-                       | SYNC_FILE_RANGE_WAIT_AFTER);
-       /*
-        * Give hints to the kernel about how we access the file:
-        * POSIX_FADV_DONTNEED : we won't re-access data in a near future after
-        * we write it.
-        *
-        * We need to call fadvise again after the file grows because the
-        * kernel does not seem to apply fadvise to non-existing parts of the
-        * file.
-        *
-        * Call fadvise _after_ having waited for the page writeback to
-        * complete because the dirty page writeback semantic is not well
-        * defined. So it can be expected to lead to lower throughput in
-        * streaming.
-        */
-       ret = posix_fadvise(outfd, orig_offset - stream->max_sb_size,
-                       stream->max_sb_size, POSIX_FADV_DONTNEED);
-       if (ret && ret != -ENOSYS) {
-               errno = ret;
-               PERROR("posix_fadvise on fd %i", outfd);
-       }
-}
-
-/*
- * Initialise the necessary environnement :
- * - create a new context
- * - create the poll_pipe
- * - create the should_quit pipe (for signal handler)
- * - create the thread pipe (for splice)
- *
- * Takes a function pointer as argument, this function is called when data is
- * available on a buffer. This function is responsible to do the
- * kernctl_get_next_subbuf, read the data with mmap or splice depending on the
- * buffer configuration and then kernctl_put_next_subbuf at the end.
- *
- * Returns a pointer to the new context or NULL on error.
- */
-struct lttng_consumer_local_data *lttng_consumer_create(
-               enum lttng_consumer_type type,
-               ssize_t (*buffer_ready)(struct lttng_consumer_stream *stream,
-                       struct lttng_consumer_local_data *ctx, bool locked_by_caller),
-               int (*recv_channel)(struct lttng_consumer_channel *channel),
-               int (*recv_stream)(struct lttng_consumer_stream *stream),
-               int (*update_stream)(uint64_t stream_key, uint32_t state))
-{
-       int ret;
-       struct lttng_consumer_local_data *ctx;
-
-       LTTNG_ASSERT(the_consumer_data.type == LTTNG_CONSUMER_UNKNOWN ||
-                       the_consumer_data.type == type);
-       the_consumer_data.type = type;
-
-       ctx = zmalloc(sizeof(struct lttng_consumer_local_data));
-       if (ctx == NULL) {
-               PERROR("allocating context");
-               goto error;
-       }
-
-       ctx->consumer_error_socket = -1;
-       ctx->consumer_metadata_socket = -1;
-       pthread_mutex_init(&ctx->metadata_socket_lock, NULL);
-       /* assign the callbacks */
-       ctx->on_buffer_ready = buffer_ready;
-       ctx->on_recv_channel = recv_channel;
-       ctx->on_recv_stream = recv_stream;
-       ctx->on_update_stream = update_stream;
-
-       ctx->consumer_data_pipe = lttng_pipe_open(0);
-       if (!ctx->consumer_data_pipe) {
-               goto error_poll_pipe;
-       }
-
-       ctx->consumer_wakeup_pipe = lttng_pipe_open(0);
-       if (!ctx->consumer_wakeup_pipe) {
-               goto error_wakeup_pipe;
-       }
-
-       ret = pipe(ctx->consumer_should_quit);
-       if (ret < 0) {
-               PERROR("Error creating recv pipe");
-               goto error_quit_pipe;
-       }
-
-       ret = pipe(ctx->consumer_channel_pipe);
-       if (ret < 0) {
-               PERROR("Error creating channel pipe");
-               goto error_channel_pipe;
-       }
-
-       ctx->consumer_metadata_pipe = lttng_pipe_open(0);
-       if (!ctx->consumer_metadata_pipe) {
-               goto error_metadata_pipe;
-       }
-
-       ctx->channel_monitor_pipe = -1;
-
-       return ctx;
-
-error_metadata_pipe:
-       utils_close_pipe(ctx->consumer_channel_pipe);
-error_channel_pipe:
-       utils_close_pipe(ctx->consumer_should_quit);
-error_quit_pipe:
-       lttng_pipe_destroy(ctx->consumer_wakeup_pipe);
-error_wakeup_pipe:
-       lttng_pipe_destroy(ctx->consumer_data_pipe);
-error_poll_pipe:
-       free(ctx);
-error:
-       return NULL;
-}
-
-/*
- * Iterate over all streams of the hashtable and free them properly.
- */
-static void destroy_data_stream_ht(struct lttng_ht *ht)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_stream *stream;
-
-       if (ht == NULL) {
-               return;
-       }
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
-               /*
-                * Ignore return value since we are currently cleaning up so any error
-                * can't be handled.
-                */
-               (void) consumer_del_stream(stream, ht);
-       }
-       rcu_read_unlock();
-
-       lttng_ht_destroy(ht);
-}
-
-/*
- * Iterate over all streams of the metadata hashtable and free them
- * properly.
- */
-static void destroy_metadata_stream_ht(struct lttng_ht *ht)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_stream *stream;
-
-       if (ht == NULL) {
-               return;
-       }
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
-               /*
-                * Ignore return value since we are currently cleaning up so any error
-                * can't be handled.
-                */
-               (void) consumer_del_metadata_stream(stream, ht);
-       }
-       rcu_read_unlock();
-
-       lttng_ht_destroy(ht);
-}
-
-/*
- * Close all fds associated with the instance and free the context.
- */
-void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx)
-{
-       int ret;
-
-       DBG("Consumer destroying it. Closing everything.");
-
-       if (!ctx) {
-               return;
-       }
-
-       destroy_data_stream_ht(data_ht);
-       destroy_metadata_stream_ht(metadata_ht);
-
-       ret = close(ctx->consumer_error_socket);
-       if (ret) {
-               PERROR("close");
-       }
-       ret = close(ctx->consumer_metadata_socket);
-       if (ret) {
-               PERROR("close");
-       }
-       utils_close_pipe(ctx->consumer_channel_pipe);
-       lttng_pipe_destroy(ctx->consumer_data_pipe);
-       lttng_pipe_destroy(ctx->consumer_metadata_pipe);
-       lttng_pipe_destroy(ctx->consumer_wakeup_pipe);
-       utils_close_pipe(ctx->consumer_should_quit);
-
-       unlink(ctx->consumer_command_sock_path);
-       free(ctx);
-}
-
-/*
- * Write the metadata stream id on the specified file descriptor.
- */
-static int write_relayd_metadata_id(int fd,
-               struct lttng_consumer_stream *stream,
-               unsigned long padding)
-{
-       ssize_t ret;
-       struct lttcomm_relayd_metadata_payload hdr;
-
-       hdr.stream_id = htobe64(stream->relayd_stream_id);
-       hdr.padding_size = htobe32(padding);
-       ret = lttng_write(fd, (void *) &hdr, sizeof(hdr));
-       if (ret < sizeof(hdr)) {
-               /*
-                * This error means that the fd's end is closed so ignore the PERROR
-                * not to clubber the error output since this can happen in a normal
-                * code path.
-                */
-               if (errno != EPIPE) {
-                       PERROR("write metadata stream id");
-               }
-               DBG3("Consumer failed to write relayd metadata id (errno: %d)", errno);
-               /*
-                * Set ret to a negative value because if ret != sizeof(hdr), we don't
-                * handle writting the missing part so report that as an error and
-                * don't lie to the caller.
-                */
-               ret = -1;
-               goto end;
-       }
-       DBG("Metadata stream id %" PRIu64 " with padding %lu written before data",
-                       stream->relayd_stream_id, padding);
-
-end:
-       return (int) ret;
-}
-
-/*
- * Mmap the ring buffer, read it and write the data to the tracefile. This is a
- * core function for writing trace buffers to either the local filesystem or
- * the network.
- *
- * It must be called with the stream and the channel lock held.
- *
- * Careful review MUST be put if any changes occur!
- *
- * Returns the number of bytes written
- */
-ssize_t lttng_consumer_on_read_subbuffer_mmap(
-               struct lttng_consumer_stream *stream,
-               const struct lttng_buffer_view *buffer,
-               unsigned long padding)
-{
-       ssize_t ret = 0;
-       off_t orig_offset = stream->out_fd_offset;
-       /* Default is on the disk */
-       int outfd = stream->out_fd;
-       struct consumer_relayd_sock_pair *relayd = NULL;
-       unsigned int relayd_hang_up = 0;
-       const size_t subbuf_content_size = buffer->size - padding;
-       size_t write_len;
-
-       /* RCU lock for the relayd pointer */
-       rcu_read_lock();
-       LTTNG_ASSERT(stream->net_seq_idx != (uint64_t) -1ULL ||
-                       stream->trace_chunk);
-
-       /* Flag that the current stream if set for network streaming. */
-       if (stream->net_seq_idx != (uint64_t) -1ULL) {
-               relayd = consumer_find_relayd(stream->net_seq_idx);
-               if (relayd == NULL) {
-                       ret = -EPIPE;
-                       goto end;
-               }
-       }
-
-       /* Handle stream on the relayd if the output is on the network */
-       if (relayd) {
-               unsigned long netlen = subbuf_content_size;
-
-               /*
-                * Lock the control socket for the complete duration of the function
-                * since from this point on we will use the socket.
-                */
-               if (stream->metadata_flag) {
-                       /* Metadata requires the control socket. */
-                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-                       if (stream->reset_metadata_flag) {
-                               ret = relayd_reset_metadata(&relayd->control_sock,
-                                               stream->relayd_stream_id,
-                                               stream->metadata_version);
-                               if (ret < 0) {
-                                       relayd_hang_up = 1;
-                                       goto write_error;
-                               }
-                               stream->reset_metadata_flag = 0;
-                       }
-                       netlen += sizeof(struct lttcomm_relayd_metadata_payload);
-               }
-
-               ret = write_relayd_stream_header(stream, netlen, padding, relayd);
-               if (ret < 0) {
-                       relayd_hang_up = 1;
-                       goto write_error;
-               }
-               /* Use the returned socket. */
-               outfd = ret;
-
-               /* Write metadata stream id before payload */
-               if (stream->metadata_flag) {
-                       ret = write_relayd_metadata_id(outfd, stream, padding);
-                       if (ret < 0) {
-                               relayd_hang_up = 1;
-                               goto write_error;
-                       }
-               }
-
-               write_len = subbuf_content_size;
-       } else {
-               /* No streaming; we have to write the full padding. */
-               if (stream->metadata_flag && stream->reset_metadata_flag) {
-                       ret = utils_truncate_stream_file(stream->out_fd, 0);
-                       if (ret < 0) {
-                               ERR("Reset metadata file");
-                               goto end;
-                       }
-                       stream->reset_metadata_flag = 0;
-               }
-
-               /*
-                * Check if we need to change the tracefile before writing the packet.
-                */
-               if (stream->chan->tracefile_size > 0 &&
-                               (stream->tracefile_size_current + buffer->size) >
-                               stream->chan->tracefile_size) {
-                       ret = consumer_stream_rotate_output_files(stream);
-                       if (ret) {
-                               goto end;
-                       }
-                       outfd = stream->out_fd;
-                       orig_offset = 0;
-               }
-               stream->tracefile_size_current += buffer->size;
-               write_len = buffer->size;
-       }
-
-       /*
-        * This call guarantee that len or less is returned. It's impossible to
-        * receive a ret value that is bigger than len.
-        */
-       ret = lttng_write(outfd, buffer->data, write_len);
-       DBG("Consumer mmap write() ret %zd (len %zu)", ret, write_len);
-       if (ret < 0 || ((size_t) ret != write_len)) {
-               /*
-                * Report error to caller if nothing was written else at least send the
-                * amount written.
-                */
-               if (ret < 0) {
-                       ret = -errno;
-               }
-               relayd_hang_up = 1;
-
-               /* Socket operation failed. We consider the relayd dead */
-               if (errno == EPIPE) {
-                       /*
-                        * This is possible if the fd is closed on the other side
-                        * (outfd) or any write problem. It can be verbose a bit for a
-                        * normal execution if for instance the relayd is stopped
-                        * abruptly. This can happen so set this to a DBG statement.
-                        */
-                       DBG("Consumer mmap write detected relayd hang up");
-               } else {
-                       /* Unhandled error, print it and stop function right now. */
-                       PERROR("Error in write mmap (ret %zd != write_len %zu)", ret,
-                                       write_len);
-               }
-               goto write_error;
-       }
-       stream->output_written += ret;
-
-       /* This call is useless on a socket so better save a syscall. */
-       if (!relayd) {
-               /* This won't block, but will start writeout asynchronously */
-               lttng_sync_file_range(outfd, stream->out_fd_offset, write_len,
-                               SYNC_FILE_RANGE_WRITE);
-               stream->out_fd_offset += write_len;
-               lttng_consumer_sync_trace_file(stream, orig_offset);
-       }
-
-write_error:
-       /*
-        * This is a special case that the relayd has closed its socket. Let's
-        * cleanup the relayd object and all associated streams.
-        */
-       if (relayd && relayd_hang_up) {
-               ERR("Relayd hangup. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
-               lttng_consumer_cleanup_relayd(relayd);
-       }
-
-end:
-       /* Unlock only if ctrl socket used */
-       if (relayd && stream->metadata_flag) {
-               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-       }
-
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Splice the data from the ring buffer to the tracefile.
- *
- * It must be called with the stream lock held.
- *
- * Returns the number of bytes spliced.
- */
-ssize_t lttng_consumer_on_read_subbuffer_splice(
-               struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *stream, unsigned long len,
-               unsigned long padding)
-{
-       ssize_t ret = 0, written = 0, ret_splice = 0;
-       loff_t offset = 0;
-       off_t orig_offset = stream->out_fd_offset;
-       int fd = stream->wait_fd;
-       /* Default is on the disk */
-       int outfd = stream->out_fd;
-       struct consumer_relayd_sock_pair *relayd = NULL;
-       int *splice_pipe;
-       unsigned int relayd_hang_up = 0;
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               /* Not supported for user space tracing */
-               return -ENOSYS;
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-       }
-
-       /* RCU lock for the relayd pointer */
-       rcu_read_lock();
-
-       /* Flag that the current stream if set for network streaming. */
-       if (stream->net_seq_idx != (uint64_t) -1ULL) {
-               relayd = consumer_find_relayd(stream->net_seq_idx);
-               if (relayd == NULL) {
-                       written = -ret;
-                       goto end;
-               }
-       }
-       splice_pipe = stream->splice_pipe;
-
-       /* Write metadata stream id before payload */
-       if (relayd) {
-               unsigned long total_len = len;
-
-               if (stream->metadata_flag) {
-                       /*
-                        * Lock the control socket for the complete duration of the function
-                        * since from this point on we will use the socket.
-                        */
-                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-
-                       if (stream->reset_metadata_flag) {
-                               ret = relayd_reset_metadata(&relayd->control_sock,
-                                               stream->relayd_stream_id,
-                                               stream->metadata_version);
-                               if (ret < 0) {
-                                       relayd_hang_up = 1;
-                                       goto write_error;
-                               }
-                               stream->reset_metadata_flag = 0;
-                       }
-                       ret = write_relayd_metadata_id(splice_pipe[1], stream,
-                                       padding);
-                       if (ret < 0) {
-                               written = ret;
-                               relayd_hang_up = 1;
-                               goto write_error;
-                       }
-
-                       total_len += sizeof(struct lttcomm_relayd_metadata_payload);
-               }
-
-               ret = write_relayd_stream_header(stream, total_len, padding, relayd);
-               if (ret < 0) {
-                       written = ret;
-                       relayd_hang_up = 1;
-                       goto write_error;
-               }
-               /* Use the returned socket. */
-               outfd = ret;
-       } else {
-               /* No streaming, we have to set the len with the full padding */
-               len += padding;
-
-               if (stream->metadata_flag && stream->reset_metadata_flag) {
-                       ret = utils_truncate_stream_file(stream->out_fd, 0);
-                       if (ret < 0) {
-                               ERR("Reset metadata file");
-                               goto end;
-                       }
-                       stream->reset_metadata_flag = 0;
-               }
-               /*
-                * Check if we need to change the tracefile before writing the packet.
-                */
-               if (stream->chan->tracefile_size > 0 &&
-                               (stream->tracefile_size_current + len) >
-                               stream->chan->tracefile_size) {
-                       ret = consumer_stream_rotate_output_files(stream);
-                       if (ret < 0) {
-                               written = ret;
-                               goto end;
-                       }
-                       outfd = stream->out_fd;
-                       orig_offset = 0;
-               }
-               stream->tracefile_size_current += len;
-       }
-
-       while (len > 0) {
-               DBG("splice chan to pipe offset %lu of len %lu (fd : %d, pipe: %d)",
-                               (unsigned long)offset, len, fd, splice_pipe[1]);
-               ret_splice = splice(fd, &offset, splice_pipe[1], NULL, len,
-                               SPLICE_F_MOVE | SPLICE_F_MORE);
-               DBG("splice chan to pipe, ret %zd", ret_splice);
-               if (ret_splice < 0) {
-                       ret = errno;
-                       written = -ret;
-                       PERROR("Error in relay splice");
-                       goto splice_error;
-               }
-
-               /* Handle stream on the relayd if the output is on the network */
-               if (relayd && stream->metadata_flag) {
-                       size_t metadata_payload_size =
-                               sizeof(struct lttcomm_relayd_metadata_payload);
-
-                       /* Update counter to fit the spliced data */
-                       ret_splice += metadata_payload_size;
-                       len += metadata_payload_size;
-                       /*
-                        * We do this so the return value can match the len passed as
-                        * argument to this function.
-                        */
-                       written -= metadata_payload_size;
-               }
-
-               /* Splice data out */
-               ret_splice = splice(splice_pipe[0], NULL, outfd, NULL,
-                               ret_splice, SPLICE_F_MOVE | SPLICE_F_MORE);
-               DBG("Consumer splice pipe to file (out_fd: %d), ret %zd",
-                               outfd, ret_splice);
-               if (ret_splice < 0) {
-                       ret = errno;
-                       written = -ret;
-                       relayd_hang_up = 1;
-                       goto write_error;
-               } else if (ret_splice > len) {
-                       /*
-                        * We don't expect this code path to be executed but you never know
-                        * so this is an extra protection agains a buggy splice().
-                        */
-                       ret = errno;
-                       written += ret_splice;
-                       PERROR("Wrote more data than requested %zd (len: %lu)", ret_splice,
-                                       len);
-                       goto splice_error;
-               } else {
-                       /* All good, update current len and continue. */
-                       len -= ret_splice;
-               }
-
-               /* This call is useless on a socket so better save a syscall. */
-               if (!relayd) {
-                       /* This won't block, but will start writeout asynchronously */
-                       lttng_sync_file_range(outfd, stream->out_fd_offset, ret_splice,
-                                       SYNC_FILE_RANGE_WRITE);
-                       stream->out_fd_offset += ret_splice;
-               }
-               stream->output_written += ret_splice;
-               written += ret_splice;
-       }
-       if (!relayd) {
-               lttng_consumer_sync_trace_file(stream, orig_offset);
-       }
-       goto end;
-
-write_error:
-       /*
-        * This is a special case that the relayd has closed its socket. Let's
-        * cleanup the relayd object and all associated streams.
-        */
-       if (relayd && relayd_hang_up) {
-               ERR("Relayd hangup. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
-               lttng_consumer_cleanup_relayd(relayd);
-               /* Skip splice error so the consumer does not fail */
-               goto end;
-       }
-
-splice_error:
-       /* send the appropriate error description to sessiond */
-       switch (ret) {
-       case EINVAL:
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_SPLICE_EINVAL);
-               break;
-       case ENOMEM:
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_SPLICE_ENOMEM);
-               break;
-       case ESPIPE:
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_SPLICE_ESPIPE);
-               break;
-       }
-
-end:
-       if (relayd && stream->metadata_flag) {
-               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-       }
-
-       rcu_read_unlock();
-       return written;
-}
-
-/*
- * Sample the snapshot positions for a specific fd
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_consumer_sample_snapshot_positions(struct lttng_consumer_stream *stream)
-{
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               return lttng_kconsumer_sample_snapshot_positions(stream);
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               return lttng_ustconsumer_sample_snapshot_positions(stream);
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-               return -ENOSYS;
-       }
-}
-/*
- * Take a snapshot for a specific fd
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_consumer_take_snapshot(struct lttng_consumer_stream *stream)
-{
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               return lttng_kconsumer_take_snapshot(stream);
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               return lttng_ustconsumer_take_snapshot(stream);
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-               return -ENOSYS;
-       }
-}
-
-/*
- * Get the produced position
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_consumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
-               unsigned long *pos)
-{
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               return lttng_kconsumer_get_produced_snapshot(stream, pos);
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               return lttng_ustconsumer_get_produced_snapshot(stream, pos);
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-               return -ENOSYS;
-       }
-}
-
-/*
- * Get the consumed position (free-running counter position in bytes).
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_consumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
-               unsigned long *pos)
-{
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               return lttng_kconsumer_get_consumed_snapshot(stream, pos);
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               return lttng_ustconsumer_get_consumed_snapshot(stream, pos);
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-               return -ENOSYS;
-       }
-}
-
-int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
-               int sock, struct pollfd *consumer_sockpoll)
-{
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               return lttng_kconsumer_recv_cmd(ctx, sock, consumer_sockpoll);
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               return lttng_ustconsumer_recv_cmd(ctx, sock, consumer_sockpoll);
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-               return -ENOSYS;
-       }
-}
-
-static
-void lttng_consumer_close_all_metadata(void)
-{
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               /*
-                * The Kernel consumer has a different metadata scheme so we don't
-                * close anything because the stream will be closed by the session
-                * daemon.
-                */
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               /*
-                * Close all metadata streams. The metadata hash table is passed and
-                * this call iterates over it by closing all wakeup fd. This is safe
-                * because at this point we are sure that the metadata producer is
-                * either dead or blocked.
-                */
-               lttng_ustconsumer_close_all_metadata(metadata_ht);
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-       }
-}
-
-/*
- * Clean up a metadata stream and free its memory.
- */
-void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
-               struct lttng_ht *ht)
-{
-       struct lttng_consumer_channel *channel = NULL;
-       bool free_channel = false;
-
-       LTTNG_ASSERT(stream);
-       /*
-        * This call should NEVER receive regular stream. It must always be
-        * metadata stream and this is crucial for data structure synchronization.
-        */
-       LTTNG_ASSERT(stream->metadata_flag);
-
-       DBG3("Consumer delete metadata stream %d", stream->wait_fd);
-
-       pthread_mutex_lock(&the_consumer_data.lock);
-       /*
-        * Note that this assumes that a stream's channel is never changed and
-        * that the stream's lock doesn't need to be taken to sample its
-        * channel.
-        */
-       channel = stream->chan;
-       pthread_mutex_lock(&channel->lock);
-       pthread_mutex_lock(&stream->lock);
-       if (channel->metadata_cache) {
-               /* Only applicable to userspace consumers. */
-               pthread_mutex_lock(&channel->metadata_cache->lock);
-       }
-
-       /* Remove any reference to that stream. */
-       consumer_stream_delete(stream, ht);
-
-       /* Close down everything including the relayd if one. */
-       consumer_stream_close(stream);
-       /* Destroy tracer buffers of the stream. */
-       consumer_stream_destroy_buffers(stream);
-
-       /* Atomically decrement channel refcount since other threads can use it. */
-       if (!uatomic_sub_return(&channel->refcount, 1)
-                       && !uatomic_read(&channel->nb_init_stream_left)) {
-               /* Go for channel deletion! */
-               free_channel = true;
-       }
-       stream->chan = NULL;
-
-       /*
-        * Nullify the stream reference so it is not used after deletion. The
-        * channel lock MUST be acquired before being able to check for a NULL
-        * pointer value.
-        */
-       channel->metadata_stream = NULL;
-
-       if (channel->metadata_cache) {
-               pthread_mutex_unlock(&channel->metadata_cache->lock);
-       }
-       pthread_mutex_unlock(&stream->lock);
-       pthread_mutex_unlock(&channel->lock);
-       pthread_mutex_unlock(&the_consumer_data.lock);
-
-       if (free_channel) {
-               consumer_del_channel(channel);
-       }
-
-       lttng_trace_chunk_put(stream->trace_chunk);
-       stream->trace_chunk = NULL;
-       consumer_stream_free(stream);
-}
-
-/*
- * Action done with the metadata stream when adding it to the consumer internal
- * data structures to handle it.
- */
-void consumer_add_metadata_stream(struct lttng_consumer_stream *stream)
-{
-       struct lttng_ht *ht = metadata_ht;
-       struct lttng_ht_iter iter;
-       struct lttng_ht_node_u64 *node;
-
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(ht);
-
-       DBG3("Adding metadata stream %" PRIu64 " to hash table", stream->key);
-
-       pthread_mutex_lock(&the_consumer_data.lock);
-       pthread_mutex_lock(&stream->chan->lock);
-       pthread_mutex_lock(&stream->chan->timer_lock);
-       pthread_mutex_lock(&stream->lock);
-
-       /*
-        * From here, refcounts are updated so be _careful_ when returning an error
-        * after this point.
-        */
-
-       rcu_read_lock();
-
-       /*
-        * Lookup the stream just to make sure it does not exist in our internal
-        * state. This should NEVER happen.
-        */
-       lttng_ht_lookup(ht, &stream->key, &iter);
-       node = lttng_ht_iter_get_node_u64(&iter);
-       LTTNG_ASSERT(!node);
-
-       /*
-        * When nb_init_stream_left reaches 0, we don't need to trigger any action
-        * in terms of destroying the associated channel, because the action that
-        * causes the count to become 0 also causes a stream to be added. The
-        * channel deletion will thus be triggered by the following removal of this
-        * stream.
-        */
-       if (uatomic_read(&stream->chan->nb_init_stream_left) > 0) {
-               /* Increment refcount before decrementing nb_init_stream_left */
-               cmm_smp_wmb();
-               uatomic_dec(&stream->chan->nb_init_stream_left);
-       }
-
-       lttng_ht_add_unique_u64(ht, &stream->node);
-
-       lttng_ht_add_u64(the_consumer_data.stream_per_chan_id_ht,
-                       &stream->node_channel_id);
-
-       /*
-        * Add stream to the stream_list_ht of the consumer data. No need to steal
-        * the key since the HT does not use it and we allow to add redundant keys
-        * into this table.
-        */
-       lttng_ht_add_u64(the_consumer_data.stream_list_ht,
-                       &stream->node_session_id);
-
-       rcu_read_unlock();
-
-       pthread_mutex_unlock(&stream->lock);
-       pthread_mutex_unlock(&stream->chan->lock);
-       pthread_mutex_unlock(&stream->chan->timer_lock);
-       pthread_mutex_unlock(&the_consumer_data.lock);
-}
-
-/*
- * Delete data stream that are flagged for deletion (endpoint_status).
- */
-static void validate_endpoint_status_data_stream(void)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_stream *stream;
-
-       DBG("Consumer delete flagged data stream");
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry(data_ht->ht, &iter.iter, stream, node.node) {
-               /* Validate delete flag of the stream */
-               if (stream->endpoint_status == CONSUMER_ENDPOINT_ACTIVE) {
-                       continue;
-               }
-               /* Delete it right now */
-               consumer_del_stream(stream, data_ht);
-       }
-       rcu_read_unlock();
-}
-
-/*
- * Delete metadata stream that are flagged for deletion (endpoint_status).
- */
-static void validate_endpoint_status_metadata_stream(
-               struct lttng_poll_event *pollset)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_stream *stream;
-
-       DBG("Consumer delete flagged metadata stream");
-
-       LTTNG_ASSERT(pollset);
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream, node.node) {
-               /* Validate delete flag of the stream */
-               if (stream->endpoint_status == CONSUMER_ENDPOINT_ACTIVE) {
-                       continue;
-               }
-               /*
-                * Remove from pollset so the metadata thread can continue without
-                * blocking on a deleted stream.
-                */
-               lttng_poll_del(pollset, stream->wait_fd);
-
-               /* Delete it right now */
-               consumer_del_metadata_stream(stream, metadata_ht);
-       }
-       rcu_read_unlock();
-}
-
-/*
- * Thread polls on metadata file descriptor and write them on disk or on the
- * network.
- */
-void *consumer_thread_metadata_poll(void *data)
-{
-       int ret, i, pollfd, err = -1;
-       uint32_t revents, nb_fd;
-       struct lttng_consumer_stream *stream = NULL;
-       struct lttng_ht_iter iter;
-       struct lttng_ht_node_u64 *node;
-       struct lttng_poll_event events;
-       struct lttng_consumer_local_data *ctx = data;
-       ssize_t len;
-
-       rcu_register_thread();
-
-       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_METADATA);
-
-       if (testpoint(consumerd_thread_metadata)) {
-               goto error_testpoint;
-       }
-
-       health_code_update();
-
-       DBG("Thread metadata poll started");
-
-       /* Size is set to 1 for the consumer_metadata pipe */
-       ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
-       if (ret < 0) {
-               ERR("Poll set creation failed");
-               goto end_poll;
-       }
-
-       ret = lttng_poll_add(&events,
-                       lttng_pipe_get_readfd(ctx->consumer_metadata_pipe), LPOLLIN);
-       if (ret < 0) {
-               goto end;
-       }
-
-       /* Main loop */
-       DBG("Metadata main loop started");
-
-       while (1) {
-restart:
-               health_code_update();
-               health_poll_entry();
-               DBG("Metadata poll wait");
-               ret = lttng_poll_wait(&events, -1);
-               DBG("Metadata poll return from wait with %d fd(s)",
-                               LTTNG_POLL_GETNB(&events));
-               health_poll_exit();
-               DBG("Metadata event caught in thread");
-               if (ret < 0) {
-                       if (errno == EINTR) {
-                               ERR("Poll EINTR caught");
-                               goto restart;
-                       }
-                       if (LTTNG_POLL_GETNB(&events) == 0) {
-                               err = 0;        /* All is OK */
-                       }
-                       goto end;
-               }
-
-               nb_fd = ret;
-
-               /* From here, the event is a metadata wait fd */
-               for (i = 0; i < nb_fd; i++) {
-                       health_code_update();
-
-                       revents = LTTNG_POLL_GETEV(&events, i);
-                       pollfd = LTTNG_POLL_GETFD(&events, i);
-
-                       if (pollfd == lttng_pipe_get_readfd(ctx->consumer_metadata_pipe)) {
-                               if (revents & LPOLLIN) {
-                                       ssize_t pipe_len;
-
-                                       pipe_len = lttng_pipe_read(ctx->consumer_metadata_pipe,
-                                                       &stream, sizeof(stream));
-                                       if (pipe_len < sizeof(stream)) {
-                                               if (pipe_len < 0) {
-                                                       PERROR("read metadata stream");
-                                               }
-                                               /*
-                                                * Remove the pipe from the poll set and continue the loop
-                                                * since their might be data to consume.
-                                                */
-                                               lttng_poll_del(&events,
-                                                               lttng_pipe_get_readfd(ctx->consumer_metadata_pipe));
-                                               lttng_pipe_read_close(ctx->consumer_metadata_pipe);
-                                               continue;
-                                       }
-
-                                       /* A NULL stream means that the state has changed. */
-                                       if (stream == NULL) {
-                                               /* Check for deleted streams. */
-                                               validate_endpoint_status_metadata_stream(&events);
-                                               goto restart;
-                                       }
-
-                                       DBG("Adding metadata stream %d to poll set",
-                                                       stream->wait_fd);
-
-                                       /* Add metadata stream to the global poll events list */
-                                       lttng_poll_add(&events, stream->wait_fd,
-                                                       LPOLLIN | LPOLLPRI | LPOLLHUP);
-                               } else if (revents & (LPOLLERR | LPOLLHUP)) {
-                                       DBG("Metadata thread pipe hung up");
-                                       /*
-                                        * Remove the pipe from the poll set and continue the loop
-                                        * since their might be data to consume.
-                                        */
-                                       lttng_poll_del(&events,
-                                                       lttng_pipe_get_readfd(ctx->consumer_metadata_pipe));
-                                       lttng_pipe_read_close(ctx->consumer_metadata_pipe);
-                                       continue;
-                               } else {
-                                       ERR("Unexpected poll events %u for sock %d", revents, pollfd);
-                                       goto end;
-                               }
-
-                               /* Handle other stream */
-                               continue;
-                       }
-
-                       rcu_read_lock();
-                       {
-                               uint64_t tmp_id = (uint64_t) pollfd;
-
-                               lttng_ht_lookup(metadata_ht, &tmp_id, &iter);
-                       }
-                       node = lttng_ht_iter_get_node_u64(&iter);
-                       LTTNG_ASSERT(node);
-
-                       stream = caa_container_of(node, struct lttng_consumer_stream,
-                                       node);
-
-                       if (revents & (LPOLLIN | LPOLLPRI)) {
-                               /* Get the data out of the metadata file descriptor */
-                               DBG("Metadata available on fd %d", pollfd);
-                               LTTNG_ASSERT(stream->wait_fd == pollfd);
-
-                               do {
-                                       health_code_update();
-
-                                       len = ctx->on_buffer_ready(stream, ctx, false);
-                                       /*
-                                        * We don't check the return value here since if we get
-                                        * a negative len, it means an error occurred thus we
-                                        * simply remove it from the poll set and free the
-                                        * stream.
-                                        */
-                               } while (len > 0);
-
-                               /* It's ok to have an unavailable sub-buffer */
-                               if (len < 0 && len != -EAGAIN && len != -ENODATA) {
-                                       /* Clean up stream from consumer and free it. */
-                                       lttng_poll_del(&events, stream->wait_fd);
-                                       consumer_del_metadata_stream(stream, metadata_ht);
-                               }
-                       } else if (revents & (LPOLLERR | LPOLLHUP)) {
-                               DBG("Metadata fd %d is hup|err.", pollfd);
-                               if (!stream->hangup_flush_done &&
-                                               (the_consumer_data.type == LTTNG_CONSUMER32_UST ||
-                                                               the_consumer_data.type ==
-                                                                               LTTNG_CONSUMER64_UST)) {
-                                       DBG("Attempting to flush and consume the UST buffers");
-                                       lttng_ustconsumer_on_stream_hangup(stream);
-
-                                       /* We just flushed the stream now read it. */
-                                       do {
-                                               health_code_update();
-
-                                               len = ctx->on_buffer_ready(stream, ctx, false);
-                                               /*
-                                                * We don't check the return value here since if we get
-                                                * a negative len, it means an error occurred thus we
-                                                * simply remove it from the poll set and free the
-                                                * stream.
-                                                */
-                                       } while (len > 0);
-                               }
-
-                               lttng_poll_del(&events, stream->wait_fd);
-                               /*
-                                * This call update the channel states, closes file descriptors
-                                * and securely free the stream.
-                                */
-                               consumer_del_metadata_stream(stream, metadata_ht);
-                       } else {
-                               ERR("Unexpected poll events %u for sock %d", revents, pollfd);
-                               rcu_read_unlock();
-                               goto end;
-                       }
-                       /* Release RCU lock for the stream looked up */
-                       rcu_read_unlock();
-               }
-       }
-
-       /* All is OK */
-       err = 0;
-end:
-       DBG("Metadata poll thread exiting");
-
-       lttng_poll_clean(&events);
-end_poll:
-error_testpoint:
-       if (err) {
-               health_error();
-               ERR("Health error occurred in %s", __func__);
-       }
-       health_unregister(health_consumerd);
-       rcu_unregister_thread();
-       return NULL;
-}
-
-/*
- * This thread polls the fds in the set to consume the data and write
- * it to tracefile if necessary.
- */
-void *consumer_thread_data_poll(void *data)
-{
-       int num_rdy, num_hup, high_prio, ret, i, err = -1;
-       struct pollfd *pollfd = NULL;
-       /* local view of the streams */
-       struct lttng_consumer_stream **local_stream = NULL, *new_stream = NULL;
-       /* local view of consumer_data.fds_count */
-       int nb_fd = 0;
-       /* 2 for the consumer_data_pipe and wake up pipe */
-       const int nb_pipes_fd = 2;
-       /* Number of FDs with CONSUMER_ENDPOINT_INACTIVE but still open. */
-       int nb_inactive_fd = 0;
-       struct lttng_consumer_local_data *ctx = data;
-       ssize_t len;
-
-       rcu_register_thread();
-
-       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_DATA);
-
-       if (testpoint(consumerd_thread_data)) {
-               goto error_testpoint;
-       }
-
-       health_code_update();
-
-       local_stream = zmalloc(sizeof(struct lttng_consumer_stream *));
-       if (local_stream == NULL) {
-               PERROR("local_stream malloc");
-               goto end;
-       }
-
-       while (1) {
-               health_code_update();
-
-               high_prio = 0;
-               num_hup = 0;
-
-               /*
-                * the fds set has been updated, we need to update our
-                * local array as well
-                */
-               pthread_mutex_lock(&the_consumer_data.lock);
-               if (the_consumer_data.need_update) {
-                       free(pollfd);
-                       pollfd = NULL;
-
-                       free(local_stream);
-                       local_stream = NULL;
-
-                       /* Allocate for all fds */
-                       pollfd = zmalloc((the_consumer_data.stream_count +
-                                                        nb_pipes_fd) *
-                                       sizeof(struct pollfd));
-                       if (pollfd == NULL) {
-                               PERROR("pollfd malloc");
-                               pthread_mutex_unlock(&the_consumer_data.lock);
-                               goto end;
-                       }
-
-                       local_stream = zmalloc((the_consumer_data.stream_count +
-                                                              nb_pipes_fd) *
-                                       sizeof(struct lttng_consumer_stream *));
-                       if (local_stream == NULL) {
-                               PERROR("local_stream malloc");
-                               pthread_mutex_unlock(&the_consumer_data.lock);
-                               goto end;
-                       }
-                       ret = update_poll_array(ctx, &pollfd, local_stream,
-                                       data_ht, &nb_inactive_fd);
-                       if (ret < 0) {
-                               ERR("Error in allocating pollfd or local_outfds");
-                               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_POLL_ERROR);
-                               pthread_mutex_unlock(&the_consumer_data.lock);
-                               goto end;
-                       }
-                       nb_fd = ret;
-                       the_consumer_data.need_update = 0;
-               }
-               pthread_mutex_unlock(&the_consumer_data.lock);
-
-               /* No FDs and consumer_quit, consumer_cleanup the thread */
-               if (nb_fd == 0 && nb_inactive_fd == 0 &&
-                               CMM_LOAD_SHARED(consumer_quit) == 1) {
-                       err = 0;        /* All is OK */
-                       goto end;
-               }
-               /* poll on the array of fds */
-       restart:
-               DBG("polling on %d fd", nb_fd + nb_pipes_fd);
-               if (testpoint(consumerd_thread_data_poll)) {
-                       goto end;
-               }
-               health_poll_entry();
-               num_rdy = poll(pollfd, nb_fd + nb_pipes_fd, -1);
-               health_poll_exit();
-               DBG("poll num_rdy : %d", num_rdy);
-               if (num_rdy == -1) {
-                       /*
-                        * Restart interrupted system call.
-                        */
-                       if (errno == EINTR) {
-                               goto restart;
-                       }
-                       PERROR("Poll error");
-                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_POLL_ERROR);
-                       goto end;
-               } else if (num_rdy == 0) {
-                       DBG("Polling thread timed out");
-                       goto end;
-               }
-
-               if (caa_unlikely(data_consumption_paused)) {
-                       DBG("Data consumption paused, sleeping...");
-                       sleep(1);
-                       goto restart;
-               }
-
-               /*
-                * If the consumer_data_pipe triggered poll go directly to the
-                * beginning of the loop to update the array. We want to prioritize
-                * array update over low-priority reads.
-                */
-               if (pollfd[nb_fd].revents & (POLLIN | POLLPRI)) {
-                       ssize_t pipe_readlen;
-
-                       DBG("consumer_data_pipe wake up");
-                       pipe_readlen = lttng_pipe_read(ctx->consumer_data_pipe,
-                                       &new_stream, sizeof(new_stream));
-                       if (pipe_readlen < sizeof(new_stream)) {
-                               PERROR("Consumer data pipe");
-                               /* Continue so we can at least handle the current stream(s). */
-                               continue;
-                       }
-
-                       /*
-                        * If the stream is NULL, just ignore it. It's also possible that
-                        * the sessiond poll thread changed the consumer_quit state and is
-                        * waking us up to test it.
-                        */
-                       if (new_stream == NULL) {
-                               validate_endpoint_status_data_stream();
-                               continue;
-                       }
-
-                       /* Continue to update the local streams and handle prio ones */
-                       continue;
-               }
-
-               /* Handle wakeup pipe. */
-               if (pollfd[nb_fd + 1].revents & (POLLIN | POLLPRI)) {
-                       char dummy;
-                       ssize_t pipe_readlen;
-
-                       pipe_readlen = lttng_pipe_read(ctx->consumer_wakeup_pipe, &dummy,
-                                       sizeof(dummy));
-                       if (pipe_readlen < 0) {
-                               PERROR("Consumer data wakeup pipe");
-                       }
-                       /* We've been awakened to handle stream(s). */
-                       ctx->has_wakeup = 0;
-               }
-
-               /* Take care of high priority channels first. */
-               for (i = 0; i < nb_fd; i++) {
-                       health_code_update();
-
-                       if (local_stream[i] == NULL) {
-                               continue;
-                       }
-                       if (pollfd[i].revents & POLLPRI) {
-                               DBG("Urgent read on fd %d", pollfd[i].fd);
-                               high_prio = 1;
-                               len = ctx->on_buffer_ready(local_stream[i], ctx, false);
-                               /* it's ok to have an unavailable sub-buffer */
-                               if (len < 0 && len != -EAGAIN && len != -ENODATA) {
-                                       /* Clean the stream and free it. */
-                                       consumer_del_stream(local_stream[i], data_ht);
-                                       local_stream[i] = NULL;
-                               } else if (len > 0) {
-                                       local_stream[i]->data_read = 1;
-                               }
-                       }
-               }
-
-               /*
-                * If we read high prio channel in this loop, try again
-                * for more high prio data.
-                */
-               if (high_prio) {
-                       continue;
-               }
-
-               /* Take care of low priority channels. */
-               for (i = 0; i < nb_fd; i++) {
-                       health_code_update();
-
-                       if (local_stream[i] == NULL) {
-                               continue;
-                       }
-                       if ((pollfd[i].revents & POLLIN) ||
-                                       local_stream[i]->hangup_flush_done ||
-                                       local_stream[i]->has_data) {
-                               DBG("Normal read on fd %d", pollfd[i].fd);
-                               len = ctx->on_buffer_ready(local_stream[i], ctx, false);
-                               /* it's ok to have an unavailable sub-buffer */
-                               if (len < 0 && len != -EAGAIN && len != -ENODATA) {
-                                       /* Clean the stream and free it. */
-                                       consumer_del_stream(local_stream[i], data_ht);
-                                       local_stream[i] = NULL;
-                               } else if (len > 0) {
-                                       local_stream[i]->data_read = 1;
-                               }
-                       }
-               }
-
-               /* Handle hangup and errors */
-               for (i = 0; i < nb_fd; i++) {
-                       health_code_update();
-
-                       if (local_stream[i] == NULL) {
-                               continue;
-                       }
-                       if (!local_stream[i]->hangup_flush_done
-                                       && (pollfd[i].revents & (POLLHUP | POLLERR | POLLNVAL))
-                                       && (the_consumer_data.type == LTTNG_CONSUMER32_UST
-                                               || the_consumer_data.type == LTTNG_CONSUMER64_UST)) {
-                               DBG("fd %d is hup|err|nval. Attempting flush and read.",
-                                               pollfd[i].fd);
-                               lttng_ustconsumer_on_stream_hangup(local_stream[i]);
-                               /* Attempt read again, for the data we just flushed. */
-                               local_stream[i]->data_read = 1;
-                       }
-                       /*
-                        * If the poll flag is HUP/ERR/NVAL and we have
-                        * read no data in this pass, we can remove the
-                        * stream from its hash table.
-                        */
-                       if ((pollfd[i].revents & POLLHUP)) {
-                               DBG("Polling fd %d tells it has hung up.", pollfd[i].fd);
-                               if (!local_stream[i]->data_read) {
-                                       consumer_del_stream(local_stream[i], data_ht);
-                                       local_stream[i] = NULL;
-                                       num_hup++;
-                               }
-                       } else if (pollfd[i].revents & POLLERR) {
-                               ERR("Error returned in polling fd %d.", pollfd[i].fd);
-                               if (!local_stream[i]->data_read) {
-                                       consumer_del_stream(local_stream[i], data_ht);
-                                       local_stream[i] = NULL;
-                                       num_hup++;
-                               }
-                       } else if (pollfd[i].revents & POLLNVAL) {
-                               ERR("Polling fd %d tells fd is not open.", pollfd[i].fd);
-                               if (!local_stream[i]->data_read) {
-                                       consumer_del_stream(local_stream[i], data_ht);
-                                       local_stream[i] = NULL;
-                                       num_hup++;
-                               }
-                       }
-                       if (local_stream[i] != NULL) {
-                               local_stream[i]->data_read = 0;
-                       }
-               }
-       }
-       /* All is OK */
-       err = 0;
-end:
-       DBG("polling thread exiting");
-       free(pollfd);
-       free(local_stream);
-
-       /*
-        * Close the write side of the pipe so epoll_wait() in
-        * consumer_thread_metadata_poll can catch it. The thread is monitoring the
-        * read side of the pipe. If we close them both, epoll_wait strangely does
-        * not return and could create a endless wait period if the pipe is the
-        * only tracked fd in the poll set. The thread will take care of closing
-        * the read side.
-        */
-       (void) lttng_pipe_write_close(ctx->consumer_metadata_pipe);
-
-error_testpoint:
-       if (err) {
-               health_error();
-               ERR("Health error occurred in %s", __func__);
-       }
-       health_unregister(health_consumerd);
-
-       rcu_unregister_thread();
-       return NULL;
-}
-
-/*
- * Close wake-up end of each stream belonging to the channel. This will
- * allow the poll() on the stream read-side to detect when the
- * write-side (application) finally closes them.
- */
-static
-void consumer_close_channel_streams(struct lttng_consumer_channel *channel)
-{
-       struct lttng_ht *ht;
-       struct lttng_consumer_stream *stream;
-       struct lttng_ht_iter iter;
-
-       ht = the_consumer_data.stream_per_chan_id_ht;
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&channel->key, lttng_ht_seed),
-                       ht->match_fct, &channel->key,
-                       &iter.iter, stream, node_channel_id.node) {
-               /*
-                * Protect against teardown with mutex.
-                */
-               pthread_mutex_lock(&stream->lock);
-               if (cds_lfht_is_node_deleted(&stream->node.node)) {
-                       goto next;
-               }
-               switch (the_consumer_data.type) {
-               case LTTNG_CONSUMER_KERNEL:
-                       break;
-               case LTTNG_CONSUMER32_UST:
-               case LTTNG_CONSUMER64_UST:
-                       if (stream->metadata_flag) {
-                               /* Safe and protected by the stream lock. */
-                               lttng_ustconsumer_close_metadata(stream->chan);
-                       } else {
-                               /*
-                                * Note: a mutex is taken internally within
-                                * liblttng-ust-ctl to protect timer wakeup_fd
-                                * use from concurrent close.
-                                */
-                               lttng_ustconsumer_close_stream_wakeup(stream);
-                       }
-                       break;
-               default:
-                       ERR("Unknown consumer_data type");
-                       abort();
-               }
-       next:
-               pthread_mutex_unlock(&stream->lock);
-       }
-       rcu_read_unlock();
-}
-
-static void destroy_channel_ht(struct lttng_ht *ht)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_channel *channel;
-       int ret;
-
-       if (ht == NULL) {
-               return;
-       }
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry(ht->ht, &iter.iter, channel, wait_fd_node.node) {
-               ret = lttng_ht_del(ht, &iter);
-               LTTNG_ASSERT(ret != 0);
-       }
-       rcu_read_unlock();
-
-       lttng_ht_destroy(ht);
-}
-
-/*
- * This thread polls the channel fds to detect when they are being
- * closed. It closes all related streams if the channel is detected as
- * closed. It is currently only used as a shim layer for UST because the
- * consumerd needs to keep the per-stream wakeup end of pipes open for
- * periodical flush.
- */
-void *consumer_thread_channel_poll(void *data)
-{
-       int ret, i, pollfd, err = -1;
-       uint32_t revents, nb_fd;
-       struct lttng_consumer_channel *chan = NULL;
-       struct lttng_ht_iter iter;
-       struct lttng_ht_node_u64 *node;
-       struct lttng_poll_event events;
-       struct lttng_consumer_local_data *ctx = data;
-       struct lttng_ht *channel_ht;
-
-       rcu_register_thread();
-
-       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_CHANNEL);
-
-       if (testpoint(consumerd_thread_channel)) {
-               goto error_testpoint;
-       }
-
-       health_code_update();
-
-       channel_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
-       if (!channel_ht) {
-               /* ENOMEM at this point. Better to bail out. */
-               goto end_ht;
-       }
-
-       DBG("Thread channel poll started");
-
-       /* Size is set to 1 for the consumer_channel pipe */
-       ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
-       if (ret < 0) {
-               ERR("Poll set creation failed");
-               goto end_poll;
-       }
-
-       ret = lttng_poll_add(&events, ctx->consumer_channel_pipe[0], LPOLLIN);
-       if (ret < 0) {
-               goto end;
-       }
-
-       /* Main loop */
-       DBG("Channel main loop started");
-
-       while (1) {
-restart:
-               health_code_update();
-               DBG("Channel poll wait");
-               health_poll_entry();
-               ret = lttng_poll_wait(&events, -1);
-               DBG("Channel poll return from wait with %d fd(s)",
-                               LTTNG_POLL_GETNB(&events));
-               health_poll_exit();
-               DBG("Channel event caught in thread");
-               if (ret < 0) {
-                       if (errno == EINTR) {
-                               ERR("Poll EINTR caught");
-                               goto restart;
-                       }
-                       if (LTTNG_POLL_GETNB(&events) == 0) {
-                               err = 0;        /* All is OK */
-                       }
-                       goto end;
-               }
-
-               nb_fd = ret;
-
-               /* From here, the event is a channel wait fd */
-               for (i = 0; i < nb_fd; i++) {
-                       health_code_update();
-
-                       revents = LTTNG_POLL_GETEV(&events, i);
-                       pollfd = LTTNG_POLL_GETFD(&events, i);
-
-                       if (pollfd == ctx->consumer_channel_pipe[0]) {
-                               if (revents & LPOLLIN) {
-                                       enum consumer_channel_action action;
-                                       uint64_t key;
-
-                                       ret = read_channel_pipe(ctx, &chan, &key, &action);
-                                       if (ret <= 0) {
-                                               if (ret < 0) {
-                                                       ERR("Error reading channel pipe");
-                                               }
-                                               lttng_poll_del(&events, ctx->consumer_channel_pipe[0]);
-                                               continue;
-                                       }
-
-                                       switch (action) {
-                                       case CONSUMER_CHANNEL_ADD:
-                                               DBG("Adding channel %d to poll set",
-                                                       chan->wait_fd);
-
-                                               lttng_ht_node_init_u64(&chan->wait_fd_node,
-                                                       chan->wait_fd);
-                                               rcu_read_lock();
-                                               lttng_ht_add_unique_u64(channel_ht,
-                                                               &chan->wait_fd_node);
-                                               rcu_read_unlock();
-                                               /* Add channel to the global poll events list */
-                                               lttng_poll_add(&events, chan->wait_fd,
-                                                               LPOLLERR | LPOLLHUP);
-                                               break;
-                                       case CONSUMER_CHANNEL_DEL:
-                                       {
-                                               /*
-                                                * This command should never be called if the channel
-                                                * has streams monitored by either the data or metadata
-                                                * thread. The consumer only notify this thread with a
-                                                * channel del. command if it receives a destroy
-                                                * channel command from the session daemon that send it
-                                                * if a command prior to the GET_CHANNEL failed.
-                                                */
-
-                                               rcu_read_lock();
-                                               chan = consumer_find_channel(key);
-                                               if (!chan) {
-                                                       rcu_read_unlock();
-                                                       ERR("UST consumer get channel key %" PRIu64 " not found for del channel", key);
-                                                       break;
-                                               }
-                                               lttng_poll_del(&events, chan->wait_fd);
-                                               iter.iter.node = &chan->wait_fd_node.node;
-                                               ret = lttng_ht_del(channel_ht, &iter);
-                                               LTTNG_ASSERT(ret == 0);
-
-                                               switch (the_consumer_data.type) {
-                                               case LTTNG_CONSUMER_KERNEL:
-                                                       break;
-                                               case LTTNG_CONSUMER32_UST:
-                                               case LTTNG_CONSUMER64_UST:
-                                                       health_code_update();
-                                                       /* Destroy streams that might have been left in the stream list. */
-                                                       clean_channel_stream_list(chan);
-                                                       break;
-                                               default:
-                                                       ERR("Unknown consumer_data type");
-                                                       abort();
-                                               }
-
-                                               /*
-                                                * Release our own refcount. Force channel deletion even if
-                                                * streams were not initialized.
-                                                */
-                                               if (!uatomic_sub_return(&chan->refcount, 1)) {
-                                                       consumer_del_channel(chan);
-                                               }
-                                               rcu_read_unlock();
-                                               goto restart;
-                                       }
-                                       case CONSUMER_CHANNEL_QUIT:
-                                               /*
-                                                * Remove the pipe from the poll set and continue the loop
-                                                * since their might be data to consume.
-                                                */
-                                               lttng_poll_del(&events, ctx->consumer_channel_pipe[0]);
-                                               continue;
-                                       default:
-                                               ERR("Unknown action");
-                                               break;
-                                       }
-                               } else if (revents & (LPOLLERR | LPOLLHUP)) {
-                                       DBG("Channel thread pipe hung up");
-                                       /*
-                                        * Remove the pipe from the poll set and continue the loop
-                                        * since their might be data to consume.
-                                        */
-                                       lttng_poll_del(&events, ctx->consumer_channel_pipe[0]);
-                                       continue;
-                               } else {
-                                       ERR("Unexpected poll events %u for sock %d", revents, pollfd);
-                                       goto end;
-                               }
-
-                               /* Handle other stream */
-                               continue;
-                       }
-
-                       rcu_read_lock();
-                       {
-                               uint64_t tmp_id = (uint64_t) pollfd;
-
-                               lttng_ht_lookup(channel_ht, &tmp_id, &iter);
-                       }
-                       node = lttng_ht_iter_get_node_u64(&iter);
-                       LTTNG_ASSERT(node);
-
-                       chan = caa_container_of(node, struct lttng_consumer_channel,
-                                       wait_fd_node);
-
-                       /* Check for error event */
-                       if (revents & (LPOLLERR | LPOLLHUP)) {
-                               DBG("Channel fd %d is hup|err.", pollfd);
-
-                               lttng_poll_del(&events, chan->wait_fd);
-                               ret = lttng_ht_del(channel_ht, &iter);
-                               LTTNG_ASSERT(ret == 0);
-
-                               /*
-                                * This will close the wait fd for each stream associated to
-                                * this channel AND monitored by the data/metadata thread thus
-                                * will be clean by the right thread.
-                                */
-                               consumer_close_channel_streams(chan);
-
-                               /* Release our own refcount */
-                               if (!uatomic_sub_return(&chan->refcount, 1)
-                                               && !uatomic_read(&chan->nb_init_stream_left)) {
-                                       consumer_del_channel(chan);
-                               }
-                       } else {
-                               ERR("Unexpected poll events %u for sock %d", revents, pollfd);
-                               rcu_read_unlock();
-                               goto end;
-                       }
-
-                       /* Release RCU lock for the channel looked up */
-                       rcu_read_unlock();
-               }
-       }
-
-       /* All is OK */
-       err = 0;
-end:
-       lttng_poll_clean(&events);
-end_poll:
-       destroy_channel_ht(channel_ht);
-end_ht:
-error_testpoint:
-       DBG("Channel poll thread exiting");
-       if (err) {
-               health_error();
-               ERR("Health error occurred in %s", __func__);
-       }
-       health_unregister(health_consumerd);
-       rcu_unregister_thread();
-       return NULL;
-}
-
-static int set_metadata_socket(struct lttng_consumer_local_data *ctx,
-               struct pollfd *sockpoll, int client_socket)
-{
-       int ret;
-
-       LTTNG_ASSERT(ctx);
-       LTTNG_ASSERT(sockpoll);
-
-       ret = lttng_consumer_poll_socket(sockpoll);
-       if (ret) {
-               goto error;
-       }
-       DBG("Metadata connection on client_socket");
-
-       /* Blocking call, waiting for transmission */
-       ctx->consumer_metadata_socket = lttcomm_accept_unix_sock(client_socket);
-       if (ctx->consumer_metadata_socket < 0) {
-               WARN("On accept metadata");
-               ret = -1;
-               goto error;
-       }
-       ret = 0;
-
-error:
-       return ret;
-}
-
-/*
- * This thread listens on the consumerd socket and receives the file
- * descriptors from the session daemon.
- */
-void *consumer_thread_sessiond_poll(void *data)
-{
-       int sock = -1, client_socket, ret, err = -1;
-       /*
-        * structure to poll for incoming data on communication socket avoids
-        * making blocking sockets.
-        */
-       struct pollfd consumer_sockpoll[2];
-       struct lttng_consumer_local_data *ctx = data;
-
-       rcu_register_thread();
-
-       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_SESSIOND);
-
-       if (testpoint(consumerd_thread_sessiond)) {
-               goto error_testpoint;
-       }
-
-       health_code_update();
-
-       DBG("Creating command socket %s", ctx->consumer_command_sock_path);
-       unlink(ctx->consumer_command_sock_path);
-       client_socket = lttcomm_create_unix_sock(ctx->consumer_command_sock_path);
-       if (client_socket < 0) {
-               ERR("Cannot create command socket");
-               goto end;
-       }
-
-       ret = lttcomm_listen_unix_sock(client_socket);
-       if (ret < 0) {
-               goto end;
-       }
-
-       DBG("Sending ready command to lttng-sessiond");
-       ret = lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_COMMAND_SOCK_READY);
-       /* return < 0 on error, but == 0 is not fatal */
-       if (ret < 0) {
-               ERR("Error sending ready command to lttng-sessiond");
-               goto end;
-       }
-
-       /* prepare the FDs to poll : to client socket and the should_quit pipe */
-       consumer_sockpoll[0].fd = ctx->consumer_should_quit[0];
-       consumer_sockpoll[0].events = POLLIN | POLLPRI;
-       consumer_sockpoll[1].fd = client_socket;
-       consumer_sockpoll[1].events = POLLIN | POLLPRI;
-
-       ret = lttng_consumer_poll_socket(consumer_sockpoll);
-       if (ret) {
-               if (ret > 0) {
-                       /* should exit */
-                       err = 0;
-               }
-               goto end;
-       }
-       DBG("Connection on client_socket");
-
-       /* Blocking call, waiting for transmission */
-       sock = lttcomm_accept_unix_sock(client_socket);
-       if (sock < 0) {
-               WARN("On accept");
-               goto end;
-       }
-
-       /*
-        * Setup metadata socket which is the second socket connection on the
-        * command unix socket.
-        */
-       ret = set_metadata_socket(ctx, consumer_sockpoll, client_socket);
-       if (ret) {
-               if (ret > 0) {
-                       /* should exit */
-                       err = 0;
-               }
-               goto end;
-       }
-
-       /* This socket is not useful anymore. */
-       ret = close(client_socket);
-       if (ret < 0) {
-               PERROR("close client_socket");
-       }
-       client_socket = -1;
-
-       /* update the polling structure to poll on the established socket */
-       consumer_sockpoll[1].fd = sock;
-       consumer_sockpoll[1].events = POLLIN | POLLPRI;
-
-       while (1) {
-               health_code_update();
-
-               health_poll_entry();
-               ret = lttng_consumer_poll_socket(consumer_sockpoll);
-               health_poll_exit();
-               if (ret) {
-                       if (ret > 0) {
-                               /* should exit */
-                               err = 0;
-                       }
-                       goto end;
-               }
-               DBG("Incoming command on sock");
-               ret = lttng_consumer_recv_cmd(ctx, sock, consumer_sockpoll);
-               if (ret <= 0) {
-                       /*
-                        * This could simply be a session daemon quitting. Don't output
-                        * ERR() here.
-                        */
-                       DBG("Communication interrupted on command socket");
-                       err = 0;
-                       goto end;
-               }
-               if (CMM_LOAD_SHARED(consumer_quit)) {
-                       DBG("consumer_thread_receive_fds received quit from signal");
-                       err = 0;        /* All is OK */
-                       goto end;
-               }
-               DBG("Received command on sock");
-       }
-       /* All is OK */
-       err = 0;
-
-end:
-       DBG("Consumer thread sessiond poll exiting");
-
-       /*
-        * Close metadata streams since the producer is the session daemon which
-        * just died.
-        *
-        * NOTE: for now, this only applies to the UST tracer.
-        */
-       lttng_consumer_close_all_metadata();
-
-       /*
-        * when all fds have hung up, the polling thread
-        * can exit cleanly
-        */
-       CMM_STORE_SHARED(consumer_quit, 1);
-
-       /*
-        * Notify the data poll thread to poll back again and test the
-        * consumer_quit state that we just set so to quit gracefully.
-        */
-       notify_thread_lttng_pipe(ctx->consumer_data_pipe);
-
-       notify_channel_pipe(ctx, NULL, -1, CONSUMER_CHANNEL_QUIT);
-
-       notify_health_quit_pipe(health_quit_pipe);
-
-       /* Cleaning up possibly open sockets. */
-       if (sock >= 0) {
-               ret = close(sock);
-               if (ret < 0) {
-                       PERROR("close sock sessiond poll");
-               }
-       }
-       if (client_socket >= 0) {
-               ret = close(client_socket);
-               if (ret < 0) {
-                       PERROR("close client_socket sessiond poll");
-               }
-       }
-
-error_testpoint:
-       if (err) {
-               health_error();
-               ERR("Health error occurred in %s", __func__);
-       }
-       health_unregister(health_consumerd);
-
-       rcu_unregister_thread();
-       return NULL;
-}
-
-static int post_consume(struct lttng_consumer_stream *stream,
-               const struct stream_subbuffer *subbuffer,
-               struct lttng_consumer_local_data *ctx)
-{
-       size_t i;
-       int ret = 0;
-       const size_t count = lttng_dynamic_array_get_count(
-                       &stream->read_subbuffer_ops.post_consume_cbs);
-
-       for (i = 0; i < count; i++) {
-               const post_consume_cb op = *(post_consume_cb *) lttng_dynamic_array_get_element(
-                               &stream->read_subbuffer_ops.post_consume_cbs,
-                               i);
-
-               ret = op(stream, subbuffer, ctx);
-               if (ret) {
-                       goto end;
-               }
-       }
-end:
-       return ret;
-}
-
-ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
-               struct lttng_consumer_local_data *ctx,
-               bool locked_by_caller)
-{
-       ssize_t ret, written_bytes = 0;
-       int rotation_ret;
-       struct stream_subbuffer subbuffer = {};
-       enum get_next_subbuffer_status get_next_status;
-
-       if (!locked_by_caller) {
-               stream->read_subbuffer_ops.lock(stream);
-       }
-
-       if (stream->read_subbuffer_ops.on_wake_up) {
-               ret = stream->read_subbuffer_ops.on_wake_up(stream);
-               if (ret) {
-                       goto end;
-               }
-       }
-
-       /*
-        * If the stream was flagged to be ready for rotation before we extract
-        * the next packet, rotate it now.
-        */
-       if (stream->rotate_ready) {
-               DBG("Rotate stream before consuming data");
-               ret = lttng_consumer_rotate_stream(ctx, stream);
-               if (ret < 0) {
-                       ERR("Stream rotation error before consuming data");
-                       goto end;
-               }
-       }
-
-       get_next_status = stream->read_subbuffer_ops.get_next_subbuffer(
-                       stream, &subbuffer);
-       switch (get_next_status) {
-       case GET_NEXT_SUBBUFFER_STATUS_OK:
-               break;
-       case GET_NEXT_SUBBUFFER_STATUS_NO_DATA:
-               /* Not an error. */
-               ret = 0;
-               goto sleep_stream;
-       case GET_NEXT_SUBBUFFER_STATUS_ERROR:
-               ret = -1;
-               goto end;
-       default:
-               abort();
-       }
-
-       ret = stream->read_subbuffer_ops.pre_consume_subbuffer(
-                       stream, &subbuffer);
-       if (ret) {
-               goto error_put_subbuf;
-       }
-
-       written_bytes = stream->read_subbuffer_ops.consume_subbuffer(
-                       ctx, stream, &subbuffer);
-       if (written_bytes <= 0) {
-               ERR("Error consuming subbuffer: (%zd)", written_bytes);
-               ret = (int) written_bytes;
-               goto error_put_subbuf;
-       }
-
-       ret = stream->read_subbuffer_ops.put_next_subbuffer(stream, &subbuffer);
-       if (ret) {
-               goto end;
-       }
-
-       ret = post_consume(stream, &subbuffer, ctx);
-       if (ret) {
-               goto end;
-       }
-
-       /*
-        * After extracting the packet, we check if the stream is now ready to
-        * be rotated and perform the action immediately.
-        *
-        * Don't overwrite `ret` as callers expect the number of bytes
-        * consumed to be returned on success.
-        */
-       rotation_ret = lttng_consumer_stream_is_rotate_ready(stream);
-       if (rotation_ret == 1) {
-               rotation_ret = lttng_consumer_rotate_stream(ctx, stream);
-               if (rotation_ret < 0) {
-                       ret = rotation_ret;
-                       ERR("Stream rotation error after consuming data");
-                       goto end;
-               }
-
-       } else if (rotation_ret < 0) {
-               ret = rotation_ret;
-               ERR("Failed to check if stream was ready to rotate after consuming data");
-               goto end;
-       }
-
-sleep_stream:
-       if (stream->read_subbuffer_ops.on_sleep) {
-               stream->read_subbuffer_ops.on_sleep(stream, ctx);
-       }
-
-       ret = written_bytes;
-end:
-       if (!locked_by_caller) {
-               stream->read_subbuffer_ops.unlock(stream);
-       }
-
-       return ret;
-error_put_subbuf:
-       (void) stream->read_subbuffer_ops.put_next_subbuffer(stream, &subbuffer);
-       goto end;
-}
-
-int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream)
-{
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               return lttng_kconsumer_on_recv_stream(stream);
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               return lttng_ustconsumer_on_recv_stream(stream);
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-               return -ENOSYS;
-       }
-}
-
-/*
- * Allocate and set consumer data hash tables.
- */
-int lttng_consumer_init(void)
-{
-       the_consumer_data.channel_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
-       if (!the_consumer_data.channel_ht) {
-               goto error;
-       }
-
-       the_consumer_data.channels_by_session_id_ht =
-                       lttng_ht_new(0, LTTNG_HT_TYPE_U64);
-       if (!the_consumer_data.channels_by_session_id_ht) {
-               goto error;
-       }
-
-       the_consumer_data.relayd_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
-       if (!the_consumer_data.relayd_ht) {
-               goto error;
-       }
-
-       the_consumer_data.stream_list_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
-       if (!the_consumer_data.stream_list_ht) {
-               goto error;
-       }
-
-       the_consumer_data.stream_per_chan_id_ht =
-                       lttng_ht_new(0, LTTNG_HT_TYPE_U64);
-       if (!the_consumer_data.stream_per_chan_id_ht) {
-               goto error;
-       }
-
-       data_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
-       if (!data_ht) {
-               goto error;
-       }
-
-       metadata_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
-       if (!metadata_ht) {
-               goto error;
-       }
-
-       the_consumer_data.chunk_registry = lttng_trace_chunk_registry_create();
-       if (!the_consumer_data.chunk_registry) {
-               goto error;
-       }
-
-       return 0;
-
-error:
-       return -1;
-}
-
-/*
- * Process the ADD_RELAYD command receive by a consumer.
- *
- * This will create a relayd socket pair and add it to the relayd hash table.
- * The caller MUST acquire a RCU read side lock before calling it.
- */
- void consumer_add_relayd_socket(uint64_t net_seq_idx, int sock_type,
-               struct lttng_consumer_local_data *ctx, int sock,
-               struct pollfd *consumer_sockpoll,
-               struct lttcomm_relayd_sock *relayd_sock, uint64_t sessiond_id,
-               uint64_t relayd_session_id)
-{
-       int fd = -1, ret = -1, relayd_created = 0;
-       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-       struct consumer_relayd_sock_pair *relayd = NULL;
-
-       LTTNG_ASSERT(ctx);
-       LTTNG_ASSERT(relayd_sock);
-
-       DBG("Consumer adding relayd socket (idx: %" PRIu64 ")", net_seq_idx);
-
-       /* Get relayd reference if exists. */
-       relayd = consumer_find_relayd(net_seq_idx);
-       if (relayd == NULL) {
-               LTTNG_ASSERT(sock_type == LTTNG_STREAM_CONTROL);
-               /* Not found. Allocate one. */
-               relayd = consumer_allocate_relayd_sock_pair(net_seq_idx);
-               if (relayd == NULL) {
-                       ret_code = LTTCOMM_CONSUMERD_ENOMEM;
-                       goto error;
-               } else {
-                       relayd->sessiond_session_id = sessiond_id;
-                       relayd_created = 1;
-               }
-
-               /*
-                * This code path MUST continue to the consumer send status message to
-                * we can notify the session daemon and continue our work without
-                * killing everything.
-                */
-       } else {
-               /*
-                * relayd key should never be found for control socket.
-                */
-               LTTNG_ASSERT(sock_type != LTTNG_STREAM_CONTROL);
-       }
-
-       /* First send a status message before receiving the fds. */
-       ret = consumer_send_status_msg(sock, LTTCOMM_CONSUMERD_SUCCESS);
-       if (ret < 0) {
-               /* Somehow, the session daemon is not responding anymore. */
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_FATAL);
-               goto error_nosignal;
-       }
-
-       /* Poll on consumer socket. */
-       ret = lttng_consumer_poll_socket(consumer_sockpoll);
-       if (ret) {
-               /* Needing to exit in the middle of a command: error. */
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_POLL_ERROR);
-               goto error_nosignal;
-       }
-
-       /* Get relayd socket from session daemon */
-       ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
-       if (ret != sizeof(fd)) {
-               fd = -1;        /* Just in case it gets set with an invalid value. */
-
-               /*
-                * Failing to receive FDs might indicate a major problem such as
-                * reaching a fd limit during the receive where the kernel returns a
-                * MSG_CTRUNC and fails to cleanup the fd in the queue. Any case, we
-                * don't take any chances and stop everything.
-                *
-                * XXX: Feature request #558 will fix that and avoid this possible
-                * issue when reaching the fd limit.
-                */
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
-               ret_code = LTTCOMM_CONSUMERD_ERROR_RECV_FD;
-               goto error;
-       }
-
-       /* Copy socket information and received FD */
-       switch (sock_type) {
-       case LTTNG_STREAM_CONTROL:
-               /* Copy received lttcomm socket */
-               lttcomm_copy_sock(&relayd->control_sock.sock, &relayd_sock->sock);
-               ret = lttcomm_create_sock(&relayd->control_sock.sock);
-               /* Handle create_sock error. */
-               if (ret < 0) {
-                       ret_code = LTTCOMM_CONSUMERD_ENOMEM;
-                       goto error;
-               }
-               /*
-                * Close the socket created internally by
-                * lttcomm_create_sock, so we can replace it by the one
-                * received from sessiond.
-                */
-               if (close(relayd->control_sock.sock.fd)) {
-                       PERROR("close");
-               }
-
-               /* Assign new file descriptor */
-               relayd->control_sock.sock.fd = fd;
-               /* Assign version values. */
-               relayd->control_sock.major = relayd_sock->major;
-               relayd->control_sock.minor = relayd_sock->minor;
-
-               relayd->relayd_session_id = relayd_session_id;
-
-               break;
-       case LTTNG_STREAM_DATA:
-               /* Copy received lttcomm socket */
-               lttcomm_copy_sock(&relayd->data_sock.sock, &relayd_sock->sock);
-               ret = lttcomm_create_sock(&relayd->data_sock.sock);
-               /* Handle create_sock error. */
-               if (ret < 0) {
-                       ret_code = LTTCOMM_CONSUMERD_ENOMEM;
-                       goto error;
-               }
-               /*
-                * Close the socket created internally by
-                * lttcomm_create_sock, so we can replace it by the one
-                * received from sessiond.
-                */
-               if (close(relayd->data_sock.sock.fd)) {
-                       PERROR("close");
-               }
-
-               /* Assign new file descriptor */
-               relayd->data_sock.sock.fd = fd;
-               /* Assign version values. */
-               relayd->data_sock.major = relayd_sock->major;
-               relayd->data_sock.minor = relayd_sock->minor;
-               break;
-       default:
-               ERR("Unknown relayd socket type (%d)", sock_type);
-               ret_code = LTTCOMM_CONSUMERD_FATAL;
-               goto error;
-       }
-
-       DBG("Consumer %s socket created successfully with net idx %" PRIu64 " (fd: %d)",
-                       sock_type == LTTNG_STREAM_CONTROL ? "control" : "data",
-                       relayd->net_seq_idx, fd);
-       /*
-        * We gave the ownership of the fd to the relayd structure. Set the
-        * fd to -1 so we don't call close() on it in the error path below.
-        */
-       fd = -1;
-
-       /* We successfully added the socket. Send status back. */
-       ret = consumer_send_status_msg(sock, ret_code);
-       if (ret < 0) {
-               /* Somehow, the session daemon is not responding anymore. */
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_FATAL);
-               goto error_nosignal;
-       }
-
-       /*
-        * Add relayd socket pair to consumer data hashtable. If object already
-        * exists or on error, the function gracefully returns.
-        */
-       relayd->ctx = ctx;
-       add_relayd(relayd);
-
-       /* All good! */
-       return;
-
-error:
-       if (consumer_send_status_msg(sock, ret_code) < 0) {
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_FATAL);
-       }
-
-error_nosignal:
-       /* Close received socket if valid. */
-       if (fd >= 0) {
-               if (close(fd)) {
-                       PERROR("close received socket");
-               }
-       }
-
-       if (relayd_created) {
-               free(relayd);
-       }
-}
-
-/*
- * Search for a relayd associated to the session id and return the reference.
- *
- * A rcu read side lock MUST be acquire before calling this function and locked
- * until the relayd object is no longer necessary.
- */
-static struct consumer_relayd_sock_pair *find_relayd_by_session_id(uint64_t id)
-{
-       struct lttng_ht_iter iter;
-       struct consumer_relayd_sock_pair *relayd = NULL;
-
-       /* Iterate over all relayd since they are indexed by net_seq_idx. */
-       cds_lfht_for_each_entry(the_consumer_data.relayd_ht->ht, &iter.iter,
-                       relayd, node.node) {
-               /*
-                * Check by sessiond id which is unique here where the relayd session
-                * id might not be when having multiple relayd.
-                */
-               if (relayd->sessiond_session_id == id) {
-                       /* Found the relayd. There can be only one per id. */
-                       goto found;
-               }
-       }
-
-       return NULL;
-
-found:
-       return relayd;
-}
-
-/*
- * Check if for a given session id there is still data needed to be extract
- * from the buffers.
- *
- * Return 1 if data is pending or else 0 meaning ready to be read.
- */
-int consumer_data_pending(uint64_t id)
-{
-       int ret;
-       struct lttng_ht_iter iter;
-       struct lttng_ht *ht;
-       struct lttng_consumer_stream *stream;
-       struct consumer_relayd_sock_pair *relayd = NULL;
-       int (*data_pending)(struct lttng_consumer_stream *);
-
-       DBG("Consumer data pending command on session id %" PRIu64, id);
-
-       rcu_read_lock();
-       pthread_mutex_lock(&the_consumer_data.lock);
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               data_pending = lttng_kconsumer_data_pending;
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               data_pending = lttng_ustconsumer_data_pending;
-               break;
-       default:
-               ERR("Unknown consumer data type");
-               abort();
-       }
-
-       /* Ease our life a bit */
-       ht = the_consumer_data.stream_list_ht;
-
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&id, lttng_ht_seed),
-                       ht->match_fct, &id,
-                       &iter.iter, stream, node_session_id.node) {
-               pthread_mutex_lock(&stream->lock);
-
-               /*
-                * A removed node from the hash table indicates that the stream has
-                * been deleted thus having a guarantee that the buffers are closed
-                * on the consumer side. However, data can still be transmitted
-                * over the network so don't skip the relayd check.
-                */
-               ret = cds_lfht_is_node_deleted(&stream->node.node);
-               if (!ret) {
-                       /* Check the stream if there is data in the buffers. */
-                       ret = data_pending(stream);
-                       if (ret == 1) {
-                               pthread_mutex_unlock(&stream->lock);
-                               goto data_pending;
-                       }
-               }
-
-               pthread_mutex_unlock(&stream->lock);
-       }
-
-       relayd = find_relayd_by_session_id(id);
-       if (relayd) {
-               unsigned int is_data_inflight = 0;
-
-               /* Send init command for data pending. */
-               pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-               ret = relayd_begin_data_pending(&relayd->control_sock,
-                               relayd->relayd_session_id);
-               if (ret < 0) {
-                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-                       /* Communication error thus the relayd so no data pending. */
-                       goto data_not_pending;
-               }
-
-               cds_lfht_for_each_entry_duplicate(ht->ht,
-                               ht->hash_fct(&id, lttng_ht_seed),
-                               ht->match_fct, &id,
-                               &iter.iter, stream, node_session_id.node) {
-                       if (stream->metadata_flag) {
-                               ret = relayd_quiescent_control(&relayd->control_sock,
-                                               stream->relayd_stream_id);
-                       } else {
-                               ret = relayd_data_pending(&relayd->control_sock,
-                                               stream->relayd_stream_id,
-                                               stream->next_net_seq_num - 1);
-                       }
-
-                       if (ret == 1) {
-                               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-                               goto data_pending;
-                       } else if (ret < 0) {
-                               ERR("Relayd data pending failed. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
-                               lttng_consumer_cleanup_relayd(relayd);
-                               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-                               goto data_not_pending;
-                       }
-               }
-
-               /* Send end command for data pending. */
-               ret = relayd_end_data_pending(&relayd->control_sock,
-                               relayd->relayd_session_id, &is_data_inflight);
-               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-               if (ret < 0) {
-                       ERR("Relayd end data pending failed. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
-                       lttng_consumer_cleanup_relayd(relayd);
-                       goto data_not_pending;
-               }
-               if (is_data_inflight) {
-                       goto data_pending;
-               }
-       }
-
-       /*
-        * Finding _no_ node in the hash table and no inflight data means that the
-        * stream(s) have been removed thus data is guaranteed to be available for
-        * analysis from the trace files.
-        */
-
-data_not_pending:
-       /* Data is available to be read by a viewer. */
-       pthread_mutex_unlock(&the_consumer_data.lock);
-       rcu_read_unlock();
-       return 0;
-
-data_pending:
-       /* Data is still being extracted from buffers. */
-       pthread_mutex_unlock(&the_consumer_data.lock);
-       rcu_read_unlock();
-       return 1;
-}
-
-/*
- * Send a ret code status message to the sessiond daemon.
- *
- * Return the sendmsg() return value.
- */
-int consumer_send_status_msg(int sock, int ret_code)
-{
-       struct lttcomm_consumer_status_msg msg;
-
-       memset(&msg, 0, sizeof(msg));
-       msg.ret_code = ret_code;
-
-       return lttcomm_send_unix_sock(sock, &msg, sizeof(msg));
-}
-
-/*
- * Send a channel status message to the sessiond daemon.
- *
- * Return the sendmsg() return value.
- */
-int consumer_send_status_channel(int sock,
-               struct lttng_consumer_channel *channel)
-{
-       struct lttcomm_consumer_status_channel msg;
-
-       LTTNG_ASSERT(sock >= 0);
-
-       memset(&msg, 0, sizeof(msg));
-       if (!channel) {
-               msg.ret_code = LTTCOMM_CONSUMERD_CHANNEL_FAIL;
-       } else {
-               msg.ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-               msg.key = channel->key;
-               msg.stream_count = channel->streams.count;
-       }
-
-       return lttcomm_send_unix_sock(sock, &msg, sizeof(msg));
-}
-
-unsigned long consumer_get_consume_start_pos(unsigned long consumed_pos,
-               unsigned long produced_pos, uint64_t nb_packets_per_stream,
-               uint64_t max_sb_size)
-{
-       unsigned long start_pos;
-
-       if (!nb_packets_per_stream) {
-               return consumed_pos;    /* Grab everything */
-       }
-       start_pos = produced_pos - lttng_offset_align_floor(produced_pos, max_sb_size);
-       start_pos -= max_sb_size * nb_packets_per_stream;
-       if ((long) (start_pos - consumed_pos) < 0) {
-               return consumed_pos;    /* Grab everything */
-       }
-       return start_pos;
-}
-
-/* Stream lock must be held by the caller. */
-static int sample_stream_positions(struct lttng_consumer_stream *stream,
-                           unsigned long *produced, unsigned long *consumed)
-{
-       int ret;
-
-       ASSERT_LOCKED(stream->lock);
-
-       ret = lttng_consumer_sample_snapshot_positions(stream);
-       if (ret < 0) {
-               ERR("Failed to sample snapshot positions");
-               goto end;
-       }
-
-       ret = lttng_consumer_get_produced_snapshot(stream, produced);
-       if (ret < 0) {
-               ERR("Failed to sample produced position");
-               goto end;
-       }
-
-       ret = lttng_consumer_get_consumed_snapshot(stream, consumed);
-       if (ret < 0) {
-               ERR("Failed to sample consumed position");
-               goto end;
-       }
-
-end:
-       return ret;
-}
-
-/*
- * Sample the rotate position for all the streams of a channel. If a stream
- * is already at the rotate position (produced == consumed), we flag it as
- * ready for rotation. The rotation of ready streams occurs after we have
- * replied to the session daemon that we have finished sampling the positions.
- * Must be called with RCU read-side lock held to ensure existence of channel.
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_consumer_rotate_channel(struct lttng_consumer_channel *channel,
-               uint64_t key, uint64_t relayd_id, uint32_t metadata,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret;
-       struct lttng_consumer_stream *stream;
-       struct lttng_ht_iter iter;
-       struct lttng_ht *ht = the_consumer_data.stream_per_chan_id_ht;
-       struct lttng_dynamic_array stream_rotation_positions;
-       uint64_t next_chunk_id, stream_count = 0;
-       enum lttng_trace_chunk_status chunk_status;
-       const bool is_local_trace = relayd_id == -1ULL;
-       struct consumer_relayd_sock_pair *relayd = NULL;
-       bool rotating_to_new_chunk = true;
-       /* Array of `struct lttng_consumer_stream *` */
-       struct lttng_dynamic_pointer_array streams_packet_to_open;
-       size_t stream_idx;
-
-       DBG("Consumer sample rotate position for channel %" PRIu64, key);
-
-       lttng_dynamic_array_init(&stream_rotation_positions,
-                       sizeof(struct relayd_stream_rotation_position), NULL);
-       lttng_dynamic_pointer_array_init(&streams_packet_to_open, NULL);
-
-       rcu_read_lock();
-
-       pthread_mutex_lock(&channel->lock);
-       LTTNG_ASSERT(channel->trace_chunk);
-       chunk_status = lttng_trace_chunk_get_id(channel->trace_chunk,
-                       &next_chunk_id);
-       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
-               ret = -1;
-               goto end_unlock_channel;
-       }
-
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&channel->key, lttng_ht_seed),
-                       ht->match_fct, &channel->key, &iter.iter,
-                       stream, node_channel_id.node) {
-               unsigned long produced_pos = 0, consumed_pos = 0;
-
-               health_code_update();
-
-               /*
-                * Lock stream because we are about to change its state.
-                */
-               pthread_mutex_lock(&stream->lock);
-
-               if (stream->trace_chunk == stream->chan->trace_chunk) {
-                       rotating_to_new_chunk = false;
-               }
-
-               /*
-                * Do not flush a packet when rotating from a NULL trace
-                * chunk. The stream has no means to output data, and the prior
-                * rotation which rotated to NULL performed that side-effect
-                * already. No new data can be produced when a stream has no
-                * associated trace chunk (e.g. a stop followed by a rotate).
-                */
-               if (stream->trace_chunk) {
-                       bool flush_active;
-
-                       if (stream->metadata_flag) {
-                               /*
-                                * Don't produce an empty metadata packet,
-                                * simply close the current one.
-                                *
-                                * Metadata is regenerated on every trace chunk
-                                * switch; there is no concern that no data was
-                                * produced.
-                                */
-                               flush_active = true;
-                       } else {
-                               /*
-                                * Only flush an empty packet if the "packet
-                                * open" could not be performed on transition
-                                * to a new trace chunk and no packets were
-                                * consumed within the chunk's lifetime.
-                                */
-                               if (stream->opened_packet_in_current_trace_chunk) {
-                                       flush_active = true;
-                               } else {
-                                       /*
-                                        * Stream could have been full at the
-                                        * time of rotation, but then have had
-                                        * no activity at all.
-                                        *
-                                        * It is important to flush a packet
-                                        * to prevent 0-length files from being
-                                        * produced as most viewers choke on
-                                        * them.
-                                        *
-                                        * Unfortunately viewers will not be
-                                        * able to know that tracing was active
-                                        * for this stream during this trace
-                                        * chunk's lifetime.
-                                        */
-                                       ret = sample_stream_positions(stream, &produced_pos, &consumed_pos);
-                                       if (ret) {
-                                               goto end_unlock_stream;
-                                       }
-
-                                       /*
-                                        * Don't flush an empty packet if data
-                                        * was produced; it will be consumed
-                                        * before the rotation completes.
-                                        */
-                                       flush_active = produced_pos != consumed_pos;
-                                       if (!flush_active) {
-                                               const char *trace_chunk_name;
-                                               uint64_t trace_chunk_id;
-
-                                               chunk_status = lttng_trace_chunk_get_name(
-                                                               stream->trace_chunk,
-                                                               &trace_chunk_name,
-                                                               NULL);
-                                               if (chunk_status == LTTNG_TRACE_CHUNK_STATUS_NONE) {
-                                                       trace_chunk_name = "none";
-                                               }
-
-                                               /*
-                                                * Consumer trace chunks are
-                                                * never anonymous.
-                                                */
-                                               chunk_status = lttng_trace_chunk_get_id(
-                                                               stream->trace_chunk,
-                                                               &trace_chunk_id);
-                                               LTTNG_ASSERT(chunk_status ==
-                                                               LTTNG_TRACE_CHUNK_STATUS_OK);
-
-                                               DBG("Unable to open packet for stream during trace chunk's lifetime. "
-                                                               "Flushing an empty packet to prevent an empty file from being created: "
-                                                               "stream id = %" PRIu64 ", trace chunk name = `%s`, trace chunk id = %" PRIu64,
-                                                               stream->key, trace_chunk_name, trace_chunk_id);
-                                       }
-                               }
-                       }
-
-                       /*
-                        * Close the current packet before sampling the
-                        * ring buffer positions.
-                        */
-                       ret = consumer_stream_flush_buffer(stream, flush_active);
-                       if (ret < 0) {
-                               ERR("Failed to flush stream %" PRIu64 " during channel rotation",
-                                               stream->key);
-                               goto end_unlock_stream;
-                       }
-               }
-
-               ret = lttng_consumer_take_snapshot(stream);
-               if (ret < 0 && ret != -ENODATA && ret != -EAGAIN) {
-                       ERR("Failed to sample snapshot position during channel rotation");
-                       goto end_unlock_stream;
-               }
-               if (!ret) {
-                       ret = lttng_consumer_get_produced_snapshot(stream,
-                                       &produced_pos);
-                       if (ret < 0) {
-                               ERR("Failed to sample produced position during channel rotation");
-                               goto end_unlock_stream;
-                       }
-
-                       ret = lttng_consumer_get_consumed_snapshot(stream,
-                                       &consumed_pos);
-                       if (ret < 0) {
-                               ERR("Failed to sample consumed position during channel rotation");
-                               goto end_unlock_stream;
-                       }
-               }
-               /*
-                * Align produced position on the start-of-packet boundary of the first
-                * packet going into the next trace chunk.
-                */
-               produced_pos = lttng_align_floor(produced_pos, stream->max_sb_size);
-               if (consumed_pos == produced_pos) {
-                       DBG("Set rotate ready for stream %" PRIu64 " produced = %lu consumed = %lu",
-                                       stream->key, produced_pos, consumed_pos);
-                       stream->rotate_ready = true;
-               } else {
-                       DBG("Different consumed and produced positions "
-                                       "for stream %" PRIu64 " produced = %lu consumed = %lu",
-                                       stream->key, produced_pos, consumed_pos);
-               }
-               /*
-                * The rotation position is based on the packet_seq_num of the
-                * packet following the last packet that was consumed for this
-                * stream, incremented by the offset between produced and
-                * consumed positions. This rotation position is a lower bound
-                * (inclusive) at which the next trace chunk starts. Since it
-                * is a lower bound, it is OK if the packet_seq_num does not
-                * correspond exactly to the same packet identified by the
-                * consumed_pos, which can happen in overwrite mode.
-                */
-               if (stream->sequence_number_unavailable) {
-                       /*
-                        * Rotation should never be performed on a session which
-                        * interacts with a pre-2.8 lttng-modules, which does
-                        * not implement packet sequence number.
-                        */
-                       ERR("Failure to rotate stream %" PRIu64 ": sequence number unavailable",
-                                       stream->key);
-                       ret = -1;
-                       goto end_unlock_stream;
-               }
-               stream->rotate_position = stream->last_sequence_number + 1 +
-                               ((produced_pos - consumed_pos) / stream->max_sb_size);
-               DBG("Set rotation position for stream %" PRIu64 " at position %" PRIu64,
-                               stream->key, stream->rotate_position);
-
-               if (!is_local_trace) {
-                       /*
-                        * The relay daemon control protocol expects a rotation
-                        * position as "the sequence number of the first packet
-                        * _after_ the current trace chunk".
-                        */
-                       const struct relayd_stream_rotation_position position = {
-                               .stream_id = stream->relayd_stream_id,
-                               .rotate_at_seq_num = stream->rotate_position,
-                       };
-
-                       ret = lttng_dynamic_array_add_element(
-                                       &stream_rotation_positions,
-                                       &position);
-                       if (ret) {
-                               ERR("Failed to allocate stream rotation position");
-                               goto end_unlock_stream;
-                       }
-                       stream_count++;
-               }
-
-               stream->opened_packet_in_current_trace_chunk = false;
-
-               if (rotating_to_new_chunk && !stream->metadata_flag) {
-                       /*
-                        * Attempt to flush an empty packet as close to the
-                        * rotation point as possible. In the event where a
-                        * stream remains inactive after the rotation point,
-                        * this ensures that the new trace chunk has a
-                        * beginning timestamp set at the begining of the
-                        * trace chunk instead of only creating an empty
-                        * packet when the trace chunk is stopped.
-                        *
-                        * This indicates to the viewers that the stream
-                        * was being recorded, but more importantly it
-                        * allows viewers to determine a useable trace
-                        * intersection.
-                        *
-                        * This presents a problem in the case where the
-                        * ring-buffer is completely full.
-                        *
-                        * Consider the following scenario:
-                        *   - The consumption of data is slow (slow network,
-                        *     for instance),
-                        *   - The ring buffer is full,
-                        *   - A rotation is initiated,
-                        *     - The flush below does nothing (no space left to
-                        *       open a new packet),
-                        *   - The other streams rotate very soon, and new
-                        *     data is produced in the new chunk,
-                        *   - This stream completes its rotation long after the
-                        *     rotation was initiated
-                        *   - The session is stopped before any event can be
-                        *     produced in this stream's buffers.
-                        *
-                        * The resulting trace chunk will have a single packet
-                        * temporaly at the end of the trace chunk for this
-                        * stream making the stream intersection more narrow
-                        * than it should be.
-                        *
-                        * To work-around this, an empty flush is performed
-                        * after the first consumption of a packet during a
-                        * rotation if open_packet fails. The idea is that
-                        * consuming a packet frees enough space to switch
-                        * packets in this scenario and allows the tracer to
-                        * "stamp" the beginning of the new trace chunk at the
-                        * earliest possible point.
-                        *
-                        * The packet open is performed after the channel
-                        * rotation to ensure that no attempt to open a packet
-                        * is performed in a stream that has no active trace
-                        * chunk.
-                        */
-                       ret = lttng_dynamic_pointer_array_add_pointer(
-                                       &streams_packet_to_open, stream);
-                       if (ret) {
-                               PERROR("Failed to add a stream pointer to array of streams in which to open a packet");
-                               ret = -1;
-                               goto end_unlock_stream;
-                       }
-               }
-
-               pthread_mutex_unlock(&stream->lock);
-       }
-       stream = NULL;
-
-       if (!is_local_trace) {
-               relayd = consumer_find_relayd(relayd_id);
-               if (!relayd) {
-                       ERR("Failed to find relayd %" PRIu64, relayd_id);
-                       ret = -1;
-                       goto end_unlock_channel;
-               }
-
-               pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-               ret = relayd_rotate_streams(&relayd->control_sock, stream_count,
-                               rotating_to_new_chunk ? &next_chunk_id : NULL,
-                               (const struct relayd_stream_rotation_position *)
-                                               stream_rotation_positions.buffer
-                                                               .data);
-               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-               if (ret < 0) {
-                       ERR("Relayd rotate stream failed. Cleaning up relayd %" PRIu64,
-                                       relayd->net_seq_idx);
-                       lttng_consumer_cleanup_relayd(relayd);
-                       goto end_unlock_channel;
-               }
-       }
-
-       for (stream_idx = 0;
-                       stream_idx < lttng_dynamic_pointer_array_get_count(
-                               &streams_packet_to_open);
-                       stream_idx++) {
-               enum consumer_stream_open_packet_status status;
-
-               stream = lttng_dynamic_pointer_array_get_pointer(
-                               &streams_packet_to_open, stream_idx);
-
-               pthread_mutex_lock(&stream->lock);
-               status = consumer_stream_open_packet(stream);
-               pthread_mutex_unlock(&stream->lock);
-               switch (status) {
-               case CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED:
-                       DBG("Opened a packet after a rotation: stream id = %" PRIu64
-                           ", channel name = %s, session id = %" PRIu64,
-                                       stream->key, stream->chan->name,
-                                       stream->chan->session_id);
-                       break;
-               case CONSUMER_STREAM_OPEN_PACKET_STATUS_NO_SPACE:
-                       /*
-                        * Can't open a packet as there is no space left
-                        * in the buffer. A new packet will be opened
-                        * once one has been consumed.
-                        */
-                       DBG("No space left to open a packet after a rotation: stream id = %" PRIu64
-                           ", channel name = %s, session id = %" PRIu64,
-                                       stream->key, stream->chan->name,
-                                       stream->chan->session_id);
-                       break;
-               case CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR:
-                       /* Logged by callee. */
-                       ret = -1;
-                       goto end_unlock_channel;
-               default:
-                       abort();
-               }
-       }
-
-       pthread_mutex_unlock(&channel->lock);
-       ret = 0;
-       goto end;
-
-end_unlock_stream:
-       pthread_mutex_unlock(&stream->lock);
-end_unlock_channel:
-       pthread_mutex_unlock(&channel->lock);
-end:
-       rcu_read_unlock();
-       lttng_dynamic_array_reset(&stream_rotation_positions);
-       lttng_dynamic_pointer_array_reset(&streams_packet_to_open);
-       return ret;
-}
-
-static
-int consumer_clear_buffer(struct lttng_consumer_stream *stream)
-{
-       int ret = 0;
-       unsigned long consumed_pos_before, consumed_pos_after;
-
-       ret = lttng_consumer_sample_snapshot_positions(stream);
-       if (ret < 0) {
-               ERR("Taking snapshot positions");
-               goto end;
-       }
-
-       ret = lttng_consumer_get_consumed_snapshot(stream, &consumed_pos_before);
-       if (ret < 0) {
-               ERR("Consumed snapshot position");
-               goto end;
-       }
-
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER_KERNEL:
-               ret = kernctl_buffer_clear(stream->wait_fd);
-               if (ret < 0) {
-                       ERR("Failed to clear kernel stream (ret = %d)", ret);
-                       goto end;
-               }
-               break;
-       case LTTNG_CONSUMER32_UST:
-       case LTTNG_CONSUMER64_UST:
-               ret = lttng_ustconsumer_clear_buffer(stream);
-               if (ret < 0) {
-                       ERR("Failed to clear ust stream (ret = %d)", ret);
-                       goto end;
-               }
-               break;
-       default:
-               ERR("Unknown consumer_data type");
-               abort();
-       }
-
-       ret = lttng_consumer_sample_snapshot_positions(stream);
-       if (ret < 0) {
-               ERR("Taking snapshot positions");
-               goto end;
-       }
-       ret = lttng_consumer_get_consumed_snapshot(stream, &consumed_pos_after);
-       if (ret < 0) {
-               ERR("Consumed snapshot position");
-               goto end;
-       }
-       DBG("clear: before: %lu after: %lu", consumed_pos_before, consumed_pos_after);
-end:
-       return ret;
-}
-
-static
-int consumer_clear_stream(struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       ret = consumer_stream_flush_buffer(stream, 1);
-       if (ret < 0) {
-               ERR("Failed to flush stream %" PRIu64 " during channel clear",
-                               stream->key);
-               ret = LTTCOMM_CONSUMERD_FATAL;
-               goto error;
-       }
-
-       ret = consumer_clear_buffer(stream);
-       if (ret < 0) {
-               ERR("Failed to clear stream %" PRIu64 " during channel clear",
-                               stream->key);
-               ret = LTTCOMM_CONSUMERD_FATAL;
-               goto error;
-       }
-
-       ret = LTTCOMM_CONSUMERD_SUCCESS;
-error:
-       return ret;
-}
-
-static
-int consumer_clear_unmonitored_channel(struct lttng_consumer_channel *channel)
-{
-       int ret;
-       struct lttng_consumer_stream *stream;
-
-       rcu_read_lock();
-       pthread_mutex_lock(&channel->lock);
-       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
-               health_code_update();
-               pthread_mutex_lock(&stream->lock);
-               ret = consumer_clear_stream(stream);
-               if (ret) {
-                       goto error_unlock;
-               }
-               pthread_mutex_unlock(&stream->lock);
-       }
-       pthread_mutex_unlock(&channel->lock);
-       rcu_read_unlock();
-       return 0;
-
-error_unlock:
-       pthread_mutex_unlock(&stream->lock);
-       pthread_mutex_unlock(&channel->lock);
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Check if a stream is ready to be rotated after extracting it.
- *
- * Return 1 if it is ready for rotation, 0 if it is not, a negative value on
- * error. Stream lock must be held.
- */
-int lttng_consumer_stream_is_rotate_ready(struct lttng_consumer_stream *stream)
-{
-       DBG("Check is rotate ready for stream %" PRIu64
-                       " ready %u rotate_position %" PRIu64
-                       " last_sequence_number %" PRIu64,
-                       stream->key, stream->rotate_ready,
-                       stream->rotate_position, stream->last_sequence_number);
-       if (stream->rotate_ready) {
-               return 1;
-       }
-
-       /*
-        * If packet seq num is unavailable, it means we are interacting
-        * with a pre-2.8 lttng-modules which does not implement the
-        * sequence number. Rotation should never be used by sessiond in this
-        * scenario.
-        */
-       if (stream->sequence_number_unavailable) {
-               ERR("Internal error: rotation used on stream %" PRIu64
-                               " with unavailable sequence number",
-                               stream->key);
-               return -1;
-       }
-
-       if (stream->rotate_position == -1ULL ||
-                       stream->last_sequence_number == -1ULL) {
-               return 0;
-       }
-
-       /*
-        * Rotate position not reached yet. The stream rotate position is
-        * the position of the next packet belonging to the next trace chunk,
-        * but consumerd considers rotation ready when reaching the last
-        * packet of the current chunk, hence the "rotate_position - 1".
-        */
-
-       DBG("Check is rotate ready for stream %" PRIu64
-                       " last_sequence_number %" PRIu64
-                       " rotate_position %" PRIu64,
-                       stream->key, stream->last_sequence_number,
-                       stream->rotate_position);
-       if (stream->last_sequence_number >= stream->rotate_position - 1) {
-               return 1;
-       }
-
-       return 0;
-}
-
-/*
- * Reset the state for a stream after a rotation occurred.
- */
-void lttng_consumer_reset_stream_rotate_state(struct lttng_consumer_stream *stream)
-{
-       DBG("lttng_consumer_reset_stream_rotate_state for stream %" PRIu64,
-                       stream->key);
-       stream->rotate_position = -1ULL;
-       stream->rotate_ready = false;
-}
-
-/*
- * Perform the rotation a local stream file.
- */
-static
-int rotate_local_stream(struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *stream)
-{
-       int ret = 0;
-
-       DBG("Rotate local stream: stream key %" PRIu64 ", channel key %" PRIu64,
-                       stream->key,
-                       stream->chan->key);
-       stream->tracefile_size_current = 0;
-       stream->tracefile_count_current = 0;
-
-       if (stream->out_fd >= 0) {
-               ret = close(stream->out_fd);
-               if (ret) {
-                       PERROR("Failed to close stream out_fd of channel \"%s\"",
-                               stream->chan->name);
-               }
-               stream->out_fd = -1;
-       }
-
-       if (stream->index_file) {
-               lttng_index_file_put(stream->index_file);
-               stream->index_file = NULL;
-       }
-
-       if (!stream->trace_chunk) {
-               goto end;
-       }
-
-       ret = consumer_stream_create_output_files(stream, true);
-end:
-       return ret;
-}
-
-/*
- * Performs the stream rotation for the rotate session feature if needed.
- * It must be called with the channel and stream locks held.
- *
- * Return 0 on success, a negative number of error.
- */
-int lttng_consumer_rotate_stream(struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       DBG("Consumer rotate stream %" PRIu64, stream->key);
-
-       /*
-        * Update the stream's 'current' chunk to the session's (channel)
-        * now-current chunk.
-        */
-       lttng_trace_chunk_put(stream->trace_chunk);
-       if (stream->chan->trace_chunk == stream->trace_chunk) {
-               /*
-                * A channel can be rotated and not have a "next" chunk
-                * to transition to. In that case, the channel's "current chunk"
-                * has not been closed yet, but it has not been updated to
-                * a "next" trace chunk either. Hence, the stream, like its
-                * parent channel, becomes part of no chunk and can't output
-                * anything until a new trace chunk is created.
-                */
-               stream->trace_chunk = NULL;
-       } else if (stream->chan->trace_chunk &&
-                       !lttng_trace_chunk_get(stream->chan->trace_chunk)) {
-               ERR("Failed to acquire a reference to channel's trace chunk during stream rotation");
-               ret = -1;
-               goto error;
-       } else {
-               /*
-                * Update the stream's trace chunk to its parent channel's
-                * current trace chunk.
-                */
-               stream->trace_chunk = stream->chan->trace_chunk;
-       }
-
-       if (stream->net_seq_idx == (uint64_t) -1ULL) {
-               ret = rotate_local_stream(ctx, stream);
-               if (ret < 0) {
-                       ERR("Failed to rotate stream, ret = %i", ret);
-                       goto error;
-               }
-       }
-
-       if (stream->metadata_flag && stream->trace_chunk) {
-               /*
-                * If the stream has transitioned to a new trace
-                * chunk, the metadata should be re-dumped to the
-                * newest chunk.
-                *
-                * However, it is possible for a stream to transition to
-                * a "no-chunk" state. This can happen if a rotation
-                * occurs on an inactive session. In such cases, the metadata
-                * regeneration will happen when the next trace chunk is
-                * created.
-                */
-               ret = consumer_metadata_stream_dump(stream);
-               if (ret) {
-                       goto error;
-               }
-       }
-       lttng_consumer_reset_stream_rotate_state(stream);
-
-       ret = 0;
-
-error:
-       return ret;
-}
-
-/*
- * Rotate all the ready streams now.
- *
- * This is especially important for low throughput streams that have already
- * been consumed, we cannot wait for their next packet to perform the
- * rotation.
- * Need to be called with RCU read-side lock held to ensure existence of
- * channel.
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_consumer_rotate_ready_streams(struct lttng_consumer_channel *channel,
-               uint64_t key, struct lttng_consumer_local_data *ctx)
-{
-       int ret;
-       struct lttng_consumer_stream *stream;
-       struct lttng_ht_iter iter;
-       struct lttng_ht *ht = the_consumer_data.stream_per_chan_id_ht;
-
-       rcu_read_lock();
-
-       DBG("Consumer rotate ready streams in channel %" PRIu64, key);
-
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&channel->key, lttng_ht_seed),
-                       ht->match_fct, &channel->key, &iter.iter,
-                       stream, node_channel_id.node) {
-               health_code_update();
-
-               pthread_mutex_lock(&stream->chan->lock);
-               pthread_mutex_lock(&stream->lock);
-
-               if (!stream->rotate_ready) {
-                       pthread_mutex_unlock(&stream->lock);
-                       pthread_mutex_unlock(&stream->chan->lock);
-                       continue;
-               }
-               DBG("Consumer rotate ready stream %" PRIu64, stream->key);
-
-               ret = lttng_consumer_rotate_stream(ctx, stream);
-               pthread_mutex_unlock(&stream->lock);
-               pthread_mutex_unlock(&stream->chan->lock);
-               if (ret) {
-                       goto end;
-               }
-       }
-
-       ret = 0;
-
-end:
-       rcu_read_unlock();
-       return ret;
-}
-
-enum lttcomm_return_code lttng_consumer_init_command(
-               struct lttng_consumer_local_data *ctx,
-               const lttng_uuid sessiond_uuid)
-{
-       enum lttcomm_return_code ret;
-       char uuid_str[LTTNG_UUID_STR_LEN];
-
-       if (ctx->sessiond_uuid.is_set) {
-               ret = LTTCOMM_CONSUMERD_ALREADY_SET;
-               goto end;
-       }
-
-       ctx->sessiond_uuid.is_set = true;
-       memcpy(ctx->sessiond_uuid.value, sessiond_uuid, sizeof(lttng_uuid));
-       ret = LTTCOMM_CONSUMERD_SUCCESS;
-       lttng_uuid_to_str(sessiond_uuid, uuid_str);
-       DBG("Received session daemon UUID: %s", uuid_str);
-end:
-       return ret;
-}
-
-enum lttcomm_return_code lttng_consumer_create_trace_chunk(
-               const uint64_t *relayd_id, uint64_t session_id,
-               uint64_t chunk_id,
-               time_t chunk_creation_timestamp,
-               const char *chunk_override_name,
-               const struct lttng_credentials *credentials,
-               struct lttng_directory_handle *chunk_directory_handle)
-{
-       int ret;
-       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-       struct lttng_trace_chunk *created_chunk = NULL, *published_chunk = NULL;
-       enum lttng_trace_chunk_status chunk_status;
-       char relayd_id_buffer[MAX_INT_DEC_LEN(*relayd_id)];
-       char creation_timestamp_buffer[ISO8601_STR_LEN];
-       const char *relayd_id_str = "(none)";
-       const char *creation_timestamp_str;
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_channel *channel;
-
-       if (relayd_id) {
-               /* Only used for logging purposes. */
-               ret = snprintf(relayd_id_buffer, sizeof(relayd_id_buffer),
-                               "%" PRIu64, *relayd_id);
-               if (ret > 0 && ret < sizeof(relayd_id_buffer)) {
-                       relayd_id_str = relayd_id_buffer;
-               } else {
-                       relayd_id_str = "(formatting error)";
-               }
-       }
-
-       /* Local protocol error. */
-       LTTNG_ASSERT(chunk_creation_timestamp);
-       ret = time_to_iso8601_str(chunk_creation_timestamp,
-                       creation_timestamp_buffer,
-                       sizeof(creation_timestamp_buffer));
-       creation_timestamp_str = !ret ? creation_timestamp_buffer :
-                       "(formatting error)";
-
-       DBG("Consumer create trace chunk command: relay_id = %s"
-                       ", session_id = %" PRIu64 ", chunk_id = %" PRIu64
-                       ", chunk_override_name = %s"
-                       ", chunk_creation_timestamp = %s",
-                       relayd_id_str, session_id, chunk_id,
-                       chunk_override_name ? : "(none)",
-                       creation_timestamp_str);
-
-       /*
-        * The trace chunk registry, as used by the consumer daemon, implicitly
-        * owns the trace chunks. This is only needed in the consumer since
-        * the consumer has no notion of a session beyond session IDs being
-        * used to identify other objects.
-        *
-        * The lttng_trace_chunk_registry_publish() call below provides a
-        * reference which is not released; it implicitly becomes the session
-        * daemon's reference to the chunk in the consumer daemon.
-        *
-        * The lifetime of trace chunks in the consumer daemon is managed by
-        * the session daemon through the LTTNG_CONSUMER_CREATE_TRACE_CHUNK
-        * and LTTNG_CONSUMER_DESTROY_TRACE_CHUNK commands.
-        */
-       created_chunk = lttng_trace_chunk_create(chunk_id,
-                       chunk_creation_timestamp, NULL);
-       if (!created_chunk) {
-               ERR("Failed to create trace chunk");
-               ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
-               goto error;
-       }
-
-       if (chunk_override_name) {
-               chunk_status = lttng_trace_chunk_override_name(created_chunk,
-                               chunk_override_name);
-               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
-                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
-                       goto error;
-               }
-       }
-
-       if (chunk_directory_handle) {
-               chunk_status = lttng_trace_chunk_set_credentials(created_chunk,
-                               credentials);
-               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
-                       ERR("Failed to set trace chunk credentials");
-                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
-                       goto error;
-               }
-               /*
-                * The consumer daemon has no ownership of the chunk output
-                * directory.
-                */
-               chunk_status = lttng_trace_chunk_set_as_user(created_chunk,
-                               chunk_directory_handle);
-               chunk_directory_handle = NULL;
-               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
-                       ERR("Failed to set trace chunk's directory handle");
-                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
-                       goto error;
-               }
-       }
-
-       published_chunk = lttng_trace_chunk_registry_publish_chunk(
-                       the_consumer_data.chunk_registry, session_id,
-                       created_chunk);
-       lttng_trace_chunk_put(created_chunk);
-       created_chunk = NULL;
-       if (!published_chunk) {
-               ERR("Failed to publish trace chunk");
-               ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
-               goto error;
-       }
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry_duplicate(
-                       the_consumer_data.channels_by_session_id_ht->ht,
-                       the_consumer_data.channels_by_session_id_ht->hash_fct(
-                                       &session_id, lttng_ht_seed),
-                       the_consumer_data.channels_by_session_id_ht->match_fct,
-                       &session_id, &iter.iter, channel,
-                       channels_by_session_id_ht_node.node) {
-               ret = lttng_consumer_channel_set_trace_chunk(channel,
-                               published_chunk);
-               if (ret) {
-                       /*
-                        * Roll-back the creation of this chunk.
-                        *
-                        * This is important since the session daemon will
-                        * assume that the creation of this chunk failed and
-                        * will never ask for it to be closed, resulting
-                        * in a leak and an inconsistent state for some
-                        * channels.
-                        */
-                       enum lttcomm_return_code close_ret;
-                       char path[LTTNG_PATH_MAX];
-
-                       DBG("Failed to set new trace chunk on existing channels, rolling back");
-                       close_ret = lttng_consumer_close_trace_chunk(relayd_id,
-                                       session_id, chunk_id,
-                                       chunk_creation_timestamp, NULL,
-                                       path);
-                       if (close_ret != LTTCOMM_CONSUMERD_SUCCESS) {
-                               ERR("Failed to roll-back the creation of new chunk: session_id = %" PRIu64 ", chunk_id = %" PRIu64,
-                                               session_id, chunk_id);
-                       }
-
-                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
-                       break;
-               }
-       }
-
-       if (relayd_id) {
-               struct consumer_relayd_sock_pair *relayd;
-
-               relayd = consumer_find_relayd(*relayd_id);
-               if (relayd) {
-                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-                       ret = relayd_create_trace_chunk(
-                                       &relayd->control_sock, published_chunk);
-                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-               } else {
-                       ERR("Failed to find relay daemon socket: relayd_id = %" PRIu64, *relayd_id);
-               }
-
-               if (!relayd || ret) {
-                       enum lttcomm_return_code close_ret;
-                       char path[LTTNG_PATH_MAX];
-
-                       close_ret = lttng_consumer_close_trace_chunk(relayd_id,
-                                       session_id,
-                                       chunk_id,
-                                       chunk_creation_timestamp,
-                                       NULL, path);
-                       if (close_ret != LTTCOMM_CONSUMERD_SUCCESS) {
-                               ERR("Failed to roll-back the creation of new chunk: session_id = %" PRIu64 ", chunk_id = %" PRIu64,
-                                               session_id,
-                                               chunk_id);
-                       }
-
-                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
-                       goto error_unlock;
-               }
-       }
-error_unlock:
-       rcu_read_unlock();
-error:
-       /* Release the reference returned by the "publish" operation. */
-       lttng_trace_chunk_put(published_chunk);
-       lttng_trace_chunk_put(created_chunk);
-       return ret_code;
-}
-
-enum lttcomm_return_code lttng_consumer_close_trace_chunk(
-               const uint64_t *relayd_id, uint64_t session_id,
-               uint64_t chunk_id, time_t chunk_close_timestamp,
-               const enum lttng_trace_chunk_command_type *close_command,
-               char *path)
-{
-       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-       struct lttng_trace_chunk *chunk;
-       char relayd_id_buffer[MAX_INT_DEC_LEN(*relayd_id)];
-       const char *relayd_id_str = "(none)";
-       const char *close_command_name = "none";
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_channel *channel;
-       enum lttng_trace_chunk_status chunk_status;
-
-       if (relayd_id) {
-               int ret;
-
-               /* Only used for logging purposes. */
-               ret = snprintf(relayd_id_buffer, sizeof(relayd_id_buffer),
-                               "%" PRIu64, *relayd_id);
-               if (ret > 0 && ret < sizeof(relayd_id_buffer)) {
-                       relayd_id_str = relayd_id_buffer;
-               } else {
-                       relayd_id_str = "(formatting error)";
-               }
-       }
-       if (close_command) {
-               close_command_name = lttng_trace_chunk_command_type_get_name(
-                               *close_command);
-       }
-
-       DBG("Consumer close trace chunk command: relayd_id = %s"
-                       ", session_id = %" PRIu64 ", chunk_id = %" PRIu64
-                       ", close command = %s",
-                       relayd_id_str, session_id, chunk_id,
-                       close_command_name);
-
-       chunk = lttng_trace_chunk_registry_find_chunk(
-                       the_consumer_data.chunk_registry, session_id, chunk_id);
-       if (!chunk) {
-               ERR("Failed to find chunk: session_id = %" PRIu64
-                               ", chunk_id = %" PRIu64,
-                               session_id, chunk_id);
-               ret_code = LTTCOMM_CONSUMERD_UNKNOWN_TRACE_CHUNK;
-               goto end;
-       }
-
-       chunk_status = lttng_trace_chunk_set_close_timestamp(chunk,
-                       chunk_close_timestamp);
-       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
-               ret_code = LTTCOMM_CONSUMERD_CLOSE_TRACE_CHUNK_FAILED;
-               goto end;
-       }
-
-       if (close_command) {
-               chunk_status = lttng_trace_chunk_set_close_command(
-                               chunk, *close_command);
-               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
-                       ret_code = LTTCOMM_CONSUMERD_CLOSE_TRACE_CHUNK_FAILED;
-                       goto end;
-               }
-       }
-
-       /*
-        * chunk is now invalid to access as we no longer hold a reference to
-        * it; it is only kept around to compare it (by address) to the
-        * current chunk found in the session's channels.
-        */
-       rcu_read_lock();
-       cds_lfht_for_each_entry(the_consumer_data.channel_ht->ht, &iter.iter,
-                       channel, node.node) {
-               int ret;
-
-               /*
-                * Only change the channel's chunk to NULL if it still
-                * references the chunk being closed. The channel may
-                * reference a newer channel in the case of a session
-                * rotation. When a session rotation occurs, the "next"
-                * chunk is created before the "current" chunk is closed.
-                */
-               if (channel->trace_chunk != chunk) {
-                       continue;
-               }
-               ret = lttng_consumer_channel_set_trace_chunk(channel, NULL);
-               if (ret) {
-                       /*
-                        * Attempt to close the chunk on as many channels as
-                        * possible.
-                        */
-                       ret_code = LTTCOMM_CONSUMERD_CLOSE_TRACE_CHUNK_FAILED;
-               }
-       }
-
-       if (relayd_id) {
-               int ret;
-               struct consumer_relayd_sock_pair *relayd;
-
-               relayd = consumer_find_relayd(*relayd_id);
-               if (relayd) {
-                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-                       ret = relayd_close_trace_chunk(
-                                       &relayd->control_sock, chunk,
-                                       path);
-                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-               } else {
-                       ERR("Failed to find relay daemon socket: relayd_id = %" PRIu64,
-                                       *relayd_id);
-               }
-
-               if (!relayd || ret) {
-                       ret_code = LTTCOMM_CONSUMERD_CLOSE_TRACE_CHUNK_FAILED;
-                       goto error_unlock;
-               }
-       }
-error_unlock:
-       rcu_read_unlock();
-end:
-       /*
-        * Release the reference returned by the "find" operation and
-        * the session daemon's implicit reference to the chunk.
-        */
-       lttng_trace_chunk_put(chunk);
-       lttng_trace_chunk_put(chunk);
-
-       return ret_code;
-}
-
-enum lttcomm_return_code lttng_consumer_trace_chunk_exists(
-               const uint64_t *relayd_id, uint64_t session_id,
-               uint64_t chunk_id)
-{
-       int ret;
-       enum lttcomm_return_code ret_code;
-       char relayd_id_buffer[MAX_INT_DEC_LEN(*relayd_id)];
-       const char *relayd_id_str = "(none)";
-       const bool is_local_trace = !relayd_id;
-       struct consumer_relayd_sock_pair *relayd = NULL;
-       bool chunk_exists_local, chunk_exists_remote;
-
-       if (relayd_id) {
-               /* Only used for logging purposes. */
-               ret = snprintf(relayd_id_buffer, sizeof(relayd_id_buffer),
-                               "%" PRIu64, *relayd_id);
-               if (ret > 0 && ret < sizeof(relayd_id_buffer)) {
-                       relayd_id_str = relayd_id_buffer;
-               } else {
-                       relayd_id_str = "(formatting error)";
-               }
-       }
-
-       DBG("Consumer trace chunk exists command: relayd_id = %s"
-                       ", chunk_id = %" PRIu64, relayd_id_str,
-                       chunk_id);
-       ret = lttng_trace_chunk_registry_chunk_exists(
-                       the_consumer_data.chunk_registry, session_id, chunk_id,
-                       &chunk_exists_local);
-       if (ret) {
-               /* Internal error. */
-               ERR("Failed to query the existence of a trace chunk");
-               ret_code = LTTCOMM_CONSUMERD_FATAL;
-               goto end;
-       }
-       DBG("Trace chunk %s locally",
-                       chunk_exists_local ? "exists" : "does not exist");
-       if (chunk_exists_local) {
-               ret_code = LTTCOMM_CONSUMERD_TRACE_CHUNK_EXISTS_LOCAL;
-               goto end;
-       } else if (is_local_trace) {
-               ret_code = LTTCOMM_CONSUMERD_UNKNOWN_TRACE_CHUNK;
-               goto end;
-       }
-
-       rcu_read_lock();
-       relayd = consumer_find_relayd(*relayd_id);
-       if (!relayd) {
-               ERR("Failed to find relayd %" PRIu64, *relayd_id);
-               ret_code = LTTCOMM_CONSUMERD_INVALID_PARAMETERS;
-               goto end_rcu_unlock;
-       }
-       DBG("Looking up existence of trace chunk on relay daemon");
-       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-       ret = relayd_trace_chunk_exists(&relayd->control_sock, chunk_id,
-                       &chunk_exists_remote);
-       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-       if (ret < 0) {
-               ERR("Failed to look-up the existence of trace chunk on relay daemon");
-               ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
-               goto end_rcu_unlock;
-       }
-
-       ret_code = chunk_exists_remote ?
-                       LTTCOMM_CONSUMERD_TRACE_CHUNK_EXISTS_REMOTE :
-                       LTTCOMM_CONSUMERD_UNKNOWN_TRACE_CHUNK;
-       DBG("Trace chunk %s on relay daemon",
-                       chunk_exists_remote ? "exists" : "does not exist");
-
-end_rcu_unlock:
-       rcu_read_unlock();
-end:
-       return ret_code;
-}
-
-static
-int consumer_clear_monitored_channel(struct lttng_consumer_channel *channel)
-{
-       struct lttng_ht *ht;
-       struct lttng_consumer_stream *stream;
-       struct lttng_ht_iter iter;
-       int ret;
-
-       ht = the_consumer_data.stream_per_chan_id_ht;
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&channel->key, lttng_ht_seed),
-                       ht->match_fct, &channel->key,
-                       &iter.iter, stream, node_channel_id.node) {
-               /*
-                * Protect against teardown with mutex.
-                */
-               pthread_mutex_lock(&stream->lock);
-               if (cds_lfht_is_node_deleted(&stream->node.node)) {
-                       goto next;
-               }
-               ret = consumer_clear_stream(stream);
-               if (ret) {
-                       goto error_unlock;
-               }
-       next:
-               pthread_mutex_unlock(&stream->lock);
-       }
-       rcu_read_unlock();
-       return LTTCOMM_CONSUMERD_SUCCESS;
-
-error_unlock:
-       pthread_mutex_unlock(&stream->lock);
-       rcu_read_unlock();
-       return ret;
-}
-
-int lttng_consumer_clear_channel(struct lttng_consumer_channel *channel)
-{
-       int ret;
-
-       DBG("Consumer clear channel %" PRIu64, channel->key);
-
-       if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA) {
-               /*
-                * Nothing to do for the metadata channel/stream.
-                * Snapshot mechanism already take care of the metadata
-                * handling/generation, and monitored channels only need to
-                * have their data stream cleared..
-                */
-               ret = LTTCOMM_CONSUMERD_SUCCESS;
-               goto end;
-       }
-
-       if (!channel->monitor) {
-               ret = consumer_clear_unmonitored_channel(channel);
-       } else {
-               ret = consumer_clear_monitored_channel(channel);
-       }
-end:
-       return ret;
-}
-
-enum lttcomm_return_code lttng_consumer_open_channel_packets(
-               struct lttng_consumer_channel *channel)
-{
-       struct lttng_consumer_stream *stream;
-       enum lttcomm_return_code ret = LTTCOMM_CONSUMERD_SUCCESS;
-
-       if (channel->metadata_stream) {
-               ERR("Open channel packets command attempted on a metadata channel");
-               ret = LTTCOMM_CONSUMERD_INVALID_PARAMETERS;
-               goto end;
-       }
-
-       rcu_read_lock();
-       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
-               enum consumer_stream_open_packet_status status;
-
-               pthread_mutex_lock(&stream->lock);
-               if (cds_lfht_is_node_deleted(&stream->node.node)) {
-                       goto next;
-               }
-
-               status = consumer_stream_open_packet(stream);
-               switch (status) {
-               case CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED:
-                       DBG("Opened a packet in \"open channel packets\" command: stream id = %" PRIu64
-                                       ", channel name = %s, session id = %" PRIu64,
-                                       stream->key, stream->chan->name,
-                                       stream->chan->session_id);
-                       stream->opened_packet_in_current_trace_chunk = true;
-                       break;
-               case CONSUMER_STREAM_OPEN_PACKET_STATUS_NO_SPACE:
-                       DBG("No space left to open a packet in \"open channel packets\" command: stream id = %" PRIu64
-                                       ", channel name = %s, session id = %" PRIu64,
-                                       stream->key, stream->chan->name,
-                                       stream->chan->session_id);
-                       break;
-               case CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR:
-                       /*
-                        * Only unexpected internal errors can lead to this
-                        * failing. Report an unknown error.
-                        */
-                       ERR("Failed to flush empty buffer in \"open channel packets\" command: stream id = %" PRIu64
-                                       ", channel id = %" PRIu64
-                                       ", channel name = %s"
-                                       ", session id = %" PRIu64,
-                                       stream->key, channel->key,
-                                       channel->name, channel->session_id);
-                       ret = LTTCOMM_CONSUMERD_UNKNOWN_ERROR;
-                       goto error_unlock;
-               default:
-                       abort();
-               }
-
-       next:
-               pthread_mutex_unlock(&stream->lock);
-       }
-
-end_rcu_unlock:
-       rcu_read_unlock();
-end:
-       return ret;
-
-error_unlock:
-       pthread_mutex_unlock(&stream->lock);
-       goto end_rcu_unlock;
-}
-
-void lttng_consumer_sigbus_handle(void *addr)
-{
-       lttng_ustconsumer_sigbus_handle(addr);
-}
diff --git a/src/common/consumer/consumer.cpp b/src/common/consumer/consumer.cpp
new file mode 100644 (file)
index 0000000..47bb5bd
--- /dev/null
@@ -0,0 +1,5255 @@
+/*
+ * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#include "common/index/ctf-index.h"
+#define _LGPL_SOURCE
+#include <poll.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <inttypes.h>
+#include <signal.h>
+
+#include <bin/lttng-consumerd/health-consumerd.h>
+#include <common/common.h>
+#include <common/utils.h>
+#include <common/time.h>
+#include <common/compat/poll.h>
+#include <common/compat/endian.h>
+#include <common/index/index.h>
+#include <common/kernel-ctl/kernel-ctl.h>
+#include <common/sessiond-comm/relayd.h>
+#include <common/sessiond-comm/sessiond-comm.h>
+#include <common/kernel-consumer/kernel-consumer.h>
+#include <common/relayd/relayd.h>
+#include <common/ust-consumer/ust-consumer.h>
+#include <common/consumer/consumer-timer.h>
+#include <common/consumer/consumer.h>
+#include <common/consumer/consumer-stream.h>
+#include <common/consumer/consumer-testpoint.h>
+#include <common/align.h>
+#include <common/consumer/consumer-metadata-cache.h>
+#include <common/trace-chunk.h>
+#include <common/trace-chunk-registry.h>
+#include <common/string-utils/format.h>
+#include <common/dynamic-array.h>
+
+lttng_consumer_global_data the_consumer_data;
+
+enum consumer_channel_action {
+       CONSUMER_CHANNEL_ADD,
+       CONSUMER_CHANNEL_DEL,
+       CONSUMER_CHANNEL_QUIT,
+};
+
+struct consumer_channel_msg {
+       enum consumer_channel_action action;
+       struct lttng_consumer_channel *chan;    /* add */
+       uint64_t key;                           /* del */
+};
+
+/* Flag used to temporarily pause data consumption from testpoints. */
+int data_consumption_paused;
+
+/*
+ * Flag to inform the polling thread to quit when all fd hung up. Updated by
+ * the consumer_thread_receive_fds when it notices that all fds has hung up.
+ * Also updated by the signal handler (consumer_should_exit()). Read by the
+ * polling threads.
+ */
+int consumer_quit;
+
+/*
+ * Global hash table containing respectively metadata and data streams. The
+ * stream element in this ht should only be updated by the metadata poll thread
+ * for the metadata and the data poll thread for the data.
+ */
+static struct lttng_ht *metadata_ht;
+static struct lttng_ht *data_ht;
+
+static const char *get_consumer_domain(void)
+{
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               return DEFAULT_KERNEL_TRACE_DIR;
+       case LTTNG_CONSUMER64_UST:
+               /* Fall-through. */
+       case LTTNG_CONSUMER32_UST:
+               return DEFAULT_UST_TRACE_DIR;
+       default:
+               abort();
+       }
+}
+
+/*
+ * Notify a thread lttng pipe to poll back again. This usually means that some
+ * global state has changed so we just send back the thread in a poll wait
+ * call.
+ */
+static void notify_thread_lttng_pipe(struct lttng_pipe *pipe)
+{
+       struct lttng_consumer_stream *null_stream = NULL;
+
+       LTTNG_ASSERT(pipe);
+
+       (void) lttng_pipe_write(pipe, &null_stream, sizeof(null_stream));
+}
+
+static void notify_health_quit_pipe(int *pipe)
+{
+       ssize_t ret;
+
+       ret = lttng_write(pipe[1], "4", 1);
+       if (ret < 1) {
+               PERROR("write consumer health quit");
+       }
+}
+
+static void notify_channel_pipe(struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_channel *chan,
+               uint64_t key,
+               enum consumer_channel_action action)
+{
+       struct consumer_channel_msg msg;
+       ssize_t ret;
+
+       memset(&msg, 0, sizeof(msg));
+
+       msg.action = action;
+       msg.chan = chan;
+       msg.key = key;
+       ret = lttng_write(ctx->consumer_channel_pipe[1], &msg, sizeof(msg));
+       if (ret < sizeof(msg)) {
+               PERROR("notify_channel_pipe write error");
+       }
+}
+
+void notify_thread_del_channel(struct lttng_consumer_local_data *ctx,
+               uint64_t key)
+{
+       notify_channel_pipe(ctx, NULL, key, CONSUMER_CHANNEL_DEL);
+}
+
+static int read_channel_pipe(struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_channel **chan,
+               uint64_t *key,
+               enum consumer_channel_action *action)
+{
+       struct consumer_channel_msg msg;
+       ssize_t ret;
+
+       ret = lttng_read(ctx->consumer_channel_pipe[0], &msg, sizeof(msg));
+       if (ret < sizeof(msg)) {
+               ret = -1;
+               goto error;
+       }
+       *action = msg.action;
+       *chan = msg.chan;
+       *key = msg.key;
+error:
+       return (int) ret;
+}
+
+/*
+ * Cleanup the stream list of a channel. Those streams are not yet globally
+ * visible
+ */
+static void clean_channel_stream_list(struct lttng_consumer_channel *channel)
+{
+       struct lttng_consumer_stream *stream, *stmp;
+
+       LTTNG_ASSERT(channel);
+
+       /* Delete streams that might have been left in the stream list. */
+       cds_list_for_each_entry_safe(stream, stmp, &channel->streams.head,
+                       send_node) {
+               cds_list_del(&stream->send_node);
+               /*
+                * Once a stream is added to this list, the buffers were created so we
+                * have a guarantee that this call will succeed. Setting the monitor
+                * mode to 0 so we don't lock nor try to delete the stream from the
+                * global hash table.
+                */
+               stream->monitor = 0;
+               consumer_stream_destroy(stream, NULL);
+       }
+}
+
+/*
+ * Find a stream. The consumer_data.lock must be locked during this
+ * call.
+ */
+static struct lttng_consumer_stream *find_stream(uint64_t key,
+               struct lttng_ht *ht)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_ht_node_u64 *node;
+       struct lttng_consumer_stream *stream = NULL;
+
+       LTTNG_ASSERT(ht);
+
+       /* -1ULL keys are lookup failures */
+       if (key == (uint64_t) -1ULL) {
+               return NULL;
+       }
+
+       rcu_read_lock();
+
+       lttng_ht_lookup(ht, &key, &iter);
+       node = lttng_ht_iter_get_node_u64(&iter);
+       if (node != NULL) {
+               stream = caa_container_of(node, struct lttng_consumer_stream, node);
+       }
+
+       rcu_read_unlock();
+
+       return stream;
+}
+
+static void steal_stream_key(uint64_t key, struct lttng_ht *ht)
+{
+       struct lttng_consumer_stream *stream;
+
+       rcu_read_lock();
+       stream = find_stream(key, ht);
+       if (stream) {
+               stream->key = (uint64_t) -1ULL;
+               /*
+                * We don't want the lookup to match, but we still need
+                * to iterate on this stream when iterating over the hash table. Just
+                * change the node key.
+                */
+               stream->node.key = (uint64_t) -1ULL;
+       }
+       rcu_read_unlock();
+}
+
+/*
+ * Return a channel object for the given key.
+ *
+ * RCU read side lock MUST be acquired before calling this function and
+ * protects the channel ptr.
+ */
+struct lttng_consumer_channel *consumer_find_channel(uint64_t key)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_ht_node_u64 *node;
+       struct lttng_consumer_channel *channel = NULL;
+
+       /* -1ULL keys are lookup failures */
+       if (key == (uint64_t) -1ULL) {
+               return NULL;
+       }
+
+       lttng_ht_lookup(the_consumer_data.channel_ht, &key, &iter);
+       node = lttng_ht_iter_get_node_u64(&iter);
+       if (node != NULL) {
+               channel = caa_container_of(node, struct lttng_consumer_channel, node);
+       }
+
+       return channel;
+}
+
+/*
+ * There is a possibility that the consumer does not have enough time between
+ * the close of the channel on the session daemon and the cleanup in here thus
+ * once we have a channel add with an existing key, we know for sure that this
+ * channel will eventually get cleaned up by all streams being closed.
+ *
+ * This function just nullifies the already existing channel key.
+ */
+static void steal_channel_key(uint64_t key)
+{
+       struct lttng_consumer_channel *channel;
+
+       rcu_read_lock();
+       channel = consumer_find_channel(key);
+       if (channel) {
+               channel->key = (uint64_t) -1ULL;
+               /*
+                * We don't want the lookup to match, but we still need to iterate on
+                * this channel when iterating over the hash table. Just change the
+                * node key.
+                */
+               channel->node.key = (uint64_t) -1ULL;
+       }
+       rcu_read_unlock();
+}
+
+static void free_channel_rcu(struct rcu_head *head)
+{
+       struct lttng_ht_node_u64 *node =
+               caa_container_of(head, struct lttng_ht_node_u64, head);
+       struct lttng_consumer_channel *channel =
+               caa_container_of(node, struct lttng_consumer_channel, node);
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               lttng_ustconsumer_free_channel(channel);
+               break;
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+       }
+       free(channel);
+}
+
+/*
+ * RCU protected relayd socket pair free.
+ */
+static void free_relayd_rcu(struct rcu_head *head)
+{
+       struct lttng_ht_node_u64 *node =
+               caa_container_of(head, struct lttng_ht_node_u64, head);
+       struct consumer_relayd_sock_pair *relayd =
+               caa_container_of(node, struct consumer_relayd_sock_pair, node);
+
+       /*
+        * Close all sockets. This is done in the call RCU since we don't want the
+        * socket fds to be reassigned thus potentially creating bad state of the
+        * relayd object.
+        *
+        * We do not have to lock the control socket mutex here since at this stage
+        * there is no one referencing to this relayd object.
+        */
+       (void) relayd_close(&relayd->control_sock);
+       (void) relayd_close(&relayd->data_sock);
+
+       pthread_mutex_destroy(&relayd->ctrl_sock_mutex);
+       free(relayd);
+}
+
+/*
+ * Destroy and free relayd socket pair object.
+ */
+void consumer_destroy_relayd(struct consumer_relayd_sock_pair *relayd)
+{
+       int ret;
+       struct lttng_ht_iter iter;
+
+       if (relayd == NULL) {
+               return;
+       }
+
+       DBG("Consumer destroy and close relayd socket pair");
+
+       iter.iter.node = &relayd->node.node;
+       ret = lttng_ht_del(the_consumer_data.relayd_ht, &iter);
+       if (ret != 0) {
+               /* We assume the relayd is being or is destroyed */
+               return;
+       }
+
+       /* RCU free() call */
+       call_rcu(&relayd->node.head, free_relayd_rcu);
+}
+
+/*
+ * Remove a channel from the global list protected by a mutex. This function is
+ * also responsible for freeing its data structures.
+ */
+void consumer_del_channel(struct lttng_consumer_channel *channel)
+{
+       struct lttng_ht_iter iter;
+
+       DBG("Consumer delete channel key %" PRIu64, channel->key);
+
+       pthread_mutex_lock(&the_consumer_data.lock);
+       pthread_mutex_lock(&channel->lock);
+
+       /* Destroy streams that might have been left in the stream list. */
+       clean_channel_stream_list(channel);
+
+       if (channel->live_timer_enabled == 1) {
+               consumer_timer_live_stop(channel);
+       }
+       if (channel->monitor_timer_enabled == 1) {
+               consumer_timer_monitor_stop(channel);
+       }
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               lttng_ustconsumer_del_channel(channel);
+               break;
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+               goto end;
+       }
+
+       lttng_trace_chunk_put(channel->trace_chunk);
+       channel->trace_chunk = NULL;
+
+       if (channel->is_published) {
+               int ret;
+
+               rcu_read_lock();
+               iter.iter.node = &channel->node.node;
+               ret = lttng_ht_del(the_consumer_data.channel_ht, &iter);
+               LTTNG_ASSERT(!ret);
+
+               iter.iter.node = &channel->channels_by_session_id_ht_node.node;
+               ret = lttng_ht_del(the_consumer_data.channels_by_session_id_ht,
+                               &iter);
+               LTTNG_ASSERT(!ret);
+               rcu_read_unlock();
+       }
+
+       channel->is_deleted = true;
+       call_rcu(&channel->node.head, free_channel_rcu);
+end:
+       pthread_mutex_unlock(&channel->lock);
+       pthread_mutex_unlock(&the_consumer_data.lock);
+}
+
+/*
+ * Iterate over the relayd hash table and destroy each element. Finally,
+ * destroy the whole hash table.
+ */
+static void cleanup_relayd_ht(void)
+{
+       struct lttng_ht_iter iter;
+       struct consumer_relayd_sock_pair *relayd;
+
+       rcu_read_lock();
+
+       cds_lfht_for_each_entry(the_consumer_data.relayd_ht->ht, &iter.iter,
+                       relayd, node.node) {
+               consumer_destroy_relayd(relayd);
+       }
+
+       rcu_read_unlock();
+
+       lttng_ht_destroy(the_consumer_data.relayd_ht);
+}
+
+/*
+ * Update the end point status of all streams having the given network sequence
+ * index (relayd index).
+ *
+ * It's atomically set without having the stream mutex locked which is fine
+ * because we handle the write/read race with a pipe wakeup for each thread.
+ */
+static void update_endpoint_status_by_netidx(uint64_t net_seq_idx,
+               enum consumer_endpoint_status status)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       DBG("Consumer set delete flag on stream by idx %" PRIu64, net_seq_idx);
+
+       rcu_read_lock();
+
+       /* Let's begin with metadata */
+       cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream, node.node) {
+               if (stream->net_seq_idx == net_seq_idx) {
+                       uatomic_set(&stream->endpoint_status, status);
+                       DBG("Delete flag set to metadata stream %d", stream->wait_fd);
+               }
+       }
+
+       /* Follow up by the data streams */
+       cds_lfht_for_each_entry(data_ht->ht, &iter.iter, stream, node.node) {
+               if (stream->net_seq_idx == net_seq_idx) {
+                       uatomic_set(&stream->endpoint_status, status);
+                       DBG("Delete flag set to data stream %d", stream->wait_fd);
+               }
+       }
+       rcu_read_unlock();
+}
+
+/*
+ * Cleanup a relayd object by flagging every associated streams for deletion,
+ * destroying the object meaning removing it from the relayd hash table,
+ * closing the sockets and freeing the memory in a RCU call.
+ *
+ * If a local data context is available, notify the threads that the streams'
+ * state have changed.
+ */
+void lttng_consumer_cleanup_relayd(struct consumer_relayd_sock_pair *relayd)
+{
+       uint64_t netidx;
+
+       LTTNG_ASSERT(relayd);
+
+       DBG("Cleaning up relayd object ID %" PRIu64, relayd->net_seq_idx);
+
+       /* Save the net sequence index before destroying the object */
+       netidx = relayd->net_seq_idx;
+
+       /*
+        * Delete the relayd from the relayd hash table, close the sockets and free
+        * the object in a RCU call.
+        */
+       consumer_destroy_relayd(relayd);
+
+       /* Set inactive endpoint to all streams */
+       update_endpoint_status_by_netidx(netidx, CONSUMER_ENDPOINT_INACTIVE);
+
+       /*
+        * With a local data context, notify the threads that the streams' state
+        * have changed. The write() action on the pipe acts as an "implicit"
+        * memory barrier ordering the updates of the end point status from the
+        * read of this status which happens AFTER receiving this notify.
+        */
+       notify_thread_lttng_pipe(relayd->ctx->consumer_data_pipe);
+       notify_thread_lttng_pipe(relayd->ctx->consumer_metadata_pipe);
+}
+
+/*
+ * Flag a relayd socket pair for destruction. Destroy it if the refcount
+ * reaches zero.
+ *
+ * RCU read side lock MUST be aquired before calling this function.
+ */
+void consumer_flag_relayd_for_destroy(struct consumer_relayd_sock_pair *relayd)
+{
+       LTTNG_ASSERT(relayd);
+
+       /* Set destroy flag for this object */
+       uatomic_set(&relayd->destroy_flag, 1);
+
+       /* Destroy the relayd if refcount is 0 */
+       if (uatomic_read(&relayd->refcount) == 0) {
+               consumer_destroy_relayd(relayd);
+       }
+}
+
+/*
+ * Completly destroy stream from every visiable data structure and the given
+ * hash table if one.
+ *
+ * One this call returns, the stream object is not longer usable nor visible.
+ */
+void consumer_del_stream(struct lttng_consumer_stream *stream,
+               struct lttng_ht *ht)
+{
+       consumer_stream_destroy(stream, ht);
+}
+
+/*
+ * XXX naming of del vs destroy is all mixed up.
+ */
+void consumer_del_stream_for_data(struct lttng_consumer_stream *stream)
+{
+       consumer_stream_destroy(stream, data_ht);
+}
+
+void consumer_del_stream_for_metadata(struct lttng_consumer_stream *stream)
+{
+       consumer_stream_destroy(stream, metadata_ht);
+}
+
+void consumer_stream_update_channel_attributes(
+               struct lttng_consumer_stream *stream,
+               struct lttng_consumer_channel *channel)
+{
+       stream->channel_read_only_attributes.tracefile_size =
+                       channel->tracefile_size;
+}
+
+/*
+ * Add a stream to the global list protected by a mutex.
+ */
+void consumer_add_data_stream(struct lttng_consumer_stream *stream)
+{
+       struct lttng_ht *ht = data_ht;
+
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(ht);
+
+       DBG3("Adding consumer stream %" PRIu64, stream->key);
+
+       pthread_mutex_lock(&the_consumer_data.lock);
+       pthread_mutex_lock(&stream->chan->lock);
+       pthread_mutex_lock(&stream->chan->timer_lock);
+       pthread_mutex_lock(&stream->lock);
+       rcu_read_lock();
+
+       /* Steal stream identifier to avoid having streams with the same key */
+       steal_stream_key(stream->key, ht);
+
+       lttng_ht_add_unique_u64(ht, &stream->node);
+
+       lttng_ht_add_u64(the_consumer_data.stream_per_chan_id_ht,
+                       &stream->node_channel_id);
+
+       /*
+        * Add stream to the stream_list_ht of the consumer data. No need to steal
+        * the key since the HT does not use it and we allow to add redundant keys
+        * into this table.
+        */
+       lttng_ht_add_u64(the_consumer_data.stream_list_ht,
+                       &stream->node_session_id);
+
+       /*
+        * When nb_init_stream_left reaches 0, we don't need to trigger any action
+        * in terms of destroying the associated channel, because the action that
+        * causes the count to become 0 also causes a stream to be added. The
+        * channel deletion will thus be triggered by the following removal of this
+        * stream.
+        */
+       if (uatomic_read(&stream->chan->nb_init_stream_left) > 0) {
+               /* Increment refcount before decrementing nb_init_stream_left */
+               cmm_smp_wmb();
+               uatomic_dec(&stream->chan->nb_init_stream_left);
+       }
+
+       /* Update consumer data once the node is inserted. */
+       the_consumer_data.stream_count++;
+       the_consumer_data.need_update = 1;
+
+       rcu_read_unlock();
+       pthread_mutex_unlock(&stream->lock);
+       pthread_mutex_unlock(&stream->chan->timer_lock);
+       pthread_mutex_unlock(&stream->chan->lock);
+       pthread_mutex_unlock(&the_consumer_data.lock);
+}
+
+/*
+ * Add relayd socket to global consumer data hashtable. RCU read side lock MUST
+ * be acquired before calling this.
+ */
+static int add_relayd(struct consumer_relayd_sock_pair *relayd)
+{
+       int ret = 0;
+       struct lttng_ht_node_u64 *node;
+       struct lttng_ht_iter iter;
+
+       LTTNG_ASSERT(relayd);
+
+       lttng_ht_lookup(the_consumer_data.relayd_ht, &relayd->net_seq_idx,
+                       &iter);
+       node = lttng_ht_iter_get_node_u64(&iter);
+       if (node != NULL) {
+               goto end;
+       }
+       lttng_ht_add_unique_u64(the_consumer_data.relayd_ht, &relayd->node);
+
+end:
+       return ret;
+}
+
+/*
+ * Allocate and return a consumer relayd socket.
+ */
+static struct consumer_relayd_sock_pair *consumer_allocate_relayd_sock_pair(
+               uint64_t net_seq_idx)
+{
+       struct consumer_relayd_sock_pair *obj = NULL;
+
+       /* net sequence index of -1 is a failure */
+       if (net_seq_idx == (uint64_t) -1ULL) {
+               goto error;
+       }
+
+       obj = (consumer_relayd_sock_pair *) zmalloc(sizeof(struct consumer_relayd_sock_pair));
+       if (obj == NULL) {
+               PERROR("zmalloc relayd sock");
+               goto error;
+       }
+
+       obj->net_seq_idx = net_seq_idx;
+       obj->refcount = 0;
+       obj->destroy_flag = 0;
+       obj->control_sock.sock.fd = -1;
+       obj->data_sock.sock.fd = -1;
+       lttng_ht_node_init_u64(&obj->node, obj->net_seq_idx);
+       pthread_mutex_init(&obj->ctrl_sock_mutex, NULL);
+
+error:
+       return obj;
+}
+
+/*
+ * Find a relayd socket pair in the global consumer data.
+ *
+ * Return the object if found else NULL.
+ * RCU read-side lock must be held across this call and while using the
+ * returned object.
+ */
+struct consumer_relayd_sock_pair *consumer_find_relayd(uint64_t key)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_ht_node_u64 *node;
+       struct consumer_relayd_sock_pair *relayd = NULL;
+
+       /* Negative keys are lookup failures */
+       if (key == (uint64_t) -1ULL) {
+               goto error;
+       }
+
+       lttng_ht_lookup(the_consumer_data.relayd_ht, &key, &iter);
+       node = lttng_ht_iter_get_node_u64(&iter);
+       if (node != NULL) {
+               relayd = caa_container_of(node, struct consumer_relayd_sock_pair, node);
+       }
+
+error:
+       return relayd;
+}
+
+/*
+ * Find a relayd and send the stream
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int consumer_send_relayd_stream(struct lttng_consumer_stream *stream,
+               char *path)
+{
+       int ret = 0;
+       struct consumer_relayd_sock_pair *relayd;
+
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->net_seq_idx != -1ULL);
+       LTTNG_ASSERT(path);
+
+       /* The stream is not metadata. Get relayd reference if exists. */
+       rcu_read_lock();
+       relayd = consumer_find_relayd(stream->net_seq_idx);
+       if (relayd != NULL) {
+               /* Add stream on the relayd */
+               pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+               ret = relayd_add_stream(&relayd->control_sock, stream->name,
+                               get_consumer_domain(), path, &stream->relayd_stream_id,
+                               stream->chan->tracefile_size,
+                               stream->chan->tracefile_count,
+                               stream->trace_chunk);
+               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+               if (ret < 0) {
+                       ERR("Relayd add stream failed. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
+                       lttng_consumer_cleanup_relayd(relayd);
+                       goto end;
+               }
+
+               uatomic_inc(&relayd->refcount);
+               stream->sent_to_relayd = 1;
+       } else {
+               ERR("Stream %" PRIu64 " relayd ID %" PRIu64 " unknown. Can't send it.",
+                               stream->key, stream->net_seq_idx);
+               ret = -1;
+               goto end;
+       }
+
+       DBG("Stream %s with key %" PRIu64 " sent to relayd id %" PRIu64,
+                       stream->name, stream->key, stream->net_seq_idx);
+
+end:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Find a relayd and send the streams sent message
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int consumer_send_relayd_streams_sent(uint64_t net_seq_idx)
+{
+       int ret = 0;
+       struct consumer_relayd_sock_pair *relayd;
+
+       LTTNG_ASSERT(net_seq_idx != -1ULL);
+
+       /* The stream is not metadata. Get relayd reference if exists. */
+       rcu_read_lock();
+       relayd = consumer_find_relayd(net_seq_idx);
+       if (relayd != NULL) {
+               /* Add stream on the relayd */
+               pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+               ret = relayd_streams_sent(&relayd->control_sock);
+               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+               if (ret < 0) {
+                       ERR("Relayd streams sent failed. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
+                       lttng_consumer_cleanup_relayd(relayd);
+                       goto end;
+               }
+       } else {
+               ERR("Relayd ID %" PRIu64 " unknown. Can't send streams_sent.",
+                               net_seq_idx);
+               ret = -1;
+               goto end;
+       }
+
+       ret = 0;
+       DBG("All streams sent relayd id %" PRIu64, net_seq_idx);
+
+end:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Find a relayd and close the stream
+ */
+void close_relayd_stream(struct lttng_consumer_stream *stream)
+{
+       struct consumer_relayd_sock_pair *relayd;
+
+       /* The stream is not metadata. Get relayd reference if exists. */
+       rcu_read_lock();
+       relayd = consumer_find_relayd(stream->net_seq_idx);
+       if (relayd) {
+               consumer_stream_relayd_close(stream, relayd);
+       }
+       rcu_read_unlock();
+}
+
+/*
+ * Handle stream for relayd transmission if the stream applies for network
+ * streaming where the net sequence index is set.
+ *
+ * Return destination file descriptor or negative value on error.
+ */
+static int write_relayd_stream_header(struct lttng_consumer_stream *stream,
+               size_t data_size, unsigned long padding,
+               struct consumer_relayd_sock_pair *relayd)
+{
+       int outfd = -1, ret;
+       struct lttcomm_relayd_data_hdr data_hdr;
+
+       /* Safety net */
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(relayd);
+
+       /* Reset data header */
+       memset(&data_hdr, 0, sizeof(data_hdr));
+
+       if (stream->metadata_flag) {
+               /* Caller MUST acquire the relayd control socket lock */
+               ret = relayd_send_metadata(&relayd->control_sock, data_size);
+               if (ret < 0) {
+                       goto error;
+               }
+
+               /* Metadata are always sent on the control socket. */
+               outfd = relayd->control_sock.sock.fd;
+       } else {
+               /* Set header with stream information */
+               data_hdr.stream_id = htobe64(stream->relayd_stream_id);
+               data_hdr.data_size = htobe32(data_size);
+               data_hdr.padding_size = htobe32(padding);
+
+               /*
+                * Note that net_seq_num below is assigned with the *current* value of
+                * next_net_seq_num and only after that the next_net_seq_num will be
+                * increment. This is why when issuing a command on the relayd using
+                * this next value, 1 should always be substracted in order to compare
+                * the last seen sequence number on the relayd side to the last sent.
+                */
+               data_hdr.net_seq_num = htobe64(stream->next_net_seq_num);
+               /* Other fields are zeroed previously */
+
+               ret = relayd_send_data_hdr(&relayd->data_sock, &data_hdr,
+                               sizeof(data_hdr));
+               if (ret < 0) {
+                       goto error;
+               }
+
+               ++stream->next_net_seq_num;
+
+               /* Set to go on data socket */
+               outfd = relayd->data_sock.sock.fd;
+       }
+
+error:
+       return outfd;
+}
+
+/*
+ * Write a character on the metadata poll pipe to wake the metadata thread.
+ * Returns 0 on success, -1 on error.
+ */
+int consumer_metadata_wakeup_pipe(const struct lttng_consumer_channel *channel)
+{
+       int ret = 0;
+
+       DBG("Waking up metadata poll thread (writing to pipe): channel name = '%s'",
+                       channel->name);
+       if (channel->monitor && channel->metadata_stream) {
+               const char dummy = 'c';
+               const ssize_t write_ret = lttng_write(
+                               channel->metadata_stream->ust_metadata_poll_pipe[1],
+                               &dummy, 1);
+
+               if (write_ret < 1) {
+                       if (errno == EWOULDBLOCK) {
+                               /*
+                                * This is fine, the metadata poll thread
+                                * is having a hard time keeping-up, but
+                                * it will eventually wake-up and consume
+                                * the available data.
+                                */
+                               ret = 0;
+                       } else {
+                               PERROR("Failed to write to UST metadata pipe while attempting to wake-up the metadata poll thread");
+                               ret = -1;
+                               goto end;
+                       }
+               }
+       }
+
+end:
+       return ret;
+}
+
+/*
+ * Trigger a dump of the metadata content. Following/during the succesful
+ * completion of this call, the metadata poll thread will start receiving
+ * metadata packets to consume.
+ *
+ * The caller must hold the channel and stream locks.
+ */
+static
+int consumer_metadata_stream_dump(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       ASSERT_LOCKED(stream->chan->lock);
+       ASSERT_LOCKED(stream->lock);
+       LTTNG_ASSERT(stream->metadata_flag);
+       LTTNG_ASSERT(stream->chan->trace_chunk);
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               /*
+                * Reset the position of what has been read from the
+                * metadata cache to 0 so we can dump it again.
+                */
+               ret = kernctl_metadata_cache_dump(stream->wait_fd);
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               /*
+                * Reset the position pushed from the metadata cache so it
+                * will write from the beginning on the next push.
+                */
+               stream->ust_metadata_pushed = 0;
+               ret = consumer_metadata_wakeup_pipe(stream->chan);
+               break;
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+       }
+       if (ret < 0) {
+               ERR("Failed to dump the metadata cache");
+       }
+       return ret;
+}
+
+static
+int lttng_consumer_channel_set_trace_chunk(
+               struct lttng_consumer_channel *channel,
+               struct lttng_trace_chunk *new_trace_chunk)
+{
+       pthread_mutex_lock(&channel->lock);
+       if (channel->is_deleted) {
+               /*
+                * The channel has been logically deleted and should no longer
+                * be used. It has released its reference to its current trace
+                * chunk and should not acquire a new one.
+                *
+                * Return success as there is nothing for the caller to do.
+                */
+               goto end;
+       }
+
+       /*
+        * The acquisition of the reference cannot fail (barring
+        * a severe internal error) since a reference to the published
+        * chunk is already held by the caller.
+        */
+       if (new_trace_chunk) {
+               const bool acquired_reference = lttng_trace_chunk_get(
+                               new_trace_chunk);
+
+               LTTNG_ASSERT(acquired_reference);
+       }
+
+       lttng_trace_chunk_put(channel->trace_chunk);
+       channel->trace_chunk = new_trace_chunk;
+end:
+       pthread_mutex_unlock(&channel->lock);
+       return 0;
+}
+
+/*
+ * Allocate and return a new lttng_consumer_channel object using the given key
+ * to initialize the hash table node.
+ *
+ * On error, return NULL.
+ */
+struct lttng_consumer_channel *consumer_allocate_channel(uint64_t key,
+               uint64_t session_id,
+               const uint64_t *chunk_id,
+               const char *pathname,
+               const char *name,
+               uint64_t relayd_id,
+               enum lttng_event_output output,
+               uint64_t tracefile_size,
+               uint64_t tracefile_count,
+               uint64_t session_id_per_pid,
+               unsigned int monitor,
+               unsigned int live_timer_interval,
+               bool is_in_live_session,
+               const char *root_shm_path,
+               const char *shm_path)
+{
+       struct lttng_consumer_channel *channel = NULL;
+       struct lttng_trace_chunk *trace_chunk = NULL;
+
+       if (chunk_id) {
+               trace_chunk = lttng_trace_chunk_registry_find_chunk(
+                               the_consumer_data.chunk_registry, session_id,
+                               *chunk_id);
+               if (!trace_chunk) {
+                       ERR("Failed to find trace chunk reference during creation of channel");
+                       goto end;
+               }
+       }
+
+       channel = (lttng_consumer_channel *) zmalloc(sizeof(*channel));
+       if (channel == NULL) {
+               PERROR("malloc struct lttng_consumer_channel");
+               goto end;
+       }
+
+       channel->key = key;
+       channel->refcount = 0;
+       channel->session_id = session_id;
+       channel->session_id_per_pid = session_id_per_pid;
+       channel->relayd_id = relayd_id;
+       channel->tracefile_size = tracefile_size;
+       channel->tracefile_count = tracefile_count;
+       channel->monitor = monitor;
+       channel->live_timer_interval = live_timer_interval;
+       channel->is_live = is_in_live_session;
+       pthread_mutex_init(&channel->lock, NULL);
+       pthread_mutex_init(&channel->timer_lock, NULL);
+
+       switch (output) {
+       case LTTNG_EVENT_SPLICE:
+               channel->output = CONSUMER_CHANNEL_SPLICE;
+               break;
+       case LTTNG_EVENT_MMAP:
+               channel->output = CONSUMER_CHANNEL_MMAP;
+               break;
+       default:
+               abort();
+               free(channel);
+               channel = NULL;
+               goto end;
+       }
+
+       /*
+        * In monitor mode, the streams associated with the channel will be put in
+        * a special list ONLY owned by this channel. So, the refcount is set to 1
+        * here meaning that the channel itself has streams that are referenced.
+        *
+        * On a channel deletion, once the channel is no longer visible, the
+        * refcount is decremented and checked for a zero value to delete it. With
+        * streams in no monitor mode, it will now be safe to destroy the channel.
+        */
+       if (!channel->monitor) {
+               channel->refcount = 1;
+       }
+
+       strncpy(channel->pathname, pathname, sizeof(channel->pathname));
+       channel->pathname[sizeof(channel->pathname) - 1] = '\0';
+
+       strncpy(channel->name, name, sizeof(channel->name));
+       channel->name[sizeof(channel->name) - 1] = '\0';
+
+       if (root_shm_path) {
+               strncpy(channel->root_shm_path, root_shm_path, sizeof(channel->root_shm_path));
+               channel->root_shm_path[sizeof(channel->root_shm_path) - 1] = '\0';
+       }
+       if (shm_path) {
+               strncpy(channel->shm_path, shm_path, sizeof(channel->shm_path));
+               channel->shm_path[sizeof(channel->shm_path) - 1] = '\0';
+       }
+
+       lttng_ht_node_init_u64(&channel->node, channel->key);
+       lttng_ht_node_init_u64(&channel->channels_by_session_id_ht_node,
+                       channel->session_id);
+
+       channel->wait_fd = -1;
+       CDS_INIT_LIST_HEAD(&channel->streams.head);
+
+       if (trace_chunk) {
+               int ret = lttng_consumer_channel_set_trace_chunk(channel,
+                               trace_chunk);
+               if (ret) {
+                       goto error;
+               }
+       }
+
+       DBG("Allocated channel (key %" PRIu64 ")", channel->key);
+
+end:
+       lttng_trace_chunk_put(trace_chunk);
+       return channel;
+error:
+       consumer_del_channel(channel);
+       channel = NULL;
+       goto end;
+}
+
+/*
+ * Add a channel to the global list protected by a mutex.
+ *
+ * Always return 0 indicating success.
+ */
+int consumer_add_channel(struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx)
+{
+       pthread_mutex_lock(&the_consumer_data.lock);
+       pthread_mutex_lock(&channel->lock);
+       pthread_mutex_lock(&channel->timer_lock);
+
+       /*
+        * This gives us a guarantee that the channel we are about to add to the
+        * channel hash table will be unique. See this function comment on the why
+        * we need to steel the channel key at this stage.
+        */
+       steal_channel_key(channel->key);
+
+       rcu_read_lock();
+       lttng_ht_add_unique_u64(the_consumer_data.channel_ht, &channel->node);
+       lttng_ht_add_u64(the_consumer_data.channels_by_session_id_ht,
+                       &channel->channels_by_session_id_ht_node);
+       rcu_read_unlock();
+       channel->is_published = true;
+
+       pthread_mutex_unlock(&channel->timer_lock);
+       pthread_mutex_unlock(&channel->lock);
+       pthread_mutex_unlock(&the_consumer_data.lock);
+
+       if (channel->wait_fd != -1 && channel->type == CONSUMER_CHANNEL_TYPE_DATA) {
+               notify_channel_pipe(ctx, channel, -1, CONSUMER_CHANNEL_ADD);
+       }
+
+       return 0;
+}
+
+/*
+ * Allocate the pollfd structure and the local view of the out fds to avoid
+ * doing a lookup in the linked list and concurrency issues when writing is
+ * needed. Called with consumer_data.lock held.
+ *
+ * Returns the number of fds in the structures.
+ */
+static int update_poll_array(struct lttng_consumer_local_data *ctx,
+               struct pollfd **pollfd, struct lttng_consumer_stream **local_stream,
+               struct lttng_ht *ht, int *nb_inactive_fd)
+{
+       int i = 0;
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       LTTNG_ASSERT(ctx);
+       LTTNG_ASSERT(ht);
+       LTTNG_ASSERT(pollfd);
+       LTTNG_ASSERT(local_stream);
+
+       DBG("Updating poll fd array");
+       *nb_inactive_fd = 0;
+       rcu_read_lock();
+       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
+               /*
+                * Only active streams with an active end point can be added to the
+                * poll set and local stream storage of the thread.
+                *
+                * There is a potential race here for endpoint_status to be updated
+                * just after the check. However, this is OK since the stream(s) will
+                * be deleted once the thread is notified that the end point state has
+                * changed where this function will be called back again.
+                *
+                * We track the number of inactive FDs because they still need to be
+                * closed by the polling thread after a wakeup on the data_pipe or
+                * metadata_pipe.
+                */
+               if (stream->endpoint_status == CONSUMER_ENDPOINT_INACTIVE) {
+                       (*nb_inactive_fd)++;
+                       continue;
+               }
+               /*
+                * This clobbers way too much the debug output. Uncomment that if you
+                * need it for debugging purposes.
+                */
+               (*pollfd)[i].fd = stream->wait_fd;
+               (*pollfd)[i].events = POLLIN | POLLPRI;
+               local_stream[i] = stream;
+               i++;
+       }
+       rcu_read_unlock();
+
+       /*
+        * Insert the consumer_data_pipe at the end of the array and don't
+        * increment i so nb_fd is the number of real FD.
+        */
+       (*pollfd)[i].fd = lttng_pipe_get_readfd(ctx->consumer_data_pipe);
+       (*pollfd)[i].events = POLLIN | POLLPRI;
+
+       (*pollfd)[i + 1].fd = lttng_pipe_get_readfd(ctx->consumer_wakeup_pipe);
+       (*pollfd)[i + 1].events = POLLIN | POLLPRI;
+       return i;
+}
+
+/*
+ * Poll on the should_quit pipe and the command socket return -1 on
+ * error, 1 if should exit, 0 if data is available on the command socket
+ */
+int lttng_consumer_poll_socket(struct pollfd *consumer_sockpoll)
+{
+       int num_rdy;
+
+restart:
+       num_rdy = poll(consumer_sockpoll, 2, -1);
+       if (num_rdy == -1) {
+               /*
+                * Restart interrupted system call.
+                */
+               if (errno == EINTR) {
+                       goto restart;
+               }
+               PERROR("Poll error");
+               return -1;
+       }
+       if (consumer_sockpoll[0].revents & (POLLIN | POLLPRI)) {
+               DBG("consumer_should_quit wake up");
+               return 1;
+       }
+       return 0;
+}
+
+/*
+ * Set the error socket.
+ */
+void lttng_consumer_set_error_sock(struct lttng_consumer_local_data *ctx,
+               int sock)
+{
+       ctx->consumer_error_socket = sock;
+}
+
+/*
+ * Set the command socket path.
+ */
+void lttng_consumer_set_command_sock_path(
+               struct lttng_consumer_local_data *ctx, char *sock)
+{
+       ctx->consumer_command_sock_path = sock;
+}
+
+/*
+ * Send return code to the session daemon.
+ * If the socket is not defined, we return 0, it is not a fatal error
+ */
+int lttng_consumer_send_error(struct lttng_consumer_local_data *ctx, int cmd)
+{
+       if (ctx->consumer_error_socket > 0) {
+               return lttcomm_send_unix_sock(ctx->consumer_error_socket, &cmd,
+                               sizeof(enum lttcomm_sessiond_command));
+       }
+
+       return 0;
+}
+
+/*
+ * Close all the tracefiles and stream fds and MUST be called when all
+ * instances are destroyed i.e. when all threads were joined and are ended.
+ */
+void lttng_consumer_cleanup(void)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_channel *channel;
+       unsigned int trace_chunks_left;
+
+       rcu_read_lock();
+
+       cds_lfht_for_each_entry(the_consumer_data.channel_ht->ht, &iter.iter,
+                       channel, node.node) {
+               consumer_del_channel(channel);
+       }
+
+       rcu_read_unlock();
+
+       lttng_ht_destroy(the_consumer_data.channel_ht);
+       lttng_ht_destroy(the_consumer_data.channels_by_session_id_ht);
+
+       cleanup_relayd_ht();
+
+       lttng_ht_destroy(the_consumer_data.stream_per_chan_id_ht);
+
+       /*
+        * This HT contains streams that are freed by either the metadata thread or
+        * the data thread so we do *nothing* on the hash table and simply destroy
+        * it.
+        */
+       lttng_ht_destroy(the_consumer_data.stream_list_ht);
+
+       /*
+        * Trace chunks in the registry may still exist if the session
+        * daemon has encountered an internal error and could not
+        * tear down its sessions and/or trace chunks properly.
+        *
+        * Release the session daemon's implicit reference to any remaining
+        * trace chunk and print an error if any trace chunk was found. Note
+        * that there are _no_ legitimate cases for trace chunks to be left,
+        * it is a leak. However, it can happen following a crash of the
+        * session daemon and not emptying the registry would cause an assertion
+        * to hit.
+        */
+       trace_chunks_left = lttng_trace_chunk_registry_put_each_chunk(
+                       the_consumer_data.chunk_registry);
+       if (trace_chunks_left) {
+               ERR("%u trace chunks are leaked by lttng-consumerd. "
+                               "This can be caused by an internal error of the session daemon.",
+                               trace_chunks_left);
+       }
+       /* Run all callbacks freeing each chunk. */
+       rcu_barrier();
+       lttng_trace_chunk_registry_destroy(the_consumer_data.chunk_registry);
+}
+
+/*
+ * Called from signal handler.
+ */
+void lttng_consumer_should_exit(struct lttng_consumer_local_data *ctx)
+{
+       ssize_t ret;
+
+       CMM_STORE_SHARED(consumer_quit, 1);
+       ret = lttng_write(ctx->consumer_should_quit[1], "4", 1);
+       if (ret < 1) {
+               PERROR("write consumer quit");
+       }
+
+       DBG("Consumer flag that it should quit");
+}
+
+
+/*
+ * Flush pending writes to trace output disk file.
+ */
+static
+void lttng_consumer_sync_trace_file(struct lttng_consumer_stream *stream,
+               off_t orig_offset)
+{
+       int ret;
+       int outfd = stream->out_fd;
+
+       /*
+        * This does a blocking write-and-wait on any page that belongs to the
+        * subbuffer prior to the one we just wrote.
+        * Don't care about error values, as these are just hints and ways to
+        * limit the amount of page cache used.
+        */
+       if (orig_offset < stream->max_sb_size) {
+               return;
+       }
+       lttng_sync_file_range(outfd, orig_offset - stream->max_sb_size,
+                       stream->max_sb_size,
+                       SYNC_FILE_RANGE_WAIT_BEFORE
+                       | SYNC_FILE_RANGE_WRITE
+                       | SYNC_FILE_RANGE_WAIT_AFTER);
+       /*
+        * Give hints to the kernel about how we access the file:
+        * POSIX_FADV_DONTNEED : we won't re-access data in a near future after
+        * we write it.
+        *
+        * We need to call fadvise again after the file grows because the
+        * kernel does not seem to apply fadvise to non-existing parts of the
+        * file.
+        *
+        * Call fadvise _after_ having waited for the page writeback to
+        * complete because the dirty page writeback semantic is not well
+        * defined. So it can be expected to lead to lower throughput in
+        * streaming.
+        */
+       ret = posix_fadvise(outfd, orig_offset - stream->max_sb_size,
+                       stream->max_sb_size, POSIX_FADV_DONTNEED);
+       if (ret && ret != -ENOSYS) {
+               errno = ret;
+               PERROR("posix_fadvise on fd %i", outfd);
+       }
+}
+
+/*
+ * Initialise the necessary environnement :
+ * - create a new context
+ * - create the poll_pipe
+ * - create the should_quit pipe (for signal handler)
+ * - create the thread pipe (for splice)
+ *
+ * Takes a function pointer as argument, this function is called when data is
+ * available on a buffer. This function is responsible to do the
+ * kernctl_get_next_subbuf, read the data with mmap or splice depending on the
+ * buffer configuration and then kernctl_put_next_subbuf at the end.
+ *
+ * Returns a pointer to the new context or NULL on error.
+ */
+struct lttng_consumer_local_data *lttng_consumer_create(
+               enum lttng_consumer_type type,
+               ssize_t (*buffer_ready)(struct lttng_consumer_stream *stream,
+                       struct lttng_consumer_local_data *ctx, bool locked_by_caller),
+               int (*recv_channel)(struct lttng_consumer_channel *channel),
+               int (*recv_stream)(struct lttng_consumer_stream *stream),
+               int (*update_stream)(uint64_t stream_key, uint32_t state))
+{
+       int ret;
+       struct lttng_consumer_local_data *ctx;
+
+       LTTNG_ASSERT(the_consumer_data.type == LTTNG_CONSUMER_UNKNOWN ||
+                       the_consumer_data.type == type);
+       the_consumer_data.type = type;
+
+       ctx = (lttng_consumer_local_data *) zmalloc(sizeof(struct lttng_consumer_local_data));
+       if (ctx == NULL) {
+               PERROR("allocating context");
+               goto error;
+       }
+
+       ctx->consumer_error_socket = -1;
+       ctx->consumer_metadata_socket = -1;
+       pthread_mutex_init(&ctx->metadata_socket_lock, NULL);
+       /* assign the callbacks */
+       ctx->on_buffer_ready = buffer_ready;
+       ctx->on_recv_channel = recv_channel;
+       ctx->on_recv_stream = recv_stream;
+       ctx->on_update_stream = update_stream;
+
+       ctx->consumer_data_pipe = lttng_pipe_open(0);
+       if (!ctx->consumer_data_pipe) {
+               goto error_poll_pipe;
+       }
+
+       ctx->consumer_wakeup_pipe = lttng_pipe_open(0);
+       if (!ctx->consumer_wakeup_pipe) {
+               goto error_wakeup_pipe;
+       }
+
+       ret = pipe(ctx->consumer_should_quit);
+       if (ret < 0) {
+               PERROR("Error creating recv pipe");
+               goto error_quit_pipe;
+       }
+
+       ret = pipe(ctx->consumer_channel_pipe);
+       if (ret < 0) {
+               PERROR("Error creating channel pipe");
+               goto error_channel_pipe;
+       }
+
+       ctx->consumer_metadata_pipe = lttng_pipe_open(0);
+       if (!ctx->consumer_metadata_pipe) {
+               goto error_metadata_pipe;
+       }
+
+       ctx->channel_monitor_pipe = -1;
+
+       return ctx;
+
+error_metadata_pipe:
+       utils_close_pipe(ctx->consumer_channel_pipe);
+error_channel_pipe:
+       utils_close_pipe(ctx->consumer_should_quit);
+error_quit_pipe:
+       lttng_pipe_destroy(ctx->consumer_wakeup_pipe);
+error_wakeup_pipe:
+       lttng_pipe_destroy(ctx->consumer_data_pipe);
+error_poll_pipe:
+       free(ctx);
+error:
+       return NULL;
+}
+
+/*
+ * Iterate over all streams of the hashtable and free them properly.
+ */
+static void destroy_data_stream_ht(struct lttng_ht *ht)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       if (ht == NULL) {
+               return;
+       }
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
+               /*
+                * Ignore return value since we are currently cleaning up so any error
+                * can't be handled.
+                */
+               (void) consumer_del_stream(stream, ht);
+       }
+       rcu_read_unlock();
+
+       lttng_ht_destroy(ht);
+}
+
+/*
+ * Iterate over all streams of the metadata hashtable and free them
+ * properly.
+ */
+static void destroy_metadata_stream_ht(struct lttng_ht *ht)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       if (ht == NULL) {
+               return;
+       }
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
+               /*
+                * Ignore return value since we are currently cleaning up so any error
+                * can't be handled.
+                */
+               (void) consumer_del_metadata_stream(stream, ht);
+       }
+       rcu_read_unlock();
+
+       lttng_ht_destroy(ht);
+}
+
+/*
+ * Close all fds associated with the instance and free the context.
+ */
+void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+
+       DBG("Consumer destroying it. Closing everything.");
+
+       if (!ctx) {
+               return;
+       }
+
+       destroy_data_stream_ht(data_ht);
+       destroy_metadata_stream_ht(metadata_ht);
+
+       ret = close(ctx->consumer_error_socket);
+       if (ret) {
+               PERROR("close");
+       }
+       ret = close(ctx->consumer_metadata_socket);
+       if (ret) {
+               PERROR("close");
+       }
+       utils_close_pipe(ctx->consumer_channel_pipe);
+       lttng_pipe_destroy(ctx->consumer_data_pipe);
+       lttng_pipe_destroy(ctx->consumer_metadata_pipe);
+       lttng_pipe_destroy(ctx->consumer_wakeup_pipe);
+       utils_close_pipe(ctx->consumer_should_quit);
+
+       unlink(ctx->consumer_command_sock_path);
+       free(ctx);
+}
+
+/*
+ * Write the metadata stream id on the specified file descriptor.
+ */
+static int write_relayd_metadata_id(int fd,
+               struct lttng_consumer_stream *stream,
+               unsigned long padding)
+{
+       ssize_t ret;
+       struct lttcomm_relayd_metadata_payload hdr;
+
+       hdr.stream_id = htobe64(stream->relayd_stream_id);
+       hdr.padding_size = htobe32(padding);
+       ret = lttng_write(fd, (void *) &hdr, sizeof(hdr));
+       if (ret < sizeof(hdr)) {
+               /*
+                * This error means that the fd's end is closed so ignore the PERROR
+                * not to clubber the error output since this can happen in a normal
+                * code path.
+                */
+               if (errno != EPIPE) {
+                       PERROR("write metadata stream id");
+               }
+               DBG3("Consumer failed to write relayd metadata id (errno: %d)", errno);
+               /*
+                * Set ret to a negative value because if ret != sizeof(hdr), we don't
+                * handle writting the missing part so report that as an error and
+                * don't lie to the caller.
+                */
+               ret = -1;
+               goto end;
+       }
+       DBG("Metadata stream id %" PRIu64 " with padding %lu written before data",
+                       stream->relayd_stream_id, padding);
+
+end:
+       return (int) ret;
+}
+
+/*
+ * Mmap the ring buffer, read it and write the data to the tracefile. This is a
+ * core function for writing trace buffers to either the local filesystem or
+ * the network.
+ *
+ * It must be called with the stream and the channel lock held.
+ *
+ * Careful review MUST be put if any changes occur!
+ *
+ * Returns the number of bytes written
+ */
+ssize_t lttng_consumer_on_read_subbuffer_mmap(
+               struct lttng_consumer_stream *stream,
+               const struct lttng_buffer_view *buffer,
+               unsigned long padding)
+{
+       ssize_t ret = 0;
+       off_t orig_offset = stream->out_fd_offset;
+       /* Default is on the disk */
+       int outfd = stream->out_fd;
+       struct consumer_relayd_sock_pair *relayd = NULL;
+       unsigned int relayd_hang_up = 0;
+       const size_t subbuf_content_size = buffer->size - padding;
+       size_t write_len;
+
+       /* RCU lock for the relayd pointer */
+       rcu_read_lock();
+       LTTNG_ASSERT(stream->net_seq_idx != (uint64_t) -1ULL ||
+                       stream->trace_chunk);
+
+       /* Flag that the current stream if set for network streaming. */
+       if (stream->net_seq_idx != (uint64_t) -1ULL) {
+               relayd = consumer_find_relayd(stream->net_seq_idx);
+               if (relayd == NULL) {
+                       ret = -EPIPE;
+                       goto end;
+               }
+       }
+
+       /* Handle stream on the relayd if the output is on the network */
+       if (relayd) {
+               unsigned long netlen = subbuf_content_size;
+
+               /*
+                * Lock the control socket for the complete duration of the function
+                * since from this point on we will use the socket.
+                */
+               if (stream->metadata_flag) {
+                       /* Metadata requires the control socket. */
+                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+                       if (stream->reset_metadata_flag) {
+                               ret = relayd_reset_metadata(&relayd->control_sock,
+                                               stream->relayd_stream_id,
+                                               stream->metadata_version);
+                               if (ret < 0) {
+                                       relayd_hang_up = 1;
+                                       goto write_error;
+                               }
+                               stream->reset_metadata_flag = 0;
+                       }
+                       netlen += sizeof(struct lttcomm_relayd_metadata_payload);
+               }
+
+               ret = write_relayd_stream_header(stream, netlen, padding, relayd);
+               if (ret < 0) {
+                       relayd_hang_up = 1;
+                       goto write_error;
+               }
+               /* Use the returned socket. */
+               outfd = ret;
+
+               /* Write metadata stream id before payload */
+               if (stream->metadata_flag) {
+                       ret = write_relayd_metadata_id(outfd, stream, padding);
+                       if (ret < 0) {
+                               relayd_hang_up = 1;
+                               goto write_error;
+                       }
+               }
+
+               write_len = subbuf_content_size;
+       } else {
+               /* No streaming; we have to write the full padding. */
+               if (stream->metadata_flag && stream->reset_metadata_flag) {
+                       ret = utils_truncate_stream_file(stream->out_fd, 0);
+                       if (ret < 0) {
+                               ERR("Reset metadata file");
+                               goto end;
+                       }
+                       stream->reset_metadata_flag = 0;
+               }
+
+               /*
+                * Check if we need to change the tracefile before writing the packet.
+                */
+               if (stream->chan->tracefile_size > 0 &&
+                               (stream->tracefile_size_current + buffer->size) >
+                               stream->chan->tracefile_size) {
+                       ret = consumer_stream_rotate_output_files(stream);
+                       if (ret) {
+                               goto end;
+                       }
+                       outfd = stream->out_fd;
+                       orig_offset = 0;
+               }
+               stream->tracefile_size_current += buffer->size;
+               write_len = buffer->size;
+       }
+
+       /*
+        * This call guarantee that len or less is returned. It's impossible to
+        * receive a ret value that is bigger than len.
+        */
+       ret = lttng_write(outfd, buffer->data, write_len);
+       DBG("Consumer mmap write() ret %zd (len %zu)", ret, write_len);
+       if (ret < 0 || ((size_t) ret != write_len)) {
+               /*
+                * Report error to caller if nothing was written else at least send the
+                * amount written.
+                */
+               if (ret < 0) {
+                       ret = -errno;
+               }
+               relayd_hang_up = 1;
+
+               /* Socket operation failed. We consider the relayd dead */
+               if (errno == EPIPE) {
+                       /*
+                        * This is possible if the fd is closed on the other side
+                        * (outfd) or any write problem. It can be verbose a bit for a
+                        * normal execution if for instance the relayd is stopped
+                        * abruptly. This can happen so set this to a DBG statement.
+                        */
+                       DBG("Consumer mmap write detected relayd hang up");
+               } else {
+                       /* Unhandled error, print it and stop function right now. */
+                       PERROR("Error in write mmap (ret %zd != write_len %zu)", ret,
+                                       write_len);
+               }
+               goto write_error;
+       }
+       stream->output_written += ret;
+
+       /* This call is useless on a socket so better save a syscall. */
+       if (!relayd) {
+               /* This won't block, but will start writeout asynchronously */
+               lttng_sync_file_range(outfd, stream->out_fd_offset, write_len,
+                               SYNC_FILE_RANGE_WRITE);
+               stream->out_fd_offset += write_len;
+               lttng_consumer_sync_trace_file(stream, orig_offset);
+       }
+
+write_error:
+       /*
+        * This is a special case that the relayd has closed its socket. Let's
+        * cleanup the relayd object and all associated streams.
+        */
+       if (relayd && relayd_hang_up) {
+               ERR("Relayd hangup. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
+               lttng_consumer_cleanup_relayd(relayd);
+       }
+
+end:
+       /* Unlock only if ctrl socket used */
+       if (relayd && stream->metadata_flag) {
+               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+       }
+
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Splice the data from the ring buffer to the tracefile.
+ *
+ * It must be called with the stream lock held.
+ *
+ * Returns the number of bytes spliced.
+ */
+ssize_t lttng_consumer_on_read_subbuffer_splice(
+               struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_stream *stream, unsigned long len,
+               unsigned long padding)
+{
+       ssize_t ret = 0, written = 0, ret_splice = 0;
+       loff_t offset = 0;
+       off_t orig_offset = stream->out_fd_offset;
+       int fd = stream->wait_fd;
+       /* Default is on the disk */
+       int outfd = stream->out_fd;
+       struct consumer_relayd_sock_pair *relayd = NULL;
+       int *splice_pipe;
+       unsigned int relayd_hang_up = 0;
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               /* Not supported for user space tracing */
+               return -ENOSYS;
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+       }
+
+       /* RCU lock for the relayd pointer */
+       rcu_read_lock();
+
+       /* Flag that the current stream if set for network streaming. */
+       if (stream->net_seq_idx != (uint64_t) -1ULL) {
+               relayd = consumer_find_relayd(stream->net_seq_idx);
+               if (relayd == NULL) {
+                       written = -ret;
+                       goto end;
+               }
+       }
+       splice_pipe = stream->splice_pipe;
+
+       /* Write metadata stream id before payload */
+       if (relayd) {
+               unsigned long total_len = len;
+
+               if (stream->metadata_flag) {
+                       /*
+                        * Lock the control socket for the complete duration of the function
+                        * since from this point on we will use the socket.
+                        */
+                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+
+                       if (stream->reset_metadata_flag) {
+                               ret = relayd_reset_metadata(&relayd->control_sock,
+                                               stream->relayd_stream_id,
+                                               stream->metadata_version);
+                               if (ret < 0) {
+                                       relayd_hang_up = 1;
+                                       goto write_error;
+                               }
+                               stream->reset_metadata_flag = 0;
+                       }
+                       ret = write_relayd_metadata_id(splice_pipe[1], stream,
+                                       padding);
+                       if (ret < 0) {
+                               written = ret;
+                               relayd_hang_up = 1;
+                               goto write_error;
+                       }
+
+                       total_len += sizeof(struct lttcomm_relayd_metadata_payload);
+               }
+
+               ret = write_relayd_stream_header(stream, total_len, padding, relayd);
+               if (ret < 0) {
+                       written = ret;
+                       relayd_hang_up = 1;
+                       goto write_error;
+               }
+               /* Use the returned socket. */
+               outfd = ret;
+       } else {
+               /* No streaming, we have to set the len with the full padding */
+               len += padding;
+
+               if (stream->metadata_flag && stream->reset_metadata_flag) {
+                       ret = utils_truncate_stream_file(stream->out_fd, 0);
+                       if (ret < 0) {
+                               ERR("Reset metadata file");
+                               goto end;
+                       }
+                       stream->reset_metadata_flag = 0;
+               }
+               /*
+                * Check if we need to change the tracefile before writing the packet.
+                */
+               if (stream->chan->tracefile_size > 0 &&
+                               (stream->tracefile_size_current + len) >
+                               stream->chan->tracefile_size) {
+                       ret = consumer_stream_rotate_output_files(stream);
+                       if (ret < 0) {
+                               written = ret;
+                               goto end;
+                       }
+                       outfd = stream->out_fd;
+                       orig_offset = 0;
+               }
+               stream->tracefile_size_current += len;
+       }
+
+       while (len > 0) {
+               DBG("splice chan to pipe offset %lu of len %lu (fd : %d, pipe: %d)",
+                               (unsigned long)offset, len, fd, splice_pipe[1]);
+               ret_splice = splice(fd, &offset, splice_pipe[1], NULL, len,
+                               SPLICE_F_MOVE | SPLICE_F_MORE);
+               DBG("splice chan to pipe, ret %zd", ret_splice);
+               if (ret_splice < 0) {
+                       ret = errno;
+                       written = -ret;
+                       PERROR("Error in relay splice");
+                       goto splice_error;
+               }
+
+               /* Handle stream on the relayd if the output is on the network */
+               if (relayd && stream->metadata_flag) {
+                       size_t metadata_payload_size =
+                               sizeof(struct lttcomm_relayd_metadata_payload);
+
+                       /* Update counter to fit the spliced data */
+                       ret_splice += metadata_payload_size;
+                       len += metadata_payload_size;
+                       /*
+                        * We do this so the return value can match the len passed as
+                        * argument to this function.
+                        */
+                       written -= metadata_payload_size;
+               }
+
+               /* Splice data out */
+               ret_splice = splice(splice_pipe[0], NULL, outfd, NULL,
+                               ret_splice, SPLICE_F_MOVE | SPLICE_F_MORE);
+               DBG("Consumer splice pipe to file (out_fd: %d), ret %zd",
+                               outfd, ret_splice);
+               if (ret_splice < 0) {
+                       ret = errno;
+                       written = -ret;
+                       relayd_hang_up = 1;
+                       goto write_error;
+               } else if (ret_splice > len) {
+                       /*
+                        * We don't expect this code path to be executed but you never know
+                        * so this is an extra protection agains a buggy splice().
+                        */
+                       ret = errno;
+                       written += ret_splice;
+                       PERROR("Wrote more data than requested %zd (len: %lu)", ret_splice,
+                                       len);
+                       goto splice_error;
+               } else {
+                       /* All good, update current len and continue. */
+                       len -= ret_splice;
+               }
+
+               /* This call is useless on a socket so better save a syscall. */
+               if (!relayd) {
+                       /* This won't block, but will start writeout asynchronously */
+                       lttng_sync_file_range(outfd, stream->out_fd_offset, ret_splice,
+                                       SYNC_FILE_RANGE_WRITE);
+                       stream->out_fd_offset += ret_splice;
+               }
+               stream->output_written += ret_splice;
+               written += ret_splice;
+       }
+       if (!relayd) {
+               lttng_consumer_sync_trace_file(stream, orig_offset);
+       }
+       goto end;
+
+write_error:
+       /*
+        * This is a special case that the relayd has closed its socket. Let's
+        * cleanup the relayd object and all associated streams.
+        */
+       if (relayd && relayd_hang_up) {
+               ERR("Relayd hangup. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
+               lttng_consumer_cleanup_relayd(relayd);
+               /* Skip splice error so the consumer does not fail */
+               goto end;
+       }
+
+splice_error:
+       /* send the appropriate error description to sessiond */
+       switch (ret) {
+       case EINVAL:
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_SPLICE_EINVAL);
+               break;
+       case ENOMEM:
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_SPLICE_ENOMEM);
+               break;
+       case ESPIPE:
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_SPLICE_ESPIPE);
+               break;
+       }
+
+end:
+       if (relayd && stream->metadata_flag) {
+               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+       }
+
+       rcu_read_unlock();
+       return written;
+}
+
+/*
+ * Sample the snapshot positions for a specific fd
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_consumer_sample_snapshot_positions(struct lttng_consumer_stream *stream)
+{
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               return lttng_kconsumer_sample_snapshot_positions(stream);
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               return lttng_ustconsumer_sample_snapshot_positions(stream);
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+               return -ENOSYS;
+       }
+}
+/*
+ * Take a snapshot for a specific fd
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_consumer_take_snapshot(struct lttng_consumer_stream *stream)
+{
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               return lttng_kconsumer_take_snapshot(stream);
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               return lttng_ustconsumer_take_snapshot(stream);
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+               return -ENOSYS;
+       }
+}
+
+/*
+ * Get the produced position
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_consumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
+               unsigned long *pos)
+{
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               return lttng_kconsumer_get_produced_snapshot(stream, pos);
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               return lttng_ustconsumer_get_produced_snapshot(stream, pos);
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+               return -ENOSYS;
+       }
+}
+
+/*
+ * Get the consumed position (free-running counter position in bytes).
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_consumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
+               unsigned long *pos)
+{
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               return lttng_kconsumer_get_consumed_snapshot(stream, pos);
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               return lttng_ustconsumer_get_consumed_snapshot(stream, pos);
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+               return -ENOSYS;
+       }
+}
+
+int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
+               int sock, struct pollfd *consumer_sockpoll)
+{
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               return lttng_kconsumer_recv_cmd(ctx, sock, consumer_sockpoll);
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               return lttng_ustconsumer_recv_cmd(ctx, sock, consumer_sockpoll);
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+               return -ENOSYS;
+       }
+}
+
+static
+void lttng_consumer_close_all_metadata(void)
+{
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               /*
+                * The Kernel consumer has a different metadata scheme so we don't
+                * close anything because the stream will be closed by the session
+                * daemon.
+                */
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               /*
+                * Close all metadata streams. The metadata hash table is passed and
+                * this call iterates over it by closing all wakeup fd. This is safe
+                * because at this point we are sure that the metadata producer is
+                * either dead or blocked.
+                */
+               lttng_ustconsumer_close_all_metadata(metadata_ht);
+               break;
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+       }
+}
+
+/*
+ * Clean up a metadata stream and free its memory.
+ */
+void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
+               struct lttng_ht *ht)
+{
+       struct lttng_consumer_channel *channel = NULL;
+       bool free_channel = false;
+
+       LTTNG_ASSERT(stream);
+       /*
+        * This call should NEVER receive regular stream. It must always be
+        * metadata stream and this is crucial for data structure synchronization.
+        */
+       LTTNG_ASSERT(stream->metadata_flag);
+
+       DBG3("Consumer delete metadata stream %d", stream->wait_fd);
+
+       pthread_mutex_lock(&the_consumer_data.lock);
+       /*
+        * Note that this assumes that a stream's channel is never changed and
+        * that the stream's lock doesn't need to be taken to sample its
+        * channel.
+        */
+       channel = stream->chan;
+       pthread_mutex_lock(&channel->lock);
+       pthread_mutex_lock(&stream->lock);
+       if (channel->metadata_cache) {
+               /* Only applicable to userspace consumers. */
+               pthread_mutex_lock(&channel->metadata_cache->lock);
+       }
+
+       /* Remove any reference to that stream. */
+       consumer_stream_delete(stream, ht);
+
+       /* Close down everything including the relayd if one. */
+       consumer_stream_close(stream);
+       /* Destroy tracer buffers of the stream. */
+       consumer_stream_destroy_buffers(stream);
+
+       /* Atomically decrement channel refcount since other threads can use it. */
+       if (!uatomic_sub_return(&channel->refcount, 1)
+                       && !uatomic_read(&channel->nb_init_stream_left)) {
+               /* Go for channel deletion! */
+               free_channel = true;
+       }
+       stream->chan = NULL;
+
+       /*
+        * Nullify the stream reference so it is not used after deletion. The
+        * channel lock MUST be acquired before being able to check for a NULL
+        * pointer value.
+        */
+       channel->metadata_stream = NULL;
+
+       if (channel->metadata_cache) {
+               pthread_mutex_unlock(&channel->metadata_cache->lock);
+       }
+       pthread_mutex_unlock(&stream->lock);
+       pthread_mutex_unlock(&channel->lock);
+       pthread_mutex_unlock(&the_consumer_data.lock);
+
+       if (free_channel) {
+               consumer_del_channel(channel);
+       }
+
+       lttng_trace_chunk_put(stream->trace_chunk);
+       stream->trace_chunk = NULL;
+       consumer_stream_free(stream);
+}
+
+/*
+ * Action done with the metadata stream when adding it to the consumer internal
+ * data structures to handle it.
+ */
+void consumer_add_metadata_stream(struct lttng_consumer_stream *stream)
+{
+       struct lttng_ht *ht = metadata_ht;
+       struct lttng_ht_iter iter;
+       struct lttng_ht_node_u64 *node;
+
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(ht);
+
+       DBG3("Adding metadata stream %" PRIu64 " to hash table", stream->key);
+
+       pthread_mutex_lock(&the_consumer_data.lock);
+       pthread_mutex_lock(&stream->chan->lock);
+       pthread_mutex_lock(&stream->chan->timer_lock);
+       pthread_mutex_lock(&stream->lock);
+
+       /*
+        * From here, refcounts are updated so be _careful_ when returning an error
+        * after this point.
+        */
+
+       rcu_read_lock();
+
+       /*
+        * Lookup the stream just to make sure it does not exist in our internal
+        * state. This should NEVER happen.
+        */
+       lttng_ht_lookup(ht, &stream->key, &iter);
+       node = lttng_ht_iter_get_node_u64(&iter);
+       LTTNG_ASSERT(!node);
+
+       /*
+        * When nb_init_stream_left reaches 0, we don't need to trigger any action
+        * in terms of destroying the associated channel, because the action that
+        * causes the count to become 0 also causes a stream to be added. The
+        * channel deletion will thus be triggered by the following removal of this
+        * stream.
+        */
+       if (uatomic_read(&stream->chan->nb_init_stream_left) > 0) {
+               /* Increment refcount before decrementing nb_init_stream_left */
+               cmm_smp_wmb();
+               uatomic_dec(&stream->chan->nb_init_stream_left);
+       }
+
+       lttng_ht_add_unique_u64(ht, &stream->node);
+
+       lttng_ht_add_u64(the_consumer_data.stream_per_chan_id_ht,
+                       &stream->node_channel_id);
+
+       /*
+        * Add stream to the stream_list_ht of the consumer data. No need to steal
+        * the key since the HT does not use it and we allow to add redundant keys
+        * into this table.
+        */
+       lttng_ht_add_u64(the_consumer_data.stream_list_ht,
+                       &stream->node_session_id);
+
+       rcu_read_unlock();
+
+       pthread_mutex_unlock(&stream->lock);
+       pthread_mutex_unlock(&stream->chan->lock);
+       pthread_mutex_unlock(&stream->chan->timer_lock);
+       pthread_mutex_unlock(&the_consumer_data.lock);
+}
+
+/*
+ * Delete data stream that are flagged for deletion (endpoint_status).
+ */
+static void validate_endpoint_status_data_stream(void)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       DBG("Consumer delete flagged data stream");
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(data_ht->ht, &iter.iter, stream, node.node) {
+               /* Validate delete flag of the stream */
+               if (stream->endpoint_status == CONSUMER_ENDPOINT_ACTIVE) {
+                       continue;
+               }
+               /* Delete it right now */
+               consumer_del_stream(stream, data_ht);
+       }
+       rcu_read_unlock();
+}
+
+/*
+ * Delete metadata stream that are flagged for deletion (endpoint_status).
+ */
+static void validate_endpoint_status_metadata_stream(
+               struct lttng_poll_event *pollset)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       DBG("Consumer delete flagged metadata stream");
+
+       LTTNG_ASSERT(pollset);
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream, node.node) {
+               /* Validate delete flag of the stream */
+               if (stream->endpoint_status == CONSUMER_ENDPOINT_ACTIVE) {
+                       continue;
+               }
+               /*
+                * Remove from pollset so the metadata thread can continue without
+                * blocking on a deleted stream.
+                */
+               lttng_poll_del(pollset, stream->wait_fd);
+
+               /* Delete it right now */
+               consumer_del_metadata_stream(stream, metadata_ht);
+       }
+       rcu_read_unlock();
+}
+
+/*
+ * Thread polls on metadata file descriptor and write them on disk or on the
+ * network.
+ */
+void *consumer_thread_metadata_poll(void *data)
+{
+       int ret, i, pollfd, err = -1;
+       uint32_t revents, nb_fd;
+       struct lttng_consumer_stream *stream = NULL;
+       struct lttng_ht_iter iter;
+       struct lttng_ht_node_u64 *node;
+       struct lttng_poll_event events;
+       struct lttng_consumer_local_data *ctx = (lttng_consumer_local_data *) data;
+       ssize_t len;
+
+       rcu_register_thread();
+
+       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_METADATA);
+
+       if (testpoint(consumerd_thread_metadata)) {
+               goto error_testpoint;
+       }
+
+       health_code_update();
+
+       DBG("Thread metadata poll started");
+
+       /* Size is set to 1 for the consumer_metadata pipe */
+       ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
+       if (ret < 0) {
+               ERR("Poll set creation failed");
+               goto end_poll;
+       }
+
+       ret = lttng_poll_add(&events,
+                       lttng_pipe_get_readfd(ctx->consumer_metadata_pipe), LPOLLIN);
+       if (ret < 0) {
+               goto end;
+       }
+
+       /* Main loop */
+       DBG("Metadata main loop started");
+
+       while (1) {
+restart:
+               health_code_update();
+               health_poll_entry();
+               DBG("Metadata poll wait");
+               ret = lttng_poll_wait(&events, -1);
+               DBG("Metadata poll return from wait with %d fd(s)",
+                               LTTNG_POLL_GETNB(&events));
+               health_poll_exit();
+               DBG("Metadata event caught in thread");
+               if (ret < 0) {
+                       if (errno == EINTR) {
+                               ERR("Poll EINTR caught");
+                               goto restart;
+                       }
+                       if (LTTNG_POLL_GETNB(&events) == 0) {
+                               err = 0;        /* All is OK */
+                       }
+                       goto end;
+               }
+
+               nb_fd = ret;
+
+               /* From here, the event is a metadata wait fd */
+               for (i = 0; i < nb_fd; i++) {
+                       health_code_update();
+
+                       revents = LTTNG_POLL_GETEV(&events, i);
+                       pollfd = LTTNG_POLL_GETFD(&events, i);
+
+                       if (pollfd == lttng_pipe_get_readfd(ctx->consumer_metadata_pipe)) {
+                               if (revents & LPOLLIN) {
+                                       ssize_t pipe_len;
+
+                                       pipe_len = lttng_pipe_read(ctx->consumer_metadata_pipe,
+                                                       &stream, sizeof(stream));
+                                       if (pipe_len < sizeof(stream)) {
+                                               if (pipe_len < 0) {
+                                                       PERROR("read metadata stream");
+                                               }
+                                               /*
+                                                * Remove the pipe from the poll set and continue the loop
+                                                * since their might be data to consume.
+                                                */
+                                               lttng_poll_del(&events,
+                                                               lttng_pipe_get_readfd(ctx->consumer_metadata_pipe));
+                                               lttng_pipe_read_close(ctx->consumer_metadata_pipe);
+                                               continue;
+                                       }
+
+                                       /* A NULL stream means that the state has changed. */
+                                       if (stream == NULL) {
+                                               /* Check for deleted streams. */
+                                               validate_endpoint_status_metadata_stream(&events);
+                                               goto restart;
+                                       }
+
+                                       DBG("Adding metadata stream %d to poll set",
+                                                       stream->wait_fd);
+
+                                       /* Add metadata stream to the global poll events list */
+                                       lttng_poll_add(&events, stream->wait_fd,
+                                                       LPOLLIN | LPOLLPRI | LPOLLHUP);
+                               } else if (revents & (LPOLLERR | LPOLLHUP)) {
+                                       DBG("Metadata thread pipe hung up");
+                                       /*
+                                        * Remove the pipe from the poll set and continue the loop
+                                        * since their might be data to consume.
+                                        */
+                                       lttng_poll_del(&events,
+                                                       lttng_pipe_get_readfd(ctx->consumer_metadata_pipe));
+                                       lttng_pipe_read_close(ctx->consumer_metadata_pipe);
+                                       continue;
+                               } else {
+                                       ERR("Unexpected poll events %u for sock %d", revents, pollfd);
+                                       goto end;
+                               }
+
+                               /* Handle other stream */
+                               continue;
+                       }
+
+                       rcu_read_lock();
+                       {
+                               uint64_t tmp_id = (uint64_t) pollfd;
+
+                               lttng_ht_lookup(metadata_ht, &tmp_id, &iter);
+                       }
+                       node = lttng_ht_iter_get_node_u64(&iter);
+                       LTTNG_ASSERT(node);
+
+                       stream = caa_container_of(node, struct lttng_consumer_stream,
+                                       node);
+
+                       if (revents & (LPOLLIN | LPOLLPRI)) {
+                               /* Get the data out of the metadata file descriptor */
+                               DBG("Metadata available on fd %d", pollfd);
+                               LTTNG_ASSERT(stream->wait_fd == pollfd);
+
+                               do {
+                                       health_code_update();
+
+                                       len = ctx->on_buffer_ready(stream, ctx, false);
+                                       /*
+                                        * We don't check the return value here since if we get
+                                        * a negative len, it means an error occurred thus we
+                                        * simply remove it from the poll set and free the
+                                        * stream.
+                                        */
+                               } while (len > 0);
+
+                               /* It's ok to have an unavailable sub-buffer */
+                               if (len < 0 && len != -EAGAIN && len != -ENODATA) {
+                                       /* Clean up stream from consumer and free it. */
+                                       lttng_poll_del(&events, stream->wait_fd);
+                                       consumer_del_metadata_stream(stream, metadata_ht);
+                               }
+                       } else if (revents & (LPOLLERR | LPOLLHUP)) {
+                               DBG("Metadata fd %d is hup|err.", pollfd);
+                               if (!stream->hangup_flush_done &&
+                                               (the_consumer_data.type == LTTNG_CONSUMER32_UST ||
+                                                               the_consumer_data.type ==
+                                                                               LTTNG_CONSUMER64_UST)) {
+                                       DBG("Attempting to flush and consume the UST buffers");
+                                       lttng_ustconsumer_on_stream_hangup(stream);
+
+                                       /* We just flushed the stream now read it. */
+                                       do {
+                                               health_code_update();
+
+                                               len = ctx->on_buffer_ready(stream, ctx, false);
+                                               /*
+                                                * We don't check the return value here since if we get
+                                                * a negative len, it means an error occurred thus we
+                                                * simply remove it from the poll set and free the
+                                                * stream.
+                                                */
+                                       } while (len > 0);
+                               }
+
+                               lttng_poll_del(&events, stream->wait_fd);
+                               /*
+                                * This call update the channel states, closes file descriptors
+                                * and securely free the stream.
+                                */
+                               consumer_del_metadata_stream(stream, metadata_ht);
+                       } else {
+                               ERR("Unexpected poll events %u for sock %d", revents, pollfd);
+                               rcu_read_unlock();
+                               goto end;
+                       }
+                       /* Release RCU lock for the stream looked up */
+                       rcu_read_unlock();
+               }
+       }
+
+       /* All is OK */
+       err = 0;
+end:
+       DBG("Metadata poll thread exiting");
+
+       lttng_poll_clean(&events);
+end_poll:
+error_testpoint:
+       if (err) {
+               health_error();
+               ERR("Health error occurred in %s", __func__);
+       }
+       health_unregister(health_consumerd);
+       rcu_unregister_thread();
+       return NULL;
+}
+
+/*
+ * This thread polls the fds in the set to consume the data and write
+ * it to tracefile if necessary.
+ */
+void *consumer_thread_data_poll(void *data)
+{
+       int num_rdy, num_hup, high_prio, ret, i, err = -1;
+       struct pollfd *pollfd = NULL;
+       /* local view of the streams */
+       struct lttng_consumer_stream **local_stream = NULL, *new_stream = NULL;
+       /* local view of consumer_data.fds_count */
+       int nb_fd = 0;
+       /* 2 for the consumer_data_pipe and wake up pipe */
+       const int nb_pipes_fd = 2;
+       /* Number of FDs with CONSUMER_ENDPOINT_INACTIVE but still open. */
+       int nb_inactive_fd = 0;
+       struct lttng_consumer_local_data *ctx = (lttng_consumer_local_data *) data;
+       ssize_t len;
+
+       rcu_register_thread();
+
+       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_DATA);
+
+       if (testpoint(consumerd_thread_data)) {
+               goto error_testpoint;
+       }
+
+       health_code_update();
+
+       local_stream = (lttng_consumer_stream **) zmalloc(sizeof(struct lttng_consumer_stream *));
+       if (local_stream == NULL) {
+               PERROR("local_stream malloc");
+               goto end;
+       }
+
+       while (1) {
+               health_code_update();
+
+               high_prio = 0;
+               num_hup = 0;
+
+               /*
+                * the fds set has been updated, we need to update our
+                * local array as well
+                */
+               pthread_mutex_lock(&the_consumer_data.lock);
+               if (the_consumer_data.need_update) {
+                       free(pollfd);
+                       pollfd = NULL;
+
+                       free(local_stream);
+                       local_stream = NULL;
+
+                       /* Allocate for all fds */
+                       pollfd = (struct pollfd *) zmalloc((the_consumer_data.stream_count +
+                                                        nb_pipes_fd) *
+                                       sizeof(struct pollfd));
+                       if (pollfd == NULL) {
+                               PERROR("pollfd malloc");
+                               pthread_mutex_unlock(&the_consumer_data.lock);
+                               goto end;
+                       }
+
+                       local_stream = (lttng_consumer_stream **) zmalloc((the_consumer_data.stream_count +
+                                                              nb_pipes_fd) *
+                                       sizeof(struct lttng_consumer_stream *));
+                       if (local_stream == NULL) {
+                               PERROR("local_stream malloc");
+                               pthread_mutex_unlock(&the_consumer_data.lock);
+                               goto end;
+                       }
+                       ret = update_poll_array(ctx, &pollfd, local_stream,
+                                       data_ht, &nb_inactive_fd);
+                       if (ret < 0) {
+                               ERR("Error in allocating pollfd or local_outfds");
+                               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_POLL_ERROR);
+                               pthread_mutex_unlock(&the_consumer_data.lock);
+                               goto end;
+                       }
+                       nb_fd = ret;
+                       the_consumer_data.need_update = 0;
+               }
+               pthread_mutex_unlock(&the_consumer_data.lock);
+
+               /* No FDs and consumer_quit, consumer_cleanup the thread */
+               if (nb_fd == 0 && nb_inactive_fd == 0 &&
+                               CMM_LOAD_SHARED(consumer_quit) == 1) {
+                       err = 0;        /* All is OK */
+                       goto end;
+               }
+               /* poll on the array of fds */
+       restart:
+               DBG("polling on %d fd", nb_fd + nb_pipes_fd);
+               if (testpoint(consumerd_thread_data_poll)) {
+                       goto end;
+               }
+               health_poll_entry();
+               num_rdy = poll(pollfd, nb_fd + nb_pipes_fd, -1);
+               health_poll_exit();
+               DBG("poll num_rdy : %d", num_rdy);
+               if (num_rdy == -1) {
+                       /*
+                        * Restart interrupted system call.
+                        */
+                       if (errno == EINTR) {
+                               goto restart;
+                       }
+                       PERROR("Poll error");
+                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_POLL_ERROR);
+                       goto end;
+               } else if (num_rdy == 0) {
+                       DBG("Polling thread timed out");
+                       goto end;
+               }
+
+               if (caa_unlikely(data_consumption_paused)) {
+                       DBG("Data consumption paused, sleeping...");
+                       sleep(1);
+                       goto restart;
+               }
+
+               /*
+                * If the consumer_data_pipe triggered poll go directly to the
+                * beginning of the loop to update the array. We want to prioritize
+                * array update over low-priority reads.
+                */
+               if (pollfd[nb_fd].revents & (POLLIN | POLLPRI)) {
+                       ssize_t pipe_readlen;
+
+                       DBG("consumer_data_pipe wake up");
+                       pipe_readlen = lttng_pipe_read(ctx->consumer_data_pipe,
+                                       &new_stream, sizeof(new_stream));
+                       if (pipe_readlen < sizeof(new_stream)) {
+                               PERROR("Consumer data pipe");
+                               /* Continue so we can at least handle the current stream(s). */
+                               continue;
+                       }
+
+                       /*
+                        * If the stream is NULL, just ignore it. It's also possible that
+                        * the sessiond poll thread changed the consumer_quit state and is
+                        * waking us up to test it.
+                        */
+                       if (new_stream == NULL) {
+                               validate_endpoint_status_data_stream();
+                               continue;
+                       }
+
+                       /* Continue to update the local streams and handle prio ones */
+                       continue;
+               }
+
+               /* Handle wakeup pipe. */
+               if (pollfd[nb_fd + 1].revents & (POLLIN | POLLPRI)) {
+                       char dummy;
+                       ssize_t pipe_readlen;
+
+                       pipe_readlen = lttng_pipe_read(ctx->consumer_wakeup_pipe, &dummy,
+                                       sizeof(dummy));
+                       if (pipe_readlen < 0) {
+                               PERROR("Consumer data wakeup pipe");
+                       }
+                       /* We've been awakened to handle stream(s). */
+                       ctx->has_wakeup = 0;
+               }
+
+               /* Take care of high priority channels first. */
+               for (i = 0; i < nb_fd; i++) {
+                       health_code_update();
+
+                       if (local_stream[i] == NULL) {
+                               continue;
+                       }
+                       if (pollfd[i].revents & POLLPRI) {
+                               DBG("Urgent read on fd %d", pollfd[i].fd);
+                               high_prio = 1;
+                               len = ctx->on_buffer_ready(local_stream[i], ctx, false);
+                               /* it's ok to have an unavailable sub-buffer */
+                               if (len < 0 && len != -EAGAIN && len != -ENODATA) {
+                                       /* Clean the stream and free it. */
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
+                               } else if (len > 0) {
+                                       local_stream[i]->data_read = 1;
+                               }
+                       }
+               }
+
+               /*
+                * If we read high prio channel in this loop, try again
+                * for more high prio data.
+                */
+               if (high_prio) {
+                       continue;
+               }
+
+               /* Take care of low priority channels. */
+               for (i = 0; i < nb_fd; i++) {
+                       health_code_update();
+
+                       if (local_stream[i] == NULL) {
+                               continue;
+                       }
+                       if ((pollfd[i].revents & POLLIN) ||
+                                       local_stream[i]->hangup_flush_done ||
+                                       local_stream[i]->has_data) {
+                               DBG("Normal read on fd %d", pollfd[i].fd);
+                               len = ctx->on_buffer_ready(local_stream[i], ctx, false);
+                               /* it's ok to have an unavailable sub-buffer */
+                               if (len < 0 && len != -EAGAIN && len != -ENODATA) {
+                                       /* Clean the stream and free it. */
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
+                               } else if (len > 0) {
+                                       local_stream[i]->data_read = 1;
+                               }
+                       }
+               }
+
+               /* Handle hangup and errors */
+               for (i = 0; i < nb_fd; i++) {
+                       health_code_update();
+
+                       if (local_stream[i] == NULL) {
+                               continue;
+                       }
+                       if (!local_stream[i]->hangup_flush_done
+                                       && (pollfd[i].revents & (POLLHUP | POLLERR | POLLNVAL))
+                                       && (the_consumer_data.type == LTTNG_CONSUMER32_UST
+                                               || the_consumer_data.type == LTTNG_CONSUMER64_UST)) {
+                               DBG("fd %d is hup|err|nval. Attempting flush and read.",
+                                               pollfd[i].fd);
+                               lttng_ustconsumer_on_stream_hangup(local_stream[i]);
+                               /* Attempt read again, for the data we just flushed. */
+                               local_stream[i]->data_read = 1;
+                       }
+                       /*
+                        * If the poll flag is HUP/ERR/NVAL and we have
+                        * read no data in this pass, we can remove the
+                        * stream from its hash table.
+                        */
+                       if ((pollfd[i].revents & POLLHUP)) {
+                               DBG("Polling fd %d tells it has hung up.", pollfd[i].fd);
+                               if (!local_stream[i]->data_read) {
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
+                                       num_hup++;
+                               }
+                       } else if (pollfd[i].revents & POLLERR) {
+                               ERR("Error returned in polling fd %d.", pollfd[i].fd);
+                               if (!local_stream[i]->data_read) {
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
+                                       num_hup++;
+                               }
+                       } else if (pollfd[i].revents & POLLNVAL) {
+                               ERR("Polling fd %d tells fd is not open.", pollfd[i].fd);
+                               if (!local_stream[i]->data_read) {
+                                       consumer_del_stream(local_stream[i], data_ht);
+                                       local_stream[i] = NULL;
+                                       num_hup++;
+                               }
+                       }
+                       if (local_stream[i] != NULL) {
+                               local_stream[i]->data_read = 0;
+                       }
+               }
+       }
+       /* All is OK */
+       err = 0;
+end:
+       DBG("polling thread exiting");
+       free(pollfd);
+       free(local_stream);
+
+       /*
+        * Close the write side of the pipe so epoll_wait() in
+        * consumer_thread_metadata_poll can catch it. The thread is monitoring the
+        * read side of the pipe. If we close them both, epoll_wait strangely does
+        * not return and could create a endless wait period if the pipe is the
+        * only tracked fd in the poll set. The thread will take care of closing
+        * the read side.
+        */
+       (void) lttng_pipe_write_close(ctx->consumer_metadata_pipe);
+
+error_testpoint:
+       if (err) {
+               health_error();
+               ERR("Health error occurred in %s", __func__);
+       }
+       health_unregister(health_consumerd);
+
+       rcu_unregister_thread();
+       return NULL;
+}
+
+/*
+ * Close wake-up end of each stream belonging to the channel. This will
+ * allow the poll() on the stream read-side to detect when the
+ * write-side (application) finally closes them.
+ */
+static
+void consumer_close_channel_streams(struct lttng_consumer_channel *channel)
+{
+       struct lttng_ht *ht;
+       struct lttng_consumer_stream *stream;
+       struct lttng_ht_iter iter;
+
+       ht = the_consumer_data.stream_per_chan_id_ht;
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&channel->key, lttng_ht_seed),
+                       ht->match_fct, &channel->key,
+                       &iter.iter, stream, node_channel_id.node) {
+               /*
+                * Protect against teardown with mutex.
+                */
+               pthread_mutex_lock(&stream->lock);
+               if (cds_lfht_is_node_deleted(&stream->node.node)) {
+                       goto next;
+               }
+               switch (the_consumer_data.type) {
+               case LTTNG_CONSUMER_KERNEL:
+                       break;
+               case LTTNG_CONSUMER32_UST:
+               case LTTNG_CONSUMER64_UST:
+                       if (stream->metadata_flag) {
+                               /* Safe and protected by the stream lock. */
+                               lttng_ustconsumer_close_metadata(stream->chan);
+                       } else {
+                               /*
+                                * Note: a mutex is taken internally within
+                                * liblttng-ust-ctl to protect timer wakeup_fd
+                                * use from concurrent close.
+                                */
+                               lttng_ustconsumer_close_stream_wakeup(stream);
+                       }
+                       break;
+               default:
+                       ERR("Unknown consumer_data type");
+                       abort();
+               }
+       next:
+               pthread_mutex_unlock(&stream->lock);
+       }
+       rcu_read_unlock();
+}
+
+static void destroy_channel_ht(struct lttng_ht *ht)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_channel *channel;
+       int ret;
+
+       if (ht == NULL) {
+               return;
+       }
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(ht->ht, &iter.iter, channel, wait_fd_node.node) {
+               ret = lttng_ht_del(ht, &iter);
+               LTTNG_ASSERT(ret != 0);
+       }
+       rcu_read_unlock();
+
+       lttng_ht_destroy(ht);
+}
+
+/*
+ * This thread polls the channel fds to detect when they are being
+ * closed. It closes all related streams if the channel is detected as
+ * closed. It is currently only used as a shim layer for UST because the
+ * consumerd needs to keep the per-stream wakeup end of pipes open for
+ * periodical flush.
+ */
+void *consumer_thread_channel_poll(void *data)
+{
+       int ret, i, pollfd, err = -1;
+       uint32_t revents, nb_fd;
+       struct lttng_consumer_channel *chan = NULL;
+       struct lttng_ht_iter iter;
+       struct lttng_ht_node_u64 *node;
+       struct lttng_poll_event events;
+       struct lttng_consumer_local_data *ctx = (lttng_consumer_local_data *) data;
+       struct lttng_ht *channel_ht;
+
+       rcu_register_thread();
+
+       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_CHANNEL);
+
+       if (testpoint(consumerd_thread_channel)) {
+               goto error_testpoint;
+       }
+
+       health_code_update();
+
+       channel_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
+       if (!channel_ht) {
+               /* ENOMEM at this point. Better to bail out. */
+               goto end_ht;
+       }
+
+       DBG("Thread channel poll started");
+
+       /* Size is set to 1 for the consumer_channel pipe */
+       ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
+       if (ret < 0) {
+               ERR("Poll set creation failed");
+               goto end_poll;
+       }
+
+       ret = lttng_poll_add(&events, ctx->consumer_channel_pipe[0], LPOLLIN);
+       if (ret < 0) {
+               goto end;
+       }
+
+       /* Main loop */
+       DBG("Channel main loop started");
+
+       while (1) {
+restart:
+               health_code_update();
+               DBG("Channel poll wait");
+               health_poll_entry();
+               ret = lttng_poll_wait(&events, -1);
+               DBG("Channel poll return from wait with %d fd(s)",
+                               LTTNG_POLL_GETNB(&events));
+               health_poll_exit();
+               DBG("Channel event caught in thread");
+               if (ret < 0) {
+                       if (errno == EINTR) {
+                               ERR("Poll EINTR caught");
+                               goto restart;
+                       }
+                       if (LTTNG_POLL_GETNB(&events) == 0) {
+                               err = 0;        /* All is OK */
+                       }
+                       goto end;
+               }
+
+               nb_fd = ret;
+
+               /* From here, the event is a channel wait fd */
+               for (i = 0; i < nb_fd; i++) {
+                       health_code_update();
+
+                       revents = LTTNG_POLL_GETEV(&events, i);
+                       pollfd = LTTNG_POLL_GETFD(&events, i);
+
+                       if (pollfd == ctx->consumer_channel_pipe[0]) {
+                               if (revents & LPOLLIN) {
+                                       enum consumer_channel_action action;
+                                       uint64_t key;
+
+                                       ret = read_channel_pipe(ctx, &chan, &key, &action);
+                                       if (ret <= 0) {
+                                               if (ret < 0) {
+                                                       ERR("Error reading channel pipe");
+                                               }
+                                               lttng_poll_del(&events, ctx->consumer_channel_pipe[0]);
+                                               continue;
+                                       }
+
+                                       switch (action) {
+                                       case CONSUMER_CHANNEL_ADD:
+                                               DBG("Adding channel %d to poll set",
+                                                       chan->wait_fd);
+
+                                               lttng_ht_node_init_u64(&chan->wait_fd_node,
+                                                       chan->wait_fd);
+                                               rcu_read_lock();
+                                               lttng_ht_add_unique_u64(channel_ht,
+                                                               &chan->wait_fd_node);
+                                               rcu_read_unlock();
+                                               /* Add channel to the global poll events list */
+                                               lttng_poll_add(&events, chan->wait_fd,
+                                                               LPOLLERR | LPOLLHUP);
+                                               break;
+                                       case CONSUMER_CHANNEL_DEL:
+                                       {
+                                               /*
+                                                * This command should never be called if the channel
+                                                * has streams monitored by either the data or metadata
+                                                * thread. The consumer only notify this thread with a
+                                                * channel del. command if it receives a destroy
+                                                * channel command from the session daemon that send it
+                                                * if a command prior to the GET_CHANNEL failed.
+                                                */
+
+                                               rcu_read_lock();
+                                               chan = consumer_find_channel(key);
+                                               if (!chan) {
+                                                       rcu_read_unlock();
+                                                       ERR("UST consumer get channel key %" PRIu64 " not found for del channel", key);
+                                                       break;
+                                               }
+                                               lttng_poll_del(&events, chan->wait_fd);
+                                               iter.iter.node = &chan->wait_fd_node.node;
+                                               ret = lttng_ht_del(channel_ht, &iter);
+                                               LTTNG_ASSERT(ret == 0);
+
+                                               switch (the_consumer_data.type) {
+                                               case LTTNG_CONSUMER_KERNEL:
+                                                       break;
+                                               case LTTNG_CONSUMER32_UST:
+                                               case LTTNG_CONSUMER64_UST:
+                                                       health_code_update();
+                                                       /* Destroy streams that might have been left in the stream list. */
+                                                       clean_channel_stream_list(chan);
+                                                       break;
+                                               default:
+                                                       ERR("Unknown consumer_data type");
+                                                       abort();
+                                               }
+
+                                               /*
+                                                * Release our own refcount. Force channel deletion even if
+                                                * streams were not initialized.
+                                                */
+                                               if (!uatomic_sub_return(&chan->refcount, 1)) {
+                                                       consumer_del_channel(chan);
+                                               }
+                                               rcu_read_unlock();
+                                               goto restart;
+                                       }
+                                       case CONSUMER_CHANNEL_QUIT:
+                                               /*
+                                                * Remove the pipe from the poll set and continue the loop
+                                                * since their might be data to consume.
+                                                */
+                                               lttng_poll_del(&events, ctx->consumer_channel_pipe[0]);
+                                               continue;
+                                       default:
+                                               ERR("Unknown action");
+                                               break;
+                                       }
+                               } else if (revents & (LPOLLERR | LPOLLHUP)) {
+                                       DBG("Channel thread pipe hung up");
+                                       /*
+                                        * Remove the pipe from the poll set and continue the loop
+                                        * since their might be data to consume.
+                                        */
+                                       lttng_poll_del(&events, ctx->consumer_channel_pipe[0]);
+                                       continue;
+                               } else {
+                                       ERR("Unexpected poll events %u for sock %d", revents, pollfd);
+                                       goto end;
+                               }
+
+                               /* Handle other stream */
+                               continue;
+                       }
+
+                       rcu_read_lock();
+                       {
+                               uint64_t tmp_id = (uint64_t) pollfd;
+
+                               lttng_ht_lookup(channel_ht, &tmp_id, &iter);
+                       }
+                       node = lttng_ht_iter_get_node_u64(&iter);
+                       LTTNG_ASSERT(node);
+
+                       chan = caa_container_of(node, struct lttng_consumer_channel,
+                                       wait_fd_node);
+
+                       /* Check for error event */
+                       if (revents & (LPOLLERR | LPOLLHUP)) {
+                               DBG("Channel fd %d is hup|err.", pollfd);
+
+                               lttng_poll_del(&events, chan->wait_fd);
+                               ret = lttng_ht_del(channel_ht, &iter);
+                               LTTNG_ASSERT(ret == 0);
+
+                               /*
+                                * This will close the wait fd for each stream associated to
+                                * this channel AND monitored by the data/metadata thread thus
+                                * will be clean by the right thread.
+                                */
+                               consumer_close_channel_streams(chan);
+
+                               /* Release our own refcount */
+                               if (!uatomic_sub_return(&chan->refcount, 1)
+                                               && !uatomic_read(&chan->nb_init_stream_left)) {
+                                       consumer_del_channel(chan);
+                               }
+                       } else {
+                               ERR("Unexpected poll events %u for sock %d", revents, pollfd);
+                               rcu_read_unlock();
+                               goto end;
+                       }
+
+                       /* Release RCU lock for the channel looked up */
+                       rcu_read_unlock();
+               }
+       }
+
+       /* All is OK */
+       err = 0;
+end:
+       lttng_poll_clean(&events);
+end_poll:
+       destroy_channel_ht(channel_ht);
+end_ht:
+error_testpoint:
+       DBG("Channel poll thread exiting");
+       if (err) {
+               health_error();
+               ERR("Health error occurred in %s", __func__);
+       }
+       health_unregister(health_consumerd);
+       rcu_unregister_thread();
+       return NULL;
+}
+
+static int set_metadata_socket(struct lttng_consumer_local_data *ctx,
+               struct pollfd *sockpoll, int client_socket)
+{
+       int ret;
+
+       LTTNG_ASSERT(ctx);
+       LTTNG_ASSERT(sockpoll);
+
+       ret = lttng_consumer_poll_socket(sockpoll);
+       if (ret) {
+               goto error;
+       }
+       DBG("Metadata connection on client_socket");
+
+       /* Blocking call, waiting for transmission */
+       ctx->consumer_metadata_socket = lttcomm_accept_unix_sock(client_socket);
+       if (ctx->consumer_metadata_socket < 0) {
+               WARN("On accept metadata");
+               ret = -1;
+               goto error;
+       }
+       ret = 0;
+
+error:
+       return ret;
+}
+
+/*
+ * This thread listens on the consumerd socket and receives the file
+ * descriptors from the session daemon.
+ */
+void *consumer_thread_sessiond_poll(void *data)
+{
+       int sock = -1, client_socket, ret, err = -1;
+       /*
+        * structure to poll for incoming data on communication socket avoids
+        * making blocking sockets.
+        */
+       struct pollfd consumer_sockpoll[2];
+       struct lttng_consumer_local_data *ctx = (lttng_consumer_local_data *) data;
+
+       rcu_register_thread();
+
+       health_register(health_consumerd, HEALTH_CONSUMERD_TYPE_SESSIOND);
+
+       if (testpoint(consumerd_thread_sessiond)) {
+               goto error_testpoint;
+       }
+
+       health_code_update();
+
+       DBG("Creating command socket %s", ctx->consumer_command_sock_path);
+       unlink(ctx->consumer_command_sock_path);
+       client_socket = lttcomm_create_unix_sock(ctx->consumer_command_sock_path);
+       if (client_socket < 0) {
+               ERR("Cannot create command socket");
+               goto end;
+       }
+
+       ret = lttcomm_listen_unix_sock(client_socket);
+       if (ret < 0) {
+               goto end;
+       }
+
+       DBG("Sending ready command to lttng-sessiond");
+       ret = lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_COMMAND_SOCK_READY);
+       /* return < 0 on error, but == 0 is not fatal */
+       if (ret < 0) {
+               ERR("Error sending ready command to lttng-sessiond");
+               goto end;
+       }
+
+       /* prepare the FDs to poll : to client socket and the should_quit pipe */
+       consumer_sockpoll[0].fd = ctx->consumer_should_quit[0];
+       consumer_sockpoll[0].events = POLLIN | POLLPRI;
+       consumer_sockpoll[1].fd = client_socket;
+       consumer_sockpoll[1].events = POLLIN | POLLPRI;
+
+       ret = lttng_consumer_poll_socket(consumer_sockpoll);
+       if (ret) {
+               if (ret > 0) {
+                       /* should exit */
+                       err = 0;
+               }
+               goto end;
+       }
+       DBG("Connection on client_socket");
+
+       /* Blocking call, waiting for transmission */
+       sock = lttcomm_accept_unix_sock(client_socket);
+       if (sock < 0) {
+               WARN("On accept");
+               goto end;
+       }
+
+       /*
+        * Setup metadata socket which is the second socket connection on the
+        * command unix socket.
+        */
+       ret = set_metadata_socket(ctx, consumer_sockpoll, client_socket);
+       if (ret) {
+               if (ret > 0) {
+                       /* should exit */
+                       err = 0;
+               }
+               goto end;
+       }
+
+       /* This socket is not useful anymore. */
+       ret = close(client_socket);
+       if (ret < 0) {
+               PERROR("close client_socket");
+       }
+       client_socket = -1;
+
+       /* update the polling structure to poll on the established socket */
+       consumer_sockpoll[1].fd = sock;
+       consumer_sockpoll[1].events = POLLIN | POLLPRI;
+
+       while (1) {
+               health_code_update();
+
+               health_poll_entry();
+               ret = lttng_consumer_poll_socket(consumer_sockpoll);
+               health_poll_exit();
+               if (ret) {
+                       if (ret > 0) {
+                               /* should exit */
+                               err = 0;
+                       }
+                       goto end;
+               }
+               DBG("Incoming command on sock");
+               ret = lttng_consumer_recv_cmd(ctx, sock, consumer_sockpoll);
+               if (ret <= 0) {
+                       /*
+                        * This could simply be a session daemon quitting. Don't output
+                        * ERR() here.
+                        */
+                       DBG("Communication interrupted on command socket");
+                       err = 0;
+                       goto end;
+               }
+               if (CMM_LOAD_SHARED(consumer_quit)) {
+                       DBG("consumer_thread_receive_fds received quit from signal");
+                       err = 0;        /* All is OK */
+                       goto end;
+               }
+               DBG("Received command on sock");
+       }
+       /* All is OK */
+       err = 0;
+
+end:
+       DBG("Consumer thread sessiond poll exiting");
+
+       /*
+        * Close metadata streams since the producer is the session daemon which
+        * just died.
+        *
+        * NOTE: for now, this only applies to the UST tracer.
+        */
+       lttng_consumer_close_all_metadata();
+
+       /*
+        * when all fds have hung up, the polling thread
+        * can exit cleanly
+        */
+       CMM_STORE_SHARED(consumer_quit, 1);
+
+       /*
+        * Notify the data poll thread to poll back again and test the
+        * consumer_quit state that we just set so to quit gracefully.
+        */
+       notify_thread_lttng_pipe(ctx->consumer_data_pipe);
+
+       notify_channel_pipe(ctx, NULL, -1, CONSUMER_CHANNEL_QUIT);
+
+       notify_health_quit_pipe(health_quit_pipe);
+
+       /* Cleaning up possibly open sockets. */
+       if (sock >= 0) {
+               ret = close(sock);
+               if (ret < 0) {
+                       PERROR("close sock sessiond poll");
+               }
+       }
+       if (client_socket >= 0) {
+               ret = close(client_socket);
+               if (ret < 0) {
+                       PERROR("close client_socket sessiond poll");
+               }
+       }
+
+error_testpoint:
+       if (err) {
+               health_error();
+               ERR("Health error occurred in %s", __func__);
+       }
+       health_unregister(health_consumerd);
+
+       rcu_unregister_thread();
+       return NULL;
+}
+
+static int post_consume(struct lttng_consumer_stream *stream,
+               const struct stream_subbuffer *subbuffer,
+               struct lttng_consumer_local_data *ctx)
+{
+       size_t i;
+       int ret = 0;
+       const size_t count = lttng_dynamic_array_get_count(
+                       &stream->read_subbuffer_ops.post_consume_cbs);
+
+       for (i = 0; i < count; i++) {
+               const post_consume_cb op = *(post_consume_cb *) lttng_dynamic_array_get_element(
+                               &stream->read_subbuffer_ops.post_consume_cbs,
+                               i);
+
+               ret = op(stream, subbuffer, ctx);
+               if (ret) {
+                       goto end;
+               }
+       }
+end:
+       return ret;
+}
+
+ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
+               struct lttng_consumer_local_data *ctx,
+               bool locked_by_caller)
+{
+       ssize_t ret, written_bytes = 0;
+       int rotation_ret;
+       struct stream_subbuffer subbuffer = {};
+       enum get_next_subbuffer_status get_next_status;
+
+       if (!locked_by_caller) {
+               stream->read_subbuffer_ops.lock(stream);
+       }
+
+       if (stream->read_subbuffer_ops.on_wake_up) {
+               ret = stream->read_subbuffer_ops.on_wake_up(stream);
+               if (ret) {
+                       goto end;
+               }
+       }
+
+       /*
+        * If the stream was flagged to be ready for rotation before we extract
+        * the next packet, rotate it now.
+        */
+       if (stream->rotate_ready) {
+               DBG("Rotate stream before consuming data");
+               ret = lttng_consumer_rotate_stream(ctx, stream);
+               if (ret < 0) {
+                       ERR("Stream rotation error before consuming data");
+                       goto end;
+               }
+       }
+
+       get_next_status = stream->read_subbuffer_ops.get_next_subbuffer(
+                       stream, &subbuffer);
+       switch (get_next_status) {
+       case GET_NEXT_SUBBUFFER_STATUS_OK:
+               break;
+       case GET_NEXT_SUBBUFFER_STATUS_NO_DATA:
+               /* Not an error. */
+               ret = 0;
+               goto sleep_stream;
+       case GET_NEXT_SUBBUFFER_STATUS_ERROR:
+               ret = -1;
+               goto end;
+       default:
+               abort();
+       }
+
+       ret = stream->read_subbuffer_ops.pre_consume_subbuffer(
+                       stream, &subbuffer);
+       if (ret) {
+               goto error_put_subbuf;
+       }
+
+       written_bytes = stream->read_subbuffer_ops.consume_subbuffer(
+                       ctx, stream, &subbuffer);
+       if (written_bytes <= 0) {
+               ERR("Error consuming subbuffer: (%zd)", written_bytes);
+               ret = (int) written_bytes;
+               goto error_put_subbuf;
+       }
+
+       ret = stream->read_subbuffer_ops.put_next_subbuffer(stream, &subbuffer);
+       if (ret) {
+               goto end;
+       }
+
+       ret = post_consume(stream, &subbuffer, ctx);
+       if (ret) {
+               goto end;
+       }
+
+       /*
+        * After extracting the packet, we check if the stream is now ready to
+        * be rotated and perform the action immediately.
+        *
+        * Don't overwrite `ret` as callers expect the number of bytes
+        * consumed to be returned on success.
+        */
+       rotation_ret = lttng_consumer_stream_is_rotate_ready(stream);
+       if (rotation_ret == 1) {
+               rotation_ret = lttng_consumer_rotate_stream(ctx, stream);
+               if (rotation_ret < 0) {
+                       ret = rotation_ret;
+                       ERR("Stream rotation error after consuming data");
+                       goto end;
+               }
+
+       } else if (rotation_ret < 0) {
+               ret = rotation_ret;
+               ERR("Failed to check if stream was ready to rotate after consuming data");
+               goto end;
+       }
+
+sleep_stream:
+       if (stream->read_subbuffer_ops.on_sleep) {
+               stream->read_subbuffer_ops.on_sleep(stream, ctx);
+       }
+
+       ret = written_bytes;
+end:
+       if (!locked_by_caller) {
+               stream->read_subbuffer_ops.unlock(stream);
+       }
+
+       return ret;
+error_put_subbuf:
+       (void) stream->read_subbuffer_ops.put_next_subbuffer(stream, &subbuffer);
+       goto end;
+}
+
+int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream)
+{
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               return lttng_kconsumer_on_recv_stream(stream);
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               return lttng_ustconsumer_on_recv_stream(stream);
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+               return -ENOSYS;
+       }
+}
+
+/*
+ * Allocate and set consumer data hash tables.
+ */
+int lttng_consumer_init(void)
+{
+       the_consumer_data.channel_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
+       if (!the_consumer_data.channel_ht) {
+               goto error;
+       }
+
+       the_consumer_data.channels_by_session_id_ht =
+                       lttng_ht_new(0, LTTNG_HT_TYPE_U64);
+       if (!the_consumer_data.channels_by_session_id_ht) {
+               goto error;
+       }
+
+       the_consumer_data.relayd_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
+       if (!the_consumer_data.relayd_ht) {
+               goto error;
+       }
+
+       the_consumer_data.stream_list_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
+       if (!the_consumer_data.stream_list_ht) {
+               goto error;
+       }
+
+       the_consumer_data.stream_per_chan_id_ht =
+                       lttng_ht_new(0, LTTNG_HT_TYPE_U64);
+       if (!the_consumer_data.stream_per_chan_id_ht) {
+               goto error;
+       }
+
+       data_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
+       if (!data_ht) {
+               goto error;
+       }
+
+       metadata_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
+       if (!metadata_ht) {
+               goto error;
+       }
+
+       the_consumer_data.chunk_registry = lttng_trace_chunk_registry_create();
+       if (!the_consumer_data.chunk_registry) {
+               goto error;
+       }
+
+       return 0;
+
+error:
+       return -1;
+}
+
+/*
+ * Process the ADD_RELAYD command receive by a consumer.
+ *
+ * This will create a relayd socket pair and add it to the relayd hash table.
+ * The caller MUST acquire a RCU read side lock before calling it.
+ */
+ void consumer_add_relayd_socket(uint64_t net_seq_idx, int sock_type,
+               struct lttng_consumer_local_data *ctx, int sock,
+               struct pollfd *consumer_sockpoll,
+               struct lttcomm_relayd_sock *relayd_sock, uint64_t sessiond_id,
+               uint64_t relayd_session_id)
+{
+       int fd = -1, ret = -1, relayd_created = 0;
+       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       struct consumer_relayd_sock_pair *relayd = NULL;
+
+       LTTNG_ASSERT(ctx);
+       LTTNG_ASSERT(relayd_sock);
+
+       DBG("Consumer adding relayd socket (idx: %" PRIu64 ")", net_seq_idx);
+
+       /* Get relayd reference if exists. */
+       relayd = consumer_find_relayd(net_seq_idx);
+       if (relayd == NULL) {
+               LTTNG_ASSERT(sock_type == LTTNG_STREAM_CONTROL);
+               /* Not found. Allocate one. */
+               relayd = consumer_allocate_relayd_sock_pair(net_seq_idx);
+               if (relayd == NULL) {
+                       ret_code = LTTCOMM_CONSUMERD_ENOMEM;
+                       goto error;
+               } else {
+                       relayd->sessiond_session_id = sessiond_id;
+                       relayd_created = 1;
+               }
+
+               /*
+                * This code path MUST continue to the consumer send status message to
+                * we can notify the session daemon and continue our work without
+                * killing everything.
+                */
+       } else {
+               /*
+                * relayd key should never be found for control socket.
+                */
+               LTTNG_ASSERT(sock_type != LTTNG_STREAM_CONTROL);
+       }
+
+       /* First send a status message before receiving the fds. */
+       ret = consumer_send_status_msg(sock, LTTCOMM_CONSUMERD_SUCCESS);
+       if (ret < 0) {
+               /* Somehow, the session daemon is not responding anymore. */
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_FATAL);
+               goto error_nosignal;
+       }
+
+       /* Poll on consumer socket. */
+       ret = lttng_consumer_poll_socket(consumer_sockpoll);
+       if (ret) {
+               /* Needing to exit in the middle of a command: error. */
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_POLL_ERROR);
+               goto error_nosignal;
+       }
+
+       /* Get relayd socket from session daemon */
+       ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
+       if (ret != sizeof(fd)) {
+               fd = -1;        /* Just in case it gets set with an invalid value. */
+
+               /*
+                * Failing to receive FDs might indicate a major problem such as
+                * reaching a fd limit during the receive where the kernel returns a
+                * MSG_CTRUNC and fails to cleanup the fd in the queue. Any case, we
+                * don't take any chances and stop everything.
+                *
+                * XXX: Feature request #558 will fix that and avoid this possible
+                * issue when reaching the fd limit.
+                */
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
+               ret_code = LTTCOMM_CONSUMERD_ERROR_RECV_FD;
+               goto error;
+       }
+
+       /* Copy socket information and received FD */
+       switch (sock_type) {
+       case LTTNG_STREAM_CONTROL:
+               /* Copy received lttcomm socket */
+               lttcomm_copy_sock(&relayd->control_sock.sock, &relayd_sock->sock);
+               ret = lttcomm_create_sock(&relayd->control_sock.sock);
+               /* Handle create_sock error. */
+               if (ret < 0) {
+                       ret_code = LTTCOMM_CONSUMERD_ENOMEM;
+                       goto error;
+               }
+               /*
+                * Close the socket created internally by
+                * lttcomm_create_sock, so we can replace it by the one
+                * received from sessiond.
+                */
+               if (close(relayd->control_sock.sock.fd)) {
+                       PERROR("close");
+               }
+
+               /* Assign new file descriptor */
+               relayd->control_sock.sock.fd = fd;
+               /* Assign version values. */
+               relayd->control_sock.major = relayd_sock->major;
+               relayd->control_sock.minor = relayd_sock->minor;
+
+               relayd->relayd_session_id = relayd_session_id;
+
+               break;
+       case LTTNG_STREAM_DATA:
+               /* Copy received lttcomm socket */
+               lttcomm_copy_sock(&relayd->data_sock.sock, &relayd_sock->sock);
+               ret = lttcomm_create_sock(&relayd->data_sock.sock);
+               /* Handle create_sock error. */
+               if (ret < 0) {
+                       ret_code = LTTCOMM_CONSUMERD_ENOMEM;
+                       goto error;
+               }
+               /*
+                * Close the socket created internally by
+                * lttcomm_create_sock, so we can replace it by the one
+                * received from sessiond.
+                */
+               if (close(relayd->data_sock.sock.fd)) {
+                       PERROR("close");
+               }
+
+               /* Assign new file descriptor */
+               relayd->data_sock.sock.fd = fd;
+               /* Assign version values. */
+               relayd->data_sock.major = relayd_sock->major;
+               relayd->data_sock.minor = relayd_sock->minor;
+               break;
+       default:
+               ERR("Unknown relayd socket type (%d)", sock_type);
+               ret_code = LTTCOMM_CONSUMERD_FATAL;
+               goto error;
+       }
+
+       DBG("Consumer %s socket created successfully with net idx %" PRIu64 " (fd: %d)",
+                       sock_type == LTTNG_STREAM_CONTROL ? "control" : "data",
+                       relayd->net_seq_idx, fd);
+       /*
+        * We gave the ownership of the fd to the relayd structure. Set the
+        * fd to -1 so we don't call close() on it in the error path below.
+        */
+       fd = -1;
+
+       /* We successfully added the socket. Send status back. */
+       ret = consumer_send_status_msg(sock, ret_code);
+       if (ret < 0) {
+               /* Somehow, the session daemon is not responding anymore. */
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_FATAL);
+               goto error_nosignal;
+       }
+
+       /*
+        * Add relayd socket pair to consumer data hashtable. If object already
+        * exists or on error, the function gracefully returns.
+        */
+       relayd->ctx = ctx;
+       add_relayd(relayd);
+
+       /* All good! */
+       return;
+
+error:
+       if (consumer_send_status_msg(sock, ret_code) < 0) {
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_FATAL);
+       }
+
+error_nosignal:
+       /* Close received socket if valid. */
+       if (fd >= 0) {
+               if (close(fd)) {
+                       PERROR("close received socket");
+               }
+       }
+
+       if (relayd_created) {
+               free(relayd);
+       }
+}
+
+/*
+ * Search for a relayd associated to the session id and return the reference.
+ *
+ * A rcu read side lock MUST be acquire before calling this function and locked
+ * until the relayd object is no longer necessary.
+ */
+static struct consumer_relayd_sock_pair *find_relayd_by_session_id(uint64_t id)
+{
+       struct lttng_ht_iter iter;
+       struct consumer_relayd_sock_pair *relayd = NULL;
+
+       /* Iterate over all relayd since they are indexed by net_seq_idx. */
+       cds_lfht_for_each_entry(the_consumer_data.relayd_ht->ht, &iter.iter,
+                       relayd, node.node) {
+               /*
+                * Check by sessiond id which is unique here where the relayd session
+                * id might not be when having multiple relayd.
+                */
+               if (relayd->sessiond_session_id == id) {
+                       /* Found the relayd. There can be only one per id. */
+                       goto found;
+               }
+       }
+
+       return NULL;
+
+found:
+       return relayd;
+}
+
+/*
+ * Check if for a given session id there is still data needed to be extract
+ * from the buffers.
+ *
+ * Return 1 if data is pending or else 0 meaning ready to be read.
+ */
+int consumer_data_pending(uint64_t id)
+{
+       int ret;
+       struct lttng_ht_iter iter;
+       struct lttng_ht *ht;
+       struct lttng_consumer_stream *stream;
+       struct consumer_relayd_sock_pair *relayd = NULL;
+       int (*data_pending)(struct lttng_consumer_stream *);
+
+       DBG("Consumer data pending command on session id %" PRIu64, id);
+
+       rcu_read_lock();
+       pthread_mutex_lock(&the_consumer_data.lock);
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               data_pending = lttng_kconsumer_data_pending;
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               data_pending = lttng_ustconsumer_data_pending;
+               break;
+       default:
+               ERR("Unknown consumer data type");
+               abort();
+       }
+
+       /* Ease our life a bit */
+       ht = the_consumer_data.stream_list_ht;
+
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&id, lttng_ht_seed),
+                       ht->match_fct, &id,
+                       &iter.iter, stream, node_session_id.node) {
+               pthread_mutex_lock(&stream->lock);
+
+               /*
+                * A removed node from the hash table indicates that the stream has
+                * been deleted thus having a guarantee that the buffers are closed
+                * on the consumer side. However, data can still be transmitted
+                * over the network so don't skip the relayd check.
+                */
+               ret = cds_lfht_is_node_deleted(&stream->node.node);
+               if (!ret) {
+                       /* Check the stream if there is data in the buffers. */
+                       ret = data_pending(stream);
+                       if (ret == 1) {
+                               pthread_mutex_unlock(&stream->lock);
+                               goto data_pending;
+                       }
+               }
+
+               pthread_mutex_unlock(&stream->lock);
+       }
+
+       relayd = find_relayd_by_session_id(id);
+       if (relayd) {
+               unsigned int is_data_inflight = 0;
+
+               /* Send init command for data pending. */
+               pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+               ret = relayd_begin_data_pending(&relayd->control_sock,
+                               relayd->relayd_session_id);
+               if (ret < 0) {
+                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+                       /* Communication error thus the relayd so no data pending. */
+                       goto data_not_pending;
+               }
+
+               cds_lfht_for_each_entry_duplicate(ht->ht,
+                               ht->hash_fct(&id, lttng_ht_seed),
+                               ht->match_fct, &id,
+                               &iter.iter, stream, node_session_id.node) {
+                       if (stream->metadata_flag) {
+                               ret = relayd_quiescent_control(&relayd->control_sock,
+                                               stream->relayd_stream_id);
+                       } else {
+                               ret = relayd_data_pending(&relayd->control_sock,
+                                               stream->relayd_stream_id,
+                                               stream->next_net_seq_num - 1);
+                       }
+
+                       if (ret == 1) {
+                               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+                               goto data_pending;
+                       } else if (ret < 0) {
+                               ERR("Relayd data pending failed. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
+                               lttng_consumer_cleanup_relayd(relayd);
+                               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+                               goto data_not_pending;
+                       }
+               }
+
+               /* Send end command for data pending. */
+               ret = relayd_end_data_pending(&relayd->control_sock,
+                               relayd->relayd_session_id, &is_data_inflight);
+               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+               if (ret < 0) {
+                       ERR("Relayd end data pending failed. Cleaning up relayd %" PRIu64".", relayd->net_seq_idx);
+                       lttng_consumer_cleanup_relayd(relayd);
+                       goto data_not_pending;
+               }
+               if (is_data_inflight) {
+                       goto data_pending;
+               }
+       }
+
+       /*
+        * Finding _no_ node in the hash table and no inflight data means that the
+        * stream(s) have been removed thus data is guaranteed to be available for
+        * analysis from the trace files.
+        */
+
+data_not_pending:
+       /* Data is available to be read by a viewer. */
+       pthread_mutex_unlock(&the_consumer_data.lock);
+       rcu_read_unlock();
+       return 0;
+
+data_pending:
+       /* Data is still being extracted from buffers. */
+       pthread_mutex_unlock(&the_consumer_data.lock);
+       rcu_read_unlock();
+       return 1;
+}
+
+/*
+ * Send a ret code status message to the sessiond daemon.
+ *
+ * Return the sendmsg() return value.
+ */
+int consumer_send_status_msg(int sock, int ret_code)
+{
+       struct lttcomm_consumer_status_msg msg;
+
+       memset(&msg, 0, sizeof(msg));
+       msg.ret_code = (lttcomm_return_code) ret_code;
+
+       return lttcomm_send_unix_sock(sock, &msg, sizeof(msg));
+}
+
+/*
+ * Send a channel status message to the sessiond daemon.
+ *
+ * Return the sendmsg() return value.
+ */
+int consumer_send_status_channel(int sock,
+               struct lttng_consumer_channel *channel)
+{
+       struct lttcomm_consumer_status_channel msg;
+
+       LTTNG_ASSERT(sock >= 0);
+
+       memset(&msg, 0, sizeof(msg));
+       if (!channel) {
+               msg.ret_code = LTTCOMM_CONSUMERD_CHANNEL_FAIL;
+       } else {
+               msg.ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+               msg.key = channel->key;
+               msg.stream_count = channel->streams.count;
+       }
+
+       return lttcomm_send_unix_sock(sock, &msg, sizeof(msg));
+}
+
+unsigned long consumer_get_consume_start_pos(unsigned long consumed_pos,
+               unsigned long produced_pos, uint64_t nb_packets_per_stream,
+               uint64_t max_sb_size)
+{
+       unsigned long start_pos;
+
+       if (!nb_packets_per_stream) {
+               return consumed_pos;    /* Grab everything */
+       }
+       start_pos = produced_pos - lttng_offset_align_floor(produced_pos, max_sb_size);
+       start_pos -= max_sb_size * nb_packets_per_stream;
+       if ((long) (start_pos - consumed_pos) < 0) {
+               return consumed_pos;    /* Grab everything */
+       }
+       return start_pos;
+}
+
+/* Stream lock must be held by the caller. */
+static int sample_stream_positions(struct lttng_consumer_stream *stream,
+                           unsigned long *produced, unsigned long *consumed)
+{
+       int ret;
+
+       ASSERT_LOCKED(stream->lock);
+
+       ret = lttng_consumer_sample_snapshot_positions(stream);
+       if (ret < 0) {
+               ERR("Failed to sample snapshot positions");
+               goto end;
+       }
+
+       ret = lttng_consumer_get_produced_snapshot(stream, produced);
+       if (ret < 0) {
+               ERR("Failed to sample produced position");
+               goto end;
+       }
+
+       ret = lttng_consumer_get_consumed_snapshot(stream, consumed);
+       if (ret < 0) {
+               ERR("Failed to sample consumed position");
+               goto end;
+       }
+
+end:
+       return ret;
+}
+
+/*
+ * Sample the rotate position for all the streams of a channel. If a stream
+ * is already at the rotate position (produced == consumed), we flag it as
+ * ready for rotation. The rotation of ready streams occurs after we have
+ * replied to the session daemon that we have finished sampling the positions.
+ * Must be called with RCU read-side lock held to ensure existence of channel.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_consumer_rotate_channel(struct lttng_consumer_channel *channel,
+               uint64_t key, uint64_t relayd_id, uint32_t metadata,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+       struct lttng_consumer_stream *stream;
+       struct lttng_ht_iter iter;
+       struct lttng_ht *ht = the_consumer_data.stream_per_chan_id_ht;
+       struct lttng_dynamic_array stream_rotation_positions;
+       uint64_t next_chunk_id, stream_count = 0;
+       enum lttng_trace_chunk_status chunk_status;
+       const bool is_local_trace = relayd_id == -1ULL;
+       struct consumer_relayd_sock_pair *relayd = NULL;
+       bool rotating_to_new_chunk = true;
+       /* Array of `struct lttng_consumer_stream *` */
+       struct lttng_dynamic_pointer_array streams_packet_to_open;
+       size_t stream_idx;
+
+       DBG("Consumer sample rotate position for channel %" PRIu64, key);
+
+       lttng_dynamic_array_init(&stream_rotation_positions,
+                       sizeof(struct relayd_stream_rotation_position), NULL);
+       lttng_dynamic_pointer_array_init(&streams_packet_to_open, NULL);
+
+       rcu_read_lock();
+
+       pthread_mutex_lock(&channel->lock);
+       LTTNG_ASSERT(channel->trace_chunk);
+       chunk_status = lttng_trace_chunk_get_id(channel->trace_chunk,
+                       &next_chunk_id);
+       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+               ret = -1;
+               goto end_unlock_channel;
+       }
+
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&channel->key, lttng_ht_seed),
+                       ht->match_fct, &channel->key, &iter.iter,
+                       stream, node_channel_id.node) {
+               unsigned long produced_pos = 0, consumed_pos = 0;
+
+               health_code_update();
+
+               /*
+                * Lock stream because we are about to change its state.
+                */
+               pthread_mutex_lock(&stream->lock);
+
+               if (stream->trace_chunk == stream->chan->trace_chunk) {
+                       rotating_to_new_chunk = false;
+               }
+
+               /*
+                * Do not flush a packet when rotating from a NULL trace
+                * chunk. The stream has no means to output data, and the prior
+                * rotation which rotated to NULL performed that side-effect
+                * already. No new data can be produced when a stream has no
+                * associated trace chunk (e.g. a stop followed by a rotate).
+                */
+               if (stream->trace_chunk) {
+                       bool flush_active;
+
+                       if (stream->metadata_flag) {
+                               /*
+                                * Don't produce an empty metadata packet,
+                                * simply close the current one.
+                                *
+                                * Metadata is regenerated on every trace chunk
+                                * switch; there is no concern that no data was
+                                * produced.
+                                */
+                               flush_active = true;
+                       } else {
+                               /*
+                                * Only flush an empty packet if the "packet
+                                * open" could not be performed on transition
+                                * to a new trace chunk and no packets were
+                                * consumed within the chunk's lifetime.
+                                */
+                               if (stream->opened_packet_in_current_trace_chunk) {
+                                       flush_active = true;
+                               } else {
+                                       /*
+                                        * Stream could have been full at the
+                                        * time of rotation, but then have had
+                                        * no activity at all.
+                                        *
+                                        * It is important to flush a packet
+                                        * to prevent 0-length files from being
+                                        * produced as most viewers choke on
+                                        * them.
+                                        *
+                                        * Unfortunately viewers will not be
+                                        * able to know that tracing was active
+                                        * for this stream during this trace
+                                        * chunk's lifetime.
+                                        */
+                                       ret = sample_stream_positions(stream, &produced_pos, &consumed_pos);
+                                       if (ret) {
+                                               goto end_unlock_stream;
+                                       }
+
+                                       /*
+                                        * Don't flush an empty packet if data
+                                        * was produced; it will be consumed
+                                        * before the rotation completes.
+                                        */
+                                       flush_active = produced_pos != consumed_pos;
+                                       if (!flush_active) {
+                                               const char *trace_chunk_name;
+                                               uint64_t trace_chunk_id;
+
+                                               chunk_status = lttng_trace_chunk_get_name(
+                                                               stream->trace_chunk,
+                                                               &trace_chunk_name,
+                                                               NULL);
+                                               if (chunk_status == LTTNG_TRACE_CHUNK_STATUS_NONE) {
+                                                       trace_chunk_name = "none";
+                                               }
+
+                                               /*
+                                                * Consumer trace chunks are
+                                                * never anonymous.
+                                                */
+                                               chunk_status = lttng_trace_chunk_get_id(
+                                                               stream->trace_chunk,
+                                                               &trace_chunk_id);
+                                               LTTNG_ASSERT(chunk_status ==
+                                                               LTTNG_TRACE_CHUNK_STATUS_OK);
+
+                                               DBG("Unable to open packet for stream during trace chunk's lifetime. "
+                                                               "Flushing an empty packet to prevent an empty file from being created: "
+                                                               "stream id = %" PRIu64 ", trace chunk name = `%s`, trace chunk id = %" PRIu64,
+                                                               stream->key, trace_chunk_name, trace_chunk_id);
+                                       }
+                               }
+                       }
+
+                       /*
+                        * Close the current packet before sampling the
+                        * ring buffer positions.
+                        */
+                       ret = consumer_stream_flush_buffer(stream, flush_active);
+                       if (ret < 0) {
+                               ERR("Failed to flush stream %" PRIu64 " during channel rotation",
+                                               stream->key);
+                               goto end_unlock_stream;
+                       }
+               }
+
+               ret = lttng_consumer_take_snapshot(stream);
+               if (ret < 0 && ret != -ENODATA && ret != -EAGAIN) {
+                       ERR("Failed to sample snapshot position during channel rotation");
+                       goto end_unlock_stream;
+               }
+               if (!ret) {
+                       ret = lttng_consumer_get_produced_snapshot(stream,
+                                       &produced_pos);
+                       if (ret < 0) {
+                               ERR("Failed to sample produced position during channel rotation");
+                               goto end_unlock_stream;
+                       }
+
+                       ret = lttng_consumer_get_consumed_snapshot(stream,
+                                       &consumed_pos);
+                       if (ret < 0) {
+                               ERR("Failed to sample consumed position during channel rotation");
+                               goto end_unlock_stream;
+                       }
+               }
+               /*
+                * Align produced position on the start-of-packet boundary of the first
+                * packet going into the next trace chunk.
+                */
+               produced_pos = lttng_align_floor(produced_pos, stream->max_sb_size);
+               if (consumed_pos == produced_pos) {
+                       DBG("Set rotate ready for stream %" PRIu64 " produced = %lu consumed = %lu",
+                                       stream->key, produced_pos, consumed_pos);
+                       stream->rotate_ready = true;
+               } else {
+                       DBG("Different consumed and produced positions "
+                                       "for stream %" PRIu64 " produced = %lu consumed = %lu",
+                                       stream->key, produced_pos, consumed_pos);
+               }
+               /*
+                * The rotation position is based on the packet_seq_num of the
+                * packet following the last packet that was consumed for this
+                * stream, incremented by the offset between produced and
+                * consumed positions. This rotation position is a lower bound
+                * (inclusive) at which the next trace chunk starts. Since it
+                * is a lower bound, it is OK if the packet_seq_num does not
+                * correspond exactly to the same packet identified by the
+                * consumed_pos, which can happen in overwrite mode.
+                */
+               if (stream->sequence_number_unavailable) {
+                       /*
+                        * Rotation should never be performed on a session which
+                        * interacts with a pre-2.8 lttng-modules, which does
+                        * not implement packet sequence number.
+                        */
+                       ERR("Failure to rotate stream %" PRIu64 ": sequence number unavailable",
+                                       stream->key);
+                       ret = -1;
+                       goto end_unlock_stream;
+               }
+               stream->rotate_position = stream->last_sequence_number + 1 +
+                               ((produced_pos - consumed_pos) / stream->max_sb_size);
+               DBG("Set rotation position for stream %" PRIu64 " at position %" PRIu64,
+                               stream->key, stream->rotate_position);
+
+               if (!is_local_trace) {
+                       /*
+                        * The relay daemon control protocol expects a rotation
+                        * position as "the sequence number of the first packet
+                        * _after_ the current trace chunk".
+                        */
+                       const struct relayd_stream_rotation_position position = {
+                               .stream_id = stream->relayd_stream_id,
+                               .rotate_at_seq_num = stream->rotate_position,
+                       };
+
+                       ret = lttng_dynamic_array_add_element(
+                                       &stream_rotation_positions,
+                                       &position);
+                       if (ret) {
+                               ERR("Failed to allocate stream rotation position");
+                               goto end_unlock_stream;
+                       }
+                       stream_count++;
+               }
+
+               stream->opened_packet_in_current_trace_chunk = false;
+
+               if (rotating_to_new_chunk && !stream->metadata_flag) {
+                       /*
+                        * Attempt to flush an empty packet as close to the
+                        * rotation point as possible. In the event where a
+                        * stream remains inactive after the rotation point,
+                        * this ensures that the new trace chunk has a
+                        * beginning timestamp set at the begining of the
+                        * trace chunk instead of only creating an empty
+                        * packet when the trace chunk is stopped.
+                        *
+                        * This indicates to the viewers that the stream
+                        * was being recorded, but more importantly it
+                        * allows viewers to determine a useable trace
+                        * intersection.
+                        *
+                        * This presents a problem in the case where the
+                        * ring-buffer is completely full.
+                        *
+                        * Consider the following scenario:
+                        *   - The consumption of data is slow (slow network,
+                        *     for instance),
+                        *   - The ring buffer is full,
+                        *   - A rotation is initiated,
+                        *     - The flush below does nothing (no space left to
+                        *       open a new packet),
+                        *   - The other streams rotate very soon, and new
+                        *     data is produced in the new chunk,
+                        *   - This stream completes its rotation long after the
+                        *     rotation was initiated
+                        *   - The session is stopped before any event can be
+                        *     produced in this stream's buffers.
+                        *
+                        * The resulting trace chunk will have a single packet
+                        * temporaly at the end of the trace chunk for this
+                        * stream making the stream intersection more narrow
+                        * than it should be.
+                        *
+                        * To work-around this, an empty flush is performed
+                        * after the first consumption of a packet during a
+                        * rotation if open_packet fails. The idea is that
+                        * consuming a packet frees enough space to switch
+                        * packets in this scenario and allows the tracer to
+                        * "stamp" the beginning of the new trace chunk at the
+                        * earliest possible point.
+                        *
+                        * The packet open is performed after the channel
+                        * rotation to ensure that no attempt to open a packet
+                        * is performed in a stream that has no active trace
+                        * chunk.
+                        */
+                       ret = lttng_dynamic_pointer_array_add_pointer(
+                                       &streams_packet_to_open, stream);
+                       if (ret) {
+                               PERROR("Failed to add a stream pointer to array of streams in which to open a packet");
+                               ret = -1;
+                               goto end_unlock_stream;
+                       }
+               }
+
+               pthread_mutex_unlock(&stream->lock);
+       }
+       stream = NULL;
+
+       if (!is_local_trace) {
+               relayd = consumer_find_relayd(relayd_id);
+               if (!relayd) {
+                       ERR("Failed to find relayd %" PRIu64, relayd_id);
+                       ret = -1;
+                       goto end_unlock_channel;
+               }
+
+               pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+               ret = relayd_rotate_streams(&relayd->control_sock, stream_count,
+                               rotating_to_new_chunk ? &next_chunk_id : NULL,
+                               (const struct relayd_stream_rotation_position *)
+                                               stream_rotation_positions.buffer
+                                                               .data);
+               pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+               if (ret < 0) {
+                       ERR("Relayd rotate stream failed. Cleaning up relayd %" PRIu64,
+                                       relayd->net_seq_idx);
+                       lttng_consumer_cleanup_relayd(relayd);
+                       goto end_unlock_channel;
+               }
+       }
+
+       for (stream_idx = 0;
+                       stream_idx < lttng_dynamic_pointer_array_get_count(
+                               &streams_packet_to_open);
+                       stream_idx++) {
+               enum consumer_stream_open_packet_status status;
+
+               stream = (lttng_consumer_stream *) lttng_dynamic_pointer_array_get_pointer(
+                               &streams_packet_to_open, stream_idx);
+
+               pthread_mutex_lock(&stream->lock);
+               status = consumer_stream_open_packet(stream);
+               pthread_mutex_unlock(&stream->lock);
+               switch (status) {
+               case CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED:
+                       DBG("Opened a packet after a rotation: stream id = %" PRIu64
+                           ", channel name = %s, session id = %" PRIu64,
+                                       stream->key, stream->chan->name,
+                                       stream->chan->session_id);
+                       break;
+               case CONSUMER_STREAM_OPEN_PACKET_STATUS_NO_SPACE:
+                       /*
+                        * Can't open a packet as there is no space left
+                        * in the buffer. A new packet will be opened
+                        * once one has been consumed.
+                        */
+                       DBG("No space left to open a packet after a rotation: stream id = %" PRIu64
+                           ", channel name = %s, session id = %" PRIu64,
+                                       stream->key, stream->chan->name,
+                                       stream->chan->session_id);
+                       break;
+               case CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR:
+                       /* Logged by callee. */
+                       ret = -1;
+                       goto end_unlock_channel;
+               default:
+                       abort();
+               }
+       }
+
+       pthread_mutex_unlock(&channel->lock);
+       ret = 0;
+       goto end;
+
+end_unlock_stream:
+       pthread_mutex_unlock(&stream->lock);
+end_unlock_channel:
+       pthread_mutex_unlock(&channel->lock);
+end:
+       rcu_read_unlock();
+       lttng_dynamic_array_reset(&stream_rotation_positions);
+       lttng_dynamic_pointer_array_reset(&streams_packet_to_open);
+       return ret;
+}
+
+static
+int consumer_clear_buffer(struct lttng_consumer_stream *stream)
+{
+       int ret = 0;
+       unsigned long consumed_pos_before, consumed_pos_after;
+
+       ret = lttng_consumer_sample_snapshot_positions(stream);
+       if (ret < 0) {
+               ERR("Taking snapshot positions");
+               goto end;
+       }
+
+       ret = lttng_consumer_get_consumed_snapshot(stream, &consumed_pos_before);
+       if (ret < 0) {
+               ERR("Consumed snapshot position");
+               goto end;
+       }
+
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER_KERNEL:
+               ret = kernctl_buffer_clear(stream->wait_fd);
+               if (ret < 0) {
+                       ERR("Failed to clear kernel stream (ret = %d)", ret);
+                       goto end;
+               }
+               break;
+       case LTTNG_CONSUMER32_UST:
+       case LTTNG_CONSUMER64_UST:
+               ret = lttng_ustconsumer_clear_buffer(stream);
+               if (ret < 0) {
+                       ERR("Failed to clear ust stream (ret = %d)", ret);
+                       goto end;
+               }
+               break;
+       default:
+               ERR("Unknown consumer_data type");
+               abort();
+       }
+
+       ret = lttng_consumer_sample_snapshot_positions(stream);
+       if (ret < 0) {
+               ERR("Taking snapshot positions");
+               goto end;
+       }
+       ret = lttng_consumer_get_consumed_snapshot(stream, &consumed_pos_after);
+       if (ret < 0) {
+               ERR("Consumed snapshot position");
+               goto end;
+       }
+       DBG("clear: before: %lu after: %lu", consumed_pos_before, consumed_pos_after);
+end:
+       return ret;
+}
+
+static
+int consumer_clear_stream(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       ret = consumer_stream_flush_buffer(stream, 1);
+       if (ret < 0) {
+               ERR("Failed to flush stream %" PRIu64 " during channel clear",
+                               stream->key);
+               ret = LTTCOMM_CONSUMERD_FATAL;
+               goto error;
+       }
+
+       ret = consumer_clear_buffer(stream);
+       if (ret < 0) {
+               ERR("Failed to clear stream %" PRIu64 " during channel clear",
+                               stream->key);
+               ret = LTTCOMM_CONSUMERD_FATAL;
+               goto error;
+       }
+
+       ret = LTTCOMM_CONSUMERD_SUCCESS;
+error:
+       return ret;
+}
+
+static
+int consumer_clear_unmonitored_channel(struct lttng_consumer_channel *channel)
+{
+       int ret;
+       struct lttng_consumer_stream *stream;
+
+       rcu_read_lock();
+       pthread_mutex_lock(&channel->lock);
+       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+               health_code_update();
+               pthread_mutex_lock(&stream->lock);
+               ret = consumer_clear_stream(stream);
+               if (ret) {
+                       goto error_unlock;
+               }
+               pthread_mutex_unlock(&stream->lock);
+       }
+       pthread_mutex_unlock(&channel->lock);
+       rcu_read_unlock();
+       return 0;
+
+error_unlock:
+       pthread_mutex_unlock(&stream->lock);
+       pthread_mutex_unlock(&channel->lock);
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Check if a stream is ready to be rotated after extracting it.
+ *
+ * Return 1 if it is ready for rotation, 0 if it is not, a negative value on
+ * error. Stream lock must be held.
+ */
+int lttng_consumer_stream_is_rotate_ready(struct lttng_consumer_stream *stream)
+{
+       DBG("Check is rotate ready for stream %" PRIu64
+                       " ready %u rotate_position %" PRIu64
+                       " last_sequence_number %" PRIu64,
+                       stream->key, stream->rotate_ready,
+                       stream->rotate_position, stream->last_sequence_number);
+       if (stream->rotate_ready) {
+               return 1;
+       }
+
+       /*
+        * If packet seq num is unavailable, it means we are interacting
+        * with a pre-2.8 lttng-modules which does not implement the
+        * sequence number. Rotation should never be used by sessiond in this
+        * scenario.
+        */
+       if (stream->sequence_number_unavailable) {
+               ERR("Internal error: rotation used on stream %" PRIu64
+                               " with unavailable sequence number",
+                               stream->key);
+               return -1;
+       }
+
+       if (stream->rotate_position == -1ULL ||
+                       stream->last_sequence_number == -1ULL) {
+               return 0;
+       }
+
+       /*
+        * Rotate position not reached yet. The stream rotate position is
+        * the position of the next packet belonging to the next trace chunk,
+        * but consumerd considers rotation ready when reaching the last
+        * packet of the current chunk, hence the "rotate_position - 1".
+        */
+
+       DBG("Check is rotate ready for stream %" PRIu64
+                       " last_sequence_number %" PRIu64
+                       " rotate_position %" PRIu64,
+                       stream->key, stream->last_sequence_number,
+                       stream->rotate_position);
+       if (stream->last_sequence_number >= stream->rotate_position - 1) {
+               return 1;
+       }
+
+       return 0;
+}
+
+/*
+ * Reset the state for a stream after a rotation occurred.
+ */
+void lttng_consumer_reset_stream_rotate_state(struct lttng_consumer_stream *stream)
+{
+       DBG("lttng_consumer_reset_stream_rotate_state for stream %" PRIu64,
+                       stream->key);
+       stream->rotate_position = -1ULL;
+       stream->rotate_ready = false;
+}
+
+/*
+ * Perform the rotation a local stream file.
+ */
+static
+int rotate_local_stream(struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_stream *stream)
+{
+       int ret = 0;
+
+       DBG("Rotate local stream: stream key %" PRIu64 ", channel key %" PRIu64,
+                       stream->key,
+                       stream->chan->key);
+       stream->tracefile_size_current = 0;
+       stream->tracefile_count_current = 0;
+
+       if (stream->out_fd >= 0) {
+               ret = close(stream->out_fd);
+               if (ret) {
+                       PERROR("Failed to close stream out_fd of channel \"%s\"",
+                               stream->chan->name);
+               }
+               stream->out_fd = -1;
+       }
+
+       if (stream->index_file) {
+               lttng_index_file_put(stream->index_file);
+               stream->index_file = NULL;
+       }
+
+       if (!stream->trace_chunk) {
+               goto end;
+       }
+
+       ret = consumer_stream_create_output_files(stream, true);
+end:
+       return ret;
+}
+
+/*
+ * Performs the stream rotation for the rotate session feature if needed.
+ * It must be called with the channel and stream locks held.
+ *
+ * Return 0 on success, a negative number of error.
+ */
+int lttng_consumer_rotate_stream(struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       DBG("Consumer rotate stream %" PRIu64, stream->key);
+
+       /*
+        * Update the stream's 'current' chunk to the session's (channel)
+        * now-current chunk.
+        */
+       lttng_trace_chunk_put(stream->trace_chunk);
+       if (stream->chan->trace_chunk == stream->trace_chunk) {
+               /*
+                * A channel can be rotated and not have a "next" chunk
+                * to transition to. In that case, the channel's "current chunk"
+                * has not been closed yet, but it has not been updated to
+                * a "next" trace chunk either. Hence, the stream, like its
+                * parent channel, becomes part of no chunk and can't output
+                * anything until a new trace chunk is created.
+                */
+               stream->trace_chunk = NULL;
+       } else if (stream->chan->trace_chunk &&
+                       !lttng_trace_chunk_get(stream->chan->trace_chunk)) {
+               ERR("Failed to acquire a reference to channel's trace chunk during stream rotation");
+               ret = -1;
+               goto error;
+       } else {
+               /*
+                * Update the stream's trace chunk to its parent channel's
+                * current trace chunk.
+                */
+               stream->trace_chunk = stream->chan->trace_chunk;
+       }
+
+       if (stream->net_seq_idx == (uint64_t) -1ULL) {
+               ret = rotate_local_stream(ctx, stream);
+               if (ret < 0) {
+                       ERR("Failed to rotate stream, ret = %i", ret);
+                       goto error;
+               }
+       }
+
+       if (stream->metadata_flag && stream->trace_chunk) {
+               /*
+                * If the stream has transitioned to a new trace
+                * chunk, the metadata should be re-dumped to the
+                * newest chunk.
+                *
+                * However, it is possible for a stream to transition to
+                * a "no-chunk" state. This can happen if a rotation
+                * occurs on an inactive session. In such cases, the metadata
+                * regeneration will happen when the next trace chunk is
+                * created.
+                */
+               ret = consumer_metadata_stream_dump(stream);
+               if (ret) {
+                       goto error;
+               }
+       }
+       lttng_consumer_reset_stream_rotate_state(stream);
+
+       ret = 0;
+
+error:
+       return ret;
+}
+
+/*
+ * Rotate all the ready streams now.
+ *
+ * This is especially important for low throughput streams that have already
+ * been consumed, we cannot wait for their next packet to perform the
+ * rotation.
+ * Need to be called with RCU read-side lock held to ensure existence of
+ * channel.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_consumer_rotate_ready_streams(struct lttng_consumer_channel *channel,
+               uint64_t key, struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+       struct lttng_consumer_stream *stream;
+       struct lttng_ht_iter iter;
+       struct lttng_ht *ht = the_consumer_data.stream_per_chan_id_ht;
+
+       rcu_read_lock();
+
+       DBG("Consumer rotate ready streams in channel %" PRIu64, key);
+
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&channel->key, lttng_ht_seed),
+                       ht->match_fct, &channel->key, &iter.iter,
+                       stream, node_channel_id.node) {
+               health_code_update();
+
+               pthread_mutex_lock(&stream->chan->lock);
+               pthread_mutex_lock(&stream->lock);
+
+               if (!stream->rotate_ready) {
+                       pthread_mutex_unlock(&stream->lock);
+                       pthread_mutex_unlock(&stream->chan->lock);
+                       continue;
+               }
+               DBG("Consumer rotate ready stream %" PRIu64, stream->key);
+
+               ret = lttng_consumer_rotate_stream(ctx, stream);
+               pthread_mutex_unlock(&stream->lock);
+               pthread_mutex_unlock(&stream->chan->lock);
+               if (ret) {
+                       goto end;
+               }
+       }
+
+       ret = 0;
+
+end:
+       rcu_read_unlock();
+       return ret;
+}
+
+enum lttcomm_return_code lttng_consumer_init_command(
+               struct lttng_consumer_local_data *ctx,
+               const lttng_uuid sessiond_uuid)
+{
+       enum lttcomm_return_code ret;
+       char uuid_str[LTTNG_UUID_STR_LEN];
+
+       if (ctx->sessiond_uuid.is_set) {
+               ret = LTTCOMM_CONSUMERD_ALREADY_SET;
+               goto end;
+       }
+
+       ctx->sessiond_uuid.is_set = true;
+       memcpy(ctx->sessiond_uuid.value, sessiond_uuid, sizeof(lttng_uuid));
+       ret = LTTCOMM_CONSUMERD_SUCCESS;
+       lttng_uuid_to_str(sessiond_uuid, uuid_str);
+       DBG("Received session daemon UUID: %s", uuid_str);
+end:
+       return ret;
+}
+
+enum lttcomm_return_code lttng_consumer_create_trace_chunk(
+               const uint64_t *relayd_id, uint64_t session_id,
+               uint64_t chunk_id,
+               time_t chunk_creation_timestamp,
+               const char *chunk_override_name,
+               const struct lttng_credentials *credentials,
+               struct lttng_directory_handle *chunk_directory_handle)
+{
+       int ret;
+       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       struct lttng_trace_chunk *created_chunk = NULL, *published_chunk = NULL;
+       enum lttng_trace_chunk_status chunk_status;
+       char relayd_id_buffer[MAX_INT_DEC_LEN(*relayd_id)];
+       char creation_timestamp_buffer[ISO8601_STR_LEN];
+       const char *relayd_id_str = "(none)";
+       const char *creation_timestamp_str;
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_channel *channel;
+
+       if (relayd_id) {
+               /* Only used for logging purposes. */
+               ret = snprintf(relayd_id_buffer, sizeof(relayd_id_buffer),
+                               "%" PRIu64, *relayd_id);
+               if (ret > 0 && ret < sizeof(relayd_id_buffer)) {
+                       relayd_id_str = relayd_id_buffer;
+               } else {
+                       relayd_id_str = "(formatting error)";
+               }
+       }
+
+       /* Local protocol error. */
+       LTTNG_ASSERT(chunk_creation_timestamp);
+       ret = time_to_iso8601_str(chunk_creation_timestamp,
+                       creation_timestamp_buffer,
+                       sizeof(creation_timestamp_buffer));
+       creation_timestamp_str = !ret ? creation_timestamp_buffer :
+                       "(formatting error)";
+
+       DBG("Consumer create trace chunk command: relay_id = %s"
+                       ", session_id = %" PRIu64 ", chunk_id = %" PRIu64
+                       ", chunk_override_name = %s"
+                       ", chunk_creation_timestamp = %s",
+                       relayd_id_str, session_id, chunk_id,
+                       chunk_override_name ? : "(none)",
+                       creation_timestamp_str);
+
+       /*
+        * The trace chunk registry, as used by the consumer daemon, implicitly
+        * owns the trace chunks. This is only needed in the consumer since
+        * the consumer has no notion of a session beyond session IDs being
+        * used to identify other objects.
+        *
+        * The lttng_trace_chunk_registry_publish() call below provides a
+        * reference which is not released; it implicitly becomes the session
+        * daemon's reference to the chunk in the consumer daemon.
+        *
+        * The lifetime of trace chunks in the consumer daemon is managed by
+        * the session daemon through the LTTNG_CONSUMER_CREATE_TRACE_CHUNK
+        * and LTTNG_CONSUMER_DESTROY_TRACE_CHUNK commands.
+        */
+       created_chunk = lttng_trace_chunk_create(chunk_id,
+                       chunk_creation_timestamp, NULL);
+       if (!created_chunk) {
+               ERR("Failed to create trace chunk");
+               ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
+               goto error;
+       }
+
+       if (chunk_override_name) {
+               chunk_status = lttng_trace_chunk_override_name(created_chunk,
+                               chunk_override_name);
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
+                       goto error;
+               }
+       }
+
+       if (chunk_directory_handle) {
+               chunk_status = lttng_trace_chunk_set_credentials(created_chunk,
+                               credentials);
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ERR("Failed to set trace chunk credentials");
+                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
+                       goto error;
+               }
+               /*
+                * The consumer daemon has no ownership of the chunk output
+                * directory.
+                */
+               chunk_status = lttng_trace_chunk_set_as_user(created_chunk,
+                               chunk_directory_handle);
+               chunk_directory_handle = NULL;
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ERR("Failed to set trace chunk's directory handle");
+                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
+                       goto error;
+               }
+       }
+
+       published_chunk = lttng_trace_chunk_registry_publish_chunk(
+                       the_consumer_data.chunk_registry, session_id,
+                       created_chunk);
+       lttng_trace_chunk_put(created_chunk);
+       created_chunk = NULL;
+       if (!published_chunk) {
+               ERR("Failed to publish trace chunk");
+               ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
+               goto error;
+       }
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry_duplicate(
+                       the_consumer_data.channels_by_session_id_ht->ht,
+                       the_consumer_data.channels_by_session_id_ht->hash_fct(
+                                       &session_id, lttng_ht_seed),
+                       the_consumer_data.channels_by_session_id_ht->match_fct,
+                       &session_id, &iter.iter, channel,
+                       channels_by_session_id_ht_node.node) {
+               ret = lttng_consumer_channel_set_trace_chunk(channel,
+                               published_chunk);
+               if (ret) {
+                       /*
+                        * Roll-back the creation of this chunk.
+                        *
+                        * This is important since the session daemon will
+                        * assume that the creation of this chunk failed and
+                        * will never ask for it to be closed, resulting
+                        * in a leak and an inconsistent state for some
+                        * channels.
+                        */
+                       enum lttcomm_return_code close_ret;
+                       char path[LTTNG_PATH_MAX];
+
+                       DBG("Failed to set new trace chunk on existing channels, rolling back");
+                       close_ret = lttng_consumer_close_trace_chunk(relayd_id,
+                                       session_id, chunk_id,
+                                       chunk_creation_timestamp, NULL,
+                                       path);
+                       if (close_ret != LTTCOMM_CONSUMERD_SUCCESS) {
+                               ERR("Failed to roll-back the creation of new chunk: session_id = %" PRIu64 ", chunk_id = %" PRIu64,
+                                               session_id, chunk_id);
+                       }
+
+                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
+                       break;
+               }
+       }
+
+       if (relayd_id) {
+               struct consumer_relayd_sock_pair *relayd;
+
+               relayd = consumer_find_relayd(*relayd_id);
+               if (relayd) {
+                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+                       ret = relayd_create_trace_chunk(
+                                       &relayd->control_sock, published_chunk);
+                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+               } else {
+                       ERR("Failed to find relay daemon socket: relayd_id = %" PRIu64, *relayd_id);
+               }
+
+               if (!relayd || ret) {
+                       enum lttcomm_return_code close_ret;
+                       char path[LTTNG_PATH_MAX];
+
+                       close_ret = lttng_consumer_close_trace_chunk(relayd_id,
+                                       session_id,
+                                       chunk_id,
+                                       chunk_creation_timestamp,
+                                       NULL, path);
+                       if (close_ret != LTTCOMM_CONSUMERD_SUCCESS) {
+                               ERR("Failed to roll-back the creation of new chunk: session_id = %" PRIu64 ", chunk_id = %" PRIu64,
+                                               session_id,
+                                               chunk_id);
+                       }
+
+                       ret_code = LTTCOMM_CONSUMERD_CREATE_TRACE_CHUNK_FAILED;
+                       goto error_unlock;
+               }
+       }
+error_unlock:
+       rcu_read_unlock();
+error:
+       /* Release the reference returned by the "publish" operation. */
+       lttng_trace_chunk_put(published_chunk);
+       lttng_trace_chunk_put(created_chunk);
+       return ret_code;
+}
+
+enum lttcomm_return_code lttng_consumer_close_trace_chunk(
+               const uint64_t *relayd_id, uint64_t session_id,
+               uint64_t chunk_id, time_t chunk_close_timestamp,
+               const enum lttng_trace_chunk_command_type *close_command,
+               char *path)
+{
+       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       struct lttng_trace_chunk *chunk;
+       char relayd_id_buffer[MAX_INT_DEC_LEN(*relayd_id)];
+       const char *relayd_id_str = "(none)";
+       const char *close_command_name = "none";
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_channel *channel;
+       enum lttng_trace_chunk_status chunk_status;
+
+       if (relayd_id) {
+               int ret;
+
+               /* Only used for logging purposes. */
+               ret = snprintf(relayd_id_buffer, sizeof(relayd_id_buffer),
+                               "%" PRIu64, *relayd_id);
+               if (ret > 0 && ret < sizeof(relayd_id_buffer)) {
+                       relayd_id_str = relayd_id_buffer;
+               } else {
+                       relayd_id_str = "(formatting error)";
+               }
+       }
+       if (close_command) {
+               close_command_name = lttng_trace_chunk_command_type_get_name(
+                               *close_command);
+       }
+
+       DBG("Consumer close trace chunk command: relayd_id = %s"
+                       ", session_id = %" PRIu64 ", chunk_id = %" PRIu64
+                       ", close command = %s",
+                       relayd_id_str, session_id, chunk_id,
+                       close_command_name);
+
+       chunk = lttng_trace_chunk_registry_find_chunk(
+                       the_consumer_data.chunk_registry, session_id, chunk_id);
+       if (!chunk) {
+               ERR("Failed to find chunk: session_id = %" PRIu64
+                               ", chunk_id = %" PRIu64,
+                               session_id, chunk_id);
+               ret_code = LTTCOMM_CONSUMERD_UNKNOWN_TRACE_CHUNK;
+               goto end;
+       }
+
+       chunk_status = lttng_trace_chunk_set_close_timestamp(chunk,
+                       chunk_close_timestamp);
+       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+               ret_code = LTTCOMM_CONSUMERD_CLOSE_TRACE_CHUNK_FAILED;
+               goto end;
+       }
+
+       if (close_command) {
+               chunk_status = lttng_trace_chunk_set_close_command(
+                               chunk, *close_command);
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ret_code = LTTCOMM_CONSUMERD_CLOSE_TRACE_CHUNK_FAILED;
+                       goto end;
+               }
+       }
+
+       /*
+        * chunk is now invalid to access as we no longer hold a reference to
+        * it; it is only kept around to compare it (by address) to the
+        * current chunk found in the session's channels.
+        */
+       rcu_read_lock();
+       cds_lfht_for_each_entry(the_consumer_data.channel_ht->ht, &iter.iter,
+                       channel, node.node) {
+               int ret;
+
+               /*
+                * Only change the channel's chunk to NULL if it still
+                * references the chunk being closed. The channel may
+                * reference a newer channel in the case of a session
+                * rotation. When a session rotation occurs, the "next"
+                * chunk is created before the "current" chunk is closed.
+                */
+               if (channel->trace_chunk != chunk) {
+                       continue;
+               }
+               ret = lttng_consumer_channel_set_trace_chunk(channel, NULL);
+               if (ret) {
+                       /*
+                        * Attempt to close the chunk on as many channels as
+                        * possible.
+                        */
+                       ret_code = LTTCOMM_CONSUMERD_CLOSE_TRACE_CHUNK_FAILED;
+               }
+       }
+
+       if (relayd_id) {
+               int ret;
+               struct consumer_relayd_sock_pair *relayd;
+
+               relayd = consumer_find_relayd(*relayd_id);
+               if (relayd) {
+                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+                       ret = relayd_close_trace_chunk(
+                                       &relayd->control_sock, chunk,
+                                       path);
+                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+               } else {
+                       ERR("Failed to find relay daemon socket: relayd_id = %" PRIu64,
+                                       *relayd_id);
+               }
+
+               if (!relayd || ret) {
+                       ret_code = LTTCOMM_CONSUMERD_CLOSE_TRACE_CHUNK_FAILED;
+                       goto error_unlock;
+               }
+       }
+error_unlock:
+       rcu_read_unlock();
+end:
+       /*
+        * Release the reference returned by the "find" operation and
+        * the session daemon's implicit reference to the chunk.
+        */
+       lttng_trace_chunk_put(chunk);
+       lttng_trace_chunk_put(chunk);
+
+       return ret_code;
+}
+
+enum lttcomm_return_code lttng_consumer_trace_chunk_exists(
+               const uint64_t *relayd_id, uint64_t session_id,
+               uint64_t chunk_id)
+{
+       int ret;
+       enum lttcomm_return_code ret_code;
+       char relayd_id_buffer[MAX_INT_DEC_LEN(*relayd_id)];
+       const char *relayd_id_str = "(none)";
+       const bool is_local_trace = !relayd_id;
+       struct consumer_relayd_sock_pair *relayd = NULL;
+       bool chunk_exists_local, chunk_exists_remote;
+
+       if (relayd_id) {
+               /* Only used for logging purposes. */
+               ret = snprintf(relayd_id_buffer, sizeof(relayd_id_buffer),
+                               "%" PRIu64, *relayd_id);
+               if (ret > 0 && ret < sizeof(relayd_id_buffer)) {
+                       relayd_id_str = relayd_id_buffer;
+               } else {
+                       relayd_id_str = "(formatting error)";
+               }
+       }
+
+       DBG("Consumer trace chunk exists command: relayd_id = %s"
+                       ", chunk_id = %" PRIu64, relayd_id_str,
+                       chunk_id);
+       ret = lttng_trace_chunk_registry_chunk_exists(
+                       the_consumer_data.chunk_registry, session_id, chunk_id,
+                       &chunk_exists_local);
+       if (ret) {
+               /* Internal error. */
+               ERR("Failed to query the existence of a trace chunk");
+               ret_code = LTTCOMM_CONSUMERD_FATAL;
+               goto end;
+       }
+       DBG("Trace chunk %s locally",
+                       chunk_exists_local ? "exists" : "does not exist");
+       if (chunk_exists_local) {
+               ret_code = LTTCOMM_CONSUMERD_TRACE_CHUNK_EXISTS_LOCAL;
+               goto end;
+       } else if (is_local_trace) {
+               ret_code = LTTCOMM_CONSUMERD_UNKNOWN_TRACE_CHUNK;
+               goto end;
+       }
+
+       rcu_read_lock();
+       relayd = consumer_find_relayd(*relayd_id);
+       if (!relayd) {
+               ERR("Failed to find relayd %" PRIu64, *relayd_id);
+               ret_code = LTTCOMM_CONSUMERD_INVALID_PARAMETERS;
+               goto end_rcu_unlock;
+       }
+       DBG("Looking up existence of trace chunk on relay daemon");
+       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+       ret = relayd_trace_chunk_exists(&relayd->control_sock, chunk_id,
+                       &chunk_exists_remote);
+       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+       if (ret < 0) {
+               ERR("Failed to look-up the existence of trace chunk on relay daemon");
+               ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
+               goto end_rcu_unlock;
+       }
+
+       ret_code = chunk_exists_remote ?
+                       LTTCOMM_CONSUMERD_TRACE_CHUNK_EXISTS_REMOTE :
+                       LTTCOMM_CONSUMERD_UNKNOWN_TRACE_CHUNK;
+       DBG("Trace chunk %s on relay daemon",
+                       chunk_exists_remote ? "exists" : "does not exist");
+
+end_rcu_unlock:
+       rcu_read_unlock();
+end:
+       return ret_code;
+}
+
+static
+int consumer_clear_monitored_channel(struct lttng_consumer_channel *channel)
+{
+       struct lttng_ht *ht;
+       struct lttng_consumer_stream *stream;
+       struct lttng_ht_iter iter;
+       int ret;
+
+       ht = the_consumer_data.stream_per_chan_id_ht;
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&channel->key, lttng_ht_seed),
+                       ht->match_fct, &channel->key,
+                       &iter.iter, stream, node_channel_id.node) {
+               /*
+                * Protect against teardown with mutex.
+                */
+               pthread_mutex_lock(&stream->lock);
+               if (cds_lfht_is_node_deleted(&stream->node.node)) {
+                       goto next;
+               }
+               ret = consumer_clear_stream(stream);
+               if (ret) {
+                       goto error_unlock;
+               }
+       next:
+               pthread_mutex_unlock(&stream->lock);
+       }
+       rcu_read_unlock();
+       return LTTCOMM_CONSUMERD_SUCCESS;
+
+error_unlock:
+       pthread_mutex_unlock(&stream->lock);
+       rcu_read_unlock();
+       return ret;
+}
+
+int lttng_consumer_clear_channel(struct lttng_consumer_channel *channel)
+{
+       int ret;
+
+       DBG("Consumer clear channel %" PRIu64, channel->key);
+
+       if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA) {
+               /*
+                * Nothing to do for the metadata channel/stream.
+                * Snapshot mechanism already take care of the metadata
+                * handling/generation, and monitored channels only need to
+                * have their data stream cleared..
+                */
+               ret = LTTCOMM_CONSUMERD_SUCCESS;
+               goto end;
+       }
+
+       if (!channel->monitor) {
+               ret = consumer_clear_unmonitored_channel(channel);
+       } else {
+               ret = consumer_clear_monitored_channel(channel);
+       }
+end:
+       return ret;
+}
+
+enum lttcomm_return_code lttng_consumer_open_channel_packets(
+               struct lttng_consumer_channel *channel)
+{
+       struct lttng_consumer_stream *stream;
+       enum lttcomm_return_code ret = LTTCOMM_CONSUMERD_SUCCESS;
+
+       if (channel->metadata_stream) {
+               ERR("Open channel packets command attempted on a metadata channel");
+               ret = LTTCOMM_CONSUMERD_INVALID_PARAMETERS;
+               goto end;
+       }
+
+       rcu_read_lock();
+       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+               enum consumer_stream_open_packet_status status;
+
+               pthread_mutex_lock(&stream->lock);
+               if (cds_lfht_is_node_deleted(&stream->node.node)) {
+                       goto next;
+               }
+
+               status = consumer_stream_open_packet(stream);
+               switch (status) {
+               case CONSUMER_STREAM_OPEN_PACKET_STATUS_OPENED:
+                       DBG("Opened a packet in \"open channel packets\" command: stream id = %" PRIu64
+                                       ", channel name = %s, session id = %" PRIu64,
+                                       stream->key, stream->chan->name,
+                                       stream->chan->session_id);
+                       stream->opened_packet_in_current_trace_chunk = true;
+                       break;
+               case CONSUMER_STREAM_OPEN_PACKET_STATUS_NO_SPACE:
+                       DBG("No space left to open a packet in \"open channel packets\" command: stream id = %" PRIu64
+                                       ", channel name = %s, session id = %" PRIu64,
+                                       stream->key, stream->chan->name,
+                                       stream->chan->session_id);
+                       break;
+               case CONSUMER_STREAM_OPEN_PACKET_STATUS_ERROR:
+                       /*
+                        * Only unexpected internal errors can lead to this
+                        * failing. Report an unknown error.
+                        */
+                       ERR("Failed to flush empty buffer in \"open channel packets\" command: stream id = %" PRIu64
+                                       ", channel id = %" PRIu64
+                                       ", channel name = %s"
+                                       ", session id = %" PRIu64,
+                                       stream->key, channel->key,
+                                       channel->name, channel->session_id);
+                       ret = LTTCOMM_CONSUMERD_UNKNOWN_ERROR;
+                       goto error_unlock;
+               default:
+                       abort();
+               }
+
+       next:
+               pthread_mutex_unlock(&stream->lock);
+       }
+
+end_rcu_unlock:
+       rcu_read_unlock();
+end:
+       return ret;
+
+error_unlock:
+       pthread_mutex_unlock(&stream->lock);
+       goto end_rcu_unlock;
+}
+
+void lttng_consumer_sigbus_handle(void *addr)
+{
+       lttng_ustconsumer_sigbus_handle(addr);
+}
index 1b0ee000b5bdd944ac4aba946a83d256327a5195..582385c82bef2454361f39b6dca0d70b294157d7 100644 (file)
@@ -802,30 +802,30 @@ struct lttng_consumer_global_data {
         * This is nested OUTSIDE the stream lock.
         * This is nested OUTSIDE the consumer_relayd_sock_pair lock.
         */
-       pthread_mutex_t lock;
+       pthread_mutex_t lock {};
 
        /*
         * Number of streams in the data stream hash table declared outside.
         * Protected by consumer_data.lock.
         */
-       int stream_count;
+       int stream_count = 0;
 
        /* Channel hash table protected by consumer_data.lock. */
-       struct lttng_ht *channel_ht;
+       struct lttng_ht *channel_ht = nullptr;
        /* Channel hash table indexed by session id. */
-       struct lttng_ht *channels_by_session_id_ht;
+       struct lttng_ht *channels_by_session_id_ht = nullptr;
        /*
         * Flag specifying if the local array of FDs needs update in the
         * poll function. Protected by consumer_data.lock.
         */
-       unsigned int need_update;
-       enum lttng_consumer_type type;
+       unsigned int need_update = 1;
+       enum lttng_consumer_type type = LTTNG_CONSUMER_UNKNOWN;
 
        /*
         * Relayd socket(s) hashtable indexed by network sequence number. Each
         * stream has an index which associate the right relayd socket to use.
         */
-       struct lttng_ht *relayd_ht;
+       struct lttng_ht *relayd_ht = nullptr;
 
        /*
         * This hash table contains all streams (metadata and data) indexed by
@@ -834,17 +834,17 @@ struct lttng_consumer_global_data {
         *
         * This HT uses the "node_session_id" of the consumer stream.
         */
-       struct lttng_ht *stream_list_ht;
+       struct lttng_ht *stream_list_ht = nullptr;
 
        /*
         * This HT uses the "node_channel_id" of the consumer stream.
         */
-       struct lttng_ht *stream_per_chan_id_ht;
+       struct lttng_ht *stream_per_chan_id_ht = nullptr;
 
        /*
         * Trace chunk registry indexed by (session_id, chunk_id).
         */
-       struct lttng_trace_chunk_registry *chunk_registry;
+       struct lttng_trace_chunk_registry *chunk_registry = nullptr;
 };
 
 /*
diff --git a/src/common/consumer/metadata-bucket.c b/src/common/consumer/metadata-bucket.c
deleted file mode 100644 (file)
index 1ee5022..0000000
+++ /dev/null
@@ -1,150 +0,0 @@
-/*
- * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#include "metadata-bucket.h"
-
-#include <common/buffer-view.h>
-#include <common/consumer/consumer.h>
-#include <common/dynamic-buffer.h>
-#include <common/macros.h>
-#include <common/error.h>
-
-struct metadata_bucket {
-       struct lttng_dynamic_buffer content;
-       struct {
-               metadata_bucket_flush_cb fn;
-               void *data;
-       } flush;
-       unsigned int buffer_count;
-};
-
-struct metadata_bucket *metadata_bucket_create(
-               metadata_bucket_flush_cb flush, void *data)
-{
-       struct metadata_bucket *bucket;
-
-       bucket = zmalloc(sizeof(typeof(*bucket)));
-       if (!bucket) {
-               PERROR("Failed to allocate buffer bucket");
-               goto end;
-       }
-
-       bucket->flush.fn = flush;
-       bucket->flush.data = data;
-       lttng_dynamic_buffer_init(&bucket->content);
-end:
-       return bucket;
-}
-
-void metadata_bucket_destroy(struct metadata_bucket *bucket)
-{
-       if (!bucket) {
-               return;
-       }
-
-       if (bucket->content.size > 0) {
-               WARN("Stream metadata bucket destroyed with remaining data: size = %zu, buffer count = %u",
-                               bucket->content.size, bucket->buffer_count);
-       }
-
-       lttng_dynamic_buffer_reset(&bucket->content);
-       free(bucket);
-}
-
-void metadata_bucket_reset(struct metadata_bucket *bucket)
-{
-       lttng_dynamic_buffer_reset(&bucket->content);
-       lttng_dynamic_buffer_init(&bucket->content);
-       bucket->buffer_count = 0;
-}
-
-enum metadata_bucket_status metadata_bucket_fill(struct metadata_bucket *bucket,
-               const struct stream_subbuffer *buffer)
-{
-       ssize_t ret;
-       struct lttng_buffer_view flushed_view;
-       struct stream_subbuffer flushed_subbuffer;
-       enum metadata_bucket_status status;
-       const bool should_flush =
-                       LTTNG_OPTIONAL_GET(buffer->info.metadata.coherent);
-       const size_t padding_this_buffer =
-                       buffer->info.metadata.padded_subbuf_size -
-                       buffer->info.metadata.subbuf_size;
-       size_t flush_size;
-
-       DBG("Metadata bucket filled with %zu bytes buffer view, sub-buffer size: %lu, padded sub-buffer size: %lu, coherent: %s",
-                       buffer->buffer.buffer.size,
-                       buffer->info.metadata.subbuf_size,
-                       buffer->info.metadata.padded_subbuf_size,
-                       buffer->info.metadata.coherent.value ? "true" : "false");
-       /*
-        * If no metadata was accumulated and this buffer should be
-        * flushed, don't copy it unecessarily; just flush it directly.
-        */
-       if (!should_flush || bucket->buffer_count != 0) {
-               /*
-                * Append the _padded_ subbuffer since they are combined
-                * into a single "virtual" subbuffer that will be
-                * flushed at once.
-                *
-                * This means that some padding will be sent over the
-                * network, but should not represent a large amount
-                * of data as incoherent subbuffers are typically
-                * pretty full.
-                *
-                * The padding of the last subbuffer (coherent) added to
-                * the bucket is not sent, which is what really matters
-                * from an efficiency point of view.
-                */
-               ret = lttng_dynamic_buffer_append_view(
-                       &bucket->content, &buffer->buffer.buffer);
-               if (ret) {
-                       status = METADATA_BUCKET_STATUS_ERROR;
-                       goto end;
-               }
-       }
-
-       bucket->buffer_count++;
-       if (!should_flush) {
-               status = METADATA_BUCKET_STATUS_OK;
-               goto end;
-       }
-
-       flushed_view = bucket->content.size != 0 ?
-               lttng_buffer_view_from_dynamic_buffer(&bucket->content, 0, -1) :
-               lttng_buffer_view_from_view(&buffer->buffer.buffer, 0, -1);
-
-       /*
-        * The flush is done with the size of all padded sub-buffers, except
-        * for the last one which we can safely "trim". The padding of the last
-        * packet will be reconstructed by the relay daemon.
-        */
-       flush_size = flushed_view.size - padding_this_buffer;
-
-       flushed_subbuffer = (typeof(flushed_subbuffer)) {
-               .buffer.buffer = flushed_view,
-               .info.metadata.subbuf_size = flush_size,
-               .info.metadata.padded_subbuf_size = flushed_view.size,
-               .info.metadata.version = buffer->info.metadata.version,
-               .info.metadata.coherent = buffer->info.metadata.coherent,
-       };
-
-       DBG("Metadata bucket flushing %zu bytes (%u sub-buffer%s)",
-                       flushed_view.size, bucket->buffer_count,
-                       bucket->buffer_count > 1 ? "s" : "");
-       ret = bucket->flush.fn(&flushed_subbuffer, bucket->flush.data);
-       if (ret >= 0) {
-               status = METADATA_BUCKET_STATUS_OK;
-       } else {
-               status = METADATA_BUCKET_STATUS_ERROR;
-       }
-
-       metadata_bucket_reset(bucket);
-
-end:
-       return status;
-}
diff --git a/src/common/consumer/metadata-bucket.cpp b/src/common/consumer/metadata-bucket.cpp
new file mode 100644 (file)
index 0000000..160185d
--- /dev/null
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#include "metadata-bucket.h"
+
+#include <common/buffer-view.h>
+#include <common/consumer/consumer.h>
+#include <common/dynamic-buffer.h>
+#include <common/macros.h>
+#include <common/error.h>
+
+struct metadata_bucket {
+       struct lttng_dynamic_buffer content;
+       struct {
+               metadata_bucket_flush_cb fn;
+               void *data;
+       } flush;
+       unsigned int buffer_count;
+};
+
+struct metadata_bucket *metadata_bucket_create(
+               metadata_bucket_flush_cb flush, void *data)
+{
+       struct metadata_bucket *bucket;
+
+       bucket = (metadata_bucket *) zmalloc(sizeof(typeof(*bucket)));
+       if (!bucket) {
+               PERROR("Failed to allocate buffer bucket");
+               goto end;
+       }
+
+       bucket->flush.fn = flush;
+       bucket->flush.data = data;
+       lttng_dynamic_buffer_init(&bucket->content);
+end:
+       return bucket;
+}
+
+void metadata_bucket_destroy(struct metadata_bucket *bucket)
+{
+       if (!bucket) {
+               return;
+       }
+
+       if (bucket->content.size > 0) {
+               WARN("Stream metadata bucket destroyed with remaining data: size = %zu, buffer count = %u",
+                               bucket->content.size, bucket->buffer_count);
+       }
+
+       lttng_dynamic_buffer_reset(&bucket->content);
+       free(bucket);
+}
+
+void metadata_bucket_reset(struct metadata_bucket *bucket)
+{
+       lttng_dynamic_buffer_reset(&bucket->content);
+       lttng_dynamic_buffer_init(&bucket->content);
+       bucket->buffer_count = 0;
+}
+
+enum metadata_bucket_status metadata_bucket_fill(struct metadata_bucket *bucket,
+               const struct stream_subbuffer *buffer)
+{
+       ssize_t ret;
+       struct lttng_buffer_view flushed_view;
+       struct stream_subbuffer flushed_subbuffer;
+       enum metadata_bucket_status status;
+       const bool should_flush =
+                       LTTNG_OPTIONAL_GET(buffer->info.metadata.coherent);
+       const size_t padding_this_buffer =
+                       buffer->info.metadata.padded_subbuf_size -
+                       buffer->info.metadata.subbuf_size;
+       size_t flush_size;
+
+       DBG("Metadata bucket filled with %zu bytes buffer view, sub-buffer size: %lu, padded sub-buffer size: %lu, coherent: %s",
+                       buffer->buffer.buffer.size,
+                       buffer->info.metadata.subbuf_size,
+                       buffer->info.metadata.padded_subbuf_size,
+                       buffer->info.metadata.coherent.value ? "true" : "false");
+       /*
+        * If no metadata was accumulated and this buffer should be
+        * flushed, don't copy it unecessarily; just flush it directly.
+        */
+       if (!should_flush || bucket->buffer_count != 0) {
+               /*
+                * Append the _padded_ subbuffer since they are combined
+                * into a single "virtual" subbuffer that will be
+                * flushed at once.
+                *
+                * This means that some padding will be sent over the
+                * network, but should not represent a large amount
+                * of data as incoherent subbuffers are typically
+                * pretty full.
+                *
+                * The padding of the last subbuffer (coherent) added to
+                * the bucket is not sent, which is what really matters
+                * from an efficiency point of view.
+                */
+               ret = lttng_dynamic_buffer_append_view(
+                       &bucket->content, &buffer->buffer.buffer);
+               if (ret) {
+                       status = METADATA_BUCKET_STATUS_ERROR;
+                       goto end;
+               }
+       }
+
+       bucket->buffer_count++;
+       if (!should_flush) {
+               status = METADATA_BUCKET_STATUS_OK;
+               goto end;
+       }
+
+       flushed_view = bucket->content.size != 0 ?
+               lttng_buffer_view_from_dynamic_buffer(&bucket->content, 0, -1) :
+               lttng_buffer_view_from_view(&buffer->buffer.buffer, 0, -1);
+
+       /*
+        * The flush is done with the size of all padded sub-buffers, except
+        * for the last one which we can safely "trim". The padding of the last
+        * packet will be reconstructed by the relay daemon.
+        */
+       flush_size = flushed_view.size - padding_this_buffer;
+
+       flushed_subbuffer = (typeof(flushed_subbuffer)) {
+               .buffer = {
+                       .buffer = flushed_view,
+               },
+               .info = {
+                       .metadata = {
+                               .subbuf_size = flush_size,
+                               .padded_subbuf_size = flushed_view.size,
+                               .version = buffer->info.metadata.version,
+                               .coherent = buffer->info.metadata.coherent,
+                       },
+               },
+       };
+
+       DBG("Metadata bucket flushing %zu bytes (%u sub-buffer%s)",
+                       flushed_view.size, bucket->buffer_count,
+                       bucket->buffer_count > 1 ? "s" : "");
+       ret = bucket->flush.fn(&flushed_subbuffer, bucket->flush.data);
+       if (ret >= 0) {
+               status = METADATA_BUCKET_STATUS_OK;
+       } else {
+               status = METADATA_BUCKET_STATUS_ERROR;
+       }
+
+       metadata_bucket_reset(bucket);
+
+end:
+       return status;
+}
index 0355eb3c0efa8c149bda515a4a8abf26a38d2140..8868811efb2ed721793e3fa6472e01216b45b0eb 100644 (file)
 
 #include <common/consumer/consumer.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct metadata_bucket;
 
 typedef ssize_t (*metadata_bucket_flush_cb)(
@@ -30,5 +34,8 @@ enum metadata_bucket_status metadata_bucket_fill(struct metadata_bucket *bucket,
 
 void metadata_bucket_reset(struct metadata_bucket *bucket);
 
-#endif /* METADATA_BUCKET_H */
+#ifdef __cplusplus
+}
+#endif
 
+#endif /* METADATA_BUCKET_H */
index cf86e2a63256c69442c1b14719f8212699dcb166..b1184130efc9298d127f668c3d315aa8bdb85717 100644 (file)
@@ -2,7 +2,9 @@
 
 noinst_LTLIBRARIES = libkernel-consumer.la
 
-libkernel_consumer_la_SOURCES = kernel-consumer.c kernel-consumer.h
+libkernel_consumer_la_SOURCES = \
+       kernel-consumer.cpp \
+       kernel-consumer.h
 
 libkernel_consumer_la_LIBADD = \
                   $(top_builddir)/src/common/kernel-ctl/libkernel-ctl.la \
diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
deleted file mode 100644 (file)
index 236c2c9..0000000
+++ /dev/null
@@ -1,1920 +0,0 @@
-/*
- * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
- * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#define _LGPL_SOURCE
-#include <poll.h>
-#include <pthread.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/mman.h>
-#include <sys/socket.h>
-#include <sys/types.h>
-#include <inttypes.h>
-#include <unistd.h>
-#include <sys/stat.h>
-#include <stdint.h>
-
-#include <bin/lttng-consumerd/health-consumerd.h>
-#include <common/common.h>
-#include <common/kernel-ctl/kernel-ctl.h>
-#include <common/sessiond-comm/sessiond-comm.h>
-#include <common/sessiond-comm/relayd.h>
-#include <common/compat/fcntl.h>
-#include <common/compat/endian.h>
-#include <common/pipe.h>
-#include <common/relayd/relayd.h>
-#include <common/utils.h>
-#include <common/consumer/consumer-stream.h>
-#include <common/index/index.h>
-#include <common/consumer/consumer-timer.h>
-#include <common/optional.h>
-#include <common/buffer-view.h>
-#include <common/consumer/consumer.h>
-#include <common/consumer/metadata-bucket.h>
-
-#include "kernel-consumer.h"
-
-extern struct lttng_consumer_global_data the_consumer_data;
-extern int consumer_poll_timeout;
-
-/*
- * Take a snapshot for a specific fd
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
-{
-       int ret = 0;
-       int infd = stream->wait_fd;
-
-       ret = kernctl_snapshot(infd);
-       /*
-        * -EAGAIN is not an error, it just means that there is no data to
-        *  be read.
-        */
-       if (ret != 0 && ret != -EAGAIN) {
-               PERROR("Getting sub-buffer snapshot.");
-       }
-
-       return ret;
-}
-
-/*
- * Sample consumed and produced positions for a specific fd.
- *
- * Returns 0 on success, < 0 on error.
- */
-int lttng_kconsumer_sample_snapshot_positions(
-               struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-
-       return kernctl_snapshot_sample_positions(stream->wait_fd);
-}
-
-/*
- * Get the produced position
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
-               unsigned long *pos)
-{
-       int ret;
-       int infd = stream->wait_fd;
-
-       ret = kernctl_snapshot_get_produced(infd, pos);
-       if (ret != 0) {
-               PERROR("kernctl_snapshot_get_produced");
-       }
-
-       return ret;
-}
-
-/*
- * Get the consumerd position
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
-               unsigned long *pos)
-{
-       int ret;
-       int infd = stream->wait_fd;
-
-       ret = kernctl_snapshot_get_consumed(infd, pos);
-       if (ret != 0) {
-               PERROR("kernctl_snapshot_get_consumed");
-       }
-
-       return ret;
-}
-
-static
-int get_current_subbuf_addr(struct lttng_consumer_stream *stream,
-               const char **addr)
-{
-       int ret;
-       unsigned long mmap_offset;
-       const char *mmap_base = stream->mmap_base;
-
-       ret = kernctl_get_mmap_read_offset(stream->wait_fd, &mmap_offset);
-       if (ret < 0) {
-               PERROR("Failed to get mmap read offset");
-               goto error;
-       }
-
-       *addr = mmap_base + mmap_offset;
-error:
-       return ret;
-}
-
-/*
- * Take a snapshot of all the stream of a channel
- * RCU read-side lock must be held across this function to ensure existence of
- * channel. The channel lock must be held by the caller.
- *
- * Returns 0 on success, < 0 on error
- */
-static int lttng_kconsumer_snapshot_channel(
-               struct lttng_consumer_channel *channel,
-               uint64_t key, char *path, uint64_t relayd_id,
-               uint64_t nb_packets_per_stream,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret;
-       struct lttng_consumer_stream *stream;
-
-       DBG("Kernel consumer snapshot channel %" PRIu64, key);
-
-       rcu_read_lock();
-
-       /* Splice is not supported yet for channel snapshot. */
-       if (channel->output != CONSUMER_CHANNEL_MMAP) {
-               ERR("Unsupported output type for channel \"%s\": mmap output is required to record a snapshot",
-                               channel->name);
-               ret = -1;
-               goto end;
-       }
-
-       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
-               unsigned long consumed_pos, produced_pos;
-
-               health_code_update();
-
-               /*
-                * Lock stream because we are about to change its state.
-                */
-               pthread_mutex_lock(&stream->lock);
-
-               LTTNG_ASSERT(channel->trace_chunk);
-               if (!lttng_trace_chunk_get(channel->trace_chunk)) {
-                       /*
-                        * Can't happen barring an internal error as the channel
-                        * holds a reference to the trace chunk.
-                        */
-                       ERR("Failed to acquire reference to channel's trace chunk");
-                       ret = -1;
-                       goto end_unlock;
-               }
-               LTTNG_ASSERT(!stream->trace_chunk);
-               stream->trace_chunk = channel->trace_chunk;
-
-               /*
-                * Assign the received relayd ID so we can use it for streaming. The streams
-                * are not visible to anyone so this is OK to change it.
-                */
-               stream->net_seq_idx = relayd_id;
-               channel->relayd_id = relayd_id;
-               if (relayd_id != (uint64_t) -1ULL) {
-                       ret = consumer_send_relayd_stream(stream, path);
-                       if (ret < 0) {
-                               ERR("sending stream to relayd");
-                               goto end_unlock;
-                       }
-               } else {
-                       ret = consumer_stream_create_output_files(stream,
-                                       false);
-                       if (ret < 0) {
-                               goto end_unlock;
-                       }
-                       DBG("Kernel consumer snapshot stream (%" PRIu64 ")",
-                                       stream->key);
-               }
-
-               ret = kernctl_buffer_flush_empty(stream->wait_fd);
-               if (ret < 0) {
-                       /*
-                        * Doing a buffer flush which does not take into
-                        * account empty packets. This is not perfect
-                        * for stream intersection, but required as a
-                        * fall-back when "flush_empty" is not
-                        * implemented by lttng-modules.
-                        */
-                       ret = kernctl_buffer_flush(stream->wait_fd);
-                       if (ret < 0) {
-                               ERR("Failed to flush kernel stream");
-                               goto end_unlock;
-                       }
-                       goto end_unlock;
-               }
-
-               ret = lttng_kconsumer_take_snapshot(stream);
-               if (ret < 0) {
-                       ERR("Taking kernel snapshot");
-                       goto end_unlock;
-               }
-
-               ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
-               if (ret < 0) {
-                       ERR("Produced kernel snapshot position");
-                       goto end_unlock;
-               }
-
-               ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
-               if (ret < 0) {
-                       ERR("Consumerd kernel snapshot position");
-                       goto end_unlock;
-               }
-
-               consumed_pos = consumer_get_consume_start_pos(consumed_pos,
-                               produced_pos, nb_packets_per_stream,
-                               stream->max_sb_size);
-
-               while ((long) (consumed_pos - produced_pos) < 0) {
-                       ssize_t read_len;
-                       unsigned long len, padded_len;
-                       const char *subbuf_addr;
-                       struct lttng_buffer_view subbuf_view;
-
-                       health_code_update();
-                       DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
-
-                       ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
-                       if (ret < 0) {
-                               if (ret != -EAGAIN) {
-                                       PERROR("kernctl_get_subbuf snapshot");
-                                       goto end_unlock;
-                               }
-                               DBG("Kernel consumer get subbuf failed. Skipping it.");
-                               consumed_pos += stream->max_sb_size;
-                               stream->chan->lost_packets++;
-                               continue;
-                       }
-
-                       ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
-                       if (ret < 0) {
-                               ERR("Snapshot kernctl_get_subbuf_size");
-                               goto error_put_subbuf;
-                       }
-
-                       ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
-                       if (ret < 0) {
-                               ERR("Snapshot kernctl_get_padded_subbuf_size");
-                               goto error_put_subbuf;
-                       }
-
-                       ret = get_current_subbuf_addr(stream, &subbuf_addr);
-                       if (ret) {
-                               goto error_put_subbuf;
-                       }
-
-                       subbuf_view = lttng_buffer_view_init(
-                                       subbuf_addr, 0, padded_len);
-                       read_len = lttng_consumer_on_read_subbuffer_mmap(
-                                       stream, &subbuf_view,
-                                       padded_len - len);
-                       /*
-                        * We write the padded len in local tracefiles but the data len
-                        * when using a relay. Display the error but continue processing
-                        * to try to release the subbuffer.
-                        */
-                       if (relayd_id != (uint64_t) -1ULL) {
-                               if (read_len != len) {
-                                       ERR("Error sending to the relay (ret: %zd != len: %lu)",
-                                                       read_len, len);
-                               }
-                       } else {
-                               if (read_len != padded_len) {
-                                       ERR("Error writing to tracefile (ret: %zd != len: %lu)",
-                                                       read_len, padded_len);
-                               }
-                       }
-
-                       ret = kernctl_put_subbuf(stream->wait_fd);
-                       if (ret < 0) {
-                               ERR("Snapshot kernctl_put_subbuf");
-                               goto end_unlock;
-                       }
-                       consumed_pos += stream->max_sb_size;
-               }
-
-               if (relayd_id == (uint64_t) -1ULL) {
-                       if (stream->out_fd >= 0) {
-                               ret = close(stream->out_fd);
-                               if (ret < 0) {
-                                       PERROR("Kernel consumer snapshot close out_fd");
-                                       goto end_unlock;
-                               }
-                               stream->out_fd = -1;
-                       }
-               } else {
-                       close_relayd_stream(stream);
-                       stream->net_seq_idx = (uint64_t) -1ULL;
-               }
-               lttng_trace_chunk_put(stream->trace_chunk);
-               stream->trace_chunk = NULL;
-               pthread_mutex_unlock(&stream->lock);
-       }
-
-       /* All good! */
-       ret = 0;
-       goto end;
-
-error_put_subbuf:
-       ret = kernctl_put_subbuf(stream->wait_fd);
-       if (ret < 0) {
-               ERR("Snapshot kernctl_put_subbuf error path");
-       }
-end_unlock:
-       pthread_mutex_unlock(&stream->lock);
-end:
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Read the whole metadata available for a snapshot.
- * RCU read-side lock must be held across this function to ensure existence of
- * metadata_channel. The channel lock must be held by the caller.
- *
- * Returns 0 on success, < 0 on error
- */
-static int lttng_kconsumer_snapshot_metadata(
-               struct lttng_consumer_channel *metadata_channel,
-               uint64_t key, char *path, uint64_t relayd_id,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret, use_relayd = 0;
-       ssize_t ret_read;
-       struct lttng_consumer_stream *metadata_stream;
-
-       LTTNG_ASSERT(ctx);
-
-       DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
-                       key, path);
-
-       rcu_read_lock();
-
-       metadata_stream = metadata_channel->metadata_stream;
-       LTTNG_ASSERT(metadata_stream);
-
-       pthread_mutex_lock(&metadata_stream->lock);
-       LTTNG_ASSERT(metadata_channel->trace_chunk);
-       LTTNG_ASSERT(metadata_stream->trace_chunk);
-
-       /* Flag once that we have a valid relayd for the stream. */
-       if (relayd_id != (uint64_t) -1ULL) {
-               use_relayd = 1;
-       }
-
-       if (use_relayd) {
-               ret = consumer_send_relayd_stream(metadata_stream, path);
-               if (ret < 0) {
-                       goto error_snapshot;
-               }
-       } else {
-               ret = consumer_stream_create_output_files(metadata_stream,
-                               false);
-               if (ret < 0) {
-                       goto error_snapshot;
-               }
-       }
-
-       do {
-               health_code_update();
-
-               ret_read = lttng_consumer_read_subbuffer(metadata_stream, ctx, true);
-               if (ret_read < 0) {
-                       ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
-                                       ret_read);
-                       ret = ret_read;
-                       goto error_snapshot;
-               }
-       } while (ret_read > 0);
-
-       if (use_relayd) {
-               close_relayd_stream(metadata_stream);
-               metadata_stream->net_seq_idx = (uint64_t) -1ULL;
-       } else {
-               if (metadata_stream->out_fd >= 0) {
-                       ret = close(metadata_stream->out_fd);
-                       if (ret < 0) {
-                               PERROR("Kernel consumer snapshot metadata close out_fd");
-                               /*
-                                * Don't go on error here since the snapshot was successful at this
-                                * point but somehow the close failed.
-                                */
-                       }
-                       metadata_stream->out_fd = -1;
-                       lttng_trace_chunk_put(metadata_stream->trace_chunk);
-                       metadata_stream->trace_chunk = NULL;
-               }
-       }
-
-       ret = 0;
-error_snapshot:
-       pthread_mutex_unlock(&metadata_stream->lock);
-       cds_list_del(&metadata_stream->send_node);
-       consumer_stream_destroy(metadata_stream, NULL);
-       metadata_channel->metadata_stream = NULL;
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Receive command from session daemon and process it.
- *
- * Return 1 on success else a negative value or 0.
- */
-int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
-               int sock, struct pollfd *consumer_sockpoll)
-{
-       int ret_func;
-       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-       struct lttcomm_consumer_msg msg;
-
-       health_code_update();
-
-       {
-               ssize_t ret_recv;
-
-               ret_recv = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
-               if (ret_recv != sizeof(msg)) {
-                       if (ret_recv > 0) {
-                               lttng_consumer_send_error(ctx,
-                                               LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
-                               ret_recv = -1;
-                       }
-                       return ret_recv;
-               }
-       }
-
-       health_code_update();
-
-       /* Deprecated command */
-       LTTNG_ASSERT(msg.cmd_type != LTTNG_CONSUMER_STOP);
-
-       health_code_update();
-
-       /* relayd needs RCU read-side protection */
-       rcu_read_lock();
-
-       switch (msg.cmd_type) {
-       case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
-       {
-               /* Session daemon status message are handled in the following call. */
-               consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
-                               msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
-                               &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
-                               msg.u.relayd_sock.relayd_session_id);
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_ADD_CHANNEL:
-       {
-               struct lttng_consumer_channel *new_channel;
-               int ret_send_status, ret_add_channel = 0;
-               const uint64_t chunk_id = msg.u.channel.chunk_id.value;
-
-               health_code_update();
-
-               /* First send a status message before receiving the fds. */
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto error_fatal;
-               }
-
-               health_code_update();
-
-               DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
-               new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
-                               msg.u.channel.session_id,
-                               msg.u.channel.chunk_id.is_set ?
-                                               &chunk_id : NULL,
-                               msg.u.channel.pathname,
-                               msg.u.channel.name,
-                               msg.u.channel.relayd_id, msg.u.channel.output,
-                               msg.u.channel.tracefile_size,
-                               msg.u.channel.tracefile_count, 0,
-                               msg.u.channel.monitor,
-                               msg.u.channel.live_timer_interval,
-                               msg.u.channel.is_live,
-                               NULL, NULL);
-               if (new_channel == NULL) {
-                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
-                       goto end_nosignal;
-               }
-               new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
-               switch (msg.u.channel.output) {
-               case LTTNG_EVENT_SPLICE:
-                       new_channel->output = CONSUMER_CHANNEL_SPLICE;
-                       break;
-               case LTTNG_EVENT_MMAP:
-                       new_channel->output = CONSUMER_CHANNEL_MMAP;
-                       break;
-               default:
-                       ERR("Channel output unknown %d", msg.u.channel.output);
-                       goto end_nosignal;
-               }
-
-               /* Translate and save channel type. */
-               switch (msg.u.channel.type) {
-               case CONSUMER_CHANNEL_TYPE_DATA:
-               case CONSUMER_CHANNEL_TYPE_METADATA:
-                       new_channel->type = msg.u.channel.type;
-                       break;
-               default:
-                       abort();
-                       goto end_nosignal;
-               };
-
-               health_code_update();
-
-               if (ctx->on_recv_channel != NULL) {
-                       int ret_recv_channel =
-                                       ctx->on_recv_channel(new_channel);
-                       if (ret_recv_channel == 0) {
-                               ret_add_channel = consumer_add_channel(
-                                               new_channel, ctx);
-                       } else if (ret_recv_channel < 0) {
-                               goto end_nosignal;
-                       }
-               } else {
-                       ret_add_channel =
-                                       consumer_add_channel(new_channel, ctx);
-               }
-               if (msg.u.channel.type == CONSUMER_CHANNEL_TYPE_DATA &&
-                               !ret_add_channel) {
-                       int monitor_start_ret;
-
-                       DBG("Consumer starting monitor timer");
-                       consumer_timer_live_start(new_channel,
-                                       msg.u.channel.live_timer_interval);
-                       monitor_start_ret = consumer_timer_monitor_start(
-                                       new_channel,
-                                       msg.u.channel.monitor_timer_interval);
-                       if (monitor_start_ret < 0) {
-                               ERR("Starting channel monitoring timer failed");
-                               goto end_nosignal;
-                       }
-               }
-
-               health_code_update();
-
-               /* If we received an error in add_channel, we need to report it. */
-               if (ret_add_channel < 0) {
-                       ret_send_status = consumer_send_status_msg(
-                                       sock, ret_add_channel);
-                       if (ret_send_status < 0) {
-                               goto error_fatal;
-                       }
-                       goto end_nosignal;
-               }
-
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_ADD_STREAM:
-       {
-               int fd;
-               struct lttng_pipe *stream_pipe;
-               struct lttng_consumer_stream *new_stream;
-               struct lttng_consumer_channel *channel;
-               int alloc_ret = 0;
-               int ret_send_status, ret_poll, ret_get_max_subbuf_size;
-               ssize_t ret_pipe_write, ret_recv;
-
-               /*
-                * Get stream's channel reference. Needed when adding the stream to the
-                * global hash table.
-                */
-               channel = consumer_find_channel(msg.u.stream.channel_key);
-               if (!channel) {
-                       /*
-                        * We could not find the channel. Can happen if cpu hotplug
-                        * happens while tearing down.
-                        */
-                       ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               }
-
-               health_code_update();
-
-               /* First send a status message before receiving the fds. */
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto error_add_stream_fatal;
-               }
-
-               health_code_update();
-
-               if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
-                       /* Channel was not found. */
-                       goto error_add_stream_nosignal;
-               }
-
-               /* Blocking call */
-               health_poll_entry();
-               ret_poll = lttng_consumer_poll_socket(consumer_sockpoll);
-               health_poll_exit();
-               if (ret_poll) {
-                       goto error_add_stream_fatal;
-               }
-
-               health_code_update();
-
-               /* Get stream file descriptor from socket */
-               ret_recv = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
-               if (ret_recv != sizeof(fd)) {
-                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
-                       ret_func = ret_recv;
-                       goto end;
-               }
-
-               health_code_update();
-
-               /*
-                * Send status code to session daemon only if the recv works. If the
-                * above recv() failed, the session daemon is notified through the
-                * error socket and the teardown is eventually done.
-                */
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto error_add_stream_nosignal;
-               }
-
-               health_code_update();
-
-               pthread_mutex_lock(&channel->lock);
-               new_stream = consumer_stream_create(
-                               channel,
-                               channel->key,
-                               fd,
-                               channel->name,
-                               channel->relayd_id,
-                               channel->session_id,
-                               channel->trace_chunk,
-                               msg.u.stream.cpu,
-                               &alloc_ret,
-                               channel->type,
-                               channel->monitor);
-               if (new_stream == NULL) {
-                       switch (alloc_ret) {
-                       case -ENOMEM:
-                       case -EINVAL:
-                       default:
-                               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
-                               break;
-                       }
-                       pthread_mutex_unlock(&channel->lock);
-                       goto error_add_stream_nosignal;
-               }
-
-               new_stream->wait_fd = fd;
-               ret_get_max_subbuf_size = kernctl_get_max_subbuf_size(
-                               new_stream->wait_fd, &new_stream->max_sb_size);
-               if (ret_get_max_subbuf_size < 0) {
-                       pthread_mutex_unlock(&channel->lock);
-                       ERR("Failed to get kernel maximal subbuffer size");
-                       goto error_add_stream_nosignal;
-               }
-
-               consumer_stream_update_channel_attributes(new_stream,
-                               channel);
-
-               /*
-                * We've just assigned the channel to the stream so increment the
-                * refcount right now. We don't need to increment the refcount for
-                * streams in no monitor because we handle manually the cleanup of
-                * those. It is very important to make sure there is NO prior
-                * consumer_del_stream() calls or else the refcount will be unbalanced.
-                */
-               if (channel->monitor) {
-                       uatomic_inc(&new_stream->chan->refcount);
-               }
-
-               /*
-                * The buffer flush is done on the session daemon side for the kernel
-                * so no need for the stream "hangup_flush_done" variable to be
-                * tracked. This is important for a kernel stream since we don't rely
-                * on the flush state of the stream to read data. It's not the case for
-                * user space tracing.
-                */
-               new_stream->hangup_flush_done = 0;
-
-               health_code_update();
-
-               pthread_mutex_lock(&new_stream->lock);
-               if (ctx->on_recv_stream) {
-                       int ret_recv_stream = ctx->on_recv_stream(new_stream);
-                       if (ret_recv_stream < 0) {
-                               pthread_mutex_unlock(&new_stream->lock);
-                               pthread_mutex_unlock(&channel->lock);
-                               consumer_stream_free(new_stream);
-                               goto error_add_stream_nosignal;
-                       }
-               }
-               health_code_update();
-
-               if (new_stream->metadata_flag) {
-                       channel->metadata_stream = new_stream;
-               }
-
-               /* Do not monitor this stream. */
-               if (!channel->monitor) {
-                       DBG("Kernel consumer add stream %s in no monitor mode with "
-                                       "relayd id %" PRIu64, new_stream->name,
-                                       new_stream->net_seq_idx);
-                       cds_list_add(&new_stream->send_node, &channel->streams.head);
-                       pthread_mutex_unlock(&new_stream->lock);
-                       pthread_mutex_unlock(&channel->lock);
-                       goto end_add_stream;
-               }
-
-               /* Send stream to relayd if the stream has an ID. */
-               if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
-                       int ret_send_relayd_stream;
-
-                       ret_send_relayd_stream = consumer_send_relayd_stream(
-                                       new_stream, new_stream->chan->pathname);
-                       if (ret_send_relayd_stream < 0) {
-                               pthread_mutex_unlock(&new_stream->lock);
-                               pthread_mutex_unlock(&channel->lock);
-                               consumer_stream_free(new_stream);
-                               goto error_add_stream_nosignal;
-                       }
-
-                       /*
-                        * If adding an extra stream to an already
-                        * existing channel (e.g. cpu hotplug), we need
-                        * to send the "streams_sent" command to relayd.
-                        */
-                       if (channel->streams_sent_to_relayd) {
-                               int ret_send_relayd_streams_sent;
-
-                               ret_send_relayd_streams_sent =
-                                               consumer_send_relayd_streams_sent(
-                                                               new_stream->net_seq_idx);
-                               if (ret_send_relayd_streams_sent < 0) {
-                                       pthread_mutex_unlock(&new_stream->lock);
-                                       pthread_mutex_unlock(&channel->lock);
-                                       goto error_add_stream_nosignal;
-                               }
-                       }
-               }
-               pthread_mutex_unlock(&new_stream->lock);
-               pthread_mutex_unlock(&channel->lock);
-
-               /* Get the right pipe where the stream will be sent. */
-               if (new_stream->metadata_flag) {
-                       consumer_add_metadata_stream(new_stream);
-                       stream_pipe = ctx->consumer_metadata_pipe;
-               } else {
-                       consumer_add_data_stream(new_stream);
-                       stream_pipe = ctx->consumer_data_pipe;
-               }
-
-               /* Visible to other threads */
-               new_stream->globally_visible = 1;
-
-               health_code_update();
-
-               ret_pipe_write = lttng_pipe_write(
-                               stream_pipe, &new_stream, sizeof(new_stream));
-               if (ret_pipe_write < 0) {
-                       ERR("Consumer write %s stream to pipe %d",
-                                       new_stream->metadata_flag ? "metadata" : "data",
-                                       lttng_pipe_get_writefd(stream_pipe));
-                       if (new_stream->metadata_flag) {
-                               consumer_del_stream_for_metadata(new_stream);
-                       } else {
-                               consumer_del_stream_for_data(new_stream);
-                       }
-                       goto error_add_stream_nosignal;
-               }
-
-               DBG("Kernel consumer ADD_STREAM %s (fd: %d) %s with relayd id %" PRIu64,
-                               new_stream->name, fd, new_stream->chan->pathname, new_stream->relayd_stream_id);
-end_add_stream:
-               break;
-error_add_stream_nosignal:
-               goto end_nosignal;
-error_add_stream_fatal:
-               goto error_fatal;
-       }
-       case LTTNG_CONSUMER_STREAMS_SENT:
-       {
-               struct lttng_consumer_channel *channel;
-               int ret_send_status;
-
-               /*
-                * Get stream's channel reference. Needed when adding the stream to the
-                * global hash table.
-                */
-               channel = consumer_find_channel(msg.u.sent_streams.channel_key);
-               if (!channel) {
-                       /*
-                        * We could not find the channel. Can happen if cpu hotplug
-                        * happens while tearing down.
-                        */
-                       ERR("Unable to find channel key %" PRIu64,
-                                       msg.u.sent_streams.channel_key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               }
-
-               health_code_update();
-
-               /*
-                * Send status code to session daemon.
-                */
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0 ||
-                               ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto error_streams_sent_nosignal;
-               }
-
-               health_code_update();
-
-               /*
-                * We should not send this message if we don't monitor the
-                * streams in this channel.
-                */
-               if (!channel->monitor) {
-                       goto end_error_streams_sent;
-               }
-
-               health_code_update();
-               /* Send stream to relayd if the stream has an ID. */
-               if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
-                       int ret_send_relay_streams;
-
-                       ret_send_relay_streams = consumer_send_relayd_streams_sent(
-                                       msg.u.sent_streams.net_seq_idx);
-                       if (ret_send_relay_streams < 0) {
-                               goto error_streams_sent_nosignal;
-                       }
-                       channel->streams_sent_to_relayd = true;
-               }
-end_error_streams_sent:
-               break;
-error_streams_sent_nosignal:
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_UPDATE_STREAM:
-       {
-               rcu_read_unlock();
-               return -ENOSYS;
-       }
-       case LTTNG_CONSUMER_DESTROY_RELAYD:
-       {
-               uint64_t index = msg.u.destroy_relayd.net_seq_idx;
-               struct consumer_relayd_sock_pair *relayd;
-               int ret_send_status;
-
-               DBG("Kernel consumer destroying relayd %" PRIu64, index);
-
-               /* Get relayd reference if exists. */
-               relayd = consumer_find_relayd(index);
-               if (relayd == NULL) {
-                       DBG("Unable to find relayd %" PRIu64, index);
-                       ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
-               }
-
-               /*
-                * Each relayd socket pair has a refcount of stream attached to it
-                * which tells if the relayd is still active or not depending on the
-                * refcount value.
-                *
-                * This will set the destroy flag of the relayd object and destroy it
-                * if the refcount reaches zero when called.
-                *
-                * The destroy can happen either here or when a stream fd hangs up.
-                */
-               if (relayd) {
-                       consumer_flag_relayd_for_destroy(relayd);
-               }
-
-               health_code_update();
-
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto error_fatal;
-               }
-
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_DATA_PENDING:
-       {
-               int32_t ret_data_pending;
-               uint64_t id = msg.u.data_pending.session_id;
-               ssize_t ret_send;
-
-               DBG("Kernel consumer data pending command for id %" PRIu64, id);
-
-               ret_data_pending = consumer_data_pending(id);
-
-               health_code_update();
-
-               /* Send back returned value to session daemon */
-               ret_send = lttcomm_send_unix_sock(sock, &ret_data_pending,
-                               sizeof(ret_data_pending));
-               if (ret_send < 0) {
-                       PERROR("send data pending ret code");
-                       goto error_fatal;
-               }
-
-               /*
-                * No need to send back a status message since the data pending
-                * returned value is the response.
-                */
-               break;
-       }
-       case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
-       {
-               struct lttng_consumer_channel *channel;
-               uint64_t key = msg.u.snapshot_channel.key;
-               int ret_send_status;
-
-               channel = consumer_find_channel(key);
-               if (!channel) {
-                       ERR("Channel %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               } else {
-                       pthread_mutex_lock(&channel->lock);
-                       if (msg.u.snapshot_channel.metadata == 1) {
-                               int ret_snapshot;
-
-                               ret_snapshot = lttng_kconsumer_snapshot_metadata(
-                                               channel, key,
-                                               msg.u.snapshot_channel.pathname,
-                                               msg.u.snapshot_channel.relayd_id,
-                                               ctx);
-                               if (ret_snapshot < 0) {
-                                       ERR("Snapshot metadata failed");
-                                       ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
-                               }
-                       } else {
-                               int ret_snapshot;
-
-                               ret_snapshot = lttng_kconsumer_snapshot_channel(
-                                               channel, key,
-                                               msg.u.snapshot_channel.pathname,
-                                               msg.u.snapshot_channel.relayd_id,
-                                               msg.u.snapshot_channel
-                                                               .nb_packets_per_stream,
-                                               ctx);
-                               if (ret_snapshot < 0) {
-                                       ERR("Snapshot channel failed");
-                                       ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
-                               }
-                       }
-                       pthread_mutex_unlock(&channel->lock);
-               }
-               health_code_update();
-
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
-               }
-               break;
-       }
-       case LTTNG_CONSUMER_DESTROY_CHANNEL:
-       {
-               uint64_t key = msg.u.destroy_channel.key;
-               struct lttng_consumer_channel *channel;
-               int ret_send_status;
-
-               channel = consumer_find_channel(key);
-               if (!channel) {
-                       ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               }
-
-               health_code_update();
-
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_destroy_channel;
-               }
-
-               health_code_update();
-
-               /* Stop right now if no channel was found. */
-               if (!channel) {
-                       goto end_destroy_channel;
-               }
-
-               /*
-                * This command should ONLY be issued for channel with streams set in
-                * no monitor mode.
-                */
-               LTTNG_ASSERT(!channel->monitor);
-
-               /*
-                * The refcount should ALWAYS be 0 in the case of a channel in no
-                * monitor mode.
-                */
-               LTTNG_ASSERT(!uatomic_sub_return(&channel->refcount, 1));
-
-               consumer_del_channel(channel);
-end_destroy_channel:
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_DISCARDED_EVENTS:
-       {
-               ssize_t ret;
-               uint64_t count;
-               struct lttng_consumer_channel *channel;
-               uint64_t id = msg.u.discarded_events.session_id;
-               uint64_t key = msg.u.discarded_events.channel_key;
-
-               DBG("Kernel consumer discarded events command for session id %"
-                               PRIu64 ", channel key %" PRIu64, id, key);
-
-               channel = consumer_find_channel(key);
-               if (!channel) {
-                       ERR("Kernel consumer discarded events channel %"
-                                       PRIu64 " not found", key);
-                       count = 0;
-               } else {
-                       count = channel->discarded_events;
-               }
-
-               health_code_update();
-
-               /* Send back returned value to session daemon */
-               ret = lttcomm_send_unix_sock(sock, &count, sizeof(count));
-               if (ret < 0) {
-                       PERROR("send discarded events");
-                       goto error_fatal;
-               }
-
-               break;
-       }
-       case LTTNG_CONSUMER_LOST_PACKETS:
-       {
-               ssize_t ret;
-               uint64_t count;
-               struct lttng_consumer_channel *channel;
-               uint64_t id = msg.u.lost_packets.session_id;
-               uint64_t key = msg.u.lost_packets.channel_key;
-
-               DBG("Kernel consumer lost packets command for session id %"
-                               PRIu64 ", channel key %" PRIu64, id, key);
-
-               channel = consumer_find_channel(key);
-               if (!channel) {
-                       ERR("Kernel consumer lost packets channel %"
-                                       PRIu64 " not found", key);
-                       count = 0;
-               } else {
-                       count = channel->lost_packets;
-               }
-
-               health_code_update();
-
-               /* Send back returned value to session daemon */
-               ret = lttcomm_send_unix_sock(sock, &count, sizeof(count));
-               if (ret < 0) {
-                       PERROR("send lost packets");
-                       goto error_fatal;
-               }
-
-               break;
-       }
-       case LTTNG_CONSUMER_SET_CHANNEL_MONITOR_PIPE:
-       {
-               int channel_monitor_pipe;
-               int ret_send_status, ret_set_channel_monitor_pipe;
-               ssize_t ret_recv;
-
-               ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-               /* Successfully received the command's type. */
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       goto error_fatal;
-               }
-
-               ret_recv = lttcomm_recv_fds_unix_sock(
-                               sock, &channel_monitor_pipe, 1);
-               if (ret_recv != sizeof(channel_monitor_pipe)) {
-                       ERR("Failed to receive channel monitor pipe");
-                       goto error_fatal;
-               }
-
-               DBG("Received channel monitor pipe (%d)", channel_monitor_pipe);
-               ret_set_channel_monitor_pipe =
-                               consumer_timer_thread_set_channel_monitor_pipe(
-                                               channel_monitor_pipe);
-               if (!ret_set_channel_monitor_pipe) {
-                       int flags;
-                       int ret_fcntl;
-
-                       ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-                       /* Set the pipe as non-blocking. */
-                       ret_fcntl = fcntl(channel_monitor_pipe, F_GETFL, 0);
-                       if (ret_fcntl == -1) {
-                               PERROR("fcntl get flags of the channel monitoring pipe");
-                               goto error_fatal;
-                       }
-                       flags = ret_fcntl;
-
-                       ret_fcntl = fcntl(channel_monitor_pipe, F_SETFL,
-                                       flags | O_NONBLOCK);
-                       if (ret_fcntl == -1) {
-                               PERROR("fcntl set O_NONBLOCK flag of the channel monitoring pipe");
-                               goto error_fatal;
-                       }
-                       DBG("Channel monitor pipe set as non-blocking");
-               } else {
-                       ret_code = LTTCOMM_CONSUMERD_ALREADY_SET;
-               }
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       goto error_fatal;
-               }
-               break;
-       }
-       case LTTNG_CONSUMER_ROTATE_CHANNEL:
-       {
-               struct lttng_consumer_channel *channel;
-               uint64_t key = msg.u.rotate_channel.key;
-               int ret_send_status;
-
-               DBG("Consumer rotate channel %" PRIu64, key);
-
-               channel = consumer_find_channel(key);
-               if (!channel) {
-                       ERR("Channel %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               } else {
-                       /*
-                        * Sample the rotate position of all the streams in this channel.
-                        */
-                       int ret_rotate_channel;
-
-                       ret_rotate_channel = lttng_consumer_rotate_channel(
-                                       channel, key,
-                                       msg.u.rotate_channel.relayd_id,
-                                       msg.u.rotate_channel.metadata, ctx);
-                       if (ret_rotate_channel < 0) {
-                               ERR("Rotate channel failed");
-                               ret_code = LTTCOMM_CONSUMERD_ROTATION_FAIL;
-                       }
-
-                       health_code_update();
-               }
-
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto error_rotate_channel;
-               }
-               if (channel) {
-                       /* Rotate the streams that are ready right now. */
-                       int ret_rotate;
-
-                       ret_rotate = lttng_consumer_rotate_ready_streams(
-                                       channel, key, ctx);
-                       if (ret_rotate < 0) {
-                               ERR("Rotate ready streams failed");
-                       }
-               }
-               break;
-error_rotate_channel:
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_CLEAR_CHANNEL:
-       {
-               struct lttng_consumer_channel *channel;
-               uint64_t key = msg.u.clear_channel.key;
-               int ret_send_status;
-
-               channel = consumer_find_channel(key);
-               if (!channel) {
-                       DBG("Channel %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               } else {
-                       int ret_clear_channel;
-
-                       ret_clear_channel =
-                                       lttng_consumer_clear_channel(channel);
-                       if (ret_clear_channel) {
-                               ERR("Clear channel failed");
-                               ret_code = ret_clear_channel;
-                       }
-
-                       health_code_update();
-               }
-
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
-               }
-
-               break;
-       }
-       case LTTNG_CONSUMER_INIT:
-       {
-               int ret_send_status;
-
-               ret_code = lttng_consumer_init_command(ctx,
-                               msg.u.init.sessiond_uuid);
-               health_code_update();
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
-               }
-               break;
-       }
-       case LTTNG_CONSUMER_CREATE_TRACE_CHUNK:
-       {
-               const struct lttng_credentials credentials = {
-                       .uid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.create_trace_chunk.credentials.value.uid),
-                       .gid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.create_trace_chunk.credentials.value.gid),
-               };
-               const bool is_local_trace =
-                               !msg.u.create_trace_chunk.relayd_id.is_set;
-               const uint64_t relayd_id =
-                               msg.u.create_trace_chunk.relayd_id.value;
-               const char *chunk_override_name =
-                               *msg.u.create_trace_chunk.override_name ?
-                                       msg.u.create_trace_chunk.override_name :
-                                       NULL;
-               struct lttng_directory_handle *chunk_directory_handle = NULL;
-
-               /*
-                * The session daemon will only provide a chunk directory file
-                * descriptor for local traces.
-                */
-               if (is_local_trace) {
-                       int chunk_dirfd;
-                       int ret_send_status;
-                       ssize_t ret_recv;
-
-                       /* Acnowledge the reception of the command. */
-                       ret_send_status = consumer_send_status_msg(
-                                       sock, LTTCOMM_CONSUMERD_SUCCESS);
-                       if (ret_send_status < 0) {
-                               /* Somehow, the session daemon is not responding anymore. */
-                               goto end_nosignal;
-                       }
-
-                       ret_recv = lttcomm_recv_fds_unix_sock(
-                                       sock, &chunk_dirfd, 1);
-                       if (ret_recv != sizeof(chunk_dirfd)) {
-                               ERR("Failed to receive trace chunk directory file descriptor");
-                               goto error_fatal;
-                       }
-
-                       DBG("Received trace chunk directory fd (%d)",
-                                       chunk_dirfd);
-                       chunk_directory_handle = lttng_directory_handle_create_from_dirfd(
-                                       chunk_dirfd);
-                       if (!chunk_directory_handle) {
-                               ERR("Failed to initialize chunk directory handle from directory file descriptor");
-                               if (close(chunk_dirfd)) {
-                                       PERROR("Failed to close chunk directory file descriptor");
-                               }
-                               goto error_fatal;
-                       }
-               }
-
-               ret_code = lttng_consumer_create_trace_chunk(
-                               !is_local_trace ? &relayd_id : NULL,
-                               msg.u.create_trace_chunk.session_id,
-                               msg.u.create_trace_chunk.chunk_id,
-                               (time_t) msg.u.create_trace_chunk
-                                               .creation_timestamp,
-                               chunk_override_name,
-                               msg.u.create_trace_chunk.credentials.is_set ?
-                                               &credentials :
-                                               NULL,
-                               chunk_directory_handle);
-               lttng_directory_handle_put(chunk_directory_handle);
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_CLOSE_TRACE_CHUNK:
-       {
-               enum lttng_trace_chunk_command_type close_command =
-                               msg.u.close_trace_chunk.close_command.value;
-               const uint64_t relayd_id =
-                               msg.u.close_trace_chunk.relayd_id.value;
-               struct lttcomm_consumer_close_trace_chunk_reply reply;
-               char path[LTTNG_PATH_MAX];
-               ssize_t ret_send;
-
-               ret_code = lttng_consumer_close_trace_chunk(
-                               msg.u.close_trace_chunk.relayd_id.is_set ?
-                                               &relayd_id :
-                                               NULL,
-                               msg.u.close_trace_chunk.session_id,
-                               msg.u.close_trace_chunk.chunk_id,
-                               (time_t) msg.u.close_trace_chunk.close_timestamp,
-                               msg.u.close_trace_chunk.close_command.is_set ?
-                                               &close_command :
-                                               NULL, path);
-               reply.ret_code = ret_code;
-               reply.path_length = strlen(path) + 1;
-               ret_send = lttcomm_send_unix_sock(sock, &reply, sizeof(reply));
-               if (ret_send != sizeof(reply)) {
-                       goto error_fatal;
-               }
-               ret_send = lttcomm_send_unix_sock(
-                               sock, path, reply.path_length);
-               if (ret_send != reply.path_length) {
-                       goto error_fatal;
-               }
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_TRACE_CHUNK_EXISTS:
-       {
-               const uint64_t relayd_id =
-                               msg.u.trace_chunk_exists.relayd_id.value;
-
-               ret_code = lttng_consumer_trace_chunk_exists(
-                               msg.u.trace_chunk_exists.relayd_id.is_set ?
-                                               &relayd_id : NULL,
-                               msg.u.trace_chunk_exists.session_id,
-                               msg.u.trace_chunk_exists.chunk_id);
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_OPEN_CHANNEL_PACKETS:
-       {
-               const uint64_t key = msg.u.open_channel_packets.key;
-               struct lttng_consumer_channel *channel =
-                               consumer_find_channel(key);
-
-               if (channel) {
-                       pthread_mutex_lock(&channel->lock);
-                       ret_code = lttng_consumer_open_channel_packets(channel);
-                       pthread_mutex_unlock(&channel->lock);
-               } else {
-                       WARN("Channel %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               }
-
-               health_code_update();
-               goto end_msg_sessiond;
-       }
-       default:
-               goto end_nosignal;
-       }
-
-end_nosignal:
-       /*
-        * Return 1 to indicate success since the 0 value can be a socket
-        * shutdown during the recv() or send() call.
-        */
-       ret_func = 1;
-       goto end;
-error_fatal:
-       /* This will issue a consumer stop. */
-       ret_func = -1;
-       goto end;
-end_msg_sessiond:
-       /*
-        * The returned value here is not useful since either way we'll return 1 to
-        * the caller because the session daemon socket management is done
-        * elsewhere. Returning a negative code or 0 will shutdown the consumer.
-        */
-       {
-               int ret_send_status;
-
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       goto error_fatal;
-               }
-       }
-
-       ret_func = 1;
-
-end:
-       health_code_update();
-       rcu_read_unlock();
-       return ret_func;
-}
-
-/*
- * Sync metadata meaning request them to the session daemon and snapshot to the
- * metadata thread can consumer them.
- *
- * Metadata stream lock MUST be acquired.
- */
-enum sync_metadata_status lttng_kconsumer_sync_metadata(
-               struct lttng_consumer_stream *metadata)
-{
-       int ret;
-       enum sync_metadata_status status;
-
-       LTTNG_ASSERT(metadata);
-
-       ret = kernctl_buffer_flush(metadata->wait_fd);
-       if (ret < 0) {
-               ERR("Failed to flush kernel stream");
-               status = SYNC_METADATA_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = kernctl_snapshot(metadata->wait_fd);
-       if (ret < 0) {
-               if (errno == EAGAIN) {
-                       /* No new metadata, exit. */
-                       DBG("Sync metadata, no new kernel metadata");
-                       status = SYNC_METADATA_STATUS_NO_DATA;
-               } else {
-                       ERR("Sync metadata, taking kernel snapshot failed.");
-                       status = SYNC_METADATA_STATUS_ERROR;
-               }
-       } else {
-               status = SYNC_METADATA_STATUS_NEW_DATA;
-       }
-
-end:
-       return status;
-}
-
-static
-int extract_common_subbuffer_info(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuf)
-{
-       int ret;
-
-       ret = kernctl_get_subbuf_size(
-                       stream->wait_fd, &subbuf->info.data.subbuf_size);
-       if (ret) {
-               goto end;
-       }
-
-       ret = kernctl_get_padded_subbuf_size(
-                       stream->wait_fd, &subbuf->info.data.padded_subbuf_size);
-       if (ret) {
-               goto end;
-       }
-
-end:
-       return ret;
-}
-
-static
-int extract_metadata_subbuffer_info(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuf)
-{
-       int ret;
-
-       ret = extract_common_subbuffer_info(stream, subbuf);
-       if (ret) {
-               goto end;
-       }
-
-       ret = kernctl_get_metadata_version(
-                       stream->wait_fd, &subbuf->info.metadata.version);
-       if (ret) {
-               goto end;
-       }
-
-end:
-       return ret;
-}
-
-static
-int extract_data_subbuffer_info(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuf)
-{
-       int ret;
-
-       ret = extract_common_subbuffer_info(stream, subbuf);
-       if (ret) {
-               goto end;
-       }
-
-       ret = kernctl_get_packet_size(
-                       stream->wait_fd, &subbuf->info.data.packet_size);
-       if (ret < 0) {
-               PERROR("Failed to get sub-buffer packet size");
-               goto end;
-       }
-
-       ret = kernctl_get_content_size(
-                       stream->wait_fd, &subbuf->info.data.content_size);
-       if (ret < 0) {
-               PERROR("Failed to get sub-buffer content size");
-               goto end;
-       }
-
-       ret = kernctl_get_timestamp_begin(
-                       stream->wait_fd, &subbuf->info.data.timestamp_begin);
-       if (ret < 0) {
-               PERROR("Failed to get sub-buffer begin timestamp");
-               goto end;
-       }
-
-       ret = kernctl_get_timestamp_end(
-                       stream->wait_fd, &subbuf->info.data.timestamp_end);
-       if (ret < 0) {
-               PERROR("Failed to get sub-buffer end timestamp");
-               goto end;
-       }
-
-       ret = kernctl_get_events_discarded(
-                       stream->wait_fd, &subbuf->info.data.events_discarded);
-       if (ret) {
-               PERROR("Failed to get sub-buffer events discarded count");
-               goto end;
-       }
-
-       ret = kernctl_get_sequence_number(stream->wait_fd,
-                       &subbuf->info.data.sequence_number.value);
-       if (ret) {
-               /* May not be supported by older LTTng-modules. */
-               if (ret != -ENOTTY) {
-                       PERROR("Failed to get sub-buffer sequence number");
-                       goto end;
-               }
-       } else {
-               subbuf->info.data.sequence_number.is_set = true;
-       }
-
-       ret = kernctl_get_stream_id(
-                       stream->wait_fd, &subbuf->info.data.stream_id);
-       if (ret < 0) {
-               PERROR("Failed to get stream id");
-               goto end;
-       }
-
-       ret = kernctl_get_instance_id(stream->wait_fd,
-                       &subbuf->info.data.stream_instance_id.value);
-       if (ret) {
-               /* May not be supported by older LTTng-modules. */
-               if (ret != -ENOTTY) {
-                       PERROR("Failed to get stream instance id");
-                       goto end;
-               }
-       } else {
-               subbuf->info.data.stream_instance_id.is_set = true;
-       }
-end:
-       return ret;
-}
-
-static
-enum get_next_subbuffer_status get_subbuffer_common(
-               struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuffer)
-{
-       int ret;
-       enum get_next_subbuffer_status status;
-
-       ret = kernctl_get_next_subbuf(stream->wait_fd);
-       switch (ret) {
-       case 0:
-               status = GET_NEXT_SUBBUFFER_STATUS_OK;
-               break;
-       case -ENODATA:
-               case -EAGAIN:
-               /*
-                * The caller only expects -ENODATA when there is no data to
-                * read, but the kernel tracer returns -EAGAIN when there is
-                * currently no data for a non-finalized stream, and -ENODATA
-                * when there is no data for a finalized stream. Those can be
-                * combined into a -ENODATA return value.
-                */
-               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
-               goto end;
-       default:
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = stream->read_subbuffer_ops.extract_subbuffer_info(
-               stream, subbuffer);
-       if (ret) {
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-       }
-end:
-       return status;
-}
-
-static
-enum get_next_subbuffer_status get_next_subbuffer_splice(
-               struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuffer)
-{
-       const enum get_next_subbuffer_status status =
-                       get_subbuffer_common(stream, subbuffer);
-
-       if (status != GET_NEXT_SUBBUFFER_STATUS_OK) {
-               goto end;
-       }
-
-       subbuffer->buffer.fd = stream->wait_fd;
-end:
-       return status;
-}
-
-static
-enum get_next_subbuffer_status get_next_subbuffer_mmap(
-               struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuffer)
-{
-       int ret;
-       enum get_next_subbuffer_status status;
-       const char *addr;
-
-       status = get_subbuffer_common(stream, subbuffer);
-       if (status != GET_NEXT_SUBBUFFER_STATUS_OK) {
-               goto end;
-       }
-
-       ret = get_current_subbuf_addr(stream, &addr);
-       if (ret) {
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-               goto end;
-       }
-
-       subbuffer->buffer.buffer = lttng_buffer_view_init(
-                       addr, 0, subbuffer->info.data.padded_subbuf_size);
-end:
-       return status;
-}
-
-static
-enum get_next_subbuffer_status get_next_subbuffer_metadata_check(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuffer)
-{
-       int ret;
-       const char *addr;
-       bool coherent;
-       enum get_next_subbuffer_status status;
-
-       ret = kernctl_get_next_subbuf_metadata_check(stream->wait_fd,
-                       &coherent);
-       if (ret) {
-               goto end;
-       }
-
-       ret = stream->read_subbuffer_ops.extract_subbuffer_info(
-                       stream, subbuffer);
-       if (ret) {
-               goto end;
-       }
-
-       LTTNG_OPTIONAL_SET(&subbuffer->info.metadata.coherent, coherent);
-
-       ret = get_current_subbuf_addr(stream, &addr);
-       if (ret) {
-               goto end;
-       }
-
-       subbuffer->buffer.buffer = lttng_buffer_view_init(
-                       addr, 0, subbuffer->info.data.padded_subbuf_size);
-       DBG("Got metadata packet with padded_subbuf_size = %lu, coherent = %s",
-                       subbuffer->info.metadata.padded_subbuf_size,
-                       coherent ? "true" : "false");
-end:
-       /*
-        * The caller only expects -ENODATA when there is no data to read, but
-        * the kernel tracer returns -EAGAIN when there is currently no data
-        * for a non-finalized stream, and -ENODATA when there is no data for a
-        * finalized stream. Those can be combined into a -ENODATA return value.
-        */
-       switch (ret) {
-       case 0:
-               status = GET_NEXT_SUBBUFFER_STATUS_OK;
-               break;
-       case -ENODATA:
-       case -EAGAIN:
-               /*
-                * The caller only expects -ENODATA when there is no data to
-                * read, but the kernel tracer returns -EAGAIN when there is
-                * currently no data for a non-finalized stream, and -ENODATA
-                * when there is no data for a finalized stream. Those can be
-                * combined into a -ENODATA return value.
-                */
-               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
-               break;
-       default:
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-               break;
-       }
-
-       return status;
-}
-
-static
-int put_next_subbuffer(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuffer)
-{
-       const int ret = kernctl_put_next_subbuf(stream->wait_fd);
-
-       if (ret) {
-               if (ret == -EFAULT) {
-                       PERROR("Error in unreserving sub buffer");
-               } else if (ret == -EIO) {
-                       /* Should never happen with newer LTTng versions */
-                       PERROR("Reader has been pushed by the writer, last sub-buffer corrupted");
-               }
-       }
-
-       return ret;
-}
-
-static
-bool is_get_next_check_metadata_available(int tracer_fd)
-{
-       const int ret = kernctl_get_next_subbuf_metadata_check(tracer_fd, NULL);
-       const bool available = ret != -ENOTTY;
-
-       if (ret == 0) {
-               /* get succeeded, make sure to put the subbuffer. */
-               kernctl_put_subbuf(tracer_fd);
-       }
-
-       return available;
-}
-
-static
-int signal_metadata(struct lttng_consumer_stream *stream,
-               struct lttng_consumer_local_data *ctx)
-{
-       ASSERT_LOCKED(stream->metadata_rdv_lock);
-       return pthread_cond_broadcast(&stream->metadata_rdv) ? -errno : 0;
-}
-
-static
-int lttng_kconsumer_set_stream_ops(
-               struct lttng_consumer_stream *stream)
-{
-       int ret = 0;
-
-       if (stream->metadata_flag && stream->chan->is_live) {
-               DBG("Attempting to enable metadata bucketization for live consumers");
-               if (is_get_next_check_metadata_available(stream->wait_fd)) {
-                       DBG("Kernel tracer supports get_next_subbuffer_metadata_check, metadata will be accumulated until a coherent state is reached");
-                       stream->read_subbuffer_ops.get_next_subbuffer =
-                                       get_next_subbuffer_metadata_check;
-                       ret = consumer_stream_enable_metadata_bucketization(
-                                       stream);
-                       if (ret) {
-                               goto end;
-                       }
-               } else {
-                       /*
-                        * The kernel tracer version is too old to indicate
-                        * when the metadata stream has reached a "coherent"
-                        * (parseable) point.
-                        *
-                        * This means that a live viewer may see an incoherent
-                        * sequence of metadata and fail to parse it.
-                        */
-                       WARN("Kernel tracer does not support get_next_subbuffer_metadata_check which may cause live clients to fail to parse the metadata stream");
-                       metadata_bucket_destroy(stream->metadata_bucket);
-                       stream->metadata_bucket = NULL;
-               }
-
-               stream->read_subbuffer_ops.on_sleep = signal_metadata;
-       }
-
-       if (!stream->read_subbuffer_ops.get_next_subbuffer) {
-               if (stream->chan->output == CONSUMER_CHANNEL_MMAP) {
-                       stream->read_subbuffer_ops.get_next_subbuffer =
-                                       get_next_subbuffer_mmap;
-               } else {
-                       stream->read_subbuffer_ops.get_next_subbuffer =
-                                       get_next_subbuffer_splice;
-               }
-       }
-
-       if (stream->metadata_flag) {
-               stream->read_subbuffer_ops.extract_subbuffer_info =
-                               extract_metadata_subbuffer_info;
-       } else {
-               stream->read_subbuffer_ops.extract_subbuffer_info =
-                               extract_data_subbuffer_info;
-               if (stream->chan->is_live) {
-                       stream->read_subbuffer_ops.send_live_beacon =
-                                       consumer_flush_kernel_index;
-               }
-       }
-
-       stream->read_subbuffer_ops.put_next_subbuffer = put_next_subbuffer;
-end:
-       return ret;
-}
-
-int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       LTTNG_ASSERT(stream);
-
-       /*
-        * Don't create anything if this is set for streaming or if there is
-        * no current trace chunk on the parent channel.
-        */
-       if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor &&
-                       stream->chan->trace_chunk) {
-               ret = consumer_stream_create_output_files(stream, true);
-               if (ret) {
-                       goto error;
-               }
-       }
-
-       if (stream->output == LTTNG_EVENT_MMAP) {
-               /* get the len of the mmap region */
-               unsigned long mmap_len;
-
-               ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
-               if (ret != 0) {
-                       PERROR("kernctl_get_mmap_len");
-                       goto error_close_fd;
-               }
-               stream->mmap_len = (size_t) mmap_len;
-
-               stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
-                               MAP_PRIVATE, stream->wait_fd, 0);
-               if (stream->mmap_base == MAP_FAILED) {
-                       PERROR("Error mmaping");
-                       ret = -1;
-                       goto error_close_fd;
-               }
-       }
-
-       ret = lttng_kconsumer_set_stream_ops(stream);
-       if (ret) {
-               goto error_close_fd;
-       }
-
-       /* we return 0 to let the library handle the FD internally */
-       return 0;
-
-error_close_fd:
-       if (stream->out_fd >= 0) {
-               int err;
-
-               err = close(stream->out_fd);
-               LTTNG_ASSERT(!err);
-               stream->out_fd = -1;
-       }
-error:
-       return ret;
-}
-
-/*
- * Check if data is still being extracted from the buffers for a specific
- * stream. Consumer data lock MUST be acquired before calling this function
- * and the stream lock.
- *
- * Return 1 if the traced data are still getting read else 0 meaning that the
- * data is available for trace viewer reading.
- */
-int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       LTTNG_ASSERT(stream);
-
-       if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
-               ret = 0;
-               goto end;
-       }
-
-       ret = kernctl_get_next_subbuf(stream->wait_fd);
-       if (ret == 0) {
-               /* There is still data so let's put back this subbuffer. */
-               ret = kernctl_put_subbuf(stream->wait_fd);
-               LTTNG_ASSERT(ret == 0);
-               ret = 1;   /* Data is pending */
-               goto end;
-       }
-
-       /* Data is NOT pending and ready to be read. */
-       ret = 0;
-
-end:
-       return ret;
-}
diff --git a/src/common/kernel-consumer/kernel-consumer.cpp b/src/common/kernel-consumer/kernel-consumer.cpp
new file mode 100644 (file)
index 0000000..aa44302
--- /dev/null
@@ -0,0 +1,1920 @@
+/*
+ * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#define _LGPL_SOURCE
+#include <poll.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <inttypes.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <stdint.h>
+
+#include <bin/lttng-consumerd/health-consumerd.h>
+#include <common/common.h>
+#include <common/kernel-ctl/kernel-ctl.h>
+#include <common/sessiond-comm/sessiond-comm.h>
+#include <common/sessiond-comm/relayd.h>
+#include <common/compat/fcntl.h>
+#include <common/compat/endian.h>
+#include <common/pipe.h>
+#include <common/relayd/relayd.h>
+#include <common/utils.h>
+#include <common/consumer/consumer-stream.h>
+#include <common/index/index.h>
+#include <common/consumer/consumer-timer.h>
+#include <common/optional.h>
+#include <common/buffer-view.h>
+#include <common/consumer/consumer.h>
+#include <common/consumer/metadata-bucket.h>
+
+#include "kernel-consumer.h"
+
+extern struct lttng_consumer_global_data the_consumer_data;
+extern int consumer_poll_timeout;
+
+/*
+ * Take a snapshot for a specific fd
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
+{
+       int ret = 0;
+       int infd = stream->wait_fd;
+
+       ret = kernctl_snapshot(infd);
+       /*
+        * -EAGAIN is not an error, it just means that there is no data to
+        *  be read.
+        */
+       if (ret != 0 && ret != -EAGAIN) {
+               PERROR("Getting sub-buffer snapshot.");
+       }
+
+       return ret;
+}
+
+/*
+ * Sample consumed and produced positions for a specific fd.
+ *
+ * Returns 0 on success, < 0 on error.
+ */
+int lttng_kconsumer_sample_snapshot_positions(
+               struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+
+       return kernctl_snapshot_sample_positions(stream->wait_fd);
+}
+
+/*
+ * Get the produced position
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
+               unsigned long *pos)
+{
+       int ret;
+       int infd = stream->wait_fd;
+
+       ret = kernctl_snapshot_get_produced(infd, pos);
+       if (ret != 0) {
+               PERROR("kernctl_snapshot_get_produced");
+       }
+
+       return ret;
+}
+
+/*
+ * Get the consumerd position
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
+               unsigned long *pos)
+{
+       int ret;
+       int infd = stream->wait_fd;
+
+       ret = kernctl_snapshot_get_consumed(infd, pos);
+       if (ret != 0) {
+               PERROR("kernctl_snapshot_get_consumed");
+       }
+
+       return ret;
+}
+
+static
+int get_current_subbuf_addr(struct lttng_consumer_stream *stream,
+               const char **addr)
+{
+       int ret;
+       unsigned long mmap_offset;
+       const char *mmap_base = (const char *) stream->mmap_base;
+
+       ret = kernctl_get_mmap_read_offset(stream->wait_fd, &mmap_offset);
+       if (ret < 0) {
+               PERROR("Failed to get mmap read offset");
+               goto error;
+       }
+
+       *addr = mmap_base + mmap_offset;
+error:
+       return ret;
+}
+
+/*
+ * Take a snapshot of all the stream of a channel
+ * RCU read-side lock must be held across this function to ensure existence of
+ * channel. The channel lock must be held by the caller.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+static int lttng_kconsumer_snapshot_channel(
+               struct lttng_consumer_channel *channel,
+               uint64_t key, char *path, uint64_t relayd_id,
+               uint64_t nb_packets_per_stream,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+       struct lttng_consumer_stream *stream;
+
+       DBG("Kernel consumer snapshot channel %" PRIu64, key);
+
+       rcu_read_lock();
+
+       /* Splice is not supported yet for channel snapshot. */
+       if (channel->output != CONSUMER_CHANNEL_MMAP) {
+               ERR("Unsupported output type for channel \"%s\": mmap output is required to record a snapshot",
+                               channel->name);
+               ret = -1;
+               goto end;
+       }
+
+       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+               unsigned long consumed_pos, produced_pos;
+
+               health_code_update();
+
+               /*
+                * Lock stream because we are about to change its state.
+                */
+               pthread_mutex_lock(&stream->lock);
+
+               LTTNG_ASSERT(channel->trace_chunk);
+               if (!lttng_trace_chunk_get(channel->trace_chunk)) {
+                       /*
+                        * Can't happen barring an internal error as the channel
+                        * holds a reference to the trace chunk.
+                        */
+                       ERR("Failed to acquire reference to channel's trace chunk");
+                       ret = -1;
+                       goto end_unlock;
+               }
+               LTTNG_ASSERT(!stream->trace_chunk);
+               stream->trace_chunk = channel->trace_chunk;
+
+               /*
+                * Assign the received relayd ID so we can use it for streaming. The streams
+                * are not visible to anyone so this is OK to change it.
+                */
+               stream->net_seq_idx = relayd_id;
+               channel->relayd_id = relayd_id;
+               if (relayd_id != (uint64_t) -1ULL) {
+                       ret = consumer_send_relayd_stream(stream, path);
+                       if (ret < 0) {
+                               ERR("sending stream to relayd");
+                               goto end_unlock;
+                       }
+               } else {
+                       ret = consumer_stream_create_output_files(stream,
+                                       false);
+                       if (ret < 0) {
+                               goto end_unlock;
+                       }
+                       DBG("Kernel consumer snapshot stream (%" PRIu64 ")",
+                                       stream->key);
+               }
+
+               ret = kernctl_buffer_flush_empty(stream->wait_fd);
+               if (ret < 0) {
+                       /*
+                        * Doing a buffer flush which does not take into
+                        * account empty packets. This is not perfect
+                        * for stream intersection, but required as a
+                        * fall-back when "flush_empty" is not
+                        * implemented by lttng-modules.
+                        */
+                       ret = kernctl_buffer_flush(stream->wait_fd);
+                       if (ret < 0) {
+                               ERR("Failed to flush kernel stream");
+                               goto end_unlock;
+                       }
+                       goto end_unlock;
+               }
+
+               ret = lttng_kconsumer_take_snapshot(stream);
+               if (ret < 0) {
+                       ERR("Taking kernel snapshot");
+                       goto end_unlock;
+               }
+
+               ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
+               if (ret < 0) {
+                       ERR("Produced kernel snapshot position");
+                       goto end_unlock;
+               }
+
+               ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
+               if (ret < 0) {
+                       ERR("Consumerd kernel snapshot position");
+                       goto end_unlock;
+               }
+
+               consumed_pos = consumer_get_consume_start_pos(consumed_pos,
+                               produced_pos, nb_packets_per_stream,
+                               stream->max_sb_size);
+
+               while ((long) (consumed_pos - produced_pos) < 0) {
+                       ssize_t read_len;
+                       unsigned long len, padded_len;
+                       const char *subbuf_addr;
+                       struct lttng_buffer_view subbuf_view;
+
+                       health_code_update();
+                       DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
+
+                       ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
+                       if (ret < 0) {
+                               if (ret != -EAGAIN) {
+                                       PERROR("kernctl_get_subbuf snapshot");
+                                       goto end_unlock;
+                               }
+                               DBG("Kernel consumer get subbuf failed. Skipping it.");
+                               consumed_pos += stream->max_sb_size;
+                               stream->chan->lost_packets++;
+                               continue;
+                       }
+
+                       ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
+                       if (ret < 0) {
+                               ERR("Snapshot kernctl_get_subbuf_size");
+                               goto error_put_subbuf;
+                       }
+
+                       ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
+                       if (ret < 0) {
+                               ERR("Snapshot kernctl_get_padded_subbuf_size");
+                               goto error_put_subbuf;
+                       }
+
+                       ret = get_current_subbuf_addr(stream, &subbuf_addr);
+                       if (ret) {
+                               goto error_put_subbuf;
+                       }
+
+                       subbuf_view = lttng_buffer_view_init(
+                                       subbuf_addr, 0, padded_len);
+                       read_len = lttng_consumer_on_read_subbuffer_mmap(
+                                       stream, &subbuf_view,
+                                       padded_len - len);
+                       /*
+                        * We write the padded len in local tracefiles but the data len
+                        * when using a relay. Display the error but continue processing
+                        * to try to release the subbuffer.
+                        */
+                       if (relayd_id != (uint64_t) -1ULL) {
+                               if (read_len != len) {
+                                       ERR("Error sending to the relay (ret: %zd != len: %lu)",
+                                                       read_len, len);
+                               }
+                       } else {
+                               if (read_len != padded_len) {
+                                       ERR("Error writing to tracefile (ret: %zd != len: %lu)",
+                                                       read_len, padded_len);
+                               }
+                       }
+
+                       ret = kernctl_put_subbuf(stream->wait_fd);
+                       if (ret < 0) {
+                               ERR("Snapshot kernctl_put_subbuf");
+                               goto end_unlock;
+                       }
+                       consumed_pos += stream->max_sb_size;
+               }
+
+               if (relayd_id == (uint64_t) -1ULL) {
+                       if (stream->out_fd >= 0) {
+                               ret = close(stream->out_fd);
+                               if (ret < 0) {
+                                       PERROR("Kernel consumer snapshot close out_fd");
+                                       goto end_unlock;
+                               }
+                               stream->out_fd = -1;
+                       }
+               } else {
+                       close_relayd_stream(stream);
+                       stream->net_seq_idx = (uint64_t) -1ULL;
+               }
+               lttng_trace_chunk_put(stream->trace_chunk);
+               stream->trace_chunk = NULL;
+               pthread_mutex_unlock(&stream->lock);
+       }
+
+       /* All good! */
+       ret = 0;
+       goto end;
+
+error_put_subbuf:
+       ret = kernctl_put_subbuf(stream->wait_fd);
+       if (ret < 0) {
+               ERR("Snapshot kernctl_put_subbuf error path");
+       }
+end_unlock:
+       pthread_mutex_unlock(&stream->lock);
+end:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Read the whole metadata available for a snapshot.
+ * RCU read-side lock must be held across this function to ensure existence of
+ * metadata_channel. The channel lock must be held by the caller.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+static int lttng_kconsumer_snapshot_metadata(
+               struct lttng_consumer_channel *metadata_channel,
+               uint64_t key, char *path, uint64_t relayd_id,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret, use_relayd = 0;
+       ssize_t ret_read;
+       struct lttng_consumer_stream *metadata_stream;
+
+       LTTNG_ASSERT(ctx);
+
+       DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
+                       key, path);
+
+       rcu_read_lock();
+
+       metadata_stream = metadata_channel->metadata_stream;
+       LTTNG_ASSERT(metadata_stream);
+
+       pthread_mutex_lock(&metadata_stream->lock);
+       LTTNG_ASSERT(metadata_channel->trace_chunk);
+       LTTNG_ASSERT(metadata_stream->trace_chunk);
+
+       /* Flag once that we have a valid relayd for the stream. */
+       if (relayd_id != (uint64_t) -1ULL) {
+               use_relayd = 1;
+       }
+
+       if (use_relayd) {
+               ret = consumer_send_relayd_stream(metadata_stream, path);
+               if (ret < 0) {
+                       goto error_snapshot;
+               }
+       } else {
+               ret = consumer_stream_create_output_files(metadata_stream,
+                               false);
+               if (ret < 0) {
+                       goto error_snapshot;
+               }
+       }
+
+       do {
+               health_code_update();
+
+               ret_read = lttng_consumer_read_subbuffer(metadata_stream, ctx, true);
+               if (ret_read < 0) {
+                       ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
+                                       ret_read);
+                       ret = ret_read;
+                       goto error_snapshot;
+               }
+       } while (ret_read > 0);
+
+       if (use_relayd) {
+               close_relayd_stream(metadata_stream);
+               metadata_stream->net_seq_idx = (uint64_t) -1ULL;
+       } else {
+               if (metadata_stream->out_fd >= 0) {
+                       ret = close(metadata_stream->out_fd);
+                       if (ret < 0) {
+                               PERROR("Kernel consumer snapshot metadata close out_fd");
+                               /*
+                                * Don't go on error here since the snapshot was successful at this
+                                * point but somehow the close failed.
+                                */
+                       }
+                       metadata_stream->out_fd = -1;
+                       lttng_trace_chunk_put(metadata_stream->trace_chunk);
+                       metadata_stream->trace_chunk = NULL;
+               }
+       }
+
+       ret = 0;
+error_snapshot:
+       pthread_mutex_unlock(&metadata_stream->lock);
+       cds_list_del(&metadata_stream->send_node);
+       consumer_stream_destroy(metadata_stream, NULL);
+       metadata_channel->metadata_stream = NULL;
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Receive command from session daemon and process it.
+ *
+ * Return 1 on success else a negative value or 0.
+ */
+int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
+               int sock, struct pollfd *consumer_sockpoll)
+{
+       int ret_func;
+       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       struct lttcomm_consumer_msg msg;
+
+       health_code_update();
+
+       {
+               ssize_t ret_recv;
+
+               ret_recv = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
+               if (ret_recv != sizeof(msg)) {
+                       if (ret_recv > 0) {
+                               lttng_consumer_send_error(ctx,
+                                               LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
+                               ret_recv = -1;
+                       }
+                       return ret_recv;
+               }
+       }
+
+       health_code_update();
+
+       /* Deprecated command */
+       LTTNG_ASSERT(msg.cmd_type != LTTNG_CONSUMER_STOP);
+
+       health_code_update();
+
+       /* relayd needs RCU read-side protection */
+       rcu_read_lock();
+
+       switch (msg.cmd_type) {
+       case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
+       {
+               /* Session daemon status message are handled in the following call. */
+               consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
+                               msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
+                               &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
+                               msg.u.relayd_sock.relayd_session_id);
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_ADD_CHANNEL:
+       {
+               struct lttng_consumer_channel *new_channel;
+               int ret_send_status, ret_add_channel = 0;
+               const uint64_t chunk_id = msg.u.channel.chunk_id.value;
+
+               health_code_update();
+
+               /* First send a status message before receiving the fds. */
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto error_fatal;
+               }
+
+               health_code_update();
+
+               DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
+               new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
+                               msg.u.channel.session_id,
+                               msg.u.channel.chunk_id.is_set ?
+                                               &chunk_id : NULL,
+                               msg.u.channel.pathname,
+                               msg.u.channel.name,
+                               msg.u.channel.relayd_id, msg.u.channel.output,
+                               msg.u.channel.tracefile_size,
+                               msg.u.channel.tracefile_count, 0,
+                               msg.u.channel.monitor,
+                               msg.u.channel.live_timer_interval,
+                               msg.u.channel.is_live,
+                               NULL, NULL);
+               if (new_channel == NULL) {
+                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
+                       goto end_nosignal;
+               }
+               new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
+               switch (msg.u.channel.output) {
+               case LTTNG_EVENT_SPLICE:
+                       new_channel->output = CONSUMER_CHANNEL_SPLICE;
+                       break;
+               case LTTNG_EVENT_MMAP:
+                       new_channel->output = CONSUMER_CHANNEL_MMAP;
+                       break;
+               default:
+                       ERR("Channel output unknown %d", msg.u.channel.output);
+                       goto end_nosignal;
+               }
+
+               /* Translate and save channel type. */
+               switch (msg.u.channel.type) {
+               case CONSUMER_CHANNEL_TYPE_DATA:
+               case CONSUMER_CHANNEL_TYPE_METADATA:
+                       new_channel->type = (consumer_channel_type) msg.u.channel.type;
+                       break;
+               default:
+                       abort();
+                       goto end_nosignal;
+               };
+
+               health_code_update();
+
+               if (ctx->on_recv_channel != NULL) {
+                       int ret_recv_channel =
+                                       ctx->on_recv_channel(new_channel);
+                       if (ret_recv_channel == 0) {
+                               ret_add_channel = consumer_add_channel(
+                                               new_channel, ctx);
+                       } else if (ret_recv_channel < 0) {
+                               goto end_nosignal;
+                       }
+               } else {
+                       ret_add_channel =
+                                       consumer_add_channel(new_channel, ctx);
+               }
+               if (msg.u.channel.type == CONSUMER_CHANNEL_TYPE_DATA &&
+                               !ret_add_channel) {
+                       int monitor_start_ret;
+
+                       DBG("Consumer starting monitor timer");
+                       consumer_timer_live_start(new_channel,
+                                       msg.u.channel.live_timer_interval);
+                       monitor_start_ret = consumer_timer_monitor_start(
+                                       new_channel,
+                                       msg.u.channel.monitor_timer_interval);
+                       if (monitor_start_ret < 0) {
+                               ERR("Starting channel monitoring timer failed");
+                               goto end_nosignal;
+                       }
+               }
+
+               health_code_update();
+
+               /* If we received an error in add_channel, we need to report it. */
+               if (ret_add_channel < 0) {
+                       ret_send_status = consumer_send_status_msg(
+                                       sock, ret_add_channel);
+                       if (ret_send_status < 0) {
+                               goto error_fatal;
+                       }
+                       goto end_nosignal;
+               }
+
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_ADD_STREAM:
+       {
+               int fd;
+               struct lttng_pipe *stream_pipe;
+               struct lttng_consumer_stream *new_stream;
+               struct lttng_consumer_channel *channel;
+               int alloc_ret = 0;
+               int ret_send_status, ret_poll, ret_get_max_subbuf_size;
+               ssize_t ret_pipe_write, ret_recv;
+
+               /*
+                * Get stream's channel reference. Needed when adding the stream to the
+                * global hash table.
+                */
+               channel = consumer_find_channel(msg.u.stream.channel_key);
+               if (!channel) {
+                       /*
+                        * We could not find the channel. Can happen if cpu hotplug
+                        * happens while tearing down.
+                        */
+                       ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               }
+
+               health_code_update();
+
+               /* First send a status message before receiving the fds. */
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto error_add_stream_fatal;
+               }
+
+               health_code_update();
+
+               if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
+                       /* Channel was not found. */
+                       goto error_add_stream_nosignal;
+               }
+
+               /* Blocking call */
+               health_poll_entry();
+               ret_poll = lttng_consumer_poll_socket(consumer_sockpoll);
+               health_poll_exit();
+               if (ret_poll) {
+                       goto error_add_stream_fatal;
+               }
+
+               health_code_update();
+
+               /* Get stream file descriptor from socket */
+               ret_recv = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
+               if (ret_recv != sizeof(fd)) {
+                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
+                       ret_func = ret_recv;
+                       goto end;
+               }
+
+               health_code_update();
+
+               /*
+                * Send status code to session daemon only if the recv works. If the
+                * above recv() failed, the session daemon is notified through the
+                * error socket and the teardown is eventually done.
+                */
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto error_add_stream_nosignal;
+               }
+
+               health_code_update();
+
+               pthread_mutex_lock(&channel->lock);
+               new_stream = consumer_stream_create(
+                               channel,
+                               channel->key,
+                               fd,
+                               channel->name,
+                               channel->relayd_id,
+                               channel->session_id,
+                               channel->trace_chunk,
+                               msg.u.stream.cpu,
+                               &alloc_ret,
+                               channel->type,
+                               channel->monitor);
+               if (new_stream == NULL) {
+                       switch (alloc_ret) {
+                       case -ENOMEM:
+                       case -EINVAL:
+                       default:
+                               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
+                               break;
+                       }
+                       pthread_mutex_unlock(&channel->lock);
+                       goto error_add_stream_nosignal;
+               }
+
+               new_stream->wait_fd = fd;
+               ret_get_max_subbuf_size = kernctl_get_max_subbuf_size(
+                               new_stream->wait_fd, &new_stream->max_sb_size);
+               if (ret_get_max_subbuf_size < 0) {
+                       pthread_mutex_unlock(&channel->lock);
+                       ERR("Failed to get kernel maximal subbuffer size");
+                       goto error_add_stream_nosignal;
+               }
+
+               consumer_stream_update_channel_attributes(new_stream,
+                               channel);
+
+               /*
+                * We've just assigned the channel to the stream so increment the
+                * refcount right now. We don't need to increment the refcount for
+                * streams in no monitor because we handle manually the cleanup of
+                * those. It is very important to make sure there is NO prior
+                * consumer_del_stream() calls or else the refcount will be unbalanced.
+                */
+               if (channel->monitor) {
+                       uatomic_inc(&new_stream->chan->refcount);
+               }
+
+               /*
+                * The buffer flush is done on the session daemon side for the kernel
+                * so no need for the stream "hangup_flush_done" variable to be
+                * tracked. This is important for a kernel stream since we don't rely
+                * on the flush state of the stream to read data. It's not the case for
+                * user space tracing.
+                */
+               new_stream->hangup_flush_done = 0;
+
+               health_code_update();
+
+               pthread_mutex_lock(&new_stream->lock);
+               if (ctx->on_recv_stream) {
+                       int ret_recv_stream = ctx->on_recv_stream(new_stream);
+                       if (ret_recv_stream < 0) {
+                               pthread_mutex_unlock(&new_stream->lock);
+                               pthread_mutex_unlock(&channel->lock);
+                               consumer_stream_free(new_stream);
+                               goto error_add_stream_nosignal;
+                       }
+               }
+               health_code_update();
+
+               if (new_stream->metadata_flag) {
+                       channel->metadata_stream = new_stream;
+               }
+
+               /* Do not monitor this stream. */
+               if (!channel->monitor) {
+                       DBG("Kernel consumer add stream %s in no monitor mode with "
+                                       "relayd id %" PRIu64, new_stream->name,
+                                       new_stream->net_seq_idx);
+                       cds_list_add(&new_stream->send_node, &channel->streams.head);
+                       pthread_mutex_unlock(&new_stream->lock);
+                       pthread_mutex_unlock(&channel->lock);
+                       goto end_add_stream;
+               }
+
+               /* Send stream to relayd if the stream has an ID. */
+               if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
+                       int ret_send_relayd_stream;
+
+                       ret_send_relayd_stream = consumer_send_relayd_stream(
+                                       new_stream, new_stream->chan->pathname);
+                       if (ret_send_relayd_stream < 0) {
+                               pthread_mutex_unlock(&new_stream->lock);
+                               pthread_mutex_unlock(&channel->lock);
+                               consumer_stream_free(new_stream);
+                               goto error_add_stream_nosignal;
+                       }
+
+                       /*
+                        * If adding an extra stream to an already
+                        * existing channel (e.g. cpu hotplug), we need
+                        * to send the "streams_sent" command to relayd.
+                        */
+                       if (channel->streams_sent_to_relayd) {
+                               int ret_send_relayd_streams_sent;
+
+                               ret_send_relayd_streams_sent =
+                                               consumer_send_relayd_streams_sent(
+                                                               new_stream->net_seq_idx);
+                               if (ret_send_relayd_streams_sent < 0) {
+                                       pthread_mutex_unlock(&new_stream->lock);
+                                       pthread_mutex_unlock(&channel->lock);
+                                       goto error_add_stream_nosignal;
+                               }
+                       }
+               }
+               pthread_mutex_unlock(&new_stream->lock);
+               pthread_mutex_unlock(&channel->lock);
+
+               /* Get the right pipe where the stream will be sent. */
+               if (new_stream->metadata_flag) {
+                       consumer_add_metadata_stream(new_stream);
+                       stream_pipe = ctx->consumer_metadata_pipe;
+               } else {
+                       consumer_add_data_stream(new_stream);
+                       stream_pipe = ctx->consumer_data_pipe;
+               }
+
+               /* Visible to other threads */
+               new_stream->globally_visible = 1;
+
+               health_code_update();
+
+               ret_pipe_write = lttng_pipe_write(
+                               stream_pipe, &new_stream, sizeof(new_stream));
+               if (ret_pipe_write < 0) {
+                       ERR("Consumer write %s stream to pipe %d",
+                                       new_stream->metadata_flag ? "metadata" : "data",
+                                       lttng_pipe_get_writefd(stream_pipe));
+                       if (new_stream->metadata_flag) {
+                               consumer_del_stream_for_metadata(new_stream);
+                       } else {
+                               consumer_del_stream_for_data(new_stream);
+                       }
+                       goto error_add_stream_nosignal;
+               }
+
+               DBG("Kernel consumer ADD_STREAM %s (fd: %d) %s with relayd id %" PRIu64,
+                               new_stream->name, fd, new_stream->chan->pathname, new_stream->relayd_stream_id);
+end_add_stream:
+               break;
+error_add_stream_nosignal:
+               goto end_nosignal;
+error_add_stream_fatal:
+               goto error_fatal;
+       }
+       case LTTNG_CONSUMER_STREAMS_SENT:
+       {
+               struct lttng_consumer_channel *channel;
+               int ret_send_status;
+
+               /*
+                * Get stream's channel reference. Needed when adding the stream to the
+                * global hash table.
+                */
+               channel = consumer_find_channel(msg.u.sent_streams.channel_key);
+               if (!channel) {
+                       /*
+                        * We could not find the channel. Can happen if cpu hotplug
+                        * happens while tearing down.
+                        */
+                       ERR("Unable to find channel key %" PRIu64,
+                                       msg.u.sent_streams.channel_key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               }
+
+               health_code_update();
+
+               /*
+                * Send status code to session daemon.
+                */
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0 ||
+                               ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto error_streams_sent_nosignal;
+               }
+
+               health_code_update();
+
+               /*
+                * We should not send this message if we don't monitor the
+                * streams in this channel.
+                */
+               if (!channel->monitor) {
+                       goto end_error_streams_sent;
+               }
+
+               health_code_update();
+               /* Send stream to relayd if the stream has an ID. */
+               if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
+                       int ret_send_relay_streams;
+
+                       ret_send_relay_streams = consumer_send_relayd_streams_sent(
+                                       msg.u.sent_streams.net_seq_idx);
+                       if (ret_send_relay_streams < 0) {
+                               goto error_streams_sent_nosignal;
+                       }
+                       channel->streams_sent_to_relayd = true;
+               }
+end_error_streams_sent:
+               break;
+error_streams_sent_nosignal:
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_UPDATE_STREAM:
+       {
+               rcu_read_unlock();
+               return -ENOSYS;
+       }
+       case LTTNG_CONSUMER_DESTROY_RELAYD:
+       {
+               uint64_t index = msg.u.destroy_relayd.net_seq_idx;
+               struct consumer_relayd_sock_pair *relayd;
+               int ret_send_status;
+
+               DBG("Kernel consumer destroying relayd %" PRIu64, index);
+
+               /* Get relayd reference if exists. */
+               relayd = consumer_find_relayd(index);
+               if (relayd == NULL) {
+                       DBG("Unable to find relayd %" PRIu64, index);
+                       ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
+               }
+
+               /*
+                * Each relayd socket pair has a refcount of stream attached to it
+                * which tells if the relayd is still active or not depending on the
+                * refcount value.
+                *
+                * This will set the destroy flag of the relayd object and destroy it
+                * if the refcount reaches zero when called.
+                *
+                * The destroy can happen either here or when a stream fd hangs up.
+                */
+               if (relayd) {
+                       consumer_flag_relayd_for_destroy(relayd);
+               }
+
+               health_code_update();
+
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto error_fatal;
+               }
+
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_DATA_PENDING:
+       {
+               int32_t ret_data_pending;
+               uint64_t id = msg.u.data_pending.session_id;
+               ssize_t ret_send;
+
+               DBG("Kernel consumer data pending command for id %" PRIu64, id);
+
+               ret_data_pending = consumer_data_pending(id);
+
+               health_code_update();
+
+               /* Send back returned value to session daemon */
+               ret_send = lttcomm_send_unix_sock(sock, &ret_data_pending,
+                               sizeof(ret_data_pending));
+               if (ret_send < 0) {
+                       PERROR("send data pending ret code");
+                       goto error_fatal;
+               }
+
+               /*
+                * No need to send back a status message since the data pending
+                * returned value is the response.
+                */
+               break;
+       }
+       case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
+       {
+               struct lttng_consumer_channel *channel;
+               uint64_t key = msg.u.snapshot_channel.key;
+               int ret_send_status;
+
+               channel = consumer_find_channel(key);
+               if (!channel) {
+                       ERR("Channel %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               } else {
+                       pthread_mutex_lock(&channel->lock);
+                       if (msg.u.snapshot_channel.metadata == 1) {
+                               int ret_snapshot;
+
+                               ret_snapshot = lttng_kconsumer_snapshot_metadata(
+                                               channel, key,
+                                               msg.u.snapshot_channel.pathname,
+                                               msg.u.snapshot_channel.relayd_id,
+                                               ctx);
+                               if (ret_snapshot < 0) {
+                                       ERR("Snapshot metadata failed");
+                                       ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
+                               }
+                       } else {
+                               int ret_snapshot;
+
+                               ret_snapshot = lttng_kconsumer_snapshot_channel(
+                                               channel, key,
+                                               msg.u.snapshot_channel.pathname,
+                                               msg.u.snapshot_channel.relayd_id,
+                                               msg.u.snapshot_channel
+                                                               .nb_packets_per_stream,
+                                               ctx);
+                               if (ret_snapshot < 0) {
+                                       ERR("Snapshot channel failed");
+                                       ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
+                               }
+                       }
+                       pthread_mutex_unlock(&channel->lock);
+               }
+               health_code_update();
+
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
+               break;
+       }
+       case LTTNG_CONSUMER_DESTROY_CHANNEL:
+       {
+               uint64_t key = msg.u.destroy_channel.key;
+               struct lttng_consumer_channel *channel;
+               int ret_send_status;
+
+               channel = consumer_find_channel(key);
+               if (!channel) {
+                       ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               }
+
+               health_code_update();
+
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_destroy_channel;
+               }
+
+               health_code_update();
+
+               /* Stop right now if no channel was found. */
+               if (!channel) {
+                       goto end_destroy_channel;
+               }
+
+               /*
+                * This command should ONLY be issued for channel with streams set in
+                * no monitor mode.
+                */
+               LTTNG_ASSERT(!channel->monitor);
+
+               /*
+                * The refcount should ALWAYS be 0 in the case of a channel in no
+                * monitor mode.
+                */
+               LTTNG_ASSERT(!uatomic_sub_return(&channel->refcount, 1));
+
+               consumer_del_channel(channel);
+end_destroy_channel:
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_DISCARDED_EVENTS:
+       {
+               ssize_t ret;
+               uint64_t count;
+               struct lttng_consumer_channel *channel;
+               uint64_t id = msg.u.discarded_events.session_id;
+               uint64_t key = msg.u.discarded_events.channel_key;
+
+               DBG("Kernel consumer discarded events command for session id %"
+                               PRIu64 ", channel key %" PRIu64, id, key);
+
+               channel = consumer_find_channel(key);
+               if (!channel) {
+                       ERR("Kernel consumer discarded events channel %"
+                                       PRIu64 " not found", key);
+                       count = 0;
+               } else {
+                       count = channel->discarded_events;
+               }
+
+               health_code_update();
+
+               /* Send back returned value to session daemon */
+               ret = lttcomm_send_unix_sock(sock, &count, sizeof(count));
+               if (ret < 0) {
+                       PERROR("send discarded events");
+                       goto error_fatal;
+               }
+
+               break;
+       }
+       case LTTNG_CONSUMER_LOST_PACKETS:
+       {
+               ssize_t ret;
+               uint64_t count;
+               struct lttng_consumer_channel *channel;
+               uint64_t id = msg.u.lost_packets.session_id;
+               uint64_t key = msg.u.lost_packets.channel_key;
+
+               DBG("Kernel consumer lost packets command for session id %"
+                               PRIu64 ", channel key %" PRIu64, id, key);
+
+               channel = consumer_find_channel(key);
+               if (!channel) {
+                       ERR("Kernel consumer lost packets channel %"
+                                       PRIu64 " not found", key);
+                       count = 0;
+               } else {
+                       count = channel->lost_packets;
+               }
+
+               health_code_update();
+
+               /* Send back returned value to session daemon */
+               ret = lttcomm_send_unix_sock(sock, &count, sizeof(count));
+               if (ret < 0) {
+                       PERROR("send lost packets");
+                       goto error_fatal;
+               }
+
+               break;
+       }
+       case LTTNG_CONSUMER_SET_CHANNEL_MONITOR_PIPE:
+       {
+               int channel_monitor_pipe;
+               int ret_send_status, ret_set_channel_monitor_pipe;
+               ssize_t ret_recv;
+
+               ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+               /* Successfully received the command's type. */
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       goto error_fatal;
+               }
+
+               ret_recv = lttcomm_recv_fds_unix_sock(
+                               sock, &channel_monitor_pipe, 1);
+               if (ret_recv != sizeof(channel_monitor_pipe)) {
+                       ERR("Failed to receive channel monitor pipe");
+                       goto error_fatal;
+               }
+
+               DBG("Received channel monitor pipe (%d)", channel_monitor_pipe);
+               ret_set_channel_monitor_pipe =
+                               consumer_timer_thread_set_channel_monitor_pipe(
+                                               channel_monitor_pipe);
+               if (!ret_set_channel_monitor_pipe) {
+                       int flags;
+                       int ret_fcntl;
+
+                       ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+                       /* Set the pipe as non-blocking. */
+                       ret_fcntl = fcntl(channel_monitor_pipe, F_GETFL, 0);
+                       if (ret_fcntl == -1) {
+                               PERROR("fcntl get flags of the channel monitoring pipe");
+                               goto error_fatal;
+                       }
+                       flags = ret_fcntl;
+
+                       ret_fcntl = fcntl(channel_monitor_pipe, F_SETFL,
+                                       flags | O_NONBLOCK);
+                       if (ret_fcntl == -1) {
+                               PERROR("fcntl set O_NONBLOCK flag of the channel monitoring pipe");
+                               goto error_fatal;
+                       }
+                       DBG("Channel monitor pipe set as non-blocking");
+               } else {
+                       ret_code = LTTCOMM_CONSUMERD_ALREADY_SET;
+               }
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       goto error_fatal;
+               }
+               break;
+       }
+       case LTTNG_CONSUMER_ROTATE_CHANNEL:
+       {
+               struct lttng_consumer_channel *channel;
+               uint64_t key = msg.u.rotate_channel.key;
+               int ret_send_status;
+
+               DBG("Consumer rotate channel %" PRIu64, key);
+
+               channel = consumer_find_channel(key);
+               if (!channel) {
+                       ERR("Channel %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               } else {
+                       /*
+                        * Sample the rotate position of all the streams in this channel.
+                        */
+                       int ret_rotate_channel;
+
+                       ret_rotate_channel = lttng_consumer_rotate_channel(
+                                       channel, key,
+                                       msg.u.rotate_channel.relayd_id,
+                                       msg.u.rotate_channel.metadata, ctx);
+                       if (ret_rotate_channel < 0) {
+                               ERR("Rotate channel failed");
+                               ret_code = LTTCOMM_CONSUMERD_ROTATION_FAIL;
+                       }
+
+                       health_code_update();
+               }
+
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto error_rotate_channel;
+               }
+               if (channel) {
+                       /* Rotate the streams that are ready right now. */
+                       int ret_rotate;
+
+                       ret_rotate = lttng_consumer_rotate_ready_streams(
+                                       channel, key, ctx);
+                       if (ret_rotate < 0) {
+                               ERR("Rotate ready streams failed");
+                       }
+               }
+               break;
+error_rotate_channel:
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_CLEAR_CHANNEL:
+       {
+               struct lttng_consumer_channel *channel;
+               uint64_t key = msg.u.clear_channel.key;
+               int ret_send_status;
+
+               channel = consumer_find_channel(key);
+               if (!channel) {
+                       DBG("Channel %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               } else {
+                       int ret_clear_channel;
+
+                       ret_clear_channel =
+                                       lttng_consumer_clear_channel(channel);
+                       if (ret_clear_channel) {
+                               ERR("Clear channel failed");
+                               ret_code = (lttcomm_return_code) ret_clear_channel;
+                       }
+
+                       health_code_update();
+               }
+
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
+
+               break;
+       }
+       case LTTNG_CONSUMER_INIT:
+       {
+               int ret_send_status;
+
+               ret_code = lttng_consumer_init_command(ctx,
+                               msg.u.init.sessiond_uuid);
+               health_code_update();
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
+               break;
+       }
+       case LTTNG_CONSUMER_CREATE_TRACE_CHUNK:
+       {
+               const struct lttng_credentials credentials = {
+                       .uid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.create_trace_chunk.credentials.value.uid),
+                       .gid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.create_trace_chunk.credentials.value.gid),
+               };
+               const bool is_local_trace =
+                               !msg.u.create_trace_chunk.relayd_id.is_set;
+               const uint64_t relayd_id =
+                               msg.u.create_trace_chunk.relayd_id.value;
+               const char *chunk_override_name =
+                               *msg.u.create_trace_chunk.override_name ?
+                                       msg.u.create_trace_chunk.override_name :
+                                       NULL;
+               struct lttng_directory_handle *chunk_directory_handle = NULL;
+
+               /*
+                * The session daemon will only provide a chunk directory file
+                * descriptor for local traces.
+                */
+               if (is_local_trace) {
+                       int chunk_dirfd;
+                       int ret_send_status;
+                       ssize_t ret_recv;
+
+                       /* Acnowledge the reception of the command. */
+                       ret_send_status = consumer_send_status_msg(
+                                       sock, LTTCOMM_CONSUMERD_SUCCESS);
+                       if (ret_send_status < 0) {
+                               /* Somehow, the session daemon is not responding anymore. */
+                               goto end_nosignal;
+                       }
+
+                       ret_recv = lttcomm_recv_fds_unix_sock(
+                                       sock, &chunk_dirfd, 1);
+                       if (ret_recv != sizeof(chunk_dirfd)) {
+                               ERR("Failed to receive trace chunk directory file descriptor");
+                               goto error_fatal;
+                       }
+
+                       DBG("Received trace chunk directory fd (%d)",
+                                       chunk_dirfd);
+                       chunk_directory_handle = lttng_directory_handle_create_from_dirfd(
+                                       chunk_dirfd);
+                       if (!chunk_directory_handle) {
+                               ERR("Failed to initialize chunk directory handle from directory file descriptor");
+                               if (close(chunk_dirfd)) {
+                                       PERROR("Failed to close chunk directory file descriptor");
+                               }
+                               goto error_fatal;
+                       }
+               }
+
+               ret_code = lttng_consumer_create_trace_chunk(
+                               !is_local_trace ? &relayd_id : NULL,
+                               msg.u.create_trace_chunk.session_id,
+                               msg.u.create_trace_chunk.chunk_id,
+                               (time_t) msg.u.create_trace_chunk
+                                               .creation_timestamp,
+                               chunk_override_name,
+                               msg.u.create_trace_chunk.credentials.is_set ?
+                                               &credentials :
+                                               NULL,
+                               chunk_directory_handle);
+               lttng_directory_handle_put(chunk_directory_handle);
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_CLOSE_TRACE_CHUNK:
+       {
+               enum lttng_trace_chunk_command_type close_command =
+                               (lttng_trace_chunk_command_type) msg.u.close_trace_chunk.close_command.value;
+               const uint64_t relayd_id =
+                               msg.u.close_trace_chunk.relayd_id.value;
+               struct lttcomm_consumer_close_trace_chunk_reply reply;
+               char path[LTTNG_PATH_MAX];
+               ssize_t ret_send;
+
+               ret_code = lttng_consumer_close_trace_chunk(
+                               msg.u.close_trace_chunk.relayd_id.is_set ?
+                                               &relayd_id :
+                                               NULL,
+                               msg.u.close_trace_chunk.session_id,
+                               msg.u.close_trace_chunk.chunk_id,
+                               (time_t) msg.u.close_trace_chunk.close_timestamp,
+                               msg.u.close_trace_chunk.close_command.is_set ?
+                                               &close_command :
+                                               NULL, path);
+               reply.ret_code = ret_code;
+               reply.path_length = strlen(path) + 1;
+               ret_send = lttcomm_send_unix_sock(sock, &reply, sizeof(reply));
+               if (ret_send != sizeof(reply)) {
+                       goto error_fatal;
+               }
+               ret_send = lttcomm_send_unix_sock(
+                               sock, path, reply.path_length);
+               if (ret_send != reply.path_length) {
+                       goto error_fatal;
+               }
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_TRACE_CHUNK_EXISTS:
+       {
+               const uint64_t relayd_id =
+                               msg.u.trace_chunk_exists.relayd_id.value;
+
+               ret_code = lttng_consumer_trace_chunk_exists(
+                               msg.u.trace_chunk_exists.relayd_id.is_set ?
+                                               &relayd_id : NULL,
+                               msg.u.trace_chunk_exists.session_id,
+                               msg.u.trace_chunk_exists.chunk_id);
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_OPEN_CHANNEL_PACKETS:
+       {
+               const uint64_t key = msg.u.open_channel_packets.key;
+               struct lttng_consumer_channel *channel =
+                               consumer_find_channel(key);
+
+               if (channel) {
+                       pthread_mutex_lock(&channel->lock);
+                       ret_code = lttng_consumer_open_channel_packets(channel);
+                       pthread_mutex_unlock(&channel->lock);
+               } else {
+                       WARN("Channel %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               }
+
+               health_code_update();
+               goto end_msg_sessiond;
+       }
+       default:
+               goto end_nosignal;
+       }
+
+end_nosignal:
+       /*
+        * Return 1 to indicate success since the 0 value can be a socket
+        * shutdown during the recv() or send() call.
+        */
+       ret_func = 1;
+       goto end;
+error_fatal:
+       /* This will issue a consumer stop. */
+       ret_func = -1;
+       goto end;
+end_msg_sessiond:
+       /*
+        * The returned value here is not useful since either way we'll return 1 to
+        * the caller because the session daemon socket management is done
+        * elsewhere. Returning a negative code or 0 will shutdown the consumer.
+        */
+       {
+               int ret_send_status;
+
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       goto error_fatal;
+               }
+       }
+
+       ret_func = 1;
+
+end:
+       health_code_update();
+       rcu_read_unlock();
+       return ret_func;
+}
+
+/*
+ * Sync metadata meaning request them to the session daemon and snapshot to the
+ * metadata thread can consumer them.
+ *
+ * Metadata stream lock MUST be acquired.
+ */
+enum sync_metadata_status lttng_kconsumer_sync_metadata(
+               struct lttng_consumer_stream *metadata)
+{
+       int ret;
+       enum sync_metadata_status status;
+
+       LTTNG_ASSERT(metadata);
+
+       ret = kernctl_buffer_flush(metadata->wait_fd);
+       if (ret < 0) {
+               ERR("Failed to flush kernel stream");
+               status = SYNC_METADATA_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = kernctl_snapshot(metadata->wait_fd);
+       if (ret < 0) {
+               if (errno == EAGAIN) {
+                       /* No new metadata, exit. */
+                       DBG("Sync metadata, no new kernel metadata");
+                       status = SYNC_METADATA_STATUS_NO_DATA;
+               } else {
+                       ERR("Sync metadata, taking kernel snapshot failed.");
+                       status = SYNC_METADATA_STATUS_ERROR;
+               }
+       } else {
+               status = SYNC_METADATA_STATUS_NEW_DATA;
+       }
+
+end:
+       return status;
+}
+
+static
+int extract_common_subbuffer_info(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuf)
+{
+       int ret;
+
+       ret = kernctl_get_subbuf_size(
+                       stream->wait_fd, &subbuf->info.data.subbuf_size);
+       if (ret) {
+               goto end;
+       }
+
+       ret = kernctl_get_padded_subbuf_size(
+                       stream->wait_fd, &subbuf->info.data.padded_subbuf_size);
+       if (ret) {
+               goto end;
+       }
+
+end:
+       return ret;
+}
+
+static
+int extract_metadata_subbuffer_info(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuf)
+{
+       int ret;
+
+       ret = extract_common_subbuffer_info(stream, subbuf);
+       if (ret) {
+               goto end;
+       }
+
+       ret = kernctl_get_metadata_version(
+                       stream->wait_fd, &subbuf->info.metadata.version);
+       if (ret) {
+               goto end;
+       }
+
+end:
+       return ret;
+}
+
+static
+int extract_data_subbuffer_info(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuf)
+{
+       int ret;
+
+       ret = extract_common_subbuffer_info(stream, subbuf);
+       if (ret) {
+               goto end;
+       }
+
+       ret = kernctl_get_packet_size(
+                       stream->wait_fd, &subbuf->info.data.packet_size);
+       if (ret < 0) {
+               PERROR("Failed to get sub-buffer packet size");
+               goto end;
+       }
+
+       ret = kernctl_get_content_size(
+                       stream->wait_fd, &subbuf->info.data.content_size);
+       if (ret < 0) {
+               PERROR("Failed to get sub-buffer content size");
+               goto end;
+       }
+
+       ret = kernctl_get_timestamp_begin(
+                       stream->wait_fd, &subbuf->info.data.timestamp_begin);
+       if (ret < 0) {
+               PERROR("Failed to get sub-buffer begin timestamp");
+               goto end;
+       }
+
+       ret = kernctl_get_timestamp_end(
+                       stream->wait_fd, &subbuf->info.data.timestamp_end);
+       if (ret < 0) {
+               PERROR("Failed to get sub-buffer end timestamp");
+               goto end;
+       }
+
+       ret = kernctl_get_events_discarded(
+                       stream->wait_fd, &subbuf->info.data.events_discarded);
+       if (ret) {
+               PERROR("Failed to get sub-buffer events discarded count");
+               goto end;
+       }
+
+       ret = kernctl_get_sequence_number(stream->wait_fd,
+                       &subbuf->info.data.sequence_number.value);
+       if (ret) {
+               /* May not be supported by older LTTng-modules. */
+               if (ret != -ENOTTY) {
+                       PERROR("Failed to get sub-buffer sequence number");
+                       goto end;
+               }
+       } else {
+               subbuf->info.data.sequence_number.is_set = true;
+       }
+
+       ret = kernctl_get_stream_id(
+                       stream->wait_fd, &subbuf->info.data.stream_id);
+       if (ret < 0) {
+               PERROR("Failed to get stream id");
+               goto end;
+       }
+
+       ret = kernctl_get_instance_id(stream->wait_fd,
+                       &subbuf->info.data.stream_instance_id.value);
+       if (ret) {
+               /* May not be supported by older LTTng-modules. */
+               if (ret != -ENOTTY) {
+                       PERROR("Failed to get stream instance id");
+                       goto end;
+               }
+       } else {
+               subbuf->info.data.stream_instance_id.is_set = true;
+       }
+end:
+       return ret;
+}
+
+static
+enum get_next_subbuffer_status get_subbuffer_common(
+               struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuffer)
+{
+       int ret;
+       enum get_next_subbuffer_status status;
+
+       ret = kernctl_get_next_subbuf(stream->wait_fd);
+       switch (ret) {
+       case 0:
+               status = GET_NEXT_SUBBUFFER_STATUS_OK;
+               break;
+       case -ENODATA:
+               case -EAGAIN:
+               /*
+                * The caller only expects -ENODATA when there is no data to
+                * read, but the kernel tracer returns -EAGAIN when there is
+                * currently no data for a non-finalized stream, and -ENODATA
+                * when there is no data for a finalized stream. Those can be
+                * combined into a -ENODATA return value.
+                */
+               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
+               goto end;
+       default:
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = stream->read_subbuffer_ops.extract_subbuffer_info(
+               stream, subbuffer);
+       if (ret) {
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+       }
+end:
+       return status;
+}
+
+static
+enum get_next_subbuffer_status get_next_subbuffer_splice(
+               struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuffer)
+{
+       const enum get_next_subbuffer_status status =
+                       get_subbuffer_common(stream, subbuffer);
+
+       if (status != GET_NEXT_SUBBUFFER_STATUS_OK) {
+               goto end;
+       }
+
+       subbuffer->buffer.fd = stream->wait_fd;
+end:
+       return status;
+}
+
+static
+enum get_next_subbuffer_status get_next_subbuffer_mmap(
+               struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuffer)
+{
+       int ret;
+       enum get_next_subbuffer_status status;
+       const char *addr;
+
+       status = get_subbuffer_common(stream, subbuffer);
+       if (status != GET_NEXT_SUBBUFFER_STATUS_OK) {
+               goto end;
+       }
+
+       ret = get_current_subbuf_addr(stream, &addr);
+       if (ret) {
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               goto end;
+       }
+
+       subbuffer->buffer.buffer = lttng_buffer_view_init(
+                       addr, 0, subbuffer->info.data.padded_subbuf_size);
+end:
+       return status;
+}
+
+static
+enum get_next_subbuffer_status get_next_subbuffer_metadata_check(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuffer)
+{
+       int ret;
+       const char *addr;
+       bool coherent;
+       enum get_next_subbuffer_status status;
+
+       ret = kernctl_get_next_subbuf_metadata_check(stream->wait_fd,
+                       &coherent);
+       if (ret) {
+               goto end;
+       }
+
+       ret = stream->read_subbuffer_ops.extract_subbuffer_info(
+                       stream, subbuffer);
+       if (ret) {
+               goto end;
+       }
+
+       LTTNG_OPTIONAL_SET(&subbuffer->info.metadata.coherent, coherent);
+
+       ret = get_current_subbuf_addr(stream, &addr);
+       if (ret) {
+               goto end;
+       }
+
+       subbuffer->buffer.buffer = lttng_buffer_view_init(
+                       addr, 0, subbuffer->info.data.padded_subbuf_size);
+       DBG("Got metadata packet with padded_subbuf_size = %lu, coherent = %s",
+                       subbuffer->info.metadata.padded_subbuf_size,
+                       coherent ? "true" : "false");
+end:
+       /*
+        * The caller only expects -ENODATA when there is no data to read, but
+        * the kernel tracer returns -EAGAIN when there is currently no data
+        * for a non-finalized stream, and -ENODATA when there is no data for a
+        * finalized stream. Those can be combined into a -ENODATA return value.
+        */
+       switch (ret) {
+       case 0:
+               status = GET_NEXT_SUBBUFFER_STATUS_OK;
+               break;
+       case -ENODATA:
+       case -EAGAIN:
+               /*
+                * The caller only expects -ENODATA when there is no data to
+                * read, but the kernel tracer returns -EAGAIN when there is
+                * currently no data for a non-finalized stream, and -ENODATA
+                * when there is no data for a finalized stream. Those can be
+                * combined into a -ENODATA return value.
+                */
+               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
+               break;
+       default:
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               break;
+       }
+
+       return status;
+}
+
+static
+int put_next_subbuffer(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuffer)
+{
+       const int ret = kernctl_put_next_subbuf(stream->wait_fd);
+
+       if (ret) {
+               if (ret == -EFAULT) {
+                       PERROR("Error in unreserving sub buffer");
+               } else if (ret == -EIO) {
+                       /* Should never happen with newer LTTng versions */
+                       PERROR("Reader has been pushed by the writer, last sub-buffer corrupted");
+               }
+       }
+
+       return ret;
+}
+
+static
+bool is_get_next_check_metadata_available(int tracer_fd)
+{
+       const int ret = kernctl_get_next_subbuf_metadata_check(tracer_fd, NULL);
+       const bool available = ret != -ENOTTY;
+
+       if (ret == 0) {
+               /* get succeeded, make sure to put the subbuffer. */
+               kernctl_put_subbuf(tracer_fd);
+       }
+
+       return available;
+}
+
+static
+int signal_metadata(struct lttng_consumer_stream *stream,
+               struct lttng_consumer_local_data *ctx)
+{
+       ASSERT_LOCKED(stream->metadata_rdv_lock);
+       return pthread_cond_broadcast(&stream->metadata_rdv) ? -errno : 0;
+}
+
+static
+int lttng_kconsumer_set_stream_ops(
+               struct lttng_consumer_stream *stream)
+{
+       int ret = 0;
+
+       if (stream->metadata_flag && stream->chan->is_live) {
+               DBG("Attempting to enable metadata bucketization for live consumers");
+               if (is_get_next_check_metadata_available(stream->wait_fd)) {
+                       DBG("Kernel tracer supports get_next_subbuffer_metadata_check, metadata will be accumulated until a coherent state is reached");
+                       stream->read_subbuffer_ops.get_next_subbuffer =
+                                       get_next_subbuffer_metadata_check;
+                       ret = consumer_stream_enable_metadata_bucketization(
+                                       stream);
+                       if (ret) {
+                               goto end;
+                       }
+               } else {
+                       /*
+                        * The kernel tracer version is too old to indicate
+                        * when the metadata stream has reached a "coherent"
+                        * (parseable) point.
+                        *
+                        * This means that a live viewer may see an incoherent
+                        * sequence of metadata and fail to parse it.
+                        */
+                       WARN("Kernel tracer does not support get_next_subbuffer_metadata_check which may cause live clients to fail to parse the metadata stream");
+                       metadata_bucket_destroy(stream->metadata_bucket);
+                       stream->metadata_bucket = NULL;
+               }
+
+               stream->read_subbuffer_ops.on_sleep = signal_metadata;
+       }
+
+       if (!stream->read_subbuffer_ops.get_next_subbuffer) {
+               if (stream->chan->output == CONSUMER_CHANNEL_MMAP) {
+                       stream->read_subbuffer_ops.get_next_subbuffer =
+                                       get_next_subbuffer_mmap;
+               } else {
+                       stream->read_subbuffer_ops.get_next_subbuffer =
+                                       get_next_subbuffer_splice;
+               }
+       }
+
+       if (stream->metadata_flag) {
+               stream->read_subbuffer_ops.extract_subbuffer_info =
+                               extract_metadata_subbuffer_info;
+       } else {
+               stream->read_subbuffer_ops.extract_subbuffer_info =
+                               extract_data_subbuffer_info;
+               if (stream->chan->is_live) {
+                       stream->read_subbuffer_ops.send_live_beacon =
+                                       consumer_flush_kernel_index;
+               }
+       }
+
+       stream->read_subbuffer_ops.put_next_subbuffer = put_next_subbuffer;
+end:
+       return ret;
+}
+
+int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       LTTNG_ASSERT(stream);
+
+       /*
+        * Don't create anything if this is set for streaming or if there is
+        * no current trace chunk on the parent channel.
+        */
+       if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor &&
+                       stream->chan->trace_chunk) {
+               ret = consumer_stream_create_output_files(stream, true);
+               if (ret) {
+                       goto error;
+               }
+       }
+
+       if (stream->output == LTTNG_EVENT_MMAP) {
+               /* get the len of the mmap region */
+               unsigned long mmap_len;
+
+               ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
+               if (ret != 0) {
+                       PERROR("kernctl_get_mmap_len");
+                       goto error_close_fd;
+               }
+               stream->mmap_len = (size_t) mmap_len;
+
+               stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
+                               MAP_PRIVATE, stream->wait_fd, 0);
+               if (stream->mmap_base == MAP_FAILED) {
+                       PERROR("Error mmaping");
+                       ret = -1;
+                       goto error_close_fd;
+               }
+       }
+
+       ret = lttng_kconsumer_set_stream_ops(stream);
+       if (ret) {
+               goto error_close_fd;
+       }
+
+       /* we return 0 to let the library handle the FD internally */
+       return 0;
+
+error_close_fd:
+       if (stream->out_fd >= 0) {
+               int err;
+
+               err = close(stream->out_fd);
+               LTTNG_ASSERT(!err);
+               stream->out_fd = -1;
+       }
+error:
+       return ret;
+}
+
+/*
+ * Check if data is still being extracted from the buffers for a specific
+ * stream. Consumer data lock MUST be acquired before calling this function
+ * and the stream lock.
+ *
+ * Return 1 if the traced data are still getting read else 0 meaning that the
+ * data is available for trace viewer reading.
+ */
+int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       LTTNG_ASSERT(stream);
+
+       if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
+               ret = 0;
+               goto end;
+       }
+
+       ret = kernctl_get_next_subbuf(stream->wait_fd);
+       if (ret == 0) {
+               /* There is still data so let's put back this subbuffer. */
+               ret = kernctl_put_subbuf(stream->wait_fd);
+               LTTNG_ASSERT(ret == 0);
+               ret = 1;   /* Data is pending */
+               goto end;
+       }
+
+       /* Data is NOT pending and ready to be read. */
+       ret = 0;
+
+end:
+       return ret;
+}
index 004becb0f0feea1f93694d8ab21bc7a778322b25..71a33b73f42316799623bd70cdec35eabff73f06 100644 (file)
 #include <stdbool.h>
 #include <common/consumer/consumer.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream);
 int lttng_kconsumer_sample_snapshot_positions(
                struct lttng_consumer_stream *stream);
@@ -27,4 +31,8 @@ int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream);
 enum sync_metadata_status lttng_kconsumer_sync_metadata(
                struct lttng_consumer_stream *metadata);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _LTTNG_KCONSUMER_H */
index 5ab0fe60284bd7c6dfc5ba675ab13d3e8eb56213..26f1667857652ace298070da8e5c112b71072a68 100644 (file)
@@ -4,7 +4,9 @@ if HAVE_LIBLTTNG_UST_CTL
 
 noinst_LTLIBRARIES = libust-consumer.la
 
-libust_consumer_la_SOURCES = ust-consumer.c ust-consumer.h
+libust_consumer_la_SOURCES = \
+       ust-consumer.cpp \
+       ust-consumer.h
 
 libust_consumer_la_LIBADD = \
                        $(UST_CTL_LIBS) \
diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
deleted file mode 100644 (file)
index 310b670..0000000
+++ /dev/null
@@ -1,3438 +0,0 @@
-/*
- * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
- * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#define _LGPL_SOURCE
-#include <lttng/ust-ctl.h>
-#include <lttng/ust-sigbus.h>
-#include <poll.h>
-#include <pthread.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/mman.h>
-#include <sys/socket.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <inttypes.h>
-#include <unistd.h>
-#include <urcu/list.h>
-#include <signal.h>
-#include <stdbool.h>
-#include <stdint.h>
-
-#include <bin/lttng-consumerd/health-consumerd.h>
-#include <common/common.h>
-#include <common/sessiond-comm/sessiond-comm.h>
-#include <common/relayd/relayd.h>
-#include <common/compat/fcntl.h>
-#include <common/compat/endian.h>
-#include <common/consumer/consumer-metadata-cache.h>
-#include <common/consumer/consumer-stream.h>
-#include <common/consumer/consumer-timer.h>
-#include <common/utils.h>
-#include <common/index/index.h>
-#include <common/consumer/consumer.h>
-#include <common/shm.h>
-#include <common/optional.h>
-
-#include "ust-consumer.h"
-
-#define INT_MAX_STR_LEN 12     /* includes \0 */
-
-extern struct lttng_consumer_global_data the_consumer_data;
-extern int consumer_poll_timeout;
-
-LTTNG_EXPORT DEFINE_LTTNG_UST_SIGBUS_STATE();
-
-/*
- * Free channel object and all streams associated with it. This MUST be used
- * only and only if the channel has _NEVER_ been added to the global channel
- * hash table.
- */
-static void destroy_channel(struct lttng_consumer_channel *channel)
-{
-       struct lttng_consumer_stream *stream, *stmp;
-
-       LTTNG_ASSERT(channel);
-
-       DBG("UST consumer cleaning stream list");
-
-       cds_list_for_each_entry_safe(stream, stmp, &channel->streams.head,
-                       send_node) {
-
-               health_code_update();
-
-               cds_list_del(&stream->send_node);
-               lttng_ust_ctl_destroy_stream(stream->ustream);
-               lttng_trace_chunk_put(stream->trace_chunk);
-               free(stream);
-       }
-
-       /*
-        * If a channel is available meaning that was created before the streams
-        * were, delete it.
-        */
-       if (channel->uchan) {
-               lttng_ustconsumer_del_channel(channel);
-               lttng_ustconsumer_free_channel(channel);
-       }
-
-       if (channel->trace_chunk) {
-               lttng_trace_chunk_put(channel->trace_chunk);
-       }
-
-       free(channel);
-}
-
-/*
- * Add channel to internal consumer state.
- *
- * Returns 0 on success or else a negative value.
- */
-static int add_channel(struct lttng_consumer_channel *channel,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret = 0;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(ctx);
-
-       if (ctx->on_recv_channel != NULL) {
-               ret = ctx->on_recv_channel(channel);
-               if (ret == 0) {
-                       ret = consumer_add_channel(channel, ctx);
-               } else if (ret < 0) {
-                       /* Most likely an ENOMEM. */
-                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
-                       goto error;
-               }
-       } else {
-               ret = consumer_add_channel(channel, ctx);
-       }
-
-       DBG("UST consumer channel added (key: %" PRIu64 ")", channel->key);
-
-error:
-       return ret;
-}
-
-/*
- * Allocate and return a consumer stream object. If _alloc_ret is not NULL, the
- * error value if applicable is set in it else it is kept untouched.
- *
- * Return NULL on error else the newly allocated stream object.
- */
-static struct lttng_consumer_stream *allocate_stream(int cpu, int key,
-               struct lttng_consumer_channel *channel,
-               struct lttng_consumer_local_data *ctx, int *_alloc_ret)
-{
-       int alloc_ret;
-       struct lttng_consumer_stream *stream = NULL;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(ctx);
-
-       stream = consumer_stream_create(
-                       channel,
-                       channel->key,
-                       key,
-                       channel->name,
-                       channel->relayd_id,
-                       channel->session_id,
-                       channel->trace_chunk,
-                       cpu,
-                       &alloc_ret,
-                       channel->type,
-                       channel->monitor);
-       if (stream == NULL) {
-               switch (alloc_ret) {
-               case -ENOENT:
-                       /*
-                        * We could not find the channel. Can happen if cpu hotplug
-                        * happens while tearing down.
-                        */
-                       DBG3("Could not find channel");
-                       break;
-               case -ENOMEM:
-               case -EINVAL:
-               default:
-                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
-                       break;
-               }
-               goto error;
-       }
-
-       consumer_stream_update_channel_attributes(stream, channel);
-
-error:
-       if (_alloc_ret) {
-               *_alloc_ret = alloc_ret;
-       }
-       return stream;
-}
-
-/*
- * Send the given stream pointer to the corresponding thread.
- *
- * Returns 0 on success else a negative value.
- */
-static int send_stream_to_thread(struct lttng_consumer_stream *stream,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret;
-       struct lttng_pipe *stream_pipe;
-
-       /* Get the right pipe where the stream will be sent. */
-       if (stream->metadata_flag) {
-               consumer_add_metadata_stream(stream);
-               stream_pipe = ctx->consumer_metadata_pipe;
-       } else {
-               consumer_add_data_stream(stream);
-               stream_pipe = ctx->consumer_data_pipe;
-       }
-
-       /*
-        * From this point on, the stream's ownership has been moved away from
-        * the channel and it becomes globally visible. Hence, remove it from
-        * the local stream list to prevent the stream from being both local and
-        * global.
-        */
-       stream->globally_visible = 1;
-       cds_list_del(&stream->send_node);
-
-       ret = lttng_pipe_write(stream_pipe, &stream, sizeof(stream));
-       if (ret < 0) {
-               ERR("Consumer write %s stream to pipe %d",
-                               stream->metadata_flag ? "metadata" : "data",
-                               lttng_pipe_get_writefd(stream_pipe));
-               if (stream->metadata_flag) {
-                       consumer_del_stream_for_metadata(stream);
-               } else {
-                       consumer_del_stream_for_data(stream);
-               }
-               goto error;
-       }
-
-error:
-       return ret;
-}
-
-static
-int get_stream_shm_path(char *stream_shm_path, const char *shm_path, int cpu)
-{
-       char cpu_nr[INT_MAX_STR_LEN];  /* int max len */
-       int ret;
-
-       strncpy(stream_shm_path, shm_path, PATH_MAX);
-       stream_shm_path[PATH_MAX - 1] = '\0';
-       ret = snprintf(cpu_nr, INT_MAX_STR_LEN, "%i", cpu);
-       if (ret < 0) {
-               PERROR("snprintf");
-               goto end;
-       }
-       strncat(stream_shm_path, cpu_nr,
-               PATH_MAX - strlen(stream_shm_path) - 1);
-       ret = 0;
-end:
-       return ret;
-}
-
-/*
- * Create streams for the given channel using liblttng-ust-ctl.
- * The channel lock must be acquired by the caller.
- *
- * Return 0 on success else a negative value.
- */
-static int create_ust_streams(struct lttng_consumer_channel *channel,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret, cpu = 0;
-       struct lttng_ust_ctl_consumer_stream *ustream;
-       struct lttng_consumer_stream *stream;
-       pthread_mutex_t *current_stream_lock = NULL;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(ctx);
-
-       /*
-        * While a stream is available from ustctl. When NULL is returned, we've
-        * reached the end of the possible stream for the channel.
-        */
-       while ((ustream = lttng_ust_ctl_create_stream(channel->uchan, cpu))) {
-               int wait_fd;
-               int ust_metadata_pipe[2];
-
-               health_code_update();
-
-               if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA && channel->monitor) {
-                       ret = utils_create_pipe_cloexec_nonblock(ust_metadata_pipe);
-                       if (ret < 0) {
-                               ERR("Create ust metadata poll pipe");
-                               goto error;
-                       }
-                       wait_fd = ust_metadata_pipe[0];
-               } else {
-                       wait_fd = lttng_ust_ctl_stream_get_wait_fd(ustream);
-               }
-
-               /* Allocate consumer stream object. */
-               stream = allocate_stream(cpu, wait_fd, channel, ctx, &ret);
-               if (!stream) {
-                       goto error_alloc;
-               }
-               stream->ustream = ustream;
-               /*
-                * Store it so we can save multiple function calls afterwards since
-                * this value is used heavily in the stream threads. This is UST
-                * specific so this is why it's done after allocation.
-                */
-               stream->wait_fd = wait_fd;
-
-               /*
-                * Increment channel refcount since the channel reference has now been
-                * assigned in the allocation process above.
-                */
-               if (stream->chan->monitor) {
-                       uatomic_inc(&stream->chan->refcount);
-               }
-
-               pthread_mutex_lock(&stream->lock);
-               current_stream_lock = &stream->lock;
-               /*
-                * Order is important this is why a list is used. On error, the caller
-                * should clean this list.
-                */
-               cds_list_add_tail(&stream->send_node, &channel->streams.head);
-
-               ret = lttng_ust_ctl_get_max_subbuf_size(stream->ustream,
-                               &stream->max_sb_size);
-               if (ret < 0) {
-                       ERR("lttng_ust_ctl_get_max_subbuf_size failed for stream %s",
-                                       stream->name);
-                       goto error;
-               }
-
-               /* Do actions once stream has been received. */
-               if (ctx->on_recv_stream) {
-                       ret = ctx->on_recv_stream(stream);
-                       if (ret < 0) {
-                               goto error;
-                       }
-               }
-
-               DBG("UST consumer add stream %s (key: %" PRIu64 ") with relayd id %" PRIu64,
-                               stream->name, stream->key, stream->relayd_stream_id);
-
-               /* Set next CPU stream. */
-               channel->streams.count = ++cpu;
-
-               /* Keep stream reference when creating metadata. */
-               if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA) {
-                       channel->metadata_stream = stream;
-                       if (channel->monitor) {
-                               /* Set metadata poll pipe if we created one */
-                               memcpy(stream->ust_metadata_poll_pipe,
-                                               ust_metadata_pipe,
-                                               sizeof(ust_metadata_pipe));
-                       }
-               }
-               pthread_mutex_unlock(&stream->lock);
-               current_stream_lock = NULL;
-       }
-
-       return 0;
-
-error:
-error_alloc:
-       if (current_stream_lock) {
-               pthread_mutex_unlock(current_stream_lock);
-       }
-       return ret;
-}
-
-static int open_ust_stream_fd(struct lttng_consumer_channel *channel, int cpu,
-               const struct lttng_credentials *session_credentials)
-{
-       char shm_path[PATH_MAX];
-       int ret;
-
-       if (!channel->shm_path[0]) {
-               return shm_create_anonymous("ust-consumer");
-       }
-       ret = get_stream_shm_path(shm_path, channel->shm_path, cpu);
-       if (ret) {
-               goto error_shm_path;
-       }
-       return run_as_open(shm_path,
-               O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR,
-               lttng_credentials_get_uid(session_credentials),
-               lttng_credentials_get_gid(session_credentials));
-
-error_shm_path:
-       return -1;
-}
-
-/*
- * Create an UST channel with the given attributes and send it to the session
- * daemon using the ust ctl API.
- *
- * Return 0 on success or else a negative value.
- */
-static int create_ust_channel(struct lttng_consumer_channel *channel,
-               struct lttng_ust_ctl_consumer_channel_attr *attr,
-               struct lttng_ust_ctl_consumer_channel **ust_chanp)
-{
-       int ret, nr_stream_fds, i, j;
-       int *stream_fds;
-       struct lttng_ust_ctl_consumer_channel *ust_channel;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(attr);
-       LTTNG_ASSERT(ust_chanp);
-       LTTNG_ASSERT(channel->buffer_credentials.is_set);
-
-       DBG3("Creating channel to ustctl with attr: [overwrite: %d, "
-                       "subbuf_size: %" PRIu64 ", num_subbuf: %" PRIu64 ", "
-                       "switch_timer_interval: %u, read_timer_interval: %u, "
-                       "output: %d, type: %d", attr->overwrite, attr->subbuf_size,
-                       attr->num_subbuf, attr->switch_timer_interval,
-                       attr->read_timer_interval, attr->output, attr->type);
-
-       if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA)
-               nr_stream_fds = 1;
-       else
-               nr_stream_fds = lttng_ust_ctl_get_nr_stream_per_channel();
-       stream_fds = zmalloc(nr_stream_fds * sizeof(*stream_fds));
-       if (!stream_fds) {
-               ret = -1;
-               goto error_alloc;
-       }
-       for (i = 0; i < nr_stream_fds; i++) {
-               stream_fds[i] = open_ust_stream_fd(channel, i,
-                               &channel->buffer_credentials.value);
-               if (stream_fds[i] < 0) {
-                       ret = -1;
-                       goto error_open;
-               }
-       }
-       ust_channel = lttng_ust_ctl_create_channel(attr, stream_fds, nr_stream_fds);
-       if (!ust_channel) {
-               ret = -1;
-               goto error_create;
-       }
-       channel->nr_stream_fds = nr_stream_fds;
-       channel->stream_fds = stream_fds;
-       *ust_chanp = ust_channel;
-
-       return 0;
-
-error_create:
-error_open:
-       for (j = i - 1; j >= 0; j--) {
-               int closeret;
-
-               closeret = close(stream_fds[j]);
-               if (closeret) {
-                       PERROR("close");
-               }
-               if (channel->shm_path[0]) {
-                       char shm_path[PATH_MAX];
-
-                       closeret = get_stream_shm_path(shm_path,
-                                       channel->shm_path, j);
-                       if (closeret) {
-                               ERR("Cannot get stream shm path");
-                       }
-                       closeret = run_as_unlink(shm_path,
-                                       lttng_credentials_get_uid(LTTNG_OPTIONAL_GET_PTR(
-                                                       channel->buffer_credentials)),
-                                       lttng_credentials_get_gid(LTTNG_OPTIONAL_GET_PTR(
-                                                       channel->buffer_credentials)));
-                       if (closeret) {
-                               PERROR("unlink %s", shm_path);
-                       }
-               }
-       }
-       /* Try to rmdir all directories under shm_path root. */
-       if (channel->root_shm_path[0]) {
-               (void) run_as_rmdir_recursive(channel->root_shm_path,
-                               lttng_credentials_get_uid(LTTNG_OPTIONAL_GET_PTR(
-                                               channel->buffer_credentials)),
-                               lttng_credentials_get_gid(LTTNG_OPTIONAL_GET_PTR(
-                                               channel->buffer_credentials)),
-                               LTTNG_DIRECTORY_HANDLE_SKIP_NON_EMPTY_FLAG);
-       }
-       free(stream_fds);
-error_alloc:
-       return ret;
-}
-
-/*
- * Send a single given stream to the session daemon using the sock.
- *
- * Return 0 on success else a negative value.
- */
-static int send_sessiond_stream(int sock, struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(sock >= 0);
-
-       DBG("UST consumer sending stream %" PRIu64 " to sessiond", stream->key);
-
-       /* Send stream to session daemon. */
-       ret = lttng_ust_ctl_send_stream_to_sessiond(sock, stream->ustream);
-       if (ret < 0) {
-               goto error;
-       }
-
-error:
-       return ret;
-}
-
-/*
- * Send channel to sessiond and relayd if applicable.
- *
- * Return 0 on success or else a negative value.
- */
-static int send_channel_to_sessiond_and_relayd(int sock,
-               struct lttng_consumer_channel *channel,
-               struct lttng_consumer_local_data *ctx, int *relayd_error)
-{
-       int ret, ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-       struct lttng_consumer_stream *stream;
-       uint64_t net_seq_idx = -1ULL;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(ctx);
-       LTTNG_ASSERT(sock >= 0);
-
-       DBG("UST consumer sending channel %s to sessiond", channel->name);
-
-       if (channel->relayd_id != (uint64_t) -1ULL) {
-               cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
-
-                       health_code_update();
-
-                       /* Try to send the stream to the relayd if one is available. */
-                       DBG("Sending stream %" PRIu64 " of channel \"%s\" to relayd",
-                                       stream->key, channel->name);
-                       ret = consumer_send_relayd_stream(stream, stream->chan->pathname);
-                       if (ret < 0) {
-                               /*
-                                * Flag that the relayd was the problem here probably due to a
-                                * communicaton error on the socket.
-                                */
-                               if (relayd_error) {
-                                       *relayd_error = 1;
-                               }
-                               ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
-                       }
-                       if (net_seq_idx == -1ULL) {
-                               net_seq_idx = stream->net_seq_idx;
-                       }
-               }
-       }
-
-       /* Inform sessiond that we are about to send channel and streams. */
-       ret = consumer_send_status_msg(sock, ret_code);
-       if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
-               /*
-                * Either the session daemon is not responding or the relayd died so we
-                * stop now.
-                */
-               goto error;
-       }
-
-       /* Send channel to sessiond. */
-       ret = lttng_ust_ctl_send_channel_to_sessiond(sock, channel->uchan);
-       if (ret < 0) {
-               goto error;
-       }
-
-       ret = lttng_ust_ctl_channel_close_wakeup_fd(channel->uchan);
-       if (ret < 0) {
-               goto error;
-       }
-
-       /* The channel was sent successfully to the sessiond at this point. */
-       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
-
-               health_code_update();
-
-               /* Send stream to session daemon. */
-               ret = send_sessiond_stream(sock, stream);
-               if (ret < 0) {
-                       goto error;
-               }
-       }
-
-       /* Tell sessiond there is no more stream. */
-       ret = lttng_ust_ctl_send_stream_to_sessiond(sock, NULL);
-       if (ret < 0) {
-               goto error;
-       }
-
-       DBG("UST consumer NULL stream sent to sessiond");
-
-       return 0;
-
-error:
-       if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
-               ret = -1;
-       }
-       return ret;
-}
-
-/*
- * Creates a channel and streams and add the channel it to the channel internal
- * state. The created stream must ONLY be sent once the GET_CHANNEL command is
- * received.
- *
- * Return 0 on success or else, a negative value is returned and the channel
- * MUST be destroyed by consumer_del_channel().
- */
-static int ask_channel(struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_channel *channel,
-               struct lttng_ust_ctl_consumer_channel_attr *attr)
-{
-       int ret;
-
-       LTTNG_ASSERT(ctx);
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(attr);
-
-       /*
-        * This value is still used by the kernel consumer since for the kernel,
-        * the stream ownership is not IN the consumer so we need to have the
-        * number of left stream that needs to be initialized so we can know when
-        * to delete the channel (see consumer.c).
-        *
-        * As for the user space tracer now, the consumer creates and sends the
-        * stream to the session daemon which only sends them to the application
-        * once every stream of a channel is received making this value useless
-        * because we they will be added to the poll thread before the application
-        * receives them. This ensures that a stream can not hang up during
-        * initilization of a channel.
-        */
-       channel->nb_init_stream_left = 0;
-
-       /* The reply msg status is handled in the following call. */
-       ret = create_ust_channel(channel, attr, &channel->uchan);
-       if (ret < 0) {
-               goto end;
-       }
-
-       channel->wait_fd = lttng_ust_ctl_channel_get_wait_fd(channel->uchan);
-
-       /*
-        * For the snapshots (no monitor), we create the metadata streams
-        * on demand, not during the channel creation.
-        */
-       if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA && !channel->monitor) {
-               ret = 0;
-               goto end;
-       }
-
-       /* Open all streams for this channel. */
-       pthread_mutex_lock(&channel->lock);
-       ret = create_ust_streams(channel, ctx);
-       pthread_mutex_unlock(&channel->lock);
-       if (ret < 0) {
-               goto end;
-       }
-
-end:
-       return ret;
-}
-
-/*
- * Send all stream of a channel to the right thread handling it.
- *
- * On error, return a negative value else 0 on success.
- */
-static int send_streams_to_thread(struct lttng_consumer_channel *channel,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret = 0;
-       struct lttng_consumer_stream *stream, *stmp;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(ctx);
-
-       /* Send streams to the corresponding thread. */
-       cds_list_for_each_entry_safe(stream, stmp, &channel->streams.head,
-                       send_node) {
-
-               health_code_update();
-
-               /* Sending the stream to the thread. */
-               ret = send_stream_to_thread(stream, ctx);
-               if (ret < 0) {
-                       /*
-                        * If we are unable to send the stream to the thread, there is
-                        * a big problem so just stop everything.
-                        */
-                       goto error;
-               }
-       }
-
-error:
-       return ret;
-}
-
-/*
- * Flush channel's streams using the given key to retrieve the channel.
- *
- * Return 0 on success else an LTTng error code.
- */
-static int flush_channel(uint64_t chan_key)
-{
-       int ret = 0;
-       struct lttng_consumer_channel *channel;
-       struct lttng_consumer_stream *stream;
-       struct lttng_ht *ht;
-       struct lttng_ht_iter iter;
-
-       DBG("UST consumer flush channel key %" PRIu64, chan_key);
-
-       rcu_read_lock();
-       channel = consumer_find_channel(chan_key);
-       if (!channel) {
-               ERR("UST consumer flush channel %" PRIu64 " not found", chan_key);
-               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
-               goto error;
-       }
-
-       ht = the_consumer_data.stream_per_chan_id_ht;
-
-       /* For each stream of the channel id, flush it. */
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&channel->key, lttng_ht_seed), ht->match_fct,
-                       &channel->key, &iter.iter, stream, node_channel_id.node) {
-
-               health_code_update();
-
-               pthread_mutex_lock(&stream->lock);
-
-               /*
-                * Protect against concurrent teardown of a stream.
-                */
-               if (cds_lfht_is_node_deleted(&stream->node.node)) {
-                       goto next;
-               }
-
-               if (!stream->quiescent) {
-                       ret = lttng_ust_ctl_flush_buffer(stream->ustream, 0);
-                       if (ret) {
-                               ERR("Failed to flush buffer while flushing channel: channel key = %" PRIu64 ", channel name = '%s'",
-                                               chan_key, channel->name);
-                               ret = LTTNG_ERR_BUFFER_FLUSH_FAILED;
-                               pthread_mutex_unlock(&stream->lock);
-                               goto error;
-                       }
-                       stream->quiescent = true;
-               }
-next:
-               pthread_mutex_unlock(&stream->lock);
-       }
-error:
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Clear quiescent state from channel's streams using the given key to
- * retrieve the channel.
- *
- * Return 0 on success else an LTTng error code.
- */
-static int clear_quiescent_channel(uint64_t chan_key)
-{
-       int ret = 0;
-       struct lttng_consumer_channel *channel;
-       struct lttng_consumer_stream *stream;
-       struct lttng_ht *ht;
-       struct lttng_ht_iter iter;
-
-       DBG("UST consumer clear quiescent channel key %" PRIu64, chan_key);
-
-       rcu_read_lock();
-       channel = consumer_find_channel(chan_key);
-       if (!channel) {
-               ERR("UST consumer clear quiescent channel %" PRIu64 " not found", chan_key);
-               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
-               goto error;
-       }
-
-       ht = the_consumer_data.stream_per_chan_id_ht;
-
-       /* For each stream of the channel id, clear quiescent state. */
-       cds_lfht_for_each_entry_duplicate(ht->ht,
-                       ht->hash_fct(&channel->key, lttng_ht_seed), ht->match_fct,
-                       &channel->key, &iter.iter, stream, node_channel_id.node) {
-
-               health_code_update();
-
-               pthread_mutex_lock(&stream->lock);
-               stream->quiescent = false;
-               pthread_mutex_unlock(&stream->lock);
-       }
-error:
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Close metadata stream wakeup_fd using the given key to retrieve the channel.
- *
- * Return 0 on success else an LTTng error code.
- */
-static int close_metadata(uint64_t chan_key)
-{
-       int ret = 0;
-       struct lttng_consumer_channel *channel;
-       unsigned int channel_monitor;
-
-       DBG("UST consumer close metadata key %" PRIu64, chan_key);
-
-       channel = consumer_find_channel(chan_key);
-       if (!channel) {
-               /*
-                * This is possible if the metadata thread has issue a delete because
-                * the endpoint point of the stream hung up. There is no way the
-                * session daemon can know about it thus use a DBG instead of an actual
-                * error.
-                */
-               DBG("UST consumer close metadata %" PRIu64 " not found", chan_key);
-               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
-               goto error;
-       }
-
-       pthread_mutex_lock(&the_consumer_data.lock);
-       pthread_mutex_lock(&channel->lock);
-       channel_monitor = channel->monitor;
-       if (cds_lfht_is_node_deleted(&channel->node.node)) {
-               goto error_unlock;
-       }
-
-       lttng_ustconsumer_close_metadata(channel);
-       pthread_mutex_unlock(&channel->lock);
-       pthread_mutex_unlock(&the_consumer_data.lock);
-
-       /*
-        * The ownership of a metadata channel depends on the type of
-        * session to which it belongs. In effect, the monitor flag is checked
-        * to determine if this metadata channel is in "snapshot" mode or not.
-        *
-        * In the non-snapshot case, the metadata channel is created along with
-        * a single stream which will remain present until the metadata channel
-        * is destroyed (on the destruction of its session). In this case, the
-        * metadata stream in "monitored" by the metadata poll thread and holds
-        * the ownership of its channel.
-        *
-        * Closing the metadata will cause the metadata stream's "metadata poll
-        * pipe" to be closed. Closing this pipe will wake-up the metadata poll
-        * thread which will teardown the metadata stream which, in return,
-        * deletes the metadata channel.
-        *
-        * In the snapshot case, the metadata stream is created and destroyed
-        * on every snapshot record. Since the channel doesn't have an owner
-        * other than the session daemon, it is safe to destroy it immediately
-        * on reception of the CLOSE_METADATA command.
-        */
-       if (!channel_monitor) {
-               /*
-                * The channel and consumer_data locks must be
-                * released before this call since consumer_del_channel
-                * re-acquires the channel and consumer_data locks to teardown
-                * the channel and queue its reclamation by the "call_rcu"
-                * worker thread.
-                */
-               consumer_del_channel(channel);
-       }
-
-       return ret;
-error_unlock:
-       pthread_mutex_unlock(&channel->lock);
-       pthread_mutex_unlock(&the_consumer_data.lock);
-error:
-       return ret;
-}
-
-/*
- * RCU read side lock MUST be acquired before calling this function.
- *
- * Return 0 on success else an LTTng error code.
- */
-static int setup_metadata(struct lttng_consumer_local_data *ctx, uint64_t key)
-{
-       int ret;
-       struct lttng_consumer_channel *metadata;
-
-       DBG("UST consumer setup metadata key %" PRIu64, key);
-
-       metadata = consumer_find_channel(key);
-       if (!metadata) {
-               ERR("UST consumer push metadata %" PRIu64 " not found", key);
-               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
-               goto end;
-       }
-
-       /*
-        * In no monitor mode, the metadata channel has no stream(s) so skip the
-        * ownership transfer to the metadata thread.
-        */
-       if (!metadata->monitor) {
-               DBG("Metadata channel in no monitor");
-               ret = 0;
-               goto end;
-       }
-
-       /*
-        * Send metadata stream to relayd if one available. Availability is
-        * known if the stream is still in the list of the channel.
-        */
-       if (cds_list_empty(&metadata->streams.head)) {
-               ERR("Metadata channel key %" PRIu64 ", no stream available.", key);
-               ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
-               goto error_no_stream;
-       }
-
-       /* Send metadata stream to relayd if needed. */
-       if (metadata->metadata_stream->net_seq_idx != (uint64_t) -1ULL) {
-               ret = consumer_send_relayd_stream(metadata->metadata_stream,
-                               metadata->pathname);
-               if (ret < 0) {
-                       ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
-                       goto error;
-               }
-               ret = consumer_send_relayd_streams_sent(
-                               metadata->metadata_stream->net_seq_idx);
-               if (ret < 0) {
-                       ret = LTTCOMM_CONSUMERD_RELAYD_FAIL;
-                       goto error;
-               }
-       }
-
-       /*
-        * Ownership of metadata stream is passed along. Freeing is handled by
-        * the callee.
-        */
-       ret = send_streams_to_thread(metadata, ctx);
-       if (ret < 0) {
-               /*
-                * If we are unable to send the stream to the thread, there is
-                * a big problem so just stop everything.
-                */
-               ret = LTTCOMM_CONSUMERD_FATAL;
-               goto send_streams_error;
-       }
-       /* List MUST be empty after or else it could be reused. */
-       LTTNG_ASSERT(cds_list_empty(&metadata->streams.head));
-
-       ret = 0;
-       goto end;
-
-error:
-       /*
-        * Delete metadata channel on error. At this point, the metadata stream can
-        * NOT be monitored by the metadata thread thus having the guarantee that
-        * the stream is still in the local stream list of the channel. This call
-        * will make sure to clean that list.
-        */
-       consumer_stream_destroy(metadata->metadata_stream, NULL);
-       cds_list_del(&metadata->metadata_stream->send_node);
-       metadata->metadata_stream = NULL;
-send_streams_error:
-error_no_stream:
-end:
-       return ret;
-}
-
-/*
- * Snapshot the whole metadata.
- * RCU read-side lock must be held by the caller.
- *
- * Returns 0 on success, < 0 on error
- */
-static int snapshot_metadata(struct lttng_consumer_channel *metadata_channel,
-               uint64_t key, char *path, uint64_t relayd_id,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret = 0;
-       struct lttng_consumer_stream *metadata_stream;
-
-       LTTNG_ASSERT(path);
-       LTTNG_ASSERT(ctx);
-
-       DBG("UST consumer snapshot metadata with key %" PRIu64 " at path %s",
-                       key, path);
-
-       rcu_read_lock();
-
-       LTTNG_ASSERT(!metadata_channel->monitor);
-
-       health_code_update();
-
-       /*
-        * Ask the sessiond if we have new metadata waiting and update the
-        * consumer metadata cache.
-        */
-       ret = lttng_ustconsumer_request_metadata(ctx, metadata_channel, 0, 1);
-       if (ret < 0) {
-               goto error;
-       }
-
-       health_code_update();
-
-       /*
-        * The metadata stream is NOT created in no monitor mode when the channel
-        * is created on a sessiond ask channel command.
-        */
-       ret = create_ust_streams(metadata_channel, ctx);
-       if (ret < 0) {
-               goto error;
-       }
-
-       metadata_stream = metadata_channel->metadata_stream;
-       LTTNG_ASSERT(metadata_stream);
-
-       pthread_mutex_lock(&metadata_stream->lock);
-       if (relayd_id != (uint64_t) -1ULL) {
-               metadata_stream->net_seq_idx = relayd_id;
-               ret = consumer_send_relayd_stream(metadata_stream, path);
-       } else {
-               ret = consumer_stream_create_output_files(metadata_stream,
-                               false);
-       }
-       pthread_mutex_unlock(&metadata_stream->lock);
-       if (ret < 0) {
-               goto error_stream;
-       }
-
-       do {
-               health_code_update();
-
-               ret = lttng_consumer_read_subbuffer(metadata_stream, ctx, true);
-               if (ret < 0) {
-                       goto error_stream;
-               }
-       } while (ret > 0);
-
-error_stream:
-       /*
-        * Clean up the stream completly because the next snapshot will use a new
-        * metadata stream.
-        */
-       consumer_stream_destroy(metadata_stream, NULL);
-       cds_list_del(&metadata_stream->send_node);
-       metadata_channel->metadata_stream = NULL;
-
-error:
-       rcu_read_unlock();
-       return ret;
-}
-
-static
-int get_current_subbuf_addr(struct lttng_consumer_stream *stream,
-               const char **addr)
-{
-       int ret;
-       unsigned long mmap_offset;
-       const char *mmap_base;
-
-       mmap_base = lttng_ust_ctl_get_mmap_base(stream->ustream);
-       if (!mmap_base) {
-               ERR("Failed to get mmap base for stream `%s`",
-                               stream->name);
-               ret = -EPERM;
-               goto error;
-       }
-
-       ret = lttng_ust_ctl_get_mmap_read_offset(stream->ustream, &mmap_offset);
-       if (ret != 0) {
-               ERR("Failed to get mmap offset for stream `%s`", stream->name);
-               ret = -EINVAL;
-               goto error;
-       }
-
-       *addr = mmap_base + mmap_offset;
-error:
-       return ret;
-
-}
-
-/*
- * Take a snapshot of all the stream of a channel.
- * RCU read-side lock and the channel lock must be held by the caller.
- *
- * Returns 0 on success, < 0 on error
- */
-static int snapshot_channel(struct lttng_consumer_channel *channel,
-               uint64_t key, char *path, uint64_t relayd_id,
-               uint64_t nb_packets_per_stream,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret;
-       unsigned use_relayd = 0;
-       unsigned long consumed_pos, produced_pos;
-       struct lttng_consumer_stream *stream;
-
-       LTTNG_ASSERT(path);
-       LTTNG_ASSERT(ctx);
-
-       rcu_read_lock();
-
-       if (relayd_id != (uint64_t) -1ULL) {
-               use_relayd = 1;
-       }
-
-       LTTNG_ASSERT(!channel->monitor);
-       DBG("UST consumer snapshot channel %" PRIu64, key);
-
-       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
-               health_code_update();
-
-               /* Lock stream because we are about to change its state. */
-               pthread_mutex_lock(&stream->lock);
-               LTTNG_ASSERT(channel->trace_chunk);
-               if (!lttng_trace_chunk_get(channel->trace_chunk)) {
-                       /*
-                        * Can't happen barring an internal error as the channel
-                        * holds a reference to the trace chunk.
-                        */
-                       ERR("Failed to acquire reference to channel's trace chunk");
-                       ret = -1;
-                       goto error_unlock;
-               }
-               LTTNG_ASSERT(!stream->trace_chunk);
-               stream->trace_chunk = channel->trace_chunk;
-
-               stream->net_seq_idx = relayd_id;
-
-               if (use_relayd) {
-                       ret = consumer_send_relayd_stream(stream, path);
-                       if (ret < 0) {
-                               goto error_unlock;
-                       }
-               } else {
-                       ret = consumer_stream_create_output_files(stream,
-                                       false);
-                       if (ret < 0) {
-                               goto error_unlock;
-                       }
-                       DBG("UST consumer snapshot stream (%" PRIu64 ")",
-                                       stream->key);
-               }
-
-               /*
-                * If tracing is active, we want to perform a "full" buffer flush.
-                * Else, if quiescent, it has already been done by the prior stop.
-                */
-               if (!stream->quiescent) {
-                       ret = lttng_ust_ctl_flush_buffer(stream->ustream, 0);
-                       if (ret < 0) {
-                               ERR("Failed to flush buffer during snapshot of channel: channel key = %" PRIu64 ", channel name = '%s'",
-                                               channel->key, channel->name);
-                               goto error_unlock;
-                       }
-               }
-
-               ret = lttng_ustconsumer_take_snapshot(stream);
-               if (ret < 0) {
-                       ERR("Taking UST snapshot");
-                       goto error_unlock;
-               }
-
-               ret = lttng_ustconsumer_get_produced_snapshot(stream, &produced_pos);
-               if (ret < 0) {
-                       ERR("Produced UST snapshot position");
-                       goto error_unlock;
-               }
-
-               ret = lttng_ustconsumer_get_consumed_snapshot(stream, &consumed_pos);
-               if (ret < 0) {
-                       ERR("Consumerd UST snapshot position");
-                       goto error_unlock;
-               }
-
-               /*
-                * The original value is sent back if max stream size is larger than
-                * the possible size of the snapshot. Also, we assume that the session
-                * daemon should never send a maximum stream size that is lower than
-                * subbuffer size.
-                */
-               consumed_pos = consumer_get_consume_start_pos(consumed_pos,
-                               produced_pos, nb_packets_per_stream,
-                               stream->max_sb_size);
-
-               while ((long) (consumed_pos - produced_pos) < 0) {
-                       ssize_t read_len;
-                       unsigned long len, padded_len;
-                       const char *subbuf_addr;
-                       struct lttng_buffer_view subbuf_view;
-
-                       health_code_update();
-
-                       DBG("UST consumer taking snapshot at pos %lu", consumed_pos);
-
-                       ret = lttng_ust_ctl_get_subbuf(stream->ustream, &consumed_pos);
-                       if (ret < 0) {
-                               if (ret != -EAGAIN) {
-                                       PERROR("lttng_ust_ctl_get_subbuf snapshot");
-                                       goto error_close_stream;
-                               }
-                               DBG("UST consumer get subbuf failed. Skipping it.");
-                               consumed_pos += stream->max_sb_size;
-                               stream->chan->lost_packets++;
-                               continue;
-                       }
-
-                       ret = lttng_ust_ctl_get_subbuf_size(stream->ustream, &len);
-                       if (ret < 0) {
-                               ERR("Snapshot lttng_ust_ctl_get_subbuf_size");
-                               goto error_put_subbuf;
-                       }
-
-                       ret = lttng_ust_ctl_get_padded_subbuf_size(stream->ustream, &padded_len);
-                       if (ret < 0) {
-                               ERR("Snapshot lttng_ust_ctl_get_padded_subbuf_size");
-                               goto error_put_subbuf;
-                       }
-
-                       ret = get_current_subbuf_addr(stream, &subbuf_addr);
-                       if (ret) {
-                               goto error_put_subbuf;
-                       }
-
-                       subbuf_view = lttng_buffer_view_init(
-                                       subbuf_addr, 0, padded_len);
-                       read_len = lttng_consumer_on_read_subbuffer_mmap(
-                                       stream, &subbuf_view, padded_len - len);
-                       if (use_relayd) {
-                               if (read_len != len) {
-                                       ret = -EPERM;
-                                       goto error_put_subbuf;
-                               }
-                       } else {
-                               if (read_len != padded_len) {
-                                       ret = -EPERM;
-                                       goto error_put_subbuf;
-                               }
-                       }
-
-                       ret = lttng_ust_ctl_put_subbuf(stream->ustream);
-                       if (ret < 0) {
-                               ERR("Snapshot lttng_ust_ctl_put_subbuf");
-                               goto error_close_stream;
-                       }
-                       consumed_pos += stream->max_sb_size;
-               }
-
-               /* Simply close the stream so we can use it on the next snapshot. */
-               consumer_stream_close(stream);
-               pthread_mutex_unlock(&stream->lock);
-       }
-
-       rcu_read_unlock();
-       return 0;
-
-error_put_subbuf:
-       if (lttng_ust_ctl_put_subbuf(stream->ustream) < 0) {
-               ERR("Snapshot lttng_ust_ctl_put_subbuf");
-       }
-error_close_stream:
-       consumer_stream_close(stream);
-error_unlock:
-       pthread_mutex_unlock(&stream->lock);
-       rcu_read_unlock();
-       return ret;
-}
-
-static
-void metadata_stream_reset_cache_consumed_position(
-               struct lttng_consumer_stream *stream)
-{
-       ASSERT_LOCKED(stream->lock);
-
-       DBG("Reset metadata cache of session %" PRIu64,
-                       stream->chan->session_id);
-       stream->ust_metadata_pushed = 0;
-}
-
-/*
- * Receive the metadata updates from the sessiond. Supports receiving
- * overlapping metadata, but is needs to always belong to a contiguous
- * range starting from 0.
- * Be careful about the locks held when calling this function: it needs
- * the metadata cache flush to concurrently progress in order to
- * complete.
- */
-int lttng_ustconsumer_recv_metadata(int sock, uint64_t key, uint64_t offset,
-               uint64_t len, uint64_t version,
-               struct lttng_consumer_channel *channel, int timer, int wait)
-{
-       int ret, ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-       char *metadata_str;
-       enum consumer_metadata_cache_write_status cache_write_status;
-
-       DBG("UST consumer push metadata key %" PRIu64 " of len %" PRIu64, key, len);
-
-       metadata_str = zmalloc(len * sizeof(char));
-       if (!metadata_str) {
-               PERROR("zmalloc metadata string");
-               ret_code = LTTCOMM_CONSUMERD_ENOMEM;
-               goto end;
-       }
-
-       health_code_update();
-
-       /* Receive metadata string. */
-       ret = lttcomm_recv_unix_sock(sock, metadata_str, len);
-       if (ret < 0) {
-               /* Session daemon is dead so return gracefully. */
-               ret_code = ret;
-               goto end_free;
-       }
-
-       health_code_update();
-
-       pthread_mutex_lock(&channel->metadata_cache->lock);
-       cache_write_status = consumer_metadata_cache_write(
-                       channel->metadata_cache, offset, len, version,
-                       metadata_str);
-       pthread_mutex_unlock(&channel->metadata_cache->lock);
-       switch (cache_write_status) {
-       case CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE:
-               /*
-                * The write entirely overlapped with existing contents of the
-                * same metadata version (same content); there is nothing to do.
-                */
-               break;
-       case CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED:
-               /*
-                * The metadata cache was invalidated (previously pushed
-                * content has been overwritten). Reset the stream's consumed
-                * metadata position to ensure the metadata poll thread consumes
-                * the whole cache.
-                */
-               pthread_mutex_lock(&channel->metadata_stream->lock);
-               metadata_stream_reset_cache_consumed_position(
-                               channel->metadata_stream);
-               pthread_mutex_unlock(&channel->metadata_stream->lock);
-               /* Fall-through. */
-       case CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT:
-               /*
-                * In both cases, the metadata poll thread has new data to
-                * consume.
-                */
-               ret = consumer_metadata_wakeup_pipe(channel);
-               if (ret) {
-                       ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
-                       goto end_free;
-               }
-               break;
-       case CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR:
-               /* Unable to handle metadata. Notify session daemon. */
-               ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
-               /*
-                * Skip metadata flush on write error since the offset and len might
-                * not have been updated which could create an infinite loop below when
-                * waiting for the metadata cache to be flushed.
-                */
-               goto end_free;
-       default:
-               abort();
-       }
-
-       if (!wait) {
-               goto end_free;
-       }
-       while (consumer_metadata_cache_flushed(channel, offset + len, timer)) {
-               DBG("Waiting for metadata to be flushed");
-
-               health_code_update();
-
-               usleep(DEFAULT_METADATA_AVAILABILITY_WAIT_TIME);
-       }
-
-end_free:
-       free(metadata_str);
-end:
-       return ret_code;
-}
-
-/*
- * Receive command from session daemon and process it.
- *
- * Return 1 on success else a negative value or 0.
- */
-int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
-               int sock, struct pollfd *consumer_sockpoll)
-{
-       int ret_func;
-       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-       struct lttcomm_consumer_msg msg;
-       struct lttng_consumer_channel *channel = NULL;
-
-       health_code_update();
-
-       {
-               ssize_t ret_recv;
-
-               ret_recv = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
-               if (ret_recv != sizeof(msg)) {
-                       DBG("Consumer received unexpected message size %zd (expects %zu)",
-                                       ret_recv, sizeof(msg));
-                       /*
-                        * The ret value might 0 meaning an orderly shutdown but this is ok
-                        * since the caller handles this.
-                        */
-                       if (ret_recv > 0) {
-                               lttng_consumer_send_error(ctx,
-                                               LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
-                               ret_recv = -1;
-                       }
-                       return ret_recv;
-               }
-       }
-
-       health_code_update();
-
-       /* deprecated */
-       LTTNG_ASSERT(msg.cmd_type != LTTNG_CONSUMER_STOP);
-
-       health_code_update();
-
-       /* relayd needs RCU read-side lock */
-       rcu_read_lock();
-
-       switch (msg.cmd_type) {
-       case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
-       {
-               /* Session daemon status message are handled in the following call. */
-               consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
-                               msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
-                               &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
-                               msg.u.relayd_sock.relayd_session_id);
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_DESTROY_RELAYD:
-       {
-               uint64_t index = msg.u.destroy_relayd.net_seq_idx;
-               struct consumer_relayd_sock_pair *relayd;
-
-               DBG("UST consumer destroying relayd %" PRIu64, index);
-
-               /* Get relayd reference if exists. */
-               relayd = consumer_find_relayd(index);
-               if (relayd == NULL) {
-                       DBG("Unable to find relayd %" PRIu64, index);
-                       ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
-               }
-
-               /*
-                * Each relayd socket pair has a refcount of stream attached to it
-                * which tells if the relayd is still active or not depending on the
-                * refcount value.
-                *
-                * This will set the destroy flag of the relayd object and destroy it
-                * if the refcount reaches zero when called.
-                *
-                * The destroy can happen either here or when a stream fd hangs up.
-                */
-               if (relayd) {
-                       consumer_flag_relayd_for_destroy(relayd);
-               }
-
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_UPDATE_STREAM:
-       {
-               rcu_read_unlock();
-               return -ENOSYS;
-       }
-       case LTTNG_CONSUMER_DATA_PENDING:
-       {
-               int is_data_pending;
-               ssize_t ret_send;
-               uint64_t id = msg.u.data_pending.session_id;
-
-               DBG("UST consumer data pending command for id %" PRIu64, id);
-
-               is_data_pending = consumer_data_pending(id);
-
-               /* Send back returned value to session daemon */
-               ret_send = lttcomm_send_unix_sock(sock, &is_data_pending,
-                               sizeof(is_data_pending));
-               if (ret_send < 0) {
-                       DBG("Error when sending the data pending ret code: %zd",
-                                       ret_send);
-                       goto error_fatal;
-               }
-
-               /*
-                * No need to send back a status message since the data pending
-                * returned value is the response.
-                */
-               break;
-       }
-       case LTTNG_CONSUMER_ASK_CHANNEL_CREATION:
-       {
-               int ret_ask_channel, ret_add_channel, ret_send;
-               struct lttng_ust_ctl_consumer_channel_attr attr;
-               const uint64_t chunk_id = msg.u.ask_channel.chunk_id.value;
-               const struct lttng_credentials buffer_credentials = {
-                       .uid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.ask_channel.buffer_credentials.uid),
-                       .gid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.ask_channel.buffer_credentials.gid),
-               };
-
-               /* Create a plain object and reserve a channel key. */
-               channel = consumer_allocate_channel(
-                               msg.u.ask_channel.key,
-                               msg.u.ask_channel.session_id,
-                               msg.u.ask_channel.chunk_id.is_set ?
-                                               &chunk_id : NULL,
-                               msg.u.ask_channel.pathname,
-                               msg.u.ask_channel.name,
-                               msg.u.ask_channel.relayd_id,
-                               (enum lttng_event_output) msg.u.ask_channel.output,
-                               msg.u.ask_channel.tracefile_size,
-                               msg.u.ask_channel.tracefile_count,
-                               msg.u.ask_channel.session_id_per_pid,
-                               msg.u.ask_channel.monitor,
-                               msg.u.ask_channel.live_timer_interval,
-                               msg.u.ask_channel.is_live,
-                               msg.u.ask_channel.root_shm_path,
-                               msg.u.ask_channel.shm_path);
-               if (!channel) {
-                       goto end_channel_error;
-               }
-
-               LTTNG_OPTIONAL_SET(&channel->buffer_credentials,
-                               buffer_credentials);
-
-               /*
-                * Assign UST application UID to the channel. This value is ignored for
-                * per PID buffers. This is specific to UST thus setting this after the
-                * allocation.
-                */
-               channel->ust_app_uid = msg.u.ask_channel.ust_app_uid;
-
-               /* Build channel attributes from received message. */
-               attr.subbuf_size = msg.u.ask_channel.subbuf_size;
-               attr.num_subbuf = msg.u.ask_channel.num_subbuf;
-               attr.overwrite = msg.u.ask_channel.overwrite;
-               attr.switch_timer_interval = msg.u.ask_channel.switch_timer_interval;
-               attr.read_timer_interval = msg.u.ask_channel.read_timer_interval;
-               attr.chan_id = msg.u.ask_channel.chan_id;
-               memcpy(attr.uuid, msg.u.ask_channel.uuid, sizeof(attr.uuid));
-               attr.blocking_timeout= msg.u.ask_channel.blocking_timeout;
-
-               /* Match channel buffer type to the UST abi. */
-               switch (msg.u.ask_channel.output) {
-               case LTTNG_EVENT_MMAP:
-               default:
-                       attr.output = LTTNG_UST_ABI_MMAP;
-                       break;
-               }
-
-               /* Translate and save channel type. */
-               switch (msg.u.ask_channel.type) {
-               case LTTNG_UST_ABI_CHAN_PER_CPU:
-                       channel->type = CONSUMER_CHANNEL_TYPE_DATA;
-                       attr.type = LTTNG_UST_ABI_CHAN_PER_CPU;
-                       /*
-                        * Set refcount to 1 for owner. Below, we will
-                        * pass ownership to the
-                        * consumer_thread_channel_poll() thread.
-                        */
-                       channel->refcount = 1;
-                       break;
-               case LTTNG_UST_ABI_CHAN_METADATA:
-                       channel->type = CONSUMER_CHANNEL_TYPE_METADATA;
-                       attr.type = LTTNG_UST_ABI_CHAN_METADATA;
-                       break;
-               default:
-                       abort();
-                       goto error_fatal;
-               };
-
-               health_code_update();
-
-               ret_ask_channel = ask_channel(ctx, channel, &attr);
-               if (ret_ask_channel < 0) {
-                       goto end_channel_error;
-               }
-
-               if (msg.u.ask_channel.type == LTTNG_UST_ABI_CHAN_METADATA) {
-                       int ret_allocate;
-
-                       ret_allocate = consumer_metadata_cache_allocate(
-                                       channel);
-                       if (ret_allocate < 0) {
-                               ERR("Allocating metadata cache");
-                               goto end_channel_error;
-                       }
-                       consumer_timer_switch_start(channel, attr.switch_timer_interval);
-                       attr.switch_timer_interval = 0;
-               } else {
-                       int monitor_start_ret;
-
-                       consumer_timer_live_start(channel,
-                                       msg.u.ask_channel.live_timer_interval);
-                       monitor_start_ret = consumer_timer_monitor_start(
-                                       channel,
-                                       msg.u.ask_channel.monitor_timer_interval);
-                       if (monitor_start_ret < 0) {
-                               ERR("Starting channel monitoring timer failed");
-                               goto end_channel_error;
-                       }
-               }
-
-               health_code_update();
-
-               /*
-                * Add the channel to the internal state AFTER all streams were created
-                * and successfully sent to session daemon. This way, all streams must
-                * be ready before this channel is visible to the threads.
-                * If add_channel succeeds, ownership of the channel is
-                * passed to consumer_thread_channel_poll().
-                */
-               ret_add_channel = add_channel(channel, ctx);
-               if (ret_add_channel < 0) {
-                       if (msg.u.ask_channel.type == LTTNG_UST_ABI_CHAN_METADATA) {
-                               if (channel->switch_timer_enabled == 1) {
-                                       consumer_timer_switch_stop(channel);
-                               }
-                               consumer_metadata_cache_destroy(channel);
-                       }
-                       if (channel->live_timer_enabled == 1) {
-                               consumer_timer_live_stop(channel);
-                       }
-                       if (channel->monitor_timer_enabled == 1) {
-                               consumer_timer_monitor_stop(channel);
-                       }
-                       goto end_channel_error;
-               }
-
-               health_code_update();
-
-               /*
-                * Channel and streams are now created. Inform the session daemon that
-                * everything went well and should wait to receive the channel and
-                * streams with ustctl API.
-                */
-               ret_send = consumer_send_status_channel(sock, channel);
-               if (ret_send < 0) {
-                       /*
-                        * There is probably a problem on the socket.
-                        */
-                       goto error_fatal;
-               }
-
-               break;
-       }
-       case LTTNG_CONSUMER_GET_CHANNEL:
-       {
-               int ret, relayd_err = 0;
-               uint64_t key = msg.u.get_channel.key;
-               struct lttng_consumer_channel *found_channel;
-
-               found_channel = consumer_find_channel(key);
-               if (!found_channel) {
-                       ERR("UST consumer get channel key %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-                       goto end_get_channel;
-               }
-
-               health_code_update();
-
-               /* Send the channel to sessiond (and relayd, if applicable). */
-               ret = send_channel_to_sessiond_and_relayd(
-                               sock, found_channel, ctx, &relayd_err);
-               if (ret < 0) {
-                       if (relayd_err) {
-                               /*
-                                * We were unable to send to the relayd the stream so avoid
-                                * sending back a fatal error to the thread since this is OK
-                                * and the consumer can continue its work. The above call
-                                * has sent the error status message to the sessiond.
-                                */
-                               goto end_get_channel_nosignal;
-                       }
-                       /*
-                        * The communicaton was broken hence there is a bad state between
-                        * the consumer and sessiond so stop everything.
-                        */
-                       goto error_get_channel_fatal;
-               }
-
-               health_code_update();
-
-               /*
-                * In no monitor mode, the streams ownership is kept inside the channel
-                * so don't send them to the data thread.
-                */
-               if (!found_channel->monitor) {
-                       goto end_get_channel;
-               }
-
-               ret = send_streams_to_thread(found_channel, ctx);
-               if (ret < 0) {
-                       /*
-                        * If we are unable to send the stream to the thread, there is
-                        * a big problem so just stop everything.
-                        */
-                       goto error_get_channel_fatal;
-               }
-               /* List MUST be empty after or else it could be reused. */
-               LTTNG_ASSERT(cds_list_empty(&found_channel->streams.head));
-end_get_channel:
-               goto end_msg_sessiond;
-error_get_channel_fatal:
-               goto error_fatal;
-end_get_channel_nosignal:
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_DESTROY_CHANNEL:
-       {
-               uint64_t key = msg.u.destroy_channel.key;
-
-               /*
-                * Only called if streams have not been sent to stream
-                * manager thread. However, channel has been sent to
-                * channel manager thread.
-                */
-               notify_thread_del_channel(ctx, key);
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_CLOSE_METADATA:
-       {
-               int ret;
-
-               ret = close_metadata(msg.u.close_metadata.key);
-               if (ret != 0) {
-                       ret_code = ret;
-               }
-
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_FLUSH_CHANNEL:
-       {
-               int ret;
-
-               ret = flush_channel(msg.u.flush_channel.key);
-               if (ret != 0) {
-                       ret_code = ret;
-               }
-
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_CLEAR_QUIESCENT_CHANNEL:
-       {
-               int ret;
-
-               ret = clear_quiescent_channel(
-                               msg.u.clear_quiescent_channel.key);
-               if (ret != 0) {
-                       ret_code = ret;
-               }
-
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_PUSH_METADATA:
-       {
-               int ret;
-               uint64_t len = msg.u.push_metadata.len;
-               uint64_t key = msg.u.push_metadata.key;
-               uint64_t offset = msg.u.push_metadata.target_offset;
-               uint64_t version = msg.u.push_metadata.version;
-               struct lttng_consumer_channel *found_channel;
-
-               DBG("UST consumer push metadata key %" PRIu64 " of len %" PRIu64, key,
-                               len);
-
-               found_channel = consumer_find_channel(key);
-               if (!found_channel) {
-                       /*
-                        * This is possible if the metadata creation on the consumer side
-                        * is in flight vis-a-vis a concurrent push metadata from the
-                        * session daemon.  Simply return that the channel failed and the
-                        * session daemon will handle that message correctly considering
-                        * that this race is acceptable thus the DBG() statement here.
-                        */
-                       DBG("UST consumer push metadata %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHANNEL_FAIL;
-                       goto end_push_metadata_msg_sessiond;
-               }
-
-               health_code_update();
-
-               if (!len) {
-                       /*
-                        * There is nothing to receive. We have simply
-                        * checked whether the channel can be found.
-                        */
-                       ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-                       goto end_push_metadata_msg_sessiond;
-               }
-
-               /* Tell session daemon we are ready to receive the metadata. */
-               ret = consumer_send_status_msg(sock, LTTCOMM_CONSUMERD_SUCCESS);
-               if (ret < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto error_push_metadata_fatal;
-               }
-
-               health_code_update();
-
-               /* Wait for more data. */
-               health_poll_entry();
-               ret = lttng_consumer_poll_socket(consumer_sockpoll);
-               health_poll_exit();
-               if (ret) {
-                       goto error_push_metadata_fatal;
-               }
-
-               health_code_update();
-
-               ret = lttng_ustconsumer_recv_metadata(sock, key, offset, len,
-                               version, found_channel, 0, 1);
-               if (ret < 0) {
-                       /* error receiving from sessiond */
-                       goto error_push_metadata_fatal;
-               } else {
-                       ret_code = ret;
-                       goto end_push_metadata_msg_sessiond;
-               }
-end_push_metadata_msg_sessiond:
-               goto end_msg_sessiond;
-error_push_metadata_fatal:
-               goto error_fatal;
-       }
-       case LTTNG_CONSUMER_SETUP_METADATA:
-       {
-               int ret;
-
-               ret = setup_metadata(ctx, msg.u.setup_metadata.key);
-               if (ret) {
-                       ret_code = ret;
-               }
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
-       {
-               struct lttng_consumer_channel *found_channel;
-               uint64_t key = msg.u.snapshot_channel.key;
-               int ret_send;
-
-               found_channel = consumer_find_channel(key);
-               if (!found_channel) {
-                       DBG("UST snapshot channel not found for key %" PRIu64, key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               } else {
-                       if (msg.u.snapshot_channel.metadata) {
-                               int ret_snapshot;
-
-                               ret_snapshot = snapshot_metadata(found_channel,
-                                               key,
-                                               msg.u.snapshot_channel.pathname,
-                                               msg.u.snapshot_channel.relayd_id,
-                                               ctx);
-                               if (ret_snapshot < 0) {
-                                       ERR("Snapshot metadata failed");
-                                       ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
-                               }
-                       } else {
-                               int ret_snapshot;
-
-                               ret_snapshot = snapshot_channel(found_channel,
-                                               key,
-                                               msg.u.snapshot_channel.pathname,
-                                               msg.u.snapshot_channel.relayd_id,
-                                               msg.u.snapshot_channel
-                                                               .nb_packets_per_stream,
-                                               ctx);
-                               if (ret_snapshot < 0) {
-                                       ERR("Snapshot channel failed");
-                                       ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
-                               }
-                       }
-               }
-               health_code_update();
-               ret_send = consumer_send_status_msg(sock, ret_code);
-               if (ret_send < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
-               }
-               health_code_update();
-               break;
-       }
-       case LTTNG_CONSUMER_DISCARDED_EVENTS:
-       {
-               int ret = 0;
-               uint64_t discarded_events;
-               struct lttng_ht_iter iter;
-               struct lttng_ht *ht;
-               struct lttng_consumer_stream *stream;
-               uint64_t id = msg.u.discarded_events.session_id;
-               uint64_t key = msg.u.discarded_events.channel_key;
-
-               DBG("UST consumer discarded events command for session id %"
-                               PRIu64, id);
-               rcu_read_lock();
-               pthread_mutex_lock(&the_consumer_data.lock);
-
-               ht = the_consumer_data.stream_list_ht;
-
-               /*
-                * We only need a reference to the channel, but they are not
-                * directly indexed, so we just use the first matching stream
-                * to extract the information we need, we default to 0 if not
-                * found (no events are dropped if the channel is not yet in
-                * use).
-                */
-               discarded_events = 0;
-               cds_lfht_for_each_entry_duplicate(ht->ht,
-                               ht->hash_fct(&id, lttng_ht_seed),
-                               ht->match_fct, &id,
-                               &iter.iter, stream, node_session_id.node) {
-                       if (stream->chan->key == key) {
-                               discarded_events = stream->chan->discarded_events;
-                               break;
-                       }
-               }
-               pthread_mutex_unlock(&the_consumer_data.lock);
-               rcu_read_unlock();
-
-               DBG("UST consumer discarded events command for session id %"
-                               PRIu64 ", channel key %" PRIu64, id, key);
-
-               health_code_update();
-
-               /* Send back returned value to session daemon */
-               ret = lttcomm_send_unix_sock(sock, &discarded_events, sizeof(discarded_events));
-               if (ret < 0) {
-                       PERROR("send discarded events");
-                       goto error_fatal;
-               }
-
-               break;
-       }
-       case LTTNG_CONSUMER_LOST_PACKETS:
-       {
-               int ret;
-               uint64_t lost_packets;
-               struct lttng_ht_iter iter;
-               struct lttng_ht *ht;
-               struct lttng_consumer_stream *stream;
-               uint64_t id = msg.u.lost_packets.session_id;
-               uint64_t key = msg.u.lost_packets.channel_key;
-
-               DBG("UST consumer lost packets command for session id %"
-                               PRIu64, id);
-               rcu_read_lock();
-               pthread_mutex_lock(&the_consumer_data.lock);
-
-               ht = the_consumer_data.stream_list_ht;
-
-               /*
-                * We only need a reference to the channel, but they are not
-                * directly indexed, so we just use the first matching stream
-                * to extract the information we need, we default to 0 if not
-                * found (no packets lost if the channel is not yet in use).
-                */
-               lost_packets = 0;
-               cds_lfht_for_each_entry_duplicate(ht->ht,
-                               ht->hash_fct(&id, lttng_ht_seed),
-                               ht->match_fct, &id,
-                               &iter.iter, stream, node_session_id.node) {
-                       if (stream->chan->key == key) {
-                               lost_packets = stream->chan->lost_packets;
-                               break;
-                       }
-               }
-               pthread_mutex_unlock(&the_consumer_data.lock);
-               rcu_read_unlock();
-
-               DBG("UST consumer lost packets command for session id %"
-                               PRIu64 ", channel key %" PRIu64, id, key);
-
-               health_code_update();
-
-               /* Send back returned value to session daemon */
-               ret = lttcomm_send_unix_sock(sock, &lost_packets,
-                               sizeof(lost_packets));
-               if (ret < 0) {
-                       PERROR("send lost packets");
-                       goto error_fatal;
-               }
-
-               break;
-       }
-       case LTTNG_CONSUMER_SET_CHANNEL_MONITOR_PIPE:
-       {
-               int channel_monitor_pipe, ret_send,
-                               ret_set_channel_monitor_pipe;
-               ssize_t ret_recv;
-
-               ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-               /* Successfully received the command's type. */
-               ret_send = consumer_send_status_msg(sock, ret_code);
-               if (ret_send < 0) {
-                       goto error_fatal;
-               }
-
-               ret_recv = lttcomm_recv_fds_unix_sock(
-                               sock, &channel_monitor_pipe, 1);
-               if (ret_recv != sizeof(channel_monitor_pipe)) {
-                       ERR("Failed to receive channel monitor pipe");
-                       goto error_fatal;
-               }
-
-               DBG("Received channel monitor pipe (%d)", channel_monitor_pipe);
-               ret_set_channel_monitor_pipe =
-                               consumer_timer_thread_set_channel_monitor_pipe(
-                                               channel_monitor_pipe);
-               if (!ret_set_channel_monitor_pipe) {
-                       int flags;
-                       int ret_fcntl;
-
-                       ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-                       /* Set the pipe as non-blocking. */
-                       ret_fcntl = fcntl(channel_monitor_pipe, F_GETFL, 0);
-                       if (ret_fcntl == -1) {
-                               PERROR("fcntl get flags of the channel monitoring pipe");
-                               goto error_fatal;
-                       }
-                       flags = ret_fcntl;
-
-                       ret_fcntl = fcntl(channel_monitor_pipe, F_SETFL,
-                                       flags | O_NONBLOCK);
-                       if (ret_fcntl == -1) {
-                               PERROR("fcntl set O_NONBLOCK flag of the channel monitoring pipe");
-                               goto error_fatal;
-                       }
-                       DBG("Channel monitor pipe set as non-blocking");
-               } else {
-                       ret_code = LTTCOMM_CONSUMERD_ALREADY_SET;
-               }
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_ROTATE_CHANNEL:
-       {
-               struct lttng_consumer_channel *found_channel;
-               uint64_t key = msg.u.rotate_channel.key;
-               int ret_send_status;
-
-               found_channel = consumer_find_channel(key);
-               if (!found_channel) {
-                       DBG("Channel %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               } else {
-                       int rotate_channel;
-
-                       /*
-                        * Sample the rotate position of all the streams in
-                        * this channel.
-                        */
-                       rotate_channel = lttng_consumer_rotate_channel(
-                                       found_channel, key,
-                                       msg.u.rotate_channel.relayd_id,
-                                       msg.u.rotate_channel.metadata, ctx);
-                       if (rotate_channel < 0) {
-                               ERR("Rotate channel failed");
-                               ret_code = LTTCOMM_CONSUMERD_ROTATION_FAIL;
-                       }
-
-                       health_code_update();
-               }
-
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_rotate_channel_nosignal;
-               }
-
-               /*
-                * Rotate the streams that are ready right now.
-                * FIXME: this is a second consecutive iteration over the
-                * streams in a channel, there is probably a better way to
-                * handle this, but it needs to be after the
-                * consumer_send_status_msg() call.
-                */
-               if (found_channel) {
-                       int ret_rotate_read_streams;
-
-                       ret_rotate_read_streams =
-                                       lttng_consumer_rotate_ready_streams(
-                                                       found_channel, key,
-                                                       ctx);
-                       if (ret_rotate_read_streams < 0) {
-                               ERR("Rotate channel failed");
-                       }
-               }
-               break;
-end_rotate_channel_nosignal:
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_CLEAR_CHANNEL:
-       {
-               struct lttng_consumer_channel *found_channel;
-               uint64_t key = msg.u.clear_channel.key;
-               int ret_send_status;
-
-               found_channel = consumer_find_channel(key);
-               if (!found_channel) {
-                       DBG("Channel %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               } else {
-                       int ret_clear_channel;
-
-                       ret_clear_channel = lttng_consumer_clear_channel(
-                                       found_channel);
-                       if (ret_clear_channel) {
-                               ERR("Clear channel failed key %" PRIu64, key);
-                               ret_code = ret_clear_channel;
-                       }
-
-                       health_code_update();
-               }
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
-               }
-               break;
-       }
-       case LTTNG_CONSUMER_INIT:
-       {
-               int ret_send_status;
-
-               ret_code = lttng_consumer_init_command(ctx,
-                               msg.u.init.sessiond_uuid);
-               health_code_update();
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
-               }
-               break;
-       }
-       case LTTNG_CONSUMER_CREATE_TRACE_CHUNK:
-       {
-               const struct lttng_credentials credentials = {
-                       .uid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.create_trace_chunk.credentials.value.uid),
-                       .gid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.create_trace_chunk.credentials.value.gid),
-               };
-               const bool is_local_trace =
-                               !msg.u.create_trace_chunk.relayd_id.is_set;
-               const uint64_t relayd_id =
-                               msg.u.create_trace_chunk.relayd_id.value;
-               const char *chunk_override_name =
-                               *msg.u.create_trace_chunk.override_name ?
-                                       msg.u.create_trace_chunk.override_name :
-                                       NULL;
-               struct lttng_directory_handle *chunk_directory_handle = NULL;
-
-               /*
-                * The session daemon will only provide a chunk directory file
-                * descriptor for local traces.
-                */
-               if (is_local_trace) {
-                       int chunk_dirfd;
-                       int ret_send_status;
-                       ssize_t ret_recv;
-
-                       /* Acnowledge the reception of the command. */
-                       ret_send_status = consumer_send_status_msg(
-                                       sock, LTTCOMM_CONSUMERD_SUCCESS);
-                       if (ret_send_status < 0) {
-                               /* Somehow, the session daemon is not responding anymore. */
-                               goto end_nosignal;
-                       }
-
-                       /*
-                        * Receive trace chunk domain dirfd.
-                        */
-                       ret_recv = lttcomm_recv_fds_unix_sock(
-                                       sock, &chunk_dirfd, 1);
-                       if (ret_recv != sizeof(chunk_dirfd)) {
-                               ERR("Failed to receive trace chunk domain directory file descriptor");
-                               goto error_fatal;
-                       }
-
-                       DBG("Received trace chunk domain directory fd (%d)",
-                                       chunk_dirfd);
-                       chunk_directory_handle = lttng_directory_handle_create_from_dirfd(
-                                       chunk_dirfd);
-                       if (!chunk_directory_handle) {
-                               ERR("Failed to initialize chunk domain directory handle from directory file descriptor");
-                               if (close(chunk_dirfd)) {
-                                       PERROR("Failed to close chunk directory file descriptor");
-                               }
-                               goto error_fatal;
-                       }
-               }
-
-               ret_code = lttng_consumer_create_trace_chunk(
-                               !is_local_trace ? &relayd_id : NULL,
-                               msg.u.create_trace_chunk.session_id,
-                               msg.u.create_trace_chunk.chunk_id,
-                               (time_t) msg.u.create_trace_chunk
-                                               .creation_timestamp,
-                               chunk_override_name,
-                               msg.u.create_trace_chunk.credentials.is_set ?
-                                               &credentials :
-                                               NULL,
-                               chunk_directory_handle);
-               lttng_directory_handle_put(chunk_directory_handle);
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_CLOSE_TRACE_CHUNK:
-       {
-               enum lttng_trace_chunk_command_type close_command =
-                               msg.u.close_trace_chunk.close_command.value;
-               const uint64_t relayd_id =
-                               msg.u.close_trace_chunk.relayd_id.value;
-               struct lttcomm_consumer_close_trace_chunk_reply reply;
-               char closed_trace_chunk_path[LTTNG_PATH_MAX] = {};
-               int ret;
-
-               ret_code = lttng_consumer_close_trace_chunk(
-                               msg.u.close_trace_chunk.relayd_id.is_set ?
-                                               &relayd_id :
-                                               NULL,
-                               msg.u.close_trace_chunk.session_id,
-                               msg.u.close_trace_chunk.chunk_id,
-                               (time_t) msg.u.close_trace_chunk.close_timestamp,
-                               msg.u.close_trace_chunk.close_command.is_set ?
-                                               &close_command :
-                                               NULL, closed_trace_chunk_path);
-               reply.ret_code = ret_code;
-               reply.path_length = strlen(closed_trace_chunk_path) + 1;
-               ret = lttcomm_send_unix_sock(sock, &reply, sizeof(reply));
-               if (ret != sizeof(reply)) {
-                       goto error_fatal;
-               }
-               ret = lttcomm_send_unix_sock(sock, closed_trace_chunk_path,
-                               reply.path_length);
-               if (ret != reply.path_length) {
-                       goto error_fatal;
-               }
-               goto end_nosignal;
-       }
-       case LTTNG_CONSUMER_TRACE_CHUNK_EXISTS:
-       {
-               const uint64_t relayd_id =
-                               msg.u.trace_chunk_exists.relayd_id.value;
-
-               ret_code = lttng_consumer_trace_chunk_exists(
-                               msg.u.trace_chunk_exists.relayd_id.is_set ?
-                                               &relayd_id : NULL,
-                               msg.u.trace_chunk_exists.session_id,
-                               msg.u.trace_chunk_exists.chunk_id);
-               goto end_msg_sessiond;
-       }
-       case LTTNG_CONSUMER_OPEN_CHANNEL_PACKETS:
-       {
-               const uint64_t key = msg.u.open_channel_packets.key;
-               struct lttng_consumer_channel *found_channel =
-                               consumer_find_channel(key);
-
-               if (found_channel) {
-                       pthread_mutex_lock(&found_channel->lock);
-                       ret_code = lttng_consumer_open_channel_packets(
-                                       found_channel);
-                       pthread_mutex_unlock(&found_channel->lock);
-               } else {
-                       /*
-                        * The channel could have disappeared in per-pid
-                        * buffering mode.
-                        */
-                       DBG("Channel %" PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
-               }
-
-               health_code_update();
-               goto end_msg_sessiond;
-       }
-       default:
-               break;
-       }
-
-end_nosignal:
-       /*
-        * Return 1 to indicate success since the 0 value can be a socket
-        * shutdown during the recv() or send() call.
-        */
-       ret_func = 1;
-       goto end;
-
-end_msg_sessiond:
-       /*
-        * The returned value here is not useful since either way we'll return 1 to
-        * the caller because the session daemon socket management is done
-        * elsewhere. Returning a negative code or 0 will shutdown the consumer.
-        */
-       {
-               int ret_send_status;
-
-               ret_send_status = consumer_send_status_msg(sock, ret_code);
-               if (ret_send_status < 0) {
-                       goto error_fatal;
-               }
-       }
-
-       ret_func = 1;
-       goto end;
-
-end_channel_error:
-       if (channel) {
-               /*
-                * Free channel here since no one has a reference to it. We don't
-                * free after that because a stream can store this pointer.
-                */
-               destroy_channel(channel);
-       }
-       /* We have to send a status channel message indicating an error. */
-       {
-               int ret_send_status;
-
-               ret_send_status = consumer_send_status_channel(sock, NULL);
-               if (ret_send_status < 0) {
-                       /* Stop everything if session daemon can not be notified. */
-                       goto error_fatal;
-               }
-       }
-
-       ret_func = 1;
-       goto end;
-
-error_fatal:
-       /* This will issue a consumer stop. */
-       ret_func = -1;
-       goto end;
-
-end:
-       rcu_read_unlock();
-       health_code_update();
-       return ret_func;
-}
-
-int lttng_ust_flush_buffer(struct lttng_consumer_stream *stream,
-               int producer_active)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-
-       return lttng_ust_ctl_flush_buffer(stream->ustream, producer_active);
-}
-
-/*
- * Take a snapshot for a specific stream.
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_ustconsumer_take_snapshot(struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-
-       return lttng_ust_ctl_snapshot(stream->ustream);
-}
-
-/*
- * Sample consumed and produced positions for a specific stream.
- *
- * Returns 0 on success, < 0 on error.
- */
-int lttng_ustconsumer_sample_snapshot_positions(
-               struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-
-       return lttng_ust_ctl_snapshot_sample_positions(stream->ustream);
-}
-
-/*
- * Get the produced position
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_ustconsumer_get_produced_snapshot(
-               struct lttng_consumer_stream *stream, unsigned long *pos)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-       LTTNG_ASSERT(pos);
-
-       return lttng_ust_ctl_snapshot_get_produced(stream->ustream, pos);
-}
-
-/*
- * Get the consumed position
- *
- * Returns 0 on success, < 0 on error
- */
-int lttng_ustconsumer_get_consumed_snapshot(
-               struct lttng_consumer_stream *stream, unsigned long *pos)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-       LTTNG_ASSERT(pos);
-
-       return lttng_ust_ctl_snapshot_get_consumed(stream->ustream, pos);
-}
-
-int lttng_ustconsumer_flush_buffer(struct lttng_consumer_stream *stream,
-               int producer)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-
-       return lttng_ust_ctl_flush_buffer(stream->ustream, producer);
-}
-
-int lttng_ustconsumer_clear_buffer(struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-
-       return lttng_ust_ctl_clear_buffer(stream->ustream);
-}
-
-int lttng_ustconsumer_get_current_timestamp(
-               struct lttng_consumer_stream *stream, uint64_t *ts)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-       LTTNG_ASSERT(ts);
-
-       return lttng_ust_ctl_get_current_timestamp(stream->ustream, ts);
-}
-
-int lttng_ustconsumer_get_sequence_number(
-               struct lttng_consumer_stream *stream, uint64_t *seq)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-       LTTNG_ASSERT(seq);
-
-       return lttng_ust_ctl_get_sequence_number(stream->ustream, seq);
-}
-
-/*
- * Called when the stream signals the consumer that it has hung up.
- */
-void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-
-       pthread_mutex_lock(&stream->lock);
-       if (!stream->quiescent) {
-               if (lttng_ust_ctl_flush_buffer(stream->ustream, 0) < 0) {
-                       ERR("Failed to flush buffer on stream hang-up");
-               } else {
-                       stream->quiescent = true;
-               }
-       }
-       pthread_mutex_unlock(&stream->lock);
-       stream->hangup_flush_done = 1;
-}
-
-void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
-{
-       int i;
-
-       LTTNG_ASSERT(chan);
-       LTTNG_ASSERT(chan->uchan);
-       LTTNG_ASSERT(chan->buffer_credentials.is_set);
-
-       if (chan->switch_timer_enabled == 1) {
-               consumer_timer_switch_stop(chan);
-       }
-       for (i = 0; i < chan->nr_stream_fds; i++) {
-               int ret;
-
-               ret = close(chan->stream_fds[i]);
-               if (ret) {
-                       PERROR("close");
-               }
-               if (chan->shm_path[0]) {
-                       char shm_path[PATH_MAX];
-
-                       ret = get_stream_shm_path(shm_path, chan->shm_path, i);
-                       if (ret) {
-                               ERR("Cannot get stream shm path");
-                       }
-                       ret = run_as_unlink(shm_path,
-                                       lttng_credentials_get_uid(LTTNG_OPTIONAL_GET_PTR(
-                                                       chan->buffer_credentials)),
-                                       lttng_credentials_get_gid(LTTNG_OPTIONAL_GET_PTR(
-                                                       chan->buffer_credentials)));
-                       if (ret) {
-                               PERROR("unlink %s", shm_path);
-                       }
-               }
-       }
-}
-
-void lttng_ustconsumer_free_channel(struct lttng_consumer_channel *chan)
-{
-       LTTNG_ASSERT(chan);
-       LTTNG_ASSERT(chan->uchan);
-       LTTNG_ASSERT(chan->buffer_credentials.is_set);
-
-       consumer_metadata_cache_destroy(chan);
-       lttng_ust_ctl_destroy_channel(chan->uchan);
-       /* Try to rmdir all directories under shm_path root. */
-       if (chan->root_shm_path[0]) {
-               (void) run_as_rmdir_recursive(chan->root_shm_path,
-                               lttng_credentials_get_uid(LTTNG_OPTIONAL_GET_PTR(
-                                               chan->buffer_credentials)),
-                               lttng_credentials_get_gid(LTTNG_OPTIONAL_GET_PTR(
-                                               chan->buffer_credentials)),
-                               LTTNG_DIRECTORY_HANDLE_SKIP_NON_EMPTY_FLAG);
-       }
-       free(chan->stream_fds);
-}
-
-void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-
-       if (stream->chan->switch_timer_enabled == 1) {
-               consumer_timer_switch_stop(stream->chan);
-       }
-       lttng_ust_ctl_destroy_stream(stream->ustream);
-}
-
-int lttng_ustconsumer_get_wakeup_fd(struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-
-       return lttng_ust_ctl_stream_get_wakeup_fd(stream->ustream);
-}
-
-int lttng_ustconsumer_close_wakeup_fd(struct lttng_consumer_stream *stream)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-
-       return lttng_ust_ctl_stream_close_wakeup_fd(stream->ustream);
-}
-
-/*
- * Write up to one packet from the metadata cache to the channel.
- *
- * Returns the number of bytes pushed from the cache into the ring buffer, or a
- * negative value on error.
- */
-static
-int commit_one_metadata_packet(struct lttng_consumer_stream *stream)
-{
-       ssize_t write_len;
-       int ret;
-
-       pthread_mutex_lock(&stream->chan->metadata_cache->lock);
-       if (stream->chan->metadata_cache->contents.size ==
-                       stream->ust_metadata_pushed) {
-               /*
-                * In the context of a user space metadata channel, a
-                * change in version can be detected in two ways:
-                *   1) During the pre-consume of the `read_subbuffer` loop,
-                *   2) When populating the metadata ring buffer (i.e. here).
-                *
-                * This function is invoked when there is no metadata
-                * available in the ring-buffer. If all data was consumed
-                * up to the size of the metadata cache, there is no metadata
-                * to insert in the ring-buffer.
-                *
-                * However, the metadata version could still have changed (a
-                * regeneration without any new data will yield the same cache
-                * size).
-                *
-                * The cache's version is checked for a version change and the
-                * consumed position is reset if one occurred.
-                *
-                * This check is only necessary for the user space domain as
-                * it has to manage the cache explicitly. If this reset was not
-                * performed, no metadata would be consumed (and no reset would
-                * occur as part of the pre-consume) until the metadata size
-                * exceeded the cache size.
-                */
-               if (stream->metadata_version !=
-                               stream->chan->metadata_cache->version) {
-                       metadata_stream_reset_cache_consumed_position(stream);
-                       consumer_stream_metadata_set_version(stream,
-                                       stream->chan->metadata_cache->version);
-               } else {
-                       ret = 0;
-                       goto end;
-               }
-       }
-
-       write_len = lttng_ust_ctl_write_one_packet_to_channel(stream->chan->uchan,
-                       &stream->chan->metadata_cache->contents.data[stream->ust_metadata_pushed],
-                       stream->chan->metadata_cache->contents.size -
-                                       stream->ust_metadata_pushed);
-       LTTNG_ASSERT(write_len != 0);
-       if (write_len < 0) {
-               ERR("Writing one metadata packet");
-               ret = write_len;
-               goto end;
-       }
-       stream->ust_metadata_pushed += write_len;
-
-       LTTNG_ASSERT(stream->chan->metadata_cache->contents.size >=
-                       stream->ust_metadata_pushed);
-       ret = write_len;
-
-       /*
-        * Switch packet (but don't open the next one) on every commit of
-        * a metadata packet. Since the subbuffer is fully filled (with padding,
-        * if needed), the stream is "quiescent" after this commit.
-        */
-       if (lttng_ust_ctl_flush_buffer(stream->ustream, 1)) {
-               ERR("Failed to flush buffer while commiting one metadata packet");
-               ret = -EIO;
-       } else {
-               stream->quiescent = true;
-       }
-end:
-       pthread_mutex_unlock(&stream->chan->metadata_cache->lock);
-       return ret;
-}
-
-
-/*
- * Sync metadata meaning request them to the session daemon and snapshot to the
- * metadata thread can consumer them.
- *
- * Metadata stream lock is held here, but we need to release it when
- * interacting with sessiond, else we cause a deadlock with live
- * awaiting on metadata to be pushed out.
- *
- * The RCU read side lock must be held by the caller.
- */
-enum sync_metadata_status lttng_ustconsumer_sync_metadata(
-               struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *metadata_stream)
-{
-       int ret;
-       enum sync_metadata_status status;
-       struct lttng_consumer_channel *metadata_channel;
-
-       LTTNG_ASSERT(ctx);
-       LTTNG_ASSERT(metadata_stream);
-
-       metadata_channel = metadata_stream->chan;
-       pthread_mutex_unlock(&metadata_stream->lock);
-       /*
-        * Request metadata from the sessiond, but don't wait for the flush
-        * because we locked the metadata thread.
-        */
-       ret = lttng_ustconsumer_request_metadata(ctx, metadata_channel, 0, 0);
-       pthread_mutex_lock(&metadata_stream->lock);
-       if (ret < 0) {
-               status = SYNC_METADATA_STATUS_ERROR;
-               goto end;
-       }
-
-       /*
-        * The metadata stream and channel can be deleted while the
-        * metadata stream lock was released. The streamed is checked
-        * for deletion before we use it further.
-        *
-        * Note that it is safe to access a logically-deleted stream since its
-        * existence is still guaranteed by the RCU read side lock. However,
-        * it should no longer be used. The close/deletion of the metadata
-        * channel and stream already guarantees that all metadata has been
-        * consumed. Therefore, there is nothing left to do in this function.
-        */
-       if (consumer_stream_is_deleted(metadata_stream)) {
-               DBG("Metadata stream %" PRIu64 " was deleted during the metadata synchronization",
-                               metadata_stream->key);
-               status = SYNC_METADATA_STATUS_NO_DATA;
-               goto end;
-       }
-
-       ret = commit_one_metadata_packet(metadata_stream);
-       if (ret < 0) {
-               status = SYNC_METADATA_STATUS_ERROR;
-               goto end;
-       } else if (ret > 0) {
-               status = SYNC_METADATA_STATUS_NEW_DATA;
-       } else /* ret == 0 */ {
-               status = SYNC_METADATA_STATUS_NO_DATA;
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_snapshot(metadata_stream->ustream);
-       if (ret < 0) {
-               ERR("Failed to take a snapshot of the metadata ring-buffer positions, ret = %d", ret);
-               status = SYNC_METADATA_STATUS_ERROR;
-               goto end;
-       }
-
-end:
-       return status;
-}
-
-/*
- * Return 0 on success else a negative value.
- */
-static int notify_if_more_data(struct lttng_consumer_stream *stream,
-               struct lttng_consumer_local_data *ctx)
-{
-       int ret;
-       struct lttng_ust_ctl_consumer_stream *ustream;
-
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(ctx);
-
-       ustream = stream->ustream;
-
-       /*
-        * First, we are going to check if there is a new subbuffer available
-        * before reading the stream wait_fd.
-        */
-       /* Get the next subbuffer */
-       ret = lttng_ust_ctl_get_next_subbuf(ustream);
-       if (ret) {
-               /* No more data found, flag the stream. */
-               stream->has_data = 0;
-               ret = 0;
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_put_subbuf(ustream);
-       LTTNG_ASSERT(!ret);
-
-       /* This stream still has data. Flag it and wake up the data thread. */
-       stream->has_data = 1;
-
-       if (stream->monitor && !stream->hangup_flush_done && !ctx->has_wakeup) {
-               ssize_t writelen;
-
-               writelen = lttng_pipe_write(ctx->consumer_wakeup_pipe, "!", 1);
-               if (writelen < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
-                       ret = writelen;
-                       goto end;
-               }
-
-               /* The wake up pipe has been notified. */
-               ctx->has_wakeup = 1;
-       }
-       ret = 0;
-
-end:
-       return ret;
-}
-
-static int consumer_stream_ust_on_wake_up(struct lttng_consumer_stream *stream)
-{
-       int ret = 0;
-
-       /*
-        * We can consume the 1 byte written into the wait_fd by
-        * UST. Don't trigger error if we cannot read this one byte
-        * (read returns 0), or if the error is EAGAIN or EWOULDBLOCK.
-        *
-        * This is only done when the stream is monitored by a thread,
-        * before the flush is done after a hangup and if the stream
-        * is not flagged with data since there might be nothing to
-        * consume in the wait fd but still have data available
-        * flagged by the consumer wake up pipe.
-        */
-       if (stream->monitor && !stream->hangup_flush_done && !stream->has_data) {
-               char dummy;
-               ssize_t readlen;
-
-               readlen = lttng_read(stream->wait_fd, &dummy, 1);
-               if (readlen < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
-                       ret = readlen;
-               }
-       }
-
-       return ret;
-}
-
-static int extract_common_subbuffer_info(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuf)
-{
-       int ret;
-
-       ret = lttng_ust_ctl_get_subbuf_size(
-                       stream->ustream, &subbuf->info.data.subbuf_size);
-       if (ret) {
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_get_padded_subbuf_size(
-                       stream->ustream, &subbuf->info.data.padded_subbuf_size);
-       if (ret) {
-               goto end;
-       }
-
-end:
-       return ret;
-}
-
-static int extract_metadata_subbuffer_info(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuf)
-{
-       int ret;
-
-       ret = extract_common_subbuffer_info(stream, subbuf);
-       if (ret) {
-               goto end;
-       }
-
-       subbuf->info.metadata.version = stream->metadata_version;
-
-end:
-       return ret;
-}
-
-static int extract_data_subbuffer_info(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuf)
-{
-       int ret;
-
-       ret = extract_common_subbuffer_info(stream, subbuf);
-       if (ret) {
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_get_packet_size(
-                       stream->ustream, &subbuf->info.data.packet_size);
-       if (ret < 0) {
-               PERROR("Failed to get sub-buffer packet size");
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_get_content_size(
-                       stream->ustream, &subbuf->info.data.content_size);
-       if (ret < 0) {
-               PERROR("Failed to get sub-buffer content size");
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_get_timestamp_begin(
-                       stream->ustream, &subbuf->info.data.timestamp_begin);
-       if (ret < 0) {
-               PERROR("Failed to get sub-buffer begin timestamp");
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_get_timestamp_end(
-                       stream->ustream, &subbuf->info.data.timestamp_end);
-       if (ret < 0) {
-               PERROR("Failed to get sub-buffer end timestamp");
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_get_events_discarded(
-                       stream->ustream, &subbuf->info.data.events_discarded);
-       if (ret) {
-               PERROR("Failed to get sub-buffer events discarded count");
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_get_sequence_number(stream->ustream,
-                       &subbuf->info.data.sequence_number.value);
-       if (ret) {
-               /* May not be supported by older LTTng-modules. */
-               if (ret != -ENOTTY) {
-                       PERROR("Failed to get sub-buffer sequence number");
-                       goto end;
-               }
-       } else {
-               subbuf->info.data.sequence_number.is_set = true;
-       }
-
-       ret = lttng_ust_ctl_get_stream_id(
-                       stream->ustream, &subbuf->info.data.stream_id);
-       if (ret < 0) {
-               PERROR("Failed to get stream id");
-               goto end;
-       }
-
-       ret = lttng_ust_ctl_get_instance_id(stream->ustream,
-                       &subbuf->info.data.stream_instance_id.value);
-       if (ret) {
-               /* May not be supported by older LTTng-modules. */
-               if (ret != -ENOTTY) {
-                       PERROR("Failed to get stream instance id");
-                       goto end;
-               }
-       } else {
-               subbuf->info.data.stream_instance_id.is_set = true;
-       }
-end:
-       return ret;
-}
-
-static int get_next_subbuffer_common(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuffer)
-{
-       int ret;
-       const char *addr;
-
-       ret = stream->read_subbuffer_ops.extract_subbuffer_info(
-                       stream, subbuffer);
-       if (ret) {
-               goto end;
-       }
-
-       ret = get_current_subbuf_addr(stream, &addr);
-       if (ret) {
-               goto end;
-       }
-
-       subbuffer->buffer.buffer = lttng_buffer_view_init(
-                       addr, 0, subbuffer->info.data.padded_subbuf_size);
-       LTTNG_ASSERT(subbuffer->buffer.buffer.data != NULL);
-end:
-       return ret;
-}
-
-static enum get_next_subbuffer_status get_next_subbuffer(
-               struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuffer)
-{
-       int ret;
-       enum get_next_subbuffer_status status;
-
-       ret = lttng_ust_ctl_get_next_subbuf(stream->ustream);
-       switch (ret) {
-       case 0:
-               status = GET_NEXT_SUBBUFFER_STATUS_OK;
-               break;
-       case -ENODATA:
-               case -EAGAIN:
-               /*
-                * The caller only expects -ENODATA when there is no data to
-                * read, but the kernel tracer returns -EAGAIN when there is
-                * currently no data for a non-finalized stream, and -ENODATA
-                * when there is no data for a finalized stream. Those can be
-                * combined into a -ENODATA return value.
-                */
-               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
-               goto end;
-       default:
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = get_next_subbuffer_common(stream, subbuffer);
-       if (ret) {
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-               goto end;
-       }
-end:
-       return status;
-}
-
-static enum get_next_subbuffer_status get_next_subbuffer_metadata(
-               struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuffer)
-{
-       int ret;
-       bool cache_empty;
-       bool got_subbuffer;
-       bool coherent;
-       bool buffer_empty;
-       unsigned long consumed_pos, produced_pos;
-       enum get_next_subbuffer_status status;
-
-       do {
-               ret = lttng_ust_ctl_get_next_subbuf(stream->ustream);
-               if (ret == 0) {
-                       got_subbuffer = true;
-               } else {
-                       got_subbuffer = false;
-                       if (ret != -EAGAIN) {
-                               /* Fatal error. */
-                               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-                               goto end;
-                       }
-               }
-
-               /*
-                * Determine if the cache is empty and ensure that a sub-buffer
-                * is made available if the cache is not empty.
-                */
-               if (!got_subbuffer) {
-                       ret = commit_one_metadata_packet(stream);
-                       if (ret < 0 && ret != -ENOBUFS) {
-                               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-                               goto end;
-                       } else if (ret == 0) {
-                               /* Not an error, the cache is empty. */
-                               cache_empty = true;
-                               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
-                               goto end;
-                       } else {
-                               cache_empty = false;
-                       }
-               } else {
-                       pthread_mutex_lock(&stream->chan->metadata_cache->lock);
-                       cache_empty = stream->chan->metadata_cache->contents.size ==
-                                       stream->ust_metadata_pushed;
-                       pthread_mutex_unlock(&stream->chan->metadata_cache->lock);
-               }
-       } while (!got_subbuffer);
-
-       /* Populate sub-buffer infos and view. */
-       ret = get_next_subbuffer_common(stream, subbuffer);
-       if (ret) {
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = lttng_ustconsumer_sample_snapshot_positions(stream);
-       if (ret < 0) {
-               /*
-                * -EAGAIN is not expected since we got a sub-buffer and haven't
-                * pushed the consumption position yet (on put_next).
-                */
-               PERROR("Failed to take a snapshot of metadata buffer positions");
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = lttng_ustconsumer_get_consumed_snapshot(stream, &consumed_pos);
-       if (ret) {
-               PERROR("Failed to get metadata consumed position");
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-               goto end;
-       }
-
-       ret = lttng_ustconsumer_get_produced_snapshot(stream, &produced_pos);
-       if (ret) {
-               PERROR("Failed to get metadata produced position");
-               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
-               goto end;
-       }
-
-       /* Last sub-buffer of the ring buffer ? */
-       buffer_empty = (consumed_pos + stream->max_sb_size) == produced_pos;
-
-       /*
-        * The sessiond registry lock ensures that coherent units of metadata
-        * are pushed to the consumer daemon at once. Hence, if a sub-buffer is
-        * acquired, the cache is empty, and it is the only available sub-buffer
-        * available, it is safe to assume that it is "coherent".
-        */
-       coherent = got_subbuffer && cache_empty && buffer_empty;
-
-       LTTNG_OPTIONAL_SET(&subbuffer->info.metadata.coherent, coherent);
-       status = GET_NEXT_SUBBUFFER_STATUS_OK;
-end:
-       return status;
-}
-
-static int put_next_subbuffer(struct lttng_consumer_stream *stream,
-               struct stream_subbuffer *subbuffer)
-{
-       const int ret = lttng_ust_ctl_put_next_subbuf(stream->ustream);
-
-       LTTNG_ASSERT(ret == 0);
-       return ret;
-}
-
-static int signal_metadata(struct lttng_consumer_stream *stream,
-               struct lttng_consumer_local_data *ctx)
-{
-       ASSERT_LOCKED(stream->metadata_rdv_lock);
-       return pthread_cond_broadcast(&stream->metadata_rdv) ? -errno : 0;
-}
-
-static int lttng_ustconsumer_set_stream_ops(
-               struct lttng_consumer_stream *stream)
-{
-       int ret = 0;
-
-       stream->read_subbuffer_ops.on_wake_up = consumer_stream_ust_on_wake_up;
-       if (stream->metadata_flag) {
-               stream->read_subbuffer_ops.get_next_subbuffer =
-                               get_next_subbuffer_metadata;
-               stream->read_subbuffer_ops.extract_subbuffer_info =
-                               extract_metadata_subbuffer_info;
-               stream->read_subbuffer_ops.reset_metadata =
-                               metadata_stream_reset_cache_consumed_position;
-               if (stream->chan->is_live) {
-                       stream->read_subbuffer_ops.on_sleep = signal_metadata;
-                       ret = consumer_stream_enable_metadata_bucketization(
-                                       stream);
-                       if (ret) {
-                               goto end;
-                       }
-               }
-       } else {
-               stream->read_subbuffer_ops.get_next_subbuffer =
-                               get_next_subbuffer;
-               stream->read_subbuffer_ops.extract_subbuffer_info =
-                               extract_data_subbuffer_info;
-               stream->read_subbuffer_ops.on_sleep = notify_if_more_data;
-               if (stream->chan->is_live) {
-                       stream->read_subbuffer_ops.send_live_beacon =
-                                       consumer_flush_ust_index;
-               }
-       }
-
-       stream->read_subbuffer_ops.put_next_subbuffer = put_next_subbuffer;
-end:
-       return ret;
-}
-
-/*
- * Called when a stream is created.
- *
- * Return 0 on success or else a negative value.
- */
-int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       LTTNG_ASSERT(stream);
-
-       /*
-        * Don't create anything if this is set for streaming or if there is
-        * no current trace chunk on the parent channel.
-        */
-       if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor &&
-                       stream->chan->trace_chunk) {
-               ret = consumer_stream_create_output_files(stream, true);
-               if (ret) {
-                       goto error;
-               }
-       }
-
-       lttng_ustconsumer_set_stream_ops(stream);
-       ret = 0;
-
-error:
-       return ret;
-}
-
-/*
- * Check if data is still being extracted from the buffers for a specific
- * stream. Consumer data lock MUST be acquired before calling this function
- * and the stream lock.
- *
- * Return 1 if the traced data are still getting read else 0 meaning that the
- * data is available for trace viewer reading.
- */
-int lttng_ustconsumer_data_pending(struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream->ustream);
-       ASSERT_LOCKED(stream->lock);
-
-       DBG("UST consumer checking data pending");
-
-       if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
-               ret = 0;
-               goto end;
-       }
-
-       if (stream->chan->type == CONSUMER_CHANNEL_TYPE_METADATA) {
-               uint64_t contiguous, pushed;
-
-               /* Ease our life a bit. */
-               pthread_mutex_lock(&stream->chan->metadata_cache->lock);
-               contiguous = stream->chan->metadata_cache->contents.size;
-               pthread_mutex_unlock(&stream->chan->metadata_cache->lock);
-               pushed = stream->ust_metadata_pushed;
-
-               /*
-                * We can simply check whether all contiguously available data
-                * has been pushed to the ring buffer, since the push operation
-                * is performed within get_next_subbuf(), and because both
-                * get_next_subbuf() and put_next_subbuf() are issued atomically
-                * thanks to the stream lock within
-                * lttng_ustconsumer_read_subbuffer(). This basically means that
-                * whetnever ust_metadata_pushed is incremented, the associated
-                * metadata has been consumed from the metadata stream.
-                */
-               DBG("UST consumer metadata pending check: contiguous %" PRIu64 " vs pushed %" PRIu64,
-                               contiguous, pushed);
-               LTTNG_ASSERT(((int64_t) (contiguous - pushed)) >= 0);
-               if ((contiguous != pushed) ||
-                               (((int64_t) contiguous - pushed) > 0 || contiguous == 0)) {
-                       ret = 1;        /* Data is pending */
-                       goto end;
-               }
-       } else {
-               ret = lttng_ust_ctl_get_next_subbuf(stream->ustream);
-               if (ret == 0) {
-                       /*
-                        * There is still data so let's put back this
-                        * subbuffer.
-                        */
-                       ret = lttng_ust_ctl_put_subbuf(stream->ustream);
-                       LTTNG_ASSERT(ret == 0);
-                       ret = 1;        /* Data is pending */
-                       goto end;
-               }
-       }
-
-       /* Data is NOT pending so ready to be read. */
-       ret = 0;
-
-end:
-       return ret;
-}
-
-/*
- * Stop a given metadata channel timer if enabled and close the wait fd which
- * is the poll pipe of the metadata stream.
- *
- * This MUST be called with the metadata channel lock acquired.
- */
-void lttng_ustconsumer_close_metadata(struct lttng_consumer_channel *metadata)
-{
-       int ret;
-
-       LTTNG_ASSERT(metadata);
-       LTTNG_ASSERT(metadata->type == CONSUMER_CHANNEL_TYPE_METADATA);
-
-       DBG("Closing metadata channel key %" PRIu64, metadata->key);
-
-       if (metadata->switch_timer_enabled == 1) {
-               consumer_timer_switch_stop(metadata);
-       }
-
-       if (!metadata->metadata_stream) {
-               goto end;
-       }
-
-       /*
-        * Closing write side so the thread monitoring the stream wakes up if any
-        * and clean the metadata stream.
-        */
-       if (metadata->metadata_stream->ust_metadata_poll_pipe[1] >= 0) {
-               ret = close(metadata->metadata_stream->ust_metadata_poll_pipe[1]);
-               if (ret < 0) {
-                       PERROR("closing metadata pipe write side");
-               }
-               metadata->metadata_stream->ust_metadata_poll_pipe[1] = -1;
-       }
-
-end:
-       return;
-}
-
-/*
- * Close every metadata stream wait fd of the metadata hash table. This
- * function MUST be used very carefully so not to run into a race between the
- * metadata thread handling streams and this function closing their wait fd.
- *
- * For UST, this is used when the session daemon hangs up. Its the metadata
- * producer so calling this is safe because we are assured that no state change
- * can occur in the metadata thread for the streams in the hash table.
- */
-void lttng_ustconsumer_close_all_metadata(struct lttng_ht *metadata_ht)
-{
-       struct lttng_ht_iter iter;
-       struct lttng_consumer_stream *stream;
-
-       LTTNG_ASSERT(metadata_ht);
-       LTTNG_ASSERT(metadata_ht->ht);
-
-       DBG("UST consumer closing all metadata streams");
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream,
-                       node.node) {
-
-               health_code_update();
-
-               pthread_mutex_lock(&stream->chan->lock);
-               lttng_ustconsumer_close_metadata(stream->chan);
-               pthread_mutex_unlock(&stream->chan->lock);
-
-       }
-       rcu_read_unlock();
-}
-
-void lttng_ustconsumer_close_stream_wakeup(struct lttng_consumer_stream *stream)
-{
-       int ret;
-
-       ret = lttng_ust_ctl_stream_close_wakeup_fd(stream->ustream);
-       if (ret < 0) {
-               ERR("Unable to close wakeup fd");
-       }
-}
-
-/*
- * Please refer to consumer-timer.c before adding any lock within this
- * function or any of its callees. Timers have a very strict locking
- * semantic with respect to teardown. Failure to respect this semantic
- * introduces deadlocks.
- *
- * DON'T hold the metadata lock when calling this function, else this
- * can cause deadlock involving consumer awaiting for metadata to be
- * pushed out due to concurrent interaction with the session daemon.
- */
-int lttng_ustconsumer_request_metadata(struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_channel *channel, int timer, int wait)
-{
-       struct lttcomm_metadata_request_msg request;
-       struct lttcomm_consumer_msg msg;
-       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
-       uint64_t len, key, offset, version;
-       int ret;
-
-       LTTNG_ASSERT(channel);
-       LTTNG_ASSERT(channel->metadata_cache);
-
-       memset(&request, 0, sizeof(request));
-
-       /* send the metadata request to sessiond */
-       switch (the_consumer_data.type) {
-       case LTTNG_CONSUMER64_UST:
-               request.bits_per_long = 64;
-               break;
-       case LTTNG_CONSUMER32_UST:
-               request.bits_per_long = 32;
-               break;
-       default:
-               request.bits_per_long = 0;
-               break;
-       }
-
-       request.session_id = channel->session_id;
-       request.session_id_per_pid = channel->session_id_per_pid;
-       /*
-        * Request the application UID here so the metadata of that application can
-        * be sent back. The channel UID corresponds to the user UID of the session
-        * used for the rights on the stream file(s).
-        */
-       request.uid = channel->ust_app_uid;
-       request.key = channel->key;
-
-       DBG("Sending metadata request to sessiond, session id %" PRIu64
-                       ", per-pid %" PRIu64 ", app UID %u and channel key %" PRIu64,
-                       request.session_id, request.session_id_per_pid, request.uid,
-                       request.key);
-
-       pthread_mutex_lock(&ctx->metadata_socket_lock);
-
-       health_code_update();
-
-       ret = lttcomm_send_unix_sock(ctx->consumer_metadata_socket, &request,
-                       sizeof(request));
-       if (ret < 0) {
-               ERR("Asking metadata to sessiond");
-               goto end;
-       }
-
-       health_code_update();
-
-       /* Receive the metadata from sessiond */
-       ret = lttcomm_recv_unix_sock(ctx->consumer_metadata_socket, &msg,
-                       sizeof(msg));
-       if (ret != sizeof(msg)) {
-               DBG("Consumer received unexpected message size %d (expects %zu)",
-                       ret, sizeof(msg));
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
-               /*
-                * The ret value might 0 meaning an orderly shutdown but this is ok
-                * since the caller handles this.
-                */
-               goto end;
-       }
-
-       health_code_update();
-
-       if (msg.cmd_type == LTTNG_ERR_UND) {
-               /* No registry found */
-               (void) consumer_send_status_msg(ctx->consumer_metadata_socket,
-                               ret_code);
-               ret = 0;
-               goto end;
-       } else if (msg.cmd_type != LTTNG_CONSUMER_PUSH_METADATA) {
-               ERR("Unexpected cmd_type received %d", msg.cmd_type);
-               ret = -1;
-               goto end;
-       }
-
-       len = msg.u.push_metadata.len;
-       key = msg.u.push_metadata.key;
-       offset = msg.u.push_metadata.target_offset;
-       version = msg.u.push_metadata.version;
-
-       LTTNG_ASSERT(key == channel->key);
-       if (len == 0) {
-               DBG("No new metadata to receive for key %" PRIu64, key);
-       }
-
-       health_code_update();
-
-       /* Tell session daemon we are ready to receive the metadata. */
-       ret = consumer_send_status_msg(ctx->consumer_metadata_socket,
-                       LTTCOMM_CONSUMERD_SUCCESS);
-       if (ret < 0 || len == 0) {
-               /*
-                * Somehow, the session daemon is not responding anymore or there is
-                * nothing to receive.
-                */
-               goto end;
-       }
-
-       health_code_update();
-
-       ret = lttng_ustconsumer_recv_metadata(ctx->consumer_metadata_socket,
-                       key, offset, len, version, channel, timer, wait);
-       if (ret >= 0) {
-               /*
-                * Only send the status msg if the sessiond is alive meaning a positive
-                * ret code.
-                */
-               (void) consumer_send_status_msg(ctx->consumer_metadata_socket, ret);
-       }
-       ret = 0;
-
-end:
-       health_code_update();
-
-       pthread_mutex_unlock(&ctx->metadata_socket_lock);
-       return ret;
-}
-
-/*
- * Return the ustctl call for the get stream id.
- */
-int lttng_ustconsumer_get_stream_id(struct lttng_consumer_stream *stream,
-               uint64_t *stream_id)
-{
-       LTTNG_ASSERT(stream);
-       LTTNG_ASSERT(stream_id);
-
-       return lttng_ust_ctl_get_stream_id(stream->ustream, stream_id);
-}
-
-void lttng_ustconsumer_sigbus_handle(void *addr)
-{
-       lttng_ust_ctl_sigbus_handle(addr);
-}
diff --git a/src/common/ust-consumer/ust-consumer.cpp b/src/common/ust-consumer/ust-consumer.cpp
new file mode 100644 (file)
index 0000000..c9ec3c5
--- /dev/null
@@ -0,0 +1,3439 @@
+/*
+ * Copyright (C) 2011 Julien Desfossez <julien.desfossez@polymtl.ca>
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#define _LGPL_SOURCE
+#include <lttng/ust-ctl.h>
+#include <lttng/ust-sigbus.h>
+#include <poll.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <inttypes.h>
+#include <unistd.h>
+#include <urcu/list.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <bin/lttng-consumerd/health-consumerd.h>
+#include <common/common.h>
+#include <common/sessiond-comm/sessiond-comm.h>
+#include <common/relayd/relayd.h>
+#include <common/compat/fcntl.h>
+#include <common/compat/endian.h>
+#include <common/consumer/consumer-metadata-cache.h>
+#include <common/consumer/consumer-stream.h>
+#include <common/consumer/consumer-timer.h>
+#include <common/utils.h>
+#include <common/index/index.h>
+#include <common/consumer/consumer.h>
+#include <common/shm.h>
+#include <common/optional.h>
+
+#include "ust-consumer.h"
+
+#define INT_MAX_STR_LEN 12     /* includes \0 */
+
+extern struct lttng_consumer_global_data the_consumer_data;
+extern int consumer_poll_timeout;
+
+LTTNG_EXPORT DEFINE_LTTNG_UST_SIGBUS_STATE();
+
+/*
+ * Free channel object and all streams associated with it. This MUST be used
+ * only and only if the channel has _NEVER_ been added to the global channel
+ * hash table.
+ */
+static void destroy_channel(struct lttng_consumer_channel *channel)
+{
+       struct lttng_consumer_stream *stream, *stmp;
+
+       LTTNG_ASSERT(channel);
+
+       DBG("UST consumer cleaning stream list");
+
+       cds_list_for_each_entry_safe(stream, stmp, &channel->streams.head,
+                       send_node) {
+
+               health_code_update();
+
+               cds_list_del(&stream->send_node);
+               lttng_ust_ctl_destroy_stream(stream->ustream);
+               lttng_trace_chunk_put(stream->trace_chunk);
+               free(stream);
+       }
+
+       /*
+        * If a channel is available meaning that was created before the streams
+        * were, delete it.
+        */
+       if (channel->uchan) {
+               lttng_ustconsumer_del_channel(channel);
+               lttng_ustconsumer_free_channel(channel);
+       }
+
+       if (channel->trace_chunk) {
+               lttng_trace_chunk_put(channel->trace_chunk);
+       }
+
+       free(channel);
+}
+
+/*
+ * Add channel to internal consumer state.
+ *
+ * Returns 0 on success or else a negative value.
+ */
+static int add_channel(struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret = 0;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(ctx);
+
+       if (ctx->on_recv_channel != NULL) {
+               ret = ctx->on_recv_channel(channel);
+               if (ret == 0) {
+                       ret = consumer_add_channel(channel, ctx);
+               } else if (ret < 0) {
+                       /* Most likely an ENOMEM. */
+                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
+                       goto error;
+               }
+       } else {
+               ret = consumer_add_channel(channel, ctx);
+       }
+
+       DBG("UST consumer channel added (key: %" PRIu64 ")", channel->key);
+
+error:
+       return ret;
+}
+
+/*
+ * Allocate and return a consumer stream object. If _alloc_ret is not NULL, the
+ * error value if applicable is set in it else it is kept untouched.
+ *
+ * Return NULL on error else the newly allocated stream object.
+ */
+static struct lttng_consumer_stream *allocate_stream(int cpu, int key,
+               struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx, int *_alloc_ret)
+{
+       int alloc_ret;
+       struct lttng_consumer_stream *stream = NULL;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(ctx);
+
+       stream = consumer_stream_create(
+                       channel,
+                       channel->key,
+                       key,
+                       channel->name,
+                       channel->relayd_id,
+                       channel->session_id,
+                       channel->trace_chunk,
+                       cpu,
+                       &alloc_ret,
+                       channel->type,
+                       channel->monitor);
+       if (stream == NULL) {
+               switch (alloc_ret) {
+               case -ENOENT:
+                       /*
+                        * We could not find the channel. Can happen if cpu hotplug
+                        * happens while tearing down.
+                        */
+                       DBG3("Could not find channel");
+                       break;
+               case -ENOMEM:
+               case -EINVAL:
+               default:
+                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
+                       break;
+               }
+               goto error;
+       }
+
+       consumer_stream_update_channel_attributes(stream, channel);
+
+error:
+       if (_alloc_ret) {
+               *_alloc_ret = alloc_ret;
+       }
+       return stream;
+}
+
+/*
+ * Send the given stream pointer to the corresponding thread.
+ *
+ * Returns 0 on success else a negative value.
+ */
+static int send_stream_to_thread(struct lttng_consumer_stream *stream,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+       struct lttng_pipe *stream_pipe;
+
+       /* Get the right pipe where the stream will be sent. */
+       if (stream->metadata_flag) {
+               consumer_add_metadata_stream(stream);
+               stream_pipe = ctx->consumer_metadata_pipe;
+       } else {
+               consumer_add_data_stream(stream);
+               stream_pipe = ctx->consumer_data_pipe;
+       }
+
+       /*
+        * From this point on, the stream's ownership has been moved away from
+        * the channel and it becomes globally visible. Hence, remove it from
+        * the local stream list to prevent the stream from being both local and
+        * global.
+        */
+       stream->globally_visible = 1;
+       cds_list_del(&stream->send_node);
+
+       ret = lttng_pipe_write(stream_pipe, &stream, sizeof(stream));
+       if (ret < 0) {
+               ERR("Consumer write %s stream to pipe %d",
+                               stream->metadata_flag ? "metadata" : "data",
+                               lttng_pipe_get_writefd(stream_pipe));
+               if (stream->metadata_flag) {
+                       consumer_del_stream_for_metadata(stream);
+               } else {
+                       consumer_del_stream_for_data(stream);
+               }
+               goto error;
+       }
+
+error:
+       return ret;
+}
+
+static
+int get_stream_shm_path(char *stream_shm_path, const char *shm_path, int cpu)
+{
+       char cpu_nr[INT_MAX_STR_LEN];  /* int max len */
+       int ret;
+
+       strncpy(stream_shm_path, shm_path, PATH_MAX);
+       stream_shm_path[PATH_MAX - 1] = '\0';
+       ret = snprintf(cpu_nr, INT_MAX_STR_LEN, "%i", cpu);
+       if (ret < 0) {
+               PERROR("snprintf");
+               goto end;
+       }
+       strncat(stream_shm_path, cpu_nr,
+               PATH_MAX - strlen(stream_shm_path) - 1);
+       ret = 0;
+end:
+       return ret;
+}
+
+/*
+ * Create streams for the given channel using liblttng-ust-ctl.
+ * The channel lock must be acquired by the caller.
+ *
+ * Return 0 on success else a negative value.
+ */
+static int create_ust_streams(struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret, cpu = 0;
+       struct lttng_ust_ctl_consumer_stream *ustream;
+       struct lttng_consumer_stream *stream;
+       pthread_mutex_t *current_stream_lock = NULL;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(ctx);
+
+       /*
+        * While a stream is available from ustctl. When NULL is returned, we've
+        * reached the end of the possible stream for the channel.
+        */
+       while ((ustream = lttng_ust_ctl_create_stream(channel->uchan, cpu))) {
+               int wait_fd;
+               int ust_metadata_pipe[2];
+
+               health_code_update();
+
+               if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA && channel->monitor) {
+                       ret = utils_create_pipe_cloexec_nonblock(ust_metadata_pipe);
+                       if (ret < 0) {
+                               ERR("Create ust metadata poll pipe");
+                               goto error;
+                       }
+                       wait_fd = ust_metadata_pipe[0];
+               } else {
+                       wait_fd = lttng_ust_ctl_stream_get_wait_fd(ustream);
+               }
+
+               /* Allocate consumer stream object. */
+               stream = allocate_stream(cpu, wait_fd, channel, ctx, &ret);
+               if (!stream) {
+                       goto error_alloc;
+               }
+               stream->ustream = ustream;
+               /*
+                * Store it so we can save multiple function calls afterwards since
+                * this value is used heavily in the stream threads. This is UST
+                * specific so this is why it's done after allocation.
+                */
+               stream->wait_fd = wait_fd;
+
+               /*
+                * Increment channel refcount since the channel reference has now been
+                * assigned in the allocation process above.
+                */
+               if (stream->chan->monitor) {
+                       uatomic_inc(&stream->chan->refcount);
+               }
+
+               pthread_mutex_lock(&stream->lock);
+               current_stream_lock = &stream->lock;
+               /*
+                * Order is important this is why a list is used. On error, the caller
+                * should clean this list.
+                */
+               cds_list_add_tail(&stream->send_node, &channel->streams.head);
+
+               ret = lttng_ust_ctl_get_max_subbuf_size(stream->ustream,
+                               &stream->max_sb_size);
+               if (ret < 0) {
+                       ERR("lttng_ust_ctl_get_max_subbuf_size failed for stream %s",
+                                       stream->name);
+                       goto error;
+               }
+
+               /* Do actions once stream has been received. */
+               if (ctx->on_recv_stream) {
+                       ret = ctx->on_recv_stream(stream);
+                       if (ret < 0) {
+                               goto error;
+                       }
+               }
+
+               DBG("UST consumer add stream %s (key: %" PRIu64 ") with relayd id %" PRIu64,
+                               stream->name, stream->key, stream->relayd_stream_id);
+
+               /* Set next CPU stream. */
+               channel->streams.count = ++cpu;
+
+               /* Keep stream reference when creating metadata. */
+               if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA) {
+                       channel->metadata_stream = stream;
+                       if (channel->monitor) {
+                               /* Set metadata poll pipe if we created one */
+                               memcpy(stream->ust_metadata_poll_pipe,
+                                               ust_metadata_pipe,
+                                               sizeof(ust_metadata_pipe));
+                       }
+               }
+               pthread_mutex_unlock(&stream->lock);
+               current_stream_lock = NULL;
+       }
+
+       return 0;
+
+error:
+error_alloc:
+       if (current_stream_lock) {
+               pthread_mutex_unlock(current_stream_lock);
+       }
+       return ret;
+}
+
+static int open_ust_stream_fd(struct lttng_consumer_channel *channel, int cpu,
+               const struct lttng_credentials *session_credentials)
+{
+       char shm_path[PATH_MAX];
+       int ret;
+
+       if (!channel->shm_path[0]) {
+               return shm_create_anonymous("ust-consumer");
+       }
+       ret = get_stream_shm_path(shm_path, channel->shm_path, cpu);
+       if (ret) {
+               goto error_shm_path;
+       }
+       return run_as_open(shm_path,
+               O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR,
+               lttng_credentials_get_uid(session_credentials),
+               lttng_credentials_get_gid(session_credentials));
+
+error_shm_path:
+       return -1;
+}
+
+/*
+ * Create an UST channel with the given attributes and send it to the session
+ * daemon using the ust ctl API.
+ *
+ * Return 0 on success or else a negative value.
+ */
+static int create_ust_channel(struct lttng_consumer_channel *channel,
+               struct lttng_ust_ctl_consumer_channel_attr *attr,
+               struct lttng_ust_ctl_consumer_channel **ust_chanp)
+{
+       int ret, nr_stream_fds, i, j;
+       int *stream_fds;
+       struct lttng_ust_ctl_consumer_channel *ust_channel;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(attr);
+       LTTNG_ASSERT(ust_chanp);
+       LTTNG_ASSERT(channel->buffer_credentials.is_set);
+
+       DBG3("Creating channel to ustctl with attr: [overwrite: %d, "
+                       "subbuf_size: %" PRIu64 ", num_subbuf: %" PRIu64 ", "
+                       "switch_timer_interval: %u, read_timer_interval: %u, "
+                       "output: %d, type: %d", attr->overwrite, attr->subbuf_size,
+                       attr->num_subbuf, attr->switch_timer_interval,
+                       attr->read_timer_interval, attr->output, attr->type);
+
+       if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA)
+               nr_stream_fds = 1;
+       else
+               nr_stream_fds = lttng_ust_ctl_get_nr_stream_per_channel();
+       stream_fds = (int *) zmalloc(nr_stream_fds * sizeof(*stream_fds));
+       if (!stream_fds) {
+               ret = -1;
+               goto error_alloc;
+       }
+       for (i = 0; i < nr_stream_fds; i++) {
+               stream_fds[i] = open_ust_stream_fd(channel, i,
+                               &channel->buffer_credentials.value);
+               if (stream_fds[i] < 0) {
+                       ret = -1;
+                       goto error_open;
+               }
+       }
+       ust_channel = lttng_ust_ctl_create_channel(attr, stream_fds, nr_stream_fds);
+       if (!ust_channel) {
+               ret = -1;
+               goto error_create;
+       }
+       channel->nr_stream_fds = nr_stream_fds;
+       channel->stream_fds = stream_fds;
+       *ust_chanp = ust_channel;
+
+       return 0;
+
+error_create:
+error_open:
+       for (j = i - 1; j >= 0; j--) {
+               int closeret;
+
+               closeret = close(stream_fds[j]);
+               if (closeret) {
+                       PERROR("close");
+               }
+               if (channel->shm_path[0]) {
+                       char shm_path[PATH_MAX];
+
+                       closeret = get_stream_shm_path(shm_path,
+                                       channel->shm_path, j);
+                       if (closeret) {
+                               ERR("Cannot get stream shm path");
+                       }
+                       closeret = run_as_unlink(shm_path,
+                                       lttng_credentials_get_uid(LTTNG_OPTIONAL_GET_PTR(
+                                                       channel->buffer_credentials)),
+                                       lttng_credentials_get_gid(LTTNG_OPTIONAL_GET_PTR(
+                                                       channel->buffer_credentials)));
+                       if (closeret) {
+                               PERROR("unlink %s", shm_path);
+                       }
+               }
+       }
+       /* Try to rmdir all directories under shm_path root. */
+       if (channel->root_shm_path[0]) {
+               (void) run_as_rmdir_recursive(channel->root_shm_path,
+                               lttng_credentials_get_uid(LTTNG_OPTIONAL_GET_PTR(
+                                               channel->buffer_credentials)),
+                               lttng_credentials_get_gid(LTTNG_OPTIONAL_GET_PTR(
+                                               channel->buffer_credentials)),
+                               LTTNG_DIRECTORY_HANDLE_SKIP_NON_EMPTY_FLAG);
+       }
+       free(stream_fds);
+error_alloc:
+       return ret;
+}
+
+/*
+ * Send a single given stream to the session daemon using the sock.
+ *
+ * Return 0 on success else a negative value.
+ */
+static int send_sessiond_stream(int sock, struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(sock >= 0);
+
+       DBG("UST consumer sending stream %" PRIu64 " to sessiond", stream->key);
+
+       /* Send stream to session daemon. */
+       ret = lttng_ust_ctl_send_stream_to_sessiond(sock, stream->ustream);
+       if (ret < 0) {
+               goto error;
+       }
+
+error:
+       return ret;
+}
+
+/*
+ * Send channel to sessiond and relayd if applicable.
+ *
+ * Return 0 on success or else a negative value.
+ */
+static int send_channel_to_sessiond_and_relayd(int sock,
+               struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx, int *relayd_error)
+{
+       int ret, ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       struct lttng_consumer_stream *stream;
+       uint64_t net_seq_idx = -1ULL;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(ctx);
+       LTTNG_ASSERT(sock >= 0);
+
+       DBG("UST consumer sending channel %s to sessiond", channel->name);
+
+       if (channel->relayd_id != (uint64_t) -1ULL) {
+               cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+
+                       health_code_update();
+
+                       /* Try to send the stream to the relayd if one is available. */
+                       DBG("Sending stream %" PRIu64 " of channel \"%s\" to relayd",
+                                       stream->key, channel->name);
+                       ret = consumer_send_relayd_stream(stream, stream->chan->pathname);
+                       if (ret < 0) {
+                               /*
+                                * Flag that the relayd was the problem here probably due to a
+                                * communicaton error on the socket.
+                                */
+                               if (relayd_error) {
+                                       *relayd_error = 1;
+                               }
+                               ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
+                       }
+                       if (net_seq_idx == -1ULL) {
+                               net_seq_idx = stream->net_seq_idx;
+                       }
+               }
+       }
+
+       /* Inform sessiond that we are about to send channel and streams. */
+       ret = consumer_send_status_msg(sock, ret_code);
+       if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
+               /*
+                * Either the session daemon is not responding or the relayd died so we
+                * stop now.
+                */
+               goto error;
+       }
+
+       /* Send channel to sessiond. */
+       ret = lttng_ust_ctl_send_channel_to_sessiond(sock, channel->uchan);
+       if (ret < 0) {
+               goto error;
+       }
+
+       ret = lttng_ust_ctl_channel_close_wakeup_fd(channel->uchan);
+       if (ret < 0) {
+               goto error;
+       }
+
+       /* The channel was sent successfully to the sessiond at this point. */
+       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+
+               health_code_update();
+
+               /* Send stream to session daemon. */
+               ret = send_sessiond_stream(sock, stream);
+               if (ret < 0) {
+                       goto error;
+               }
+       }
+
+       /* Tell sessiond there is no more stream. */
+       ret = lttng_ust_ctl_send_stream_to_sessiond(sock, NULL);
+       if (ret < 0) {
+               goto error;
+       }
+
+       DBG("UST consumer NULL stream sent to sessiond");
+
+       return 0;
+
+error:
+       if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
+               ret = -1;
+       }
+       return ret;
+}
+
+/*
+ * Creates a channel and streams and add the channel it to the channel internal
+ * state. The created stream must ONLY be sent once the GET_CHANNEL command is
+ * received.
+ *
+ * Return 0 on success or else, a negative value is returned and the channel
+ * MUST be destroyed by consumer_del_channel().
+ */
+static int ask_channel(struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_channel *channel,
+               struct lttng_ust_ctl_consumer_channel_attr *attr)
+{
+       int ret;
+
+       LTTNG_ASSERT(ctx);
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(attr);
+
+       /*
+        * This value is still used by the kernel consumer since for the kernel,
+        * the stream ownership is not IN the consumer so we need to have the
+        * number of left stream that needs to be initialized so we can know when
+        * to delete the channel (see consumer.c).
+        *
+        * As for the user space tracer now, the consumer creates and sends the
+        * stream to the session daemon which only sends them to the application
+        * once every stream of a channel is received making this value useless
+        * because we they will be added to the poll thread before the application
+        * receives them. This ensures that a stream can not hang up during
+        * initilization of a channel.
+        */
+       channel->nb_init_stream_left = 0;
+
+       /* The reply msg status is handled in the following call. */
+       ret = create_ust_channel(channel, attr, &channel->uchan);
+       if (ret < 0) {
+               goto end;
+       }
+
+       channel->wait_fd = lttng_ust_ctl_channel_get_wait_fd(channel->uchan);
+
+       /*
+        * For the snapshots (no monitor), we create the metadata streams
+        * on demand, not during the channel creation.
+        */
+       if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA && !channel->monitor) {
+               ret = 0;
+               goto end;
+       }
+
+       /* Open all streams for this channel. */
+       pthread_mutex_lock(&channel->lock);
+       ret = create_ust_streams(channel, ctx);
+       pthread_mutex_unlock(&channel->lock);
+       if (ret < 0) {
+               goto end;
+       }
+
+end:
+       return ret;
+}
+
+/*
+ * Send all stream of a channel to the right thread handling it.
+ *
+ * On error, return a negative value else 0 on success.
+ */
+static int send_streams_to_thread(struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret = 0;
+       struct lttng_consumer_stream *stream, *stmp;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(ctx);
+
+       /* Send streams to the corresponding thread. */
+       cds_list_for_each_entry_safe(stream, stmp, &channel->streams.head,
+                       send_node) {
+
+               health_code_update();
+
+               /* Sending the stream to the thread. */
+               ret = send_stream_to_thread(stream, ctx);
+               if (ret < 0) {
+                       /*
+                        * If we are unable to send the stream to the thread, there is
+                        * a big problem so just stop everything.
+                        */
+                       goto error;
+               }
+       }
+
+error:
+       return ret;
+}
+
+/*
+ * Flush channel's streams using the given key to retrieve the channel.
+ *
+ * Return 0 on success else an LTTng error code.
+ */
+static int flush_channel(uint64_t chan_key)
+{
+       int ret = 0;
+       struct lttng_consumer_channel *channel;
+       struct lttng_consumer_stream *stream;
+       struct lttng_ht *ht;
+       struct lttng_ht_iter iter;
+
+       DBG("UST consumer flush channel key %" PRIu64, chan_key);
+
+       rcu_read_lock();
+       channel = consumer_find_channel(chan_key);
+       if (!channel) {
+               ERR("UST consumer flush channel %" PRIu64 " not found", chan_key);
+               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+               goto error;
+       }
+
+       ht = the_consumer_data.stream_per_chan_id_ht;
+
+       /* For each stream of the channel id, flush it. */
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&channel->key, lttng_ht_seed), ht->match_fct,
+                       &channel->key, &iter.iter, stream, node_channel_id.node) {
+
+               health_code_update();
+
+               pthread_mutex_lock(&stream->lock);
+
+               /*
+                * Protect against concurrent teardown of a stream.
+                */
+               if (cds_lfht_is_node_deleted(&stream->node.node)) {
+                       goto next;
+               }
+
+               if (!stream->quiescent) {
+                       ret = lttng_ust_ctl_flush_buffer(stream->ustream, 0);
+                       if (ret) {
+                               ERR("Failed to flush buffer while flushing channel: channel key = %" PRIu64 ", channel name = '%s'",
+                                               chan_key, channel->name);
+                               ret = LTTNG_ERR_BUFFER_FLUSH_FAILED;
+                               pthread_mutex_unlock(&stream->lock);
+                               goto error;
+                       }
+                       stream->quiescent = true;
+               }
+next:
+               pthread_mutex_unlock(&stream->lock);
+       }
+error:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Clear quiescent state from channel's streams using the given key to
+ * retrieve the channel.
+ *
+ * Return 0 on success else an LTTng error code.
+ */
+static int clear_quiescent_channel(uint64_t chan_key)
+{
+       int ret = 0;
+       struct lttng_consumer_channel *channel;
+       struct lttng_consumer_stream *stream;
+       struct lttng_ht *ht;
+       struct lttng_ht_iter iter;
+
+       DBG("UST consumer clear quiescent channel key %" PRIu64, chan_key);
+
+       rcu_read_lock();
+       channel = consumer_find_channel(chan_key);
+       if (!channel) {
+               ERR("UST consumer clear quiescent channel %" PRIu64 " not found", chan_key);
+               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+               goto error;
+       }
+
+       ht = the_consumer_data.stream_per_chan_id_ht;
+
+       /* For each stream of the channel id, clear quiescent state. */
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&channel->key, lttng_ht_seed), ht->match_fct,
+                       &channel->key, &iter.iter, stream, node_channel_id.node) {
+
+               health_code_update();
+
+               pthread_mutex_lock(&stream->lock);
+               stream->quiescent = false;
+               pthread_mutex_unlock(&stream->lock);
+       }
+error:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Close metadata stream wakeup_fd using the given key to retrieve the channel.
+ *
+ * Return 0 on success else an LTTng error code.
+ */
+static int close_metadata(uint64_t chan_key)
+{
+       int ret = 0;
+       struct lttng_consumer_channel *channel;
+       unsigned int channel_monitor;
+
+       DBG("UST consumer close metadata key %" PRIu64, chan_key);
+
+       channel = consumer_find_channel(chan_key);
+       if (!channel) {
+               /*
+                * This is possible if the metadata thread has issue a delete because
+                * the endpoint point of the stream hung up. There is no way the
+                * session daemon can know about it thus use a DBG instead of an actual
+                * error.
+                */
+               DBG("UST consumer close metadata %" PRIu64 " not found", chan_key);
+               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+               goto error;
+       }
+
+       pthread_mutex_lock(&the_consumer_data.lock);
+       pthread_mutex_lock(&channel->lock);
+       channel_monitor = channel->monitor;
+       if (cds_lfht_is_node_deleted(&channel->node.node)) {
+               goto error_unlock;
+       }
+
+       lttng_ustconsumer_close_metadata(channel);
+       pthread_mutex_unlock(&channel->lock);
+       pthread_mutex_unlock(&the_consumer_data.lock);
+
+       /*
+        * The ownership of a metadata channel depends on the type of
+        * session to which it belongs. In effect, the monitor flag is checked
+        * to determine if this metadata channel is in "snapshot" mode or not.
+        *
+        * In the non-snapshot case, the metadata channel is created along with
+        * a single stream which will remain present until the metadata channel
+        * is destroyed (on the destruction of its session). In this case, the
+        * metadata stream in "monitored" by the metadata poll thread and holds
+        * the ownership of its channel.
+        *
+        * Closing the metadata will cause the metadata stream's "metadata poll
+        * pipe" to be closed. Closing this pipe will wake-up the metadata poll
+        * thread which will teardown the metadata stream which, in return,
+        * deletes the metadata channel.
+        *
+        * In the snapshot case, the metadata stream is created and destroyed
+        * on every snapshot record. Since the channel doesn't have an owner
+        * other than the session daemon, it is safe to destroy it immediately
+        * on reception of the CLOSE_METADATA command.
+        */
+       if (!channel_monitor) {
+               /*
+                * The channel and consumer_data locks must be
+                * released before this call since consumer_del_channel
+                * re-acquires the channel and consumer_data locks to teardown
+                * the channel and queue its reclamation by the "call_rcu"
+                * worker thread.
+                */
+               consumer_del_channel(channel);
+       }
+
+       return ret;
+error_unlock:
+       pthread_mutex_unlock(&channel->lock);
+       pthread_mutex_unlock(&the_consumer_data.lock);
+error:
+       return ret;
+}
+
+/*
+ * RCU read side lock MUST be acquired before calling this function.
+ *
+ * Return 0 on success else an LTTng error code.
+ */
+static int setup_metadata(struct lttng_consumer_local_data *ctx, uint64_t key)
+{
+       int ret;
+       struct lttng_consumer_channel *metadata;
+
+       DBG("UST consumer setup metadata key %" PRIu64, key);
+
+       metadata = consumer_find_channel(key);
+       if (!metadata) {
+               ERR("UST consumer push metadata %" PRIu64 " not found", key);
+               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+               goto end;
+       }
+
+       /*
+        * In no monitor mode, the metadata channel has no stream(s) so skip the
+        * ownership transfer to the metadata thread.
+        */
+       if (!metadata->monitor) {
+               DBG("Metadata channel in no monitor");
+               ret = 0;
+               goto end;
+       }
+
+       /*
+        * Send metadata stream to relayd if one available. Availability is
+        * known if the stream is still in the list of the channel.
+        */
+       if (cds_list_empty(&metadata->streams.head)) {
+               ERR("Metadata channel key %" PRIu64 ", no stream available.", key);
+               ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
+               goto error_no_stream;
+       }
+
+       /* Send metadata stream to relayd if needed. */
+       if (metadata->metadata_stream->net_seq_idx != (uint64_t) -1ULL) {
+               ret = consumer_send_relayd_stream(metadata->metadata_stream,
+                               metadata->pathname);
+               if (ret < 0) {
+                       ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
+                       goto error;
+               }
+               ret = consumer_send_relayd_streams_sent(
+                               metadata->metadata_stream->net_seq_idx);
+               if (ret < 0) {
+                       ret = LTTCOMM_CONSUMERD_RELAYD_FAIL;
+                       goto error;
+               }
+       }
+
+       /*
+        * Ownership of metadata stream is passed along. Freeing is handled by
+        * the callee.
+        */
+       ret = send_streams_to_thread(metadata, ctx);
+       if (ret < 0) {
+               /*
+                * If we are unable to send the stream to the thread, there is
+                * a big problem so just stop everything.
+                */
+               ret = LTTCOMM_CONSUMERD_FATAL;
+               goto send_streams_error;
+       }
+       /* List MUST be empty after or else it could be reused. */
+       LTTNG_ASSERT(cds_list_empty(&metadata->streams.head));
+
+       ret = 0;
+       goto end;
+
+error:
+       /*
+        * Delete metadata channel on error. At this point, the metadata stream can
+        * NOT be monitored by the metadata thread thus having the guarantee that
+        * the stream is still in the local stream list of the channel. This call
+        * will make sure to clean that list.
+        */
+       consumer_stream_destroy(metadata->metadata_stream, NULL);
+       cds_list_del(&metadata->metadata_stream->send_node);
+       metadata->metadata_stream = NULL;
+send_streams_error:
+error_no_stream:
+end:
+       return ret;
+}
+
+/*
+ * Snapshot the whole metadata.
+ * RCU read-side lock must be held by the caller.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+static int snapshot_metadata(struct lttng_consumer_channel *metadata_channel,
+               uint64_t key, char *path, uint64_t relayd_id,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret = 0;
+       struct lttng_consumer_stream *metadata_stream;
+
+       LTTNG_ASSERT(path);
+       LTTNG_ASSERT(ctx);
+
+       DBG("UST consumer snapshot metadata with key %" PRIu64 " at path %s",
+                       key, path);
+
+       rcu_read_lock();
+
+       LTTNG_ASSERT(!metadata_channel->monitor);
+
+       health_code_update();
+
+       /*
+        * Ask the sessiond if we have new metadata waiting and update the
+        * consumer metadata cache.
+        */
+       ret = lttng_ustconsumer_request_metadata(ctx, metadata_channel, 0, 1);
+       if (ret < 0) {
+               goto error;
+       }
+
+       health_code_update();
+
+       /*
+        * The metadata stream is NOT created in no monitor mode when the channel
+        * is created on a sessiond ask channel command.
+        */
+       ret = create_ust_streams(metadata_channel, ctx);
+       if (ret < 0) {
+               goto error;
+       }
+
+       metadata_stream = metadata_channel->metadata_stream;
+       LTTNG_ASSERT(metadata_stream);
+
+       pthread_mutex_lock(&metadata_stream->lock);
+       if (relayd_id != (uint64_t) -1ULL) {
+               metadata_stream->net_seq_idx = relayd_id;
+               ret = consumer_send_relayd_stream(metadata_stream, path);
+       } else {
+               ret = consumer_stream_create_output_files(metadata_stream,
+                               false);
+       }
+       pthread_mutex_unlock(&metadata_stream->lock);
+       if (ret < 0) {
+               goto error_stream;
+       }
+
+       do {
+               health_code_update();
+
+               ret = lttng_consumer_read_subbuffer(metadata_stream, ctx, true);
+               if (ret < 0) {
+                       goto error_stream;
+               }
+       } while (ret > 0);
+
+error_stream:
+       /*
+        * Clean up the stream completly because the next snapshot will use a new
+        * metadata stream.
+        */
+       consumer_stream_destroy(metadata_stream, NULL);
+       cds_list_del(&metadata_stream->send_node);
+       metadata_channel->metadata_stream = NULL;
+
+error:
+       rcu_read_unlock();
+       return ret;
+}
+
+static
+int get_current_subbuf_addr(struct lttng_consumer_stream *stream,
+               const char **addr)
+{
+       int ret;
+       unsigned long mmap_offset;
+       const char *mmap_base;
+
+       mmap_base = (const char *) lttng_ust_ctl_get_mmap_base(stream->ustream);
+       if (!mmap_base) {
+               ERR("Failed to get mmap base for stream `%s`",
+                               stream->name);
+               ret = -EPERM;
+               goto error;
+       }
+
+       ret = lttng_ust_ctl_get_mmap_read_offset(stream->ustream, &mmap_offset);
+       if (ret != 0) {
+               ERR("Failed to get mmap offset for stream `%s`", stream->name);
+               ret = -EINVAL;
+               goto error;
+       }
+
+       *addr = mmap_base + mmap_offset;
+error:
+       return ret;
+
+}
+
+/*
+ * Take a snapshot of all the stream of a channel.
+ * RCU read-side lock and the channel lock must be held by the caller.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+static int snapshot_channel(struct lttng_consumer_channel *channel,
+               uint64_t key, char *path, uint64_t relayd_id,
+               uint64_t nb_packets_per_stream,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+       unsigned use_relayd = 0;
+       unsigned long consumed_pos, produced_pos;
+       struct lttng_consumer_stream *stream;
+
+       LTTNG_ASSERT(path);
+       LTTNG_ASSERT(ctx);
+
+       rcu_read_lock();
+
+       if (relayd_id != (uint64_t) -1ULL) {
+               use_relayd = 1;
+       }
+
+       LTTNG_ASSERT(!channel->monitor);
+       DBG("UST consumer snapshot channel %" PRIu64, key);
+
+       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+               health_code_update();
+
+               /* Lock stream because we are about to change its state. */
+               pthread_mutex_lock(&stream->lock);
+               LTTNG_ASSERT(channel->trace_chunk);
+               if (!lttng_trace_chunk_get(channel->trace_chunk)) {
+                       /*
+                        * Can't happen barring an internal error as the channel
+                        * holds a reference to the trace chunk.
+                        */
+                       ERR("Failed to acquire reference to channel's trace chunk");
+                       ret = -1;
+                       goto error_unlock;
+               }
+               LTTNG_ASSERT(!stream->trace_chunk);
+               stream->trace_chunk = channel->trace_chunk;
+
+               stream->net_seq_idx = relayd_id;
+
+               if (use_relayd) {
+                       ret = consumer_send_relayd_stream(stream, path);
+                       if (ret < 0) {
+                               goto error_unlock;
+                       }
+               } else {
+                       ret = consumer_stream_create_output_files(stream,
+                                       false);
+                       if (ret < 0) {
+                               goto error_unlock;
+                       }
+                       DBG("UST consumer snapshot stream (%" PRIu64 ")",
+                                       stream->key);
+               }
+
+               /*
+                * If tracing is active, we want to perform a "full" buffer flush.
+                * Else, if quiescent, it has already been done by the prior stop.
+                */
+               if (!stream->quiescent) {
+                       ret = lttng_ust_ctl_flush_buffer(stream->ustream, 0);
+                       if (ret < 0) {
+                               ERR("Failed to flush buffer during snapshot of channel: channel key = %" PRIu64 ", channel name = '%s'",
+                                               channel->key, channel->name);
+                               goto error_unlock;
+                       }
+               }
+
+               ret = lttng_ustconsumer_take_snapshot(stream);
+               if (ret < 0) {
+                       ERR("Taking UST snapshot");
+                       goto error_unlock;
+               }
+
+               ret = lttng_ustconsumer_get_produced_snapshot(stream, &produced_pos);
+               if (ret < 0) {
+                       ERR("Produced UST snapshot position");
+                       goto error_unlock;
+               }
+
+               ret = lttng_ustconsumer_get_consumed_snapshot(stream, &consumed_pos);
+               if (ret < 0) {
+                       ERR("Consumerd UST snapshot position");
+                       goto error_unlock;
+               }
+
+               /*
+                * The original value is sent back if max stream size is larger than
+                * the possible size of the snapshot. Also, we assume that the session
+                * daemon should never send a maximum stream size that is lower than
+                * subbuffer size.
+                */
+               consumed_pos = consumer_get_consume_start_pos(consumed_pos,
+                               produced_pos, nb_packets_per_stream,
+                               stream->max_sb_size);
+
+               while ((long) (consumed_pos - produced_pos) < 0) {
+                       ssize_t read_len;
+                       unsigned long len, padded_len;
+                       const char *subbuf_addr;
+                       struct lttng_buffer_view subbuf_view;
+
+                       health_code_update();
+
+                       DBG("UST consumer taking snapshot at pos %lu", consumed_pos);
+
+                       ret = lttng_ust_ctl_get_subbuf(stream->ustream, &consumed_pos);
+                       if (ret < 0) {
+                               if (ret != -EAGAIN) {
+                                       PERROR("lttng_ust_ctl_get_subbuf snapshot");
+                                       goto error_close_stream;
+                               }
+                               DBG("UST consumer get subbuf failed. Skipping it.");
+                               consumed_pos += stream->max_sb_size;
+                               stream->chan->lost_packets++;
+                               continue;
+                       }
+
+                       ret = lttng_ust_ctl_get_subbuf_size(stream->ustream, &len);
+                       if (ret < 0) {
+                               ERR("Snapshot lttng_ust_ctl_get_subbuf_size");
+                               goto error_put_subbuf;
+                       }
+
+                       ret = lttng_ust_ctl_get_padded_subbuf_size(stream->ustream, &padded_len);
+                       if (ret < 0) {
+                               ERR("Snapshot lttng_ust_ctl_get_padded_subbuf_size");
+                               goto error_put_subbuf;
+                       }
+
+                       ret = get_current_subbuf_addr(stream, &subbuf_addr);
+                       if (ret) {
+                               goto error_put_subbuf;
+                       }
+
+                       subbuf_view = lttng_buffer_view_init(
+                                       subbuf_addr, 0, padded_len);
+                       read_len = lttng_consumer_on_read_subbuffer_mmap(
+                                       stream, &subbuf_view, padded_len - len);
+                       if (use_relayd) {
+                               if (read_len != len) {
+                                       ret = -EPERM;
+                                       goto error_put_subbuf;
+                               }
+                       } else {
+                               if (read_len != padded_len) {
+                                       ret = -EPERM;
+                                       goto error_put_subbuf;
+                               }
+                       }
+
+                       ret = lttng_ust_ctl_put_subbuf(stream->ustream);
+                       if (ret < 0) {
+                               ERR("Snapshot lttng_ust_ctl_put_subbuf");
+                               goto error_close_stream;
+                       }
+                       consumed_pos += stream->max_sb_size;
+               }
+
+               /* Simply close the stream so we can use it on the next snapshot. */
+               consumer_stream_close(stream);
+               pthread_mutex_unlock(&stream->lock);
+       }
+
+       rcu_read_unlock();
+       return 0;
+
+error_put_subbuf:
+       if (lttng_ust_ctl_put_subbuf(stream->ustream) < 0) {
+               ERR("Snapshot lttng_ust_ctl_put_subbuf");
+       }
+error_close_stream:
+       consumer_stream_close(stream);
+error_unlock:
+       pthread_mutex_unlock(&stream->lock);
+       rcu_read_unlock();
+       return ret;
+}
+
+static
+void metadata_stream_reset_cache_consumed_position(
+               struct lttng_consumer_stream *stream)
+{
+       ASSERT_LOCKED(stream->lock);
+
+       DBG("Reset metadata cache of session %" PRIu64,
+                       stream->chan->session_id);
+       stream->ust_metadata_pushed = 0;
+}
+
+/*
+ * Receive the metadata updates from the sessiond. Supports receiving
+ * overlapping metadata, but is needs to always belong to a contiguous
+ * range starting from 0.
+ * Be careful about the locks held when calling this function: it needs
+ * the metadata cache flush to concurrently progress in order to
+ * complete.
+ */
+int lttng_ustconsumer_recv_metadata(int sock, uint64_t key, uint64_t offset,
+               uint64_t len, uint64_t version,
+               struct lttng_consumer_channel *channel, int timer, int wait)
+{
+       int ret, ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       char *metadata_str;
+       enum consumer_metadata_cache_write_status cache_write_status;
+
+       DBG("UST consumer push metadata key %" PRIu64 " of len %" PRIu64, key, len);
+
+       metadata_str = (char *) zmalloc(len * sizeof(char));
+       if (!metadata_str) {
+               PERROR("zmalloc metadata string");
+               ret_code = LTTCOMM_CONSUMERD_ENOMEM;
+               goto end;
+       }
+
+       health_code_update();
+
+       /* Receive metadata string. */
+       ret = lttcomm_recv_unix_sock(sock, metadata_str, len);
+       if (ret < 0) {
+               /* Session daemon is dead so return gracefully. */
+               ret_code = ret;
+               goto end_free;
+       }
+
+       health_code_update();
+
+       pthread_mutex_lock(&channel->metadata_cache->lock);
+       cache_write_status = consumer_metadata_cache_write(
+                       channel->metadata_cache, offset, len, version,
+                       metadata_str);
+       pthread_mutex_unlock(&channel->metadata_cache->lock);
+       switch (cache_write_status) {
+       case CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE:
+               /*
+                * The write entirely overlapped with existing contents of the
+                * same metadata version (same content); there is nothing to do.
+                */
+               break;
+       case CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED:
+               /*
+                * The metadata cache was invalidated (previously pushed
+                * content has been overwritten). Reset the stream's consumed
+                * metadata position to ensure the metadata poll thread consumes
+                * the whole cache.
+                */
+               pthread_mutex_lock(&channel->metadata_stream->lock);
+               metadata_stream_reset_cache_consumed_position(
+                               channel->metadata_stream);
+               pthread_mutex_unlock(&channel->metadata_stream->lock);
+               /* Fall-through. */
+       case CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT:
+               /*
+                * In both cases, the metadata poll thread has new data to
+                * consume.
+                */
+               ret = consumer_metadata_wakeup_pipe(channel);
+               if (ret) {
+                       ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
+                       goto end_free;
+               }
+               break;
+       case CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR:
+               /* Unable to handle metadata. Notify session daemon. */
+               ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
+               /*
+                * Skip metadata flush on write error since the offset and len might
+                * not have been updated which could create an infinite loop below when
+                * waiting for the metadata cache to be flushed.
+                */
+               goto end_free;
+       default:
+               abort();
+       }
+
+       if (!wait) {
+               goto end_free;
+       }
+       while (consumer_metadata_cache_flushed(channel, offset + len, timer)) {
+               DBG("Waiting for metadata to be flushed");
+
+               health_code_update();
+
+               usleep(DEFAULT_METADATA_AVAILABILITY_WAIT_TIME);
+       }
+
+end_free:
+       free(metadata_str);
+end:
+       return ret_code;
+}
+
+/*
+ * Receive command from session daemon and process it.
+ *
+ * Return 1 on success else a negative value or 0.
+ */
+int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
+               int sock, struct pollfd *consumer_sockpoll)
+{
+       int ret_func;
+       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       struct lttcomm_consumer_msg msg;
+       struct lttng_consumer_channel *channel = NULL;
+
+       health_code_update();
+
+       {
+               ssize_t ret_recv;
+
+               ret_recv = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
+               if (ret_recv != sizeof(msg)) {
+                       DBG("Consumer received unexpected message size %zd (expects %zu)",
+                                       ret_recv, sizeof(msg));
+                       /*
+                        * The ret value might 0 meaning an orderly shutdown but this is ok
+                        * since the caller handles this.
+                        */
+                       if (ret_recv > 0) {
+                               lttng_consumer_send_error(ctx,
+                                               LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
+                               ret_recv = -1;
+                       }
+                       return ret_recv;
+               }
+       }
+
+       health_code_update();
+
+       /* deprecated */
+       LTTNG_ASSERT(msg.cmd_type != LTTNG_CONSUMER_STOP);
+
+       health_code_update();
+
+       /* relayd needs RCU read-side lock */
+       rcu_read_lock();
+
+       switch (msg.cmd_type) {
+       case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
+       {
+               /* Session daemon status message are handled in the following call. */
+               consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
+                               msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
+                               &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
+                               msg.u.relayd_sock.relayd_session_id);
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_DESTROY_RELAYD:
+       {
+               uint64_t index = msg.u.destroy_relayd.net_seq_idx;
+               struct consumer_relayd_sock_pair *relayd;
+
+               DBG("UST consumer destroying relayd %" PRIu64, index);
+
+               /* Get relayd reference if exists. */
+               relayd = consumer_find_relayd(index);
+               if (relayd == NULL) {
+                       DBG("Unable to find relayd %" PRIu64, index);
+                       ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
+               }
+
+               /*
+                * Each relayd socket pair has a refcount of stream attached to it
+                * which tells if the relayd is still active or not depending on the
+                * refcount value.
+                *
+                * This will set the destroy flag of the relayd object and destroy it
+                * if the refcount reaches zero when called.
+                *
+                * The destroy can happen either here or when a stream fd hangs up.
+                */
+               if (relayd) {
+                       consumer_flag_relayd_for_destroy(relayd);
+               }
+
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_UPDATE_STREAM:
+       {
+               rcu_read_unlock();
+               return -ENOSYS;
+       }
+       case LTTNG_CONSUMER_DATA_PENDING:
+       {
+               int is_data_pending;
+               ssize_t ret_send;
+               uint64_t id = msg.u.data_pending.session_id;
+
+               DBG("UST consumer data pending command for id %" PRIu64, id);
+
+               is_data_pending = consumer_data_pending(id);
+
+               /* Send back returned value to session daemon */
+               ret_send = lttcomm_send_unix_sock(sock, &is_data_pending,
+                               sizeof(is_data_pending));
+               if (ret_send < 0) {
+                       DBG("Error when sending the data pending ret code: %zd",
+                                       ret_send);
+                       goto error_fatal;
+               }
+
+               /*
+                * No need to send back a status message since the data pending
+                * returned value is the response.
+                */
+               break;
+       }
+       case LTTNG_CONSUMER_ASK_CHANNEL_CREATION:
+       {
+               int ret_ask_channel, ret_add_channel, ret_send;
+               struct lttng_ust_ctl_consumer_channel_attr attr;
+               const uint64_t chunk_id = msg.u.ask_channel.chunk_id.value;
+               const struct lttng_credentials buffer_credentials = {
+                       .uid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.ask_channel.buffer_credentials.uid),
+                       .gid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.ask_channel.buffer_credentials.gid),
+               };
+
+               /* Create a plain object and reserve a channel key. */
+               channel = consumer_allocate_channel(
+                               msg.u.ask_channel.key,
+                               msg.u.ask_channel.session_id,
+                               msg.u.ask_channel.chunk_id.is_set ?
+                                               &chunk_id : NULL,
+                               msg.u.ask_channel.pathname,
+                               msg.u.ask_channel.name,
+                               msg.u.ask_channel.relayd_id,
+                               (enum lttng_event_output) msg.u.ask_channel.output,
+                               msg.u.ask_channel.tracefile_size,
+                               msg.u.ask_channel.tracefile_count,
+                               msg.u.ask_channel.session_id_per_pid,
+                               msg.u.ask_channel.monitor,
+                               msg.u.ask_channel.live_timer_interval,
+                               msg.u.ask_channel.is_live,
+                               msg.u.ask_channel.root_shm_path,
+                               msg.u.ask_channel.shm_path);
+               if (!channel) {
+                       goto end_channel_error;
+               }
+
+               LTTNG_OPTIONAL_SET(&channel->buffer_credentials,
+                               buffer_credentials);
+
+               /*
+                * Assign UST application UID to the channel. This value is ignored for
+                * per PID buffers. This is specific to UST thus setting this after the
+                * allocation.
+                */
+               channel->ust_app_uid = msg.u.ask_channel.ust_app_uid;
+
+               /* Build channel attributes from received message. */
+               attr.subbuf_size = msg.u.ask_channel.subbuf_size;
+               attr.num_subbuf = msg.u.ask_channel.num_subbuf;
+               attr.overwrite = msg.u.ask_channel.overwrite;
+               attr.switch_timer_interval = msg.u.ask_channel.switch_timer_interval;
+               attr.read_timer_interval = msg.u.ask_channel.read_timer_interval;
+               attr.chan_id = msg.u.ask_channel.chan_id;
+               memcpy(attr.uuid, msg.u.ask_channel.uuid, sizeof(attr.uuid));
+               attr.blocking_timeout= msg.u.ask_channel.blocking_timeout;
+
+               /* Match channel buffer type to the UST abi. */
+               switch (msg.u.ask_channel.output) {
+               case LTTNG_EVENT_MMAP:
+               default:
+                       attr.output = LTTNG_UST_ABI_MMAP;
+                       break;
+               }
+
+               /* Translate and save channel type. */
+               switch (msg.u.ask_channel.type) {
+               case LTTNG_UST_ABI_CHAN_PER_CPU:
+                       channel->type = CONSUMER_CHANNEL_TYPE_DATA;
+                       attr.type = LTTNG_UST_ABI_CHAN_PER_CPU;
+                       /*
+                        * Set refcount to 1 for owner. Below, we will
+                        * pass ownership to the
+                        * consumer_thread_channel_poll() thread.
+                        */
+                       channel->refcount = 1;
+                       break;
+               case LTTNG_UST_ABI_CHAN_METADATA:
+                       channel->type = CONSUMER_CHANNEL_TYPE_METADATA;
+                       attr.type = LTTNG_UST_ABI_CHAN_METADATA;
+                       break;
+               default:
+                       abort();
+                       goto error_fatal;
+               };
+
+               health_code_update();
+
+               ret_ask_channel = ask_channel(ctx, channel, &attr);
+               if (ret_ask_channel < 0) {
+                       goto end_channel_error;
+               }
+
+               if (msg.u.ask_channel.type == LTTNG_UST_ABI_CHAN_METADATA) {
+                       int ret_allocate;
+
+                       ret_allocate = consumer_metadata_cache_allocate(
+                                       channel);
+                       if (ret_allocate < 0) {
+                               ERR("Allocating metadata cache");
+                               goto end_channel_error;
+                       }
+                       consumer_timer_switch_start(channel, attr.switch_timer_interval);
+                       attr.switch_timer_interval = 0;
+               } else {
+                       int monitor_start_ret;
+
+                       consumer_timer_live_start(channel,
+                                       msg.u.ask_channel.live_timer_interval);
+                       monitor_start_ret = consumer_timer_monitor_start(
+                                       channel,
+                                       msg.u.ask_channel.monitor_timer_interval);
+                       if (monitor_start_ret < 0) {
+                               ERR("Starting channel monitoring timer failed");
+                               goto end_channel_error;
+                       }
+               }
+
+               health_code_update();
+
+               /*
+                * Add the channel to the internal state AFTER all streams were created
+                * and successfully sent to session daemon. This way, all streams must
+                * be ready before this channel is visible to the threads.
+                * If add_channel succeeds, ownership of the channel is
+                * passed to consumer_thread_channel_poll().
+                */
+               ret_add_channel = add_channel(channel, ctx);
+               if (ret_add_channel < 0) {
+                       if (msg.u.ask_channel.type == LTTNG_UST_ABI_CHAN_METADATA) {
+                               if (channel->switch_timer_enabled == 1) {
+                                       consumer_timer_switch_stop(channel);
+                               }
+                               consumer_metadata_cache_destroy(channel);
+                       }
+                       if (channel->live_timer_enabled == 1) {
+                               consumer_timer_live_stop(channel);
+                       }
+                       if (channel->monitor_timer_enabled == 1) {
+                               consumer_timer_monitor_stop(channel);
+                       }
+                       goto end_channel_error;
+               }
+
+               health_code_update();
+
+               /*
+                * Channel and streams are now created. Inform the session daemon that
+                * everything went well and should wait to receive the channel and
+                * streams with ustctl API.
+                */
+               ret_send = consumer_send_status_channel(sock, channel);
+               if (ret_send < 0) {
+                       /*
+                        * There is probably a problem on the socket.
+                        */
+                       goto error_fatal;
+               }
+
+               break;
+       }
+       case LTTNG_CONSUMER_GET_CHANNEL:
+       {
+               int ret, relayd_err = 0;
+               uint64_t key = msg.u.get_channel.key;
+               struct lttng_consumer_channel *found_channel;
+
+               found_channel = consumer_find_channel(key);
+               if (!found_channel) {
+                       ERR("UST consumer get channel key %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+                       goto end_get_channel;
+               }
+
+               health_code_update();
+
+               /* Send the channel to sessiond (and relayd, if applicable). */
+               ret = send_channel_to_sessiond_and_relayd(
+                               sock, found_channel, ctx, &relayd_err);
+               if (ret < 0) {
+                       if (relayd_err) {
+                               /*
+                                * We were unable to send to the relayd the stream so avoid
+                                * sending back a fatal error to the thread since this is OK
+                                * and the consumer can continue its work. The above call
+                                * has sent the error status message to the sessiond.
+                                */
+                               goto end_get_channel_nosignal;
+                       }
+                       /*
+                        * The communicaton was broken hence there is a bad state between
+                        * the consumer and sessiond so stop everything.
+                        */
+                       goto error_get_channel_fatal;
+               }
+
+               health_code_update();
+
+               /*
+                * In no monitor mode, the streams ownership is kept inside the channel
+                * so don't send them to the data thread.
+                */
+               if (!found_channel->monitor) {
+                       goto end_get_channel;
+               }
+
+               ret = send_streams_to_thread(found_channel, ctx);
+               if (ret < 0) {
+                       /*
+                        * If we are unable to send the stream to the thread, there is
+                        * a big problem so just stop everything.
+                        */
+                       goto error_get_channel_fatal;
+               }
+               /* List MUST be empty after or else it could be reused. */
+               LTTNG_ASSERT(cds_list_empty(&found_channel->streams.head));
+end_get_channel:
+               goto end_msg_sessiond;
+error_get_channel_fatal:
+               goto error_fatal;
+end_get_channel_nosignal:
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_DESTROY_CHANNEL:
+       {
+               uint64_t key = msg.u.destroy_channel.key;
+
+               /*
+                * Only called if streams have not been sent to stream
+                * manager thread. However, channel has been sent to
+                * channel manager thread.
+                */
+               notify_thread_del_channel(ctx, key);
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_CLOSE_METADATA:
+       {
+               int ret;
+
+               ret = close_metadata(msg.u.close_metadata.key);
+               if (ret != 0) {
+                       ret_code = (lttcomm_return_code) ret;
+               }
+
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_FLUSH_CHANNEL:
+       {
+               int ret;
+
+               ret = flush_channel(msg.u.flush_channel.key);
+               if (ret != 0) {
+                       ret_code = (lttcomm_return_code) ret;
+               }
+
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_CLEAR_QUIESCENT_CHANNEL:
+       {
+               int ret;
+
+               ret = clear_quiescent_channel(
+                               msg.u.clear_quiescent_channel.key);
+               if (ret != 0) {
+                       ret_code = (lttcomm_return_code) ret;
+               }
+
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_PUSH_METADATA:
+       {
+               int ret;
+               uint64_t len = msg.u.push_metadata.len;
+               uint64_t key = msg.u.push_metadata.key;
+               uint64_t offset = msg.u.push_metadata.target_offset;
+               uint64_t version = msg.u.push_metadata.version;
+               struct lttng_consumer_channel *found_channel;
+
+               DBG("UST consumer push metadata key %" PRIu64 " of len %" PRIu64, key,
+                               len);
+
+               found_channel = consumer_find_channel(key);
+               if (!found_channel) {
+                       /*
+                        * This is possible if the metadata creation on the consumer side
+                        * is in flight vis-a-vis a concurrent push metadata from the
+                        * session daemon.  Simply return that the channel failed and the
+                        * session daemon will handle that message correctly considering
+                        * that this race is acceptable thus the DBG() statement here.
+                        */
+                       DBG("UST consumer push metadata %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHANNEL_FAIL;
+                       goto end_push_metadata_msg_sessiond;
+               }
+
+               health_code_update();
+
+               if (!len) {
+                       /*
+                        * There is nothing to receive. We have simply
+                        * checked whether the channel can be found.
+                        */
+                       ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+                       goto end_push_metadata_msg_sessiond;
+               }
+
+               /* Tell session daemon we are ready to receive the metadata. */
+               ret = consumer_send_status_msg(sock, LTTCOMM_CONSUMERD_SUCCESS);
+               if (ret < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto error_push_metadata_fatal;
+               }
+
+               health_code_update();
+
+               /* Wait for more data. */
+               health_poll_entry();
+               ret = lttng_consumer_poll_socket(consumer_sockpoll);
+               health_poll_exit();
+               if (ret) {
+                       goto error_push_metadata_fatal;
+               }
+
+               health_code_update();
+
+               ret = lttng_ustconsumer_recv_metadata(sock, key, offset, len,
+                               version, found_channel, 0, 1);
+               if (ret < 0) {
+                       /* error receiving from sessiond */
+                       goto error_push_metadata_fatal;
+               } else {
+                       ret_code = (lttcomm_return_code) ret;
+                       goto end_push_metadata_msg_sessiond;
+               }
+end_push_metadata_msg_sessiond:
+               goto end_msg_sessiond;
+error_push_metadata_fatal:
+               goto error_fatal;
+       }
+       case LTTNG_CONSUMER_SETUP_METADATA:
+       {
+               int ret;
+
+               ret = setup_metadata(ctx, msg.u.setup_metadata.key);
+               if (ret) {
+                       ret_code = (lttcomm_return_code) ret;
+               }
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
+       {
+               struct lttng_consumer_channel *found_channel;
+               uint64_t key = msg.u.snapshot_channel.key;
+               int ret_send;
+
+               found_channel = consumer_find_channel(key);
+               if (!found_channel) {
+                       DBG("UST snapshot channel not found for key %" PRIu64, key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               } else {
+                       if (msg.u.snapshot_channel.metadata) {
+                               int ret_snapshot;
+
+                               ret_snapshot = snapshot_metadata(found_channel,
+                                               key,
+                                               msg.u.snapshot_channel.pathname,
+                                               msg.u.snapshot_channel.relayd_id,
+                                               ctx);
+                               if (ret_snapshot < 0) {
+                                       ERR("Snapshot metadata failed");
+                                       ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
+                               }
+                       } else {
+                               int ret_snapshot;
+
+                               ret_snapshot = snapshot_channel(found_channel,
+                                               key,
+                                               msg.u.snapshot_channel.pathname,
+                                               msg.u.snapshot_channel.relayd_id,
+                                               msg.u.snapshot_channel
+                                                               .nb_packets_per_stream,
+                                               ctx);
+                               if (ret_snapshot < 0) {
+                                       ERR("Snapshot channel failed");
+                                       ret_code = LTTCOMM_CONSUMERD_SNAPSHOT_FAILED;
+                               }
+                       }
+               }
+               health_code_update();
+               ret_send = consumer_send_status_msg(sock, ret_code);
+               if (ret_send < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
+               health_code_update();
+               break;
+       }
+       case LTTNG_CONSUMER_DISCARDED_EVENTS:
+       {
+               int ret = 0;
+               uint64_t discarded_events;
+               struct lttng_ht_iter iter;
+               struct lttng_ht *ht;
+               struct lttng_consumer_stream *stream;
+               uint64_t id = msg.u.discarded_events.session_id;
+               uint64_t key = msg.u.discarded_events.channel_key;
+
+               DBG("UST consumer discarded events command for session id %"
+                               PRIu64, id);
+               rcu_read_lock();
+               pthread_mutex_lock(&the_consumer_data.lock);
+
+               ht = the_consumer_data.stream_list_ht;
+
+               /*
+                * We only need a reference to the channel, but they are not
+                * directly indexed, so we just use the first matching stream
+                * to extract the information we need, we default to 0 if not
+                * found (no events are dropped if the channel is not yet in
+                * use).
+                */
+               discarded_events = 0;
+               cds_lfht_for_each_entry_duplicate(ht->ht,
+                               ht->hash_fct(&id, lttng_ht_seed),
+                               ht->match_fct, &id,
+                               &iter.iter, stream, node_session_id.node) {
+                       if (stream->chan->key == key) {
+                               discarded_events = stream->chan->discarded_events;
+                               break;
+                       }
+               }
+               pthread_mutex_unlock(&the_consumer_data.lock);
+               rcu_read_unlock();
+
+               DBG("UST consumer discarded events command for session id %"
+                               PRIu64 ", channel key %" PRIu64, id, key);
+
+               health_code_update();
+
+               /* Send back returned value to session daemon */
+               ret = lttcomm_send_unix_sock(sock, &discarded_events, sizeof(discarded_events));
+               if (ret < 0) {
+                       PERROR("send discarded events");
+                       goto error_fatal;
+               }
+
+               break;
+       }
+       case LTTNG_CONSUMER_LOST_PACKETS:
+       {
+               int ret;
+               uint64_t lost_packets;
+               struct lttng_ht_iter iter;
+               struct lttng_ht *ht;
+               struct lttng_consumer_stream *stream;
+               uint64_t id = msg.u.lost_packets.session_id;
+               uint64_t key = msg.u.lost_packets.channel_key;
+
+               DBG("UST consumer lost packets command for session id %"
+                               PRIu64, id);
+               rcu_read_lock();
+               pthread_mutex_lock(&the_consumer_data.lock);
+
+               ht = the_consumer_data.stream_list_ht;
+
+               /*
+                * We only need a reference to the channel, but they are not
+                * directly indexed, so we just use the first matching stream
+                * to extract the information we need, we default to 0 if not
+                * found (no packets lost if the channel is not yet in use).
+                */
+               lost_packets = 0;
+               cds_lfht_for_each_entry_duplicate(ht->ht,
+                               ht->hash_fct(&id, lttng_ht_seed),
+                               ht->match_fct, &id,
+                               &iter.iter, stream, node_session_id.node) {
+                       if (stream->chan->key == key) {
+                               lost_packets = stream->chan->lost_packets;
+                               break;
+                       }
+               }
+               pthread_mutex_unlock(&the_consumer_data.lock);
+               rcu_read_unlock();
+
+               DBG("UST consumer lost packets command for session id %"
+                               PRIu64 ", channel key %" PRIu64, id, key);
+
+               health_code_update();
+
+               /* Send back returned value to session daemon */
+               ret = lttcomm_send_unix_sock(sock, &lost_packets,
+                               sizeof(lost_packets));
+               if (ret < 0) {
+                       PERROR("send lost packets");
+                       goto error_fatal;
+               }
+
+               break;
+       }
+       case LTTNG_CONSUMER_SET_CHANNEL_MONITOR_PIPE:
+       {
+               int channel_monitor_pipe, ret_send,
+                               ret_set_channel_monitor_pipe;
+               ssize_t ret_recv;
+
+               ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+               /* Successfully received the command's type. */
+               ret_send = consumer_send_status_msg(sock, ret_code);
+               if (ret_send < 0) {
+                       goto error_fatal;
+               }
+
+               ret_recv = lttcomm_recv_fds_unix_sock(
+                               sock, &channel_monitor_pipe, 1);
+               if (ret_recv != sizeof(channel_monitor_pipe)) {
+                       ERR("Failed to receive channel monitor pipe");
+                       goto error_fatal;
+               }
+
+               DBG("Received channel monitor pipe (%d)", channel_monitor_pipe);
+               ret_set_channel_monitor_pipe =
+                               consumer_timer_thread_set_channel_monitor_pipe(
+                                               channel_monitor_pipe);
+               if (!ret_set_channel_monitor_pipe) {
+                       int flags;
+                       int ret_fcntl;
+
+                       ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+                       /* Set the pipe as non-blocking. */
+                       ret_fcntl = fcntl(channel_monitor_pipe, F_GETFL, 0);
+                       if (ret_fcntl == -1) {
+                               PERROR("fcntl get flags of the channel monitoring pipe");
+                               goto error_fatal;
+                       }
+                       flags = ret_fcntl;
+
+                       ret_fcntl = fcntl(channel_monitor_pipe, F_SETFL,
+                                       flags | O_NONBLOCK);
+                       if (ret_fcntl == -1) {
+                               PERROR("fcntl set O_NONBLOCK flag of the channel monitoring pipe");
+                               goto error_fatal;
+                       }
+                       DBG("Channel monitor pipe set as non-blocking");
+               } else {
+                       ret_code = LTTCOMM_CONSUMERD_ALREADY_SET;
+               }
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_ROTATE_CHANNEL:
+       {
+               struct lttng_consumer_channel *found_channel;
+               uint64_t key = msg.u.rotate_channel.key;
+               int ret_send_status;
+
+               found_channel = consumer_find_channel(key);
+               if (!found_channel) {
+                       DBG("Channel %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               } else {
+                       int rotate_channel;
+
+                       /*
+                        * Sample the rotate position of all the streams in
+                        * this channel.
+                        */
+                       rotate_channel = lttng_consumer_rotate_channel(
+                                       found_channel, key,
+                                       msg.u.rotate_channel.relayd_id,
+                                       msg.u.rotate_channel.metadata, ctx);
+                       if (rotate_channel < 0) {
+                               ERR("Rotate channel failed");
+                               ret_code = LTTCOMM_CONSUMERD_ROTATION_FAIL;
+                       }
+
+                       health_code_update();
+               }
+
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_rotate_channel_nosignal;
+               }
+
+               /*
+                * Rotate the streams that are ready right now.
+                * FIXME: this is a second consecutive iteration over the
+                * streams in a channel, there is probably a better way to
+                * handle this, but it needs to be after the
+                * consumer_send_status_msg() call.
+                */
+               if (found_channel) {
+                       int ret_rotate_read_streams;
+
+                       ret_rotate_read_streams =
+                                       lttng_consumer_rotate_ready_streams(
+                                                       found_channel, key,
+                                                       ctx);
+                       if (ret_rotate_read_streams < 0) {
+                               ERR("Rotate channel failed");
+                       }
+               }
+               break;
+end_rotate_channel_nosignal:
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_CLEAR_CHANNEL:
+       {
+               struct lttng_consumer_channel *found_channel;
+               uint64_t key = msg.u.clear_channel.key;
+               int ret_send_status;
+
+               found_channel = consumer_find_channel(key);
+               if (!found_channel) {
+                       DBG("Channel %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               } else {
+                       int ret_clear_channel;
+
+                       ret_clear_channel = lttng_consumer_clear_channel(
+                                       found_channel);
+                       if (ret_clear_channel) {
+                               ERR("Clear channel failed key %" PRIu64, key);
+                               ret_code = (lttcomm_return_code) ret_clear_channel;
+                       }
+
+                       health_code_update();
+               }
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
+               break;
+       }
+       case LTTNG_CONSUMER_INIT:
+       {
+               int ret_send_status;
+
+               ret_code = lttng_consumer_init_command(ctx,
+                               msg.u.init.sessiond_uuid);
+               health_code_update();
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
+               break;
+       }
+       case LTTNG_CONSUMER_CREATE_TRACE_CHUNK:
+       {
+               const struct lttng_credentials credentials = {
+                       .uid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.create_trace_chunk.credentials.value.uid),
+                       .gid = LTTNG_OPTIONAL_INIT_VALUE(msg.u.create_trace_chunk.credentials.value.gid),
+               };
+               const bool is_local_trace =
+                               !msg.u.create_trace_chunk.relayd_id.is_set;
+               const uint64_t relayd_id =
+                               msg.u.create_trace_chunk.relayd_id.value;
+               const char *chunk_override_name =
+                               *msg.u.create_trace_chunk.override_name ?
+                                       msg.u.create_trace_chunk.override_name :
+                                       NULL;
+               struct lttng_directory_handle *chunk_directory_handle = NULL;
+
+               /*
+                * The session daemon will only provide a chunk directory file
+                * descriptor for local traces.
+                */
+               if (is_local_trace) {
+                       int chunk_dirfd;
+                       int ret_send_status;
+                       ssize_t ret_recv;
+
+                       /* Acnowledge the reception of the command. */
+                       ret_send_status = consumer_send_status_msg(
+                                       sock, LTTCOMM_CONSUMERD_SUCCESS);
+                       if (ret_send_status < 0) {
+                               /* Somehow, the session daemon is not responding anymore. */
+                               goto end_nosignal;
+                       }
+
+                       /*
+                        * Receive trace chunk domain dirfd.
+                        */
+                       ret_recv = lttcomm_recv_fds_unix_sock(
+                                       sock, &chunk_dirfd, 1);
+                       if (ret_recv != sizeof(chunk_dirfd)) {
+                               ERR("Failed to receive trace chunk domain directory file descriptor");
+                               goto error_fatal;
+                       }
+
+                       DBG("Received trace chunk domain directory fd (%d)",
+                                       chunk_dirfd);
+                       chunk_directory_handle = lttng_directory_handle_create_from_dirfd(
+                                       chunk_dirfd);
+                       if (!chunk_directory_handle) {
+                               ERR("Failed to initialize chunk domain directory handle from directory file descriptor");
+                               if (close(chunk_dirfd)) {
+                                       PERROR("Failed to close chunk directory file descriptor");
+                               }
+                               goto error_fatal;
+                       }
+               }
+
+               ret_code = lttng_consumer_create_trace_chunk(
+                               !is_local_trace ? &relayd_id : NULL,
+                               msg.u.create_trace_chunk.session_id,
+                               msg.u.create_trace_chunk.chunk_id,
+                               (time_t) msg.u.create_trace_chunk
+                                               .creation_timestamp,
+                               chunk_override_name,
+                               msg.u.create_trace_chunk.credentials.is_set ?
+                                               &credentials :
+                                               NULL,
+                               chunk_directory_handle);
+               lttng_directory_handle_put(chunk_directory_handle);
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_CLOSE_TRACE_CHUNK:
+       {
+               enum lttng_trace_chunk_command_type close_command =
+                       (lttng_trace_chunk_command_type)
+                               msg.u.close_trace_chunk.close_command.value;
+               const uint64_t relayd_id =
+                               msg.u.close_trace_chunk.relayd_id.value;
+               struct lttcomm_consumer_close_trace_chunk_reply reply;
+               char closed_trace_chunk_path[LTTNG_PATH_MAX] = {};
+               int ret;
+
+               ret_code = lttng_consumer_close_trace_chunk(
+                               msg.u.close_trace_chunk.relayd_id.is_set ?
+                                               &relayd_id :
+                                               NULL,
+                               msg.u.close_trace_chunk.session_id,
+                               msg.u.close_trace_chunk.chunk_id,
+                               (time_t) msg.u.close_trace_chunk.close_timestamp,
+                               msg.u.close_trace_chunk.close_command.is_set ?
+                                               &close_command :
+                                               NULL, closed_trace_chunk_path);
+               reply.ret_code = ret_code;
+               reply.path_length = strlen(closed_trace_chunk_path) + 1;
+               ret = lttcomm_send_unix_sock(sock, &reply, sizeof(reply));
+               if (ret != sizeof(reply)) {
+                       goto error_fatal;
+               }
+               ret = lttcomm_send_unix_sock(sock, closed_trace_chunk_path,
+                               reply.path_length);
+               if (ret != reply.path_length) {
+                       goto error_fatal;
+               }
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_TRACE_CHUNK_EXISTS:
+       {
+               const uint64_t relayd_id =
+                               msg.u.trace_chunk_exists.relayd_id.value;
+
+               ret_code = lttng_consumer_trace_chunk_exists(
+                               msg.u.trace_chunk_exists.relayd_id.is_set ?
+                                               &relayd_id : NULL,
+                               msg.u.trace_chunk_exists.session_id,
+                               msg.u.trace_chunk_exists.chunk_id);
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_OPEN_CHANNEL_PACKETS:
+       {
+               const uint64_t key = msg.u.open_channel_packets.key;
+               struct lttng_consumer_channel *found_channel =
+                               consumer_find_channel(key);
+
+               if (found_channel) {
+                       pthread_mutex_lock(&found_channel->lock);
+                       ret_code = lttng_consumer_open_channel_packets(
+                                       found_channel);
+                       pthread_mutex_unlock(&found_channel->lock);
+               } else {
+                       /*
+                        * The channel could have disappeared in per-pid
+                        * buffering mode.
+                        */
+                       DBG("Channel %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               }
+
+               health_code_update();
+               goto end_msg_sessiond;
+       }
+       default:
+               break;
+       }
+
+end_nosignal:
+       /*
+        * Return 1 to indicate success since the 0 value can be a socket
+        * shutdown during the recv() or send() call.
+        */
+       ret_func = 1;
+       goto end;
+
+end_msg_sessiond:
+       /*
+        * The returned value here is not useful since either way we'll return 1 to
+        * the caller because the session daemon socket management is done
+        * elsewhere. Returning a negative code or 0 will shutdown the consumer.
+        */
+       {
+               int ret_send_status;
+
+               ret_send_status = consumer_send_status_msg(sock, ret_code);
+               if (ret_send_status < 0) {
+                       goto error_fatal;
+               }
+       }
+
+       ret_func = 1;
+       goto end;
+
+end_channel_error:
+       if (channel) {
+               /*
+                * Free channel here since no one has a reference to it. We don't
+                * free after that because a stream can store this pointer.
+                */
+               destroy_channel(channel);
+       }
+       /* We have to send a status channel message indicating an error. */
+       {
+               int ret_send_status;
+
+               ret_send_status = consumer_send_status_channel(sock, NULL);
+               if (ret_send_status < 0) {
+                       /* Stop everything if session daemon can not be notified. */
+                       goto error_fatal;
+               }
+       }
+
+       ret_func = 1;
+       goto end;
+
+error_fatal:
+       /* This will issue a consumer stop. */
+       ret_func = -1;
+       goto end;
+
+end:
+       rcu_read_unlock();
+       health_code_update();
+       return ret_func;
+}
+
+int lttng_ust_flush_buffer(struct lttng_consumer_stream *stream,
+               int producer_active)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+
+       return lttng_ust_ctl_flush_buffer(stream->ustream, producer_active);
+}
+
+/*
+ * Take a snapshot for a specific stream.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_ustconsumer_take_snapshot(struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+
+       return lttng_ust_ctl_snapshot(stream->ustream);
+}
+
+/*
+ * Sample consumed and produced positions for a specific stream.
+ *
+ * Returns 0 on success, < 0 on error.
+ */
+int lttng_ustconsumer_sample_snapshot_positions(
+               struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+
+       return lttng_ust_ctl_snapshot_sample_positions(stream->ustream);
+}
+
+/*
+ * Get the produced position
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_ustconsumer_get_produced_snapshot(
+               struct lttng_consumer_stream *stream, unsigned long *pos)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+       LTTNG_ASSERT(pos);
+
+       return lttng_ust_ctl_snapshot_get_produced(stream->ustream, pos);
+}
+
+/*
+ * Get the consumed position
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_ustconsumer_get_consumed_snapshot(
+               struct lttng_consumer_stream *stream, unsigned long *pos)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+       LTTNG_ASSERT(pos);
+
+       return lttng_ust_ctl_snapshot_get_consumed(stream->ustream, pos);
+}
+
+int lttng_ustconsumer_flush_buffer(struct lttng_consumer_stream *stream,
+               int producer)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+
+       return lttng_ust_ctl_flush_buffer(stream->ustream, producer);
+}
+
+int lttng_ustconsumer_clear_buffer(struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+
+       return lttng_ust_ctl_clear_buffer(stream->ustream);
+}
+
+int lttng_ustconsumer_get_current_timestamp(
+               struct lttng_consumer_stream *stream, uint64_t *ts)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+       LTTNG_ASSERT(ts);
+
+       return lttng_ust_ctl_get_current_timestamp(stream->ustream, ts);
+}
+
+int lttng_ustconsumer_get_sequence_number(
+               struct lttng_consumer_stream *stream, uint64_t *seq)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+       LTTNG_ASSERT(seq);
+
+       return lttng_ust_ctl_get_sequence_number(stream->ustream, seq);
+}
+
+/*
+ * Called when the stream signals the consumer that it has hung up.
+ */
+void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+
+       pthread_mutex_lock(&stream->lock);
+       if (!stream->quiescent) {
+               if (lttng_ust_ctl_flush_buffer(stream->ustream, 0) < 0) {
+                       ERR("Failed to flush buffer on stream hang-up");
+               } else {
+                       stream->quiescent = true;
+               }
+       }
+       pthread_mutex_unlock(&stream->lock);
+       stream->hangup_flush_done = 1;
+}
+
+void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
+{
+       int i;
+
+       LTTNG_ASSERT(chan);
+       LTTNG_ASSERT(chan->uchan);
+       LTTNG_ASSERT(chan->buffer_credentials.is_set);
+
+       if (chan->switch_timer_enabled == 1) {
+               consumer_timer_switch_stop(chan);
+       }
+       for (i = 0; i < chan->nr_stream_fds; i++) {
+               int ret;
+
+               ret = close(chan->stream_fds[i]);
+               if (ret) {
+                       PERROR("close");
+               }
+               if (chan->shm_path[0]) {
+                       char shm_path[PATH_MAX];
+
+                       ret = get_stream_shm_path(shm_path, chan->shm_path, i);
+                       if (ret) {
+                               ERR("Cannot get stream shm path");
+                       }
+                       ret = run_as_unlink(shm_path,
+                                       lttng_credentials_get_uid(LTTNG_OPTIONAL_GET_PTR(
+                                                       chan->buffer_credentials)),
+                                       lttng_credentials_get_gid(LTTNG_OPTIONAL_GET_PTR(
+                                                       chan->buffer_credentials)));
+                       if (ret) {
+                               PERROR("unlink %s", shm_path);
+                       }
+               }
+       }
+}
+
+void lttng_ustconsumer_free_channel(struct lttng_consumer_channel *chan)
+{
+       LTTNG_ASSERT(chan);
+       LTTNG_ASSERT(chan->uchan);
+       LTTNG_ASSERT(chan->buffer_credentials.is_set);
+
+       consumer_metadata_cache_destroy(chan);
+       lttng_ust_ctl_destroy_channel(chan->uchan);
+       /* Try to rmdir all directories under shm_path root. */
+       if (chan->root_shm_path[0]) {
+               (void) run_as_rmdir_recursive(chan->root_shm_path,
+                               lttng_credentials_get_uid(LTTNG_OPTIONAL_GET_PTR(
+                                               chan->buffer_credentials)),
+                               lttng_credentials_get_gid(LTTNG_OPTIONAL_GET_PTR(
+                                               chan->buffer_credentials)),
+                               LTTNG_DIRECTORY_HANDLE_SKIP_NON_EMPTY_FLAG);
+       }
+       free(chan->stream_fds);
+}
+
+void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+
+       if (stream->chan->switch_timer_enabled == 1) {
+               consumer_timer_switch_stop(stream->chan);
+       }
+       lttng_ust_ctl_destroy_stream(stream->ustream);
+}
+
+int lttng_ustconsumer_get_wakeup_fd(struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+
+       return lttng_ust_ctl_stream_get_wakeup_fd(stream->ustream);
+}
+
+int lttng_ustconsumer_close_wakeup_fd(struct lttng_consumer_stream *stream)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+
+       return lttng_ust_ctl_stream_close_wakeup_fd(stream->ustream);
+}
+
+/*
+ * Write up to one packet from the metadata cache to the channel.
+ *
+ * Returns the number of bytes pushed from the cache into the ring buffer, or a
+ * negative value on error.
+ */
+static
+int commit_one_metadata_packet(struct lttng_consumer_stream *stream)
+{
+       ssize_t write_len;
+       int ret;
+
+       pthread_mutex_lock(&stream->chan->metadata_cache->lock);
+       if (stream->chan->metadata_cache->contents.size ==
+                       stream->ust_metadata_pushed) {
+               /*
+                * In the context of a user space metadata channel, a
+                * change in version can be detected in two ways:
+                *   1) During the pre-consume of the `read_subbuffer` loop,
+                *   2) When populating the metadata ring buffer (i.e. here).
+                *
+                * This function is invoked when there is no metadata
+                * available in the ring-buffer. If all data was consumed
+                * up to the size of the metadata cache, there is no metadata
+                * to insert in the ring-buffer.
+                *
+                * However, the metadata version could still have changed (a
+                * regeneration without any new data will yield the same cache
+                * size).
+                *
+                * The cache's version is checked for a version change and the
+                * consumed position is reset if one occurred.
+                *
+                * This check is only necessary for the user space domain as
+                * it has to manage the cache explicitly. If this reset was not
+                * performed, no metadata would be consumed (and no reset would
+                * occur as part of the pre-consume) until the metadata size
+                * exceeded the cache size.
+                */
+               if (stream->metadata_version !=
+                               stream->chan->metadata_cache->version) {
+                       metadata_stream_reset_cache_consumed_position(stream);
+                       consumer_stream_metadata_set_version(stream,
+                                       stream->chan->metadata_cache->version);
+               } else {
+                       ret = 0;
+                       goto end;
+               }
+       }
+
+       write_len = lttng_ust_ctl_write_one_packet_to_channel(stream->chan->uchan,
+                       &stream->chan->metadata_cache->contents.data[stream->ust_metadata_pushed],
+                       stream->chan->metadata_cache->contents.size -
+                                       stream->ust_metadata_pushed);
+       LTTNG_ASSERT(write_len != 0);
+       if (write_len < 0) {
+               ERR("Writing one metadata packet");
+               ret = write_len;
+               goto end;
+       }
+       stream->ust_metadata_pushed += write_len;
+
+       LTTNG_ASSERT(stream->chan->metadata_cache->contents.size >=
+                       stream->ust_metadata_pushed);
+       ret = write_len;
+
+       /*
+        * Switch packet (but don't open the next one) on every commit of
+        * a metadata packet. Since the subbuffer is fully filled (with padding,
+        * if needed), the stream is "quiescent" after this commit.
+        */
+       if (lttng_ust_ctl_flush_buffer(stream->ustream, 1)) {
+               ERR("Failed to flush buffer while commiting one metadata packet");
+               ret = -EIO;
+       } else {
+               stream->quiescent = true;
+       }
+end:
+       pthread_mutex_unlock(&stream->chan->metadata_cache->lock);
+       return ret;
+}
+
+
+/*
+ * Sync metadata meaning request them to the session daemon and snapshot to the
+ * metadata thread can consumer them.
+ *
+ * Metadata stream lock is held here, but we need to release it when
+ * interacting with sessiond, else we cause a deadlock with live
+ * awaiting on metadata to be pushed out.
+ *
+ * The RCU read side lock must be held by the caller.
+ */
+enum sync_metadata_status lttng_ustconsumer_sync_metadata(
+               struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_stream *metadata_stream)
+{
+       int ret;
+       enum sync_metadata_status status;
+       struct lttng_consumer_channel *metadata_channel;
+
+       LTTNG_ASSERT(ctx);
+       LTTNG_ASSERT(metadata_stream);
+
+       metadata_channel = metadata_stream->chan;
+       pthread_mutex_unlock(&metadata_stream->lock);
+       /*
+        * Request metadata from the sessiond, but don't wait for the flush
+        * because we locked the metadata thread.
+        */
+       ret = lttng_ustconsumer_request_metadata(ctx, metadata_channel, 0, 0);
+       pthread_mutex_lock(&metadata_stream->lock);
+       if (ret < 0) {
+               status = SYNC_METADATA_STATUS_ERROR;
+               goto end;
+       }
+
+       /*
+        * The metadata stream and channel can be deleted while the
+        * metadata stream lock was released. The streamed is checked
+        * for deletion before we use it further.
+        *
+        * Note that it is safe to access a logically-deleted stream since its
+        * existence is still guaranteed by the RCU read side lock. However,
+        * it should no longer be used. The close/deletion of the metadata
+        * channel and stream already guarantees that all metadata has been
+        * consumed. Therefore, there is nothing left to do in this function.
+        */
+       if (consumer_stream_is_deleted(metadata_stream)) {
+               DBG("Metadata stream %" PRIu64 " was deleted during the metadata synchronization",
+                               metadata_stream->key);
+               status = SYNC_METADATA_STATUS_NO_DATA;
+               goto end;
+       }
+
+       ret = commit_one_metadata_packet(metadata_stream);
+       if (ret < 0) {
+               status = SYNC_METADATA_STATUS_ERROR;
+               goto end;
+       } else if (ret > 0) {
+               status = SYNC_METADATA_STATUS_NEW_DATA;
+       } else /* ret == 0 */ {
+               status = SYNC_METADATA_STATUS_NO_DATA;
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_snapshot(metadata_stream->ustream);
+       if (ret < 0) {
+               ERR("Failed to take a snapshot of the metadata ring-buffer positions, ret = %d", ret);
+               status = SYNC_METADATA_STATUS_ERROR;
+               goto end;
+       }
+
+end:
+       return status;
+}
+
+/*
+ * Return 0 on success else a negative value.
+ */
+static int notify_if_more_data(struct lttng_consumer_stream *stream,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+       struct lttng_ust_ctl_consumer_stream *ustream;
+
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(ctx);
+
+       ustream = stream->ustream;
+
+       /*
+        * First, we are going to check if there is a new subbuffer available
+        * before reading the stream wait_fd.
+        */
+       /* Get the next subbuffer */
+       ret = lttng_ust_ctl_get_next_subbuf(ustream);
+       if (ret) {
+               /* No more data found, flag the stream. */
+               stream->has_data = 0;
+               ret = 0;
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_put_subbuf(ustream);
+       LTTNG_ASSERT(!ret);
+
+       /* This stream still has data. Flag it and wake up the data thread. */
+       stream->has_data = 1;
+
+       if (stream->monitor && !stream->hangup_flush_done && !ctx->has_wakeup) {
+               ssize_t writelen;
+
+               writelen = lttng_pipe_write(ctx->consumer_wakeup_pipe, "!", 1);
+               if (writelen < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
+                       ret = writelen;
+                       goto end;
+               }
+
+               /* The wake up pipe has been notified. */
+               ctx->has_wakeup = 1;
+       }
+       ret = 0;
+
+end:
+       return ret;
+}
+
+static int consumer_stream_ust_on_wake_up(struct lttng_consumer_stream *stream)
+{
+       int ret = 0;
+
+       /*
+        * We can consume the 1 byte written into the wait_fd by
+        * UST. Don't trigger error if we cannot read this one byte
+        * (read returns 0), or if the error is EAGAIN or EWOULDBLOCK.
+        *
+        * This is only done when the stream is monitored by a thread,
+        * before the flush is done after a hangup and if the stream
+        * is not flagged with data since there might be nothing to
+        * consume in the wait fd but still have data available
+        * flagged by the consumer wake up pipe.
+        */
+       if (stream->monitor && !stream->hangup_flush_done && !stream->has_data) {
+               char dummy;
+               ssize_t readlen;
+
+               readlen = lttng_read(stream->wait_fd, &dummy, 1);
+               if (readlen < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
+                       ret = readlen;
+               }
+       }
+
+       return ret;
+}
+
+static int extract_common_subbuffer_info(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuf)
+{
+       int ret;
+
+       ret = lttng_ust_ctl_get_subbuf_size(
+                       stream->ustream, &subbuf->info.data.subbuf_size);
+       if (ret) {
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_get_padded_subbuf_size(
+                       stream->ustream, &subbuf->info.data.padded_subbuf_size);
+       if (ret) {
+               goto end;
+       }
+
+end:
+       return ret;
+}
+
+static int extract_metadata_subbuffer_info(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuf)
+{
+       int ret;
+
+       ret = extract_common_subbuffer_info(stream, subbuf);
+       if (ret) {
+               goto end;
+       }
+
+       subbuf->info.metadata.version = stream->metadata_version;
+
+end:
+       return ret;
+}
+
+static int extract_data_subbuffer_info(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuf)
+{
+       int ret;
+
+       ret = extract_common_subbuffer_info(stream, subbuf);
+       if (ret) {
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_get_packet_size(
+                       stream->ustream, &subbuf->info.data.packet_size);
+       if (ret < 0) {
+               PERROR("Failed to get sub-buffer packet size");
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_get_content_size(
+                       stream->ustream, &subbuf->info.data.content_size);
+       if (ret < 0) {
+               PERROR("Failed to get sub-buffer content size");
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_get_timestamp_begin(
+                       stream->ustream, &subbuf->info.data.timestamp_begin);
+       if (ret < 0) {
+               PERROR("Failed to get sub-buffer begin timestamp");
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_get_timestamp_end(
+                       stream->ustream, &subbuf->info.data.timestamp_end);
+       if (ret < 0) {
+               PERROR("Failed to get sub-buffer end timestamp");
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_get_events_discarded(
+                       stream->ustream, &subbuf->info.data.events_discarded);
+       if (ret) {
+               PERROR("Failed to get sub-buffer events discarded count");
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_get_sequence_number(stream->ustream,
+                       &subbuf->info.data.sequence_number.value);
+       if (ret) {
+               /* May not be supported by older LTTng-modules. */
+               if (ret != -ENOTTY) {
+                       PERROR("Failed to get sub-buffer sequence number");
+                       goto end;
+               }
+       } else {
+               subbuf->info.data.sequence_number.is_set = true;
+       }
+
+       ret = lttng_ust_ctl_get_stream_id(
+                       stream->ustream, &subbuf->info.data.stream_id);
+       if (ret < 0) {
+               PERROR("Failed to get stream id");
+               goto end;
+       }
+
+       ret = lttng_ust_ctl_get_instance_id(stream->ustream,
+                       &subbuf->info.data.stream_instance_id.value);
+       if (ret) {
+               /* May not be supported by older LTTng-modules. */
+               if (ret != -ENOTTY) {
+                       PERROR("Failed to get stream instance id");
+                       goto end;
+               }
+       } else {
+               subbuf->info.data.stream_instance_id.is_set = true;
+       }
+end:
+       return ret;
+}
+
+static int get_next_subbuffer_common(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuffer)
+{
+       int ret;
+       const char *addr;
+
+       ret = stream->read_subbuffer_ops.extract_subbuffer_info(
+                       stream, subbuffer);
+       if (ret) {
+               goto end;
+       }
+
+       ret = get_current_subbuf_addr(stream, &addr);
+       if (ret) {
+               goto end;
+       }
+
+       subbuffer->buffer.buffer = lttng_buffer_view_init(
+                       addr, 0, subbuffer->info.data.padded_subbuf_size);
+       LTTNG_ASSERT(subbuffer->buffer.buffer.data != NULL);
+end:
+       return ret;
+}
+
+static enum get_next_subbuffer_status get_next_subbuffer(
+               struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuffer)
+{
+       int ret;
+       enum get_next_subbuffer_status status;
+
+       ret = lttng_ust_ctl_get_next_subbuf(stream->ustream);
+       switch (ret) {
+       case 0:
+               status = GET_NEXT_SUBBUFFER_STATUS_OK;
+               break;
+       case -ENODATA:
+               case -EAGAIN:
+               /*
+                * The caller only expects -ENODATA when there is no data to
+                * read, but the kernel tracer returns -EAGAIN when there is
+                * currently no data for a non-finalized stream, and -ENODATA
+                * when there is no data for a finalized stream. Those can be
+                * combined into a -ENODATA return value.
+                */
+               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
+               goto end;
+       default:
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = get_next_subbuffer_common(stream, subbuffer);
+       if (ret) {
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               goto end;
+       }
+end:
+       return status;
+}
+
+static enum get_next_subbuffer_status get_next_subbuffer_metadata(
+               struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuffer)
+{
+       int ret;
+       bool cache_empty;
+       bool got_subbuffer;
+       bool coherent;
+       bool buffer_empty;
+       unsigned long consumed_pos, produced_pos;
+       enum get_next_subbuffer_status status;
+
+       do {
+               ret = lttng_ust_ctl_get_next_subbuf(stream->ustream);
+               if (ret == 0) {
+                       got_subbuffer = true;
+               } else {
+                       got_subbuffer = false;
+                       if (ret != -EAGAIN) {
+                               /* Fatal error. */
+                               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+                               goto end;
+                       }
+               }
+
+               /*
+                * Determine if the cache is empty and ensure that a sub-buffer
+                * is made available if the cache is not empty.
+                */
+               if (!got_subbuffer) {
+                       ret = commit_one_metadata_packet(stream);
+                       if (ret < 0 && ret != -ENOBUFS) {
+                               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+                               goto end;
+                       } else if (ret == 0) {
+                               /* Not an error, the cache is empty. */
+                               cache_empty = true;
+                               status = GET_NEXT_SUBBUFFER_STATUS_NO_DATA;
+                               goto end;
+                       } else {
+                               cache_empty = false;
+                       }
+               } else {
+                       pthread_mutex_lock(&stream->chan->metadata_cache->lock);
+                       cache_empty = stream->chan->metadata_cache->contents.size ==
+                                       stream->ust_metadata_pushed;
+                       pthread_mutex_unlock(&stream->chan->metadata_cache->lock);
+               }
+       } while (!got_subbuffer);
+
+       /* Populate sub-buffer infos and view. */
+       ret = get_next_subbuffer_common(stream, subbuffer);
+       if (ret) {
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = lttng_ustconsumer_sample_snapshot_positions(stream);
+       if (ret < 0) {
+               /*
+                * -EAGAIN is not expected since we got a sub-buffer and haven't
+                * pushed the consumption position yet (on put_next).
+                */
+               PERROR("Failed to take a snapshot of metadata buffer positions");
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = lttng_ustconsumer_get_consumed_snapshot(stream, &consumed_pos);
+       if (ret) {
+               PERROR("Failed to get metadata consumed position");
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               goto end;
+       }
+
+       ret = lttng_ustconsumer_get_produced_snapshot(stream, &produced_pos);
+       if (ret) {
+               PERROR("Failed to get metadata produced position");
+               status = GET_NEXT_SUBBUFFER_STATUS_ERROR;
+               goto end;
+       }
+
+       /* Last sub-buffer of the ring buffer ? */
+       buffer_empty = (consumed_pos + stream->max_sb_size) == produced_pos;
+
+       /*
+        * The sessiond registry lock ensures that coherent units of metadata
+        * are pushed to the consumer daemon at once. Hence, if a sub-buffer is
+        * acquired, the cache is empty, and it is the only available sub-buffer
+        * available, it is safe to assume that it is "coherent".
+        */
+       coherent = got_subbuffer && cache_empty && buffer_empty;
+
+       LTTNG_OPTIONAL_SET(&subbuffer->info.metadata.coherent, coherent);
+       status = GET_NEXT_SUBBUFFER_STATUS_OK;
+end:
+       return status;
+}
+
+static int put_next_subbuffer(struct lttng_consumer_stream *stream,
+               struct stream_subbuffer *subbuffer)
+{
+       const int ret = lttng_ust_ctl_put_next_subbuf(stream->ustream);
+
+       LTTNG_ASSERT(ret == 0);
+       return ret;
+}
+
+static int signal_metadata(struct lttng_consumer_stream *stream,
+               struct lttng_consumer_local_data *ctx)
+{
+       ASSERT_LOCKED(stream->metadata_rdv_lock);
+       return pthread_cond_broadcast(&stream->metadata_rdv) ? -errno : 0;
+}
+
+static int lttng_ustconsumer_set_stream_ops(
+               struct lttng_consumer_stream *stream)
+{
+       int ret = 0;
+
+       stream->read_subbuffer_ops.on_wake_up = consumer_stream_ust_on_wake_up;
+       if (stream->metadata_flag) {
+               stream->read_subbuffer_ops.get_next_subbuffer =
+                               get_next_subbuffer_metadata;
+               stream->read_subbuffer_ops.extract_subbuffer_info =
+                               extract_metadata_subbuffer_info;
+               stream->read_subbuffer_ops.reset_metadata =
+                               metadata_stream_reset_cache_consumed_position;
+               if (stream->chan->is_live) {
+                       stream->read_subbuffer_ops.on_sleep = signal_metadata;
+                       ret = consumer_stream_enable_metadata_bucketization(
+                                       stream);
+                       if (ret) {
+                               goto end;
+                       }
+               }
+       } else {
+               stream->read_subbuffer_ops.get_next_subbuffer =
+                               get_next_subbuffer;
+               stream->read_subbuffer_ops.extract_subbuffer_info =
+                               extract_data_subbuffer_info;
+               stream->read_subbuffer_ops.on_sleep = notify_if_more_data;
+               if (stream->chan->is_live) {
+                       stream->read_subbuffer_ops.send_live_beacon =
+                                       consumer_flush_ust_index;
+               }
+       }
+
+       stream->read_subbuffer_ops.put_next_subbuffer = put_next_subbuffer;
+end:
+       return ret;
+}
+
+/*
+ * Called when a stream is created.
+ *
+ * Return 0 on success or else a negative value.
+ */
+int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       LTTNG_ASSERT(stream);
+
+       /*
+        * Don't create anything if this is set for streaming or if there is
+        * no current trace chunk on the parent channel.
+        */
+       if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor &&
+                       stream->chan->trace_chunk) {
+               ret = consumer_stream_create_output_files(stream, true);
+               if (ret) {
+                       goto error;
+               }
+       }
+
+       lttng_ustconsumer_set_stream_ops(stream);
+       ret = 0;
+
+error:
+       return ret;
+}
+
+/*
+ * Check if data is still being extracted from the buffers for a specific
+ * stream. Consumer data lock MUST be acquired before calling this function
+ * and the stream lock.
+ *
+ * Return 1 if the traced data are still getting read else 0 meaning that the
+ * data is available for trace viewer reading.
+ */
+int lttng_ustconsumer_data_pending(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream->ustream);
+       ASSERT_LOCKED(stream->lock);
+
+       DBG("UST consumer checking data pending");
+
+       if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
+               ret = 0;
+               goto end;
+       }
+
+       if (stream->chan->type == CONSUMER_CHANNEL_TYPE_METADATA) {
+               uint64_t contiguous, pushed;
+
+               /* Ease our life a bit. */
+               pthread_mutex_lock(&stream->chan->metadata_cache->lock);
+               contiguous = stream->chan->metadata_cache->contents.size;
+               pthread_mutex_unlock(&stream->chan->metadata_cache->lock);
+               pushed = stream->ust_metadata_pushed;
+
+               /*
+                * We can simply check whether all contiguously available data
+                * has been pushed to the ring buffer, since the push operation
+                * is performed within get_next_subbuf(), and because both
+                * get_next_subbuf() and put_next_subbuf() are issued atomically
+                * thanks to the stream lock within
+                * lttng_ustconsumer_read_subbuffer(). This basically means that
+                * whetnever ust_metadata_pushed is incremented, the associated
+                * metadata has been consumed from the metadata stream.
+                */
+               DBG("UST consumer metadata pending check: contiguous %" PRIu64 " vs pushed %" PRIu64,
+                               contiguous, pushed);
+               LTTNG_ASSERT(((int64_t) (contiguous - pushed)) >= 0);
+               if ((contiguous != pushed) ||
+                               (((int64_t) contiguous - pushed) > 0 || contiguous == 0)) {
+                       ret = 1;        /* Data is pending */
+                       goto end;
+               }
+       } else {
+               ret = lttng_ust_ctl_get_next_subbuf(stream->ustream);
+               if (ret == 0) {
+                       /*
+                        * There is still data so let's put back this
+                        * subbuffer.
+                        */
+                       ret = lttng_ust_ctl_put_subbuf(stream->ustream);
+                       LTTNG_ASSERT(ret == 0);
+                       ret = 1;        /* Data is pending */
+                       goto end;
+               }
+       }
+
+       /* Data is NOT pending so ready to be read. */
+       ret = 0;
+
+end:
+       return ret;
+}
+
+/*
+ * Stop a given metadata channel timer if enabled and close the wait fd which
+ * is the poll pipe of the metadata stream.
+ *
+ * This MUST be called with the metadata channel lock acquired.
+ */
+void lttng_ustconsumer_close_metadata(struct lttng_consumer_channel *metadata)
+{
+       int ret;
+
+       LTTNG_ASSERT(metadata);
+       LTTNG_ASSERT(metadata->type == CONSUMER_CHANNEL_TYPE_METADATA);
+
+       DBG("Closing metadata channel key %" PRIu64, metadata->key);
+
+       if (metadata->switch_timer_enabled == 1) {
+               consumer_timer_switch_stop(metadata);
+       }
+
+       if (!metadata->metadata_stream) {
+               goto end;
+       }
+
+       /*
+        * Closing write side so the thread monitoring the stream wakes up if any
+        * and clean the metadata stream.
+        */
+       if (metadata->metadata_stream->ust_metadata_poll_pipe[1] >= 0) {
+               ret = close(metadata->metadata_stream->ust_metadata_poll_pipe[1]);
+               if (ret < 0) {
+                       PERROR("closing metadata pipe write side");
+               }
+               metadata->metadata_stream->ust_metadata_poll_pipe[1] = -1;
+       }
+
+end:
+       return;
+}
+
+/*
+ * Close every metadata stream wait fd of the metadata hash table. This
+ * function MUST be used very carefully so not to run into a race between the
+ * metadata thread handling streams and this function closing their wait fd.
+ *
+ * For UST, this is used when the session daemon hangs up. Its the metadata
+ * producer so calling this is safe because we are assured that no state change
+ * can occur in the metadata thread for the streams in the hash table.
+ */
+void lttng_ustconsumer_close_all_metadata(struct lttng_ht *metadata_ht)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       LTTNG_ASSERT(metadata_ht);
+       LTTNG_ASSERT(metadata_ht->ht);
+
+       DBG("UST consumer closing all metadata streams");
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream,
+                       node.node) {
+
+               health_code_update();
+
+               pthread_mutex_lock(&stream->chan->lock);
+               lttng_ustconsumer_close_metadata(stream->chan);
+               pthread_mutex_unlock(&stream->chan->lock);
+
+       }
+       rcu_read_unlock();
+}
+
+void lttng_ustconsumer_close_stream_wakeup(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       ret = lttng_ust_ctl_stream_close_wakeup_fd(stream->ustream);
+       if (ret < 0) {
+               ERR("Unable to close wakeup fd");
+       }
+}
+
+/*
+ * Please refer to consumer-timer.c before adding any lock within this
+ * function or any of its callees. Timers have a very strict locking
+ * semantic with respect to teardown. Failure to respect this semantic
+ * introduces deadlocks.
+ *
+ * DON'T hold the metadata lock when calling this function, else this
+ * can cause deadlock involving consumer awaiting for metadata to be
+ * pushed out due to concurrent interaction with the session daemon.
+ */
+int lttng_ustconsumer_request_metadata(struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_channel *channel, int timer, int wait)
+{
+       struct lttcomm_metadata_request_msg request;
+       struct lttcomm_consumer_msg msg;
+       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       uint64_t len, key, offset, version;
+       int ret;
+
+       LTTNG_ASSERT(channel);
+       LTTNG_ASSERT(channel->metadata_cache);
+
+       memset(&request, 0, sizeof(request));
+
+       /* send the metadata request to sessiond */
+       switch (the_consumer_data.type) {
+       case LTTNG_CONSUMER64_UST:
+               request.bits_per_long = 64;
+               break;
+       case LTTNG_CONSUMER32_UST:
+               request.bits_per_long = 32;
+               break;
+       default:
+               request.bits_per_long = 0;
+               break;
+       }
+
+       request.session_id = channel->session_id;
+       request.session_id_per_pid = channel->session_id_per_pid;
+       /*
+        * Request the application UID here so the metadata of that application can
+        * be sent back. The channel UID corresponds to the user UID of the session
+        * used for the rights on the stream file(s).
+        */
+       request.uid = channel->ust_app_uid;
+       request.key = channel->key;
+
+       DBG("Sending metadata request to sessiond, session id %" PRIu64
+                       ", per-pid %" PRIu64 ", app UID %u and channel key %" PRIu64,
+                       request.session_id, request.session_id_per_pid, request.uid,
+                       request.key);
+
+       pthread_mutex_lock(&ctx->metadata_socket_lock);
+
+       health_code_update();
+
+       ret = lttcomm_send_unix_sock(ctx->consumer_metadata_socket, &request,
+                       sizeof(request));
+       if (ret < 0) {
+               ERR("Asking metadata to sessiond");
+               goto end;
+       }
+
+       health_code_update();
+
+       /* Receive the metadata from sessiond */
+       ret = lttcomm_recv_unix_sock(ctx->consumer_metadata_socket, &msg,
+                       sizeof(msg));
+       if (ret != sizeof(msg)) {
+               DBG("Consumer received unexpected message size %d (expects %zu)",
+                       ret, sizeof(msg));
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
+               /*
+                * The ret value might 0 meaning an orderly shutdown but this is ok
+                * since the caller handles this.
+                */
+               goto end;
+       }
+
+       health_code_update();
+
+       if (msg.cmd_type == LTTNG_ERR_UND) {
+               /* No registry found */
+               (void) consumer_send_status_msg(ctx->consumer_metadata_socket,
+                               ret_code);
+               ret = 0;
+               goto end;
+       } else if (msg.cmd_type != LTTNG_CONSUMER_PUSH_METADATA) {
+               ERR("Unexpected cmd_type received %d", msg.cmd_type);
+               ret = -1;
+               goto end;
+       }
+
+       len = msg.u.push_metadata.len;
+       key = msg.u.push_metadata.key;
+       offset = msg.u.push_metadata.target_offset;
+       version = msg.u.push_metadata.version;
+
+       LTTNG_ASSERT(key == channel->key);
+       if (len == 0) {
+               DBG("No new metadata to receive for key %" PRIu64, key);
+       }
+
+       health_code_update();
+
+       /* Tell session daemon we are ready to receive the metadata. */
+       ret = consumer_send_status_msg(ctx->consumer_metadata_socket,
+                       LTTCOMM_CONSUMERD_SUCCESS);
+       if (ret < 0 || len == 0) {
+               /*
+                * Somehow, the session daemon is not responding anymore or there is
+                * nothing to receive.
+                */
+               goto end;
+       }
+
+       health_code_update();
+
+       ret = lttng_ustconsumer_recv_metadata(ctx->consumer_metadata_socket,
+                       key, offset, len, version, channel, timer, wait);
+       if (ret >= 0) {
+               /*
+                * Only send the status msg if the sessiond is alive meaning a positive
+                * ret code.
+                */
+               (void) consumer_send_status_msg(ctx->consumer_metadata_socket, ret);
+       }
+       ret = 0;
+
+end:
+       health_code_update();
+
+       pthread_mutex_unlock(&ctx->metadata_socket_lock);
+       return ret;
+}
+
+/*
+ * Return the ustctl call for the get stream id.
+ */
+int lttng_ustconsumer_get_stream_id(struct lttng_consumer_stream *stream,
+               uint64_t *stream_id)
+{
+       LTTNG_ASSERT(stream);
+       LTTNG_ASSERT(stream_id);
+
+       return lttng_ust_ctl_get_stream_id(stream->ustream, stream_id);
+}
+
+void lttng_ustconsumer_sigbus_handle(void *addr)
+{
+       lttng_ust_ctl_sigbus_handle(addr);
+}
index e2507a7f441da932809adb3220e22bb803e9ec32..29ae853daa54d90fb8f2a008f0a84aeda94aeb64 100644 (file)
 #include <common/consumer/consumer.h>
 #include <stdbool.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #ifdef HAVE_LIBLTTNG_UST_CTL
 
 int lttng_ustconsumer_take_snapshot(struct lttng_consumer_stream *stream);
@@ -240,4 +244,8 @@ void lttng_ustconsumer_sigbus_handle(void *addr)
 }
 #endif /* HAVE_LIBLTTNG_UST_CTL */
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _LTTNG_USTCONSUMER_H */
index b9e4b8ac29d019a7456bb643982d95b038914de3..eaab5314aad582ed9bfc526a6333b4abbeb16df5 100644 (file)
@@ -12,8 +12,8 @@ if NO_SHARED
 CLEANFILES = libpause_consumer.so libpause_consumer.so.debug libpause_sessiond.so libpause_sessiond.so.debug
 EXTRA_DIST = \
             base_client.c \
-            consumer_testpoints.c \
-            sessiond_testpoints.c \
+            consumer_testpoints.cpp \
+            sessiond_testpoints.cpp \
             notification.c \
             test_notification_kernel_buffer_usage \
             test_notification_kernel_capture \
@@ -35,7 +35,7 @@ else
 FORCE_SHARED_LIB_OPTIONS = -module -shared -avoid-version \
                           -rpath $(abs_builddir)
 
-libpause_consumer_la_SOURCES = consumer_testpoints.c
+libpause_consumer_la_SOURCES = consumer_testpoints.cpp
 libpause_consumer_la_LIBADD = \
        $(top_builddir)/src/common/sessiond-comm/libsessiond-comm.la \
        $(top_builddir)/src/common/libcommon.la \
@@ -43,7 +43,7 @@ libpause_consumer_la_LIBADD = \
        $(DL_LIBS)
 libpause_consumer_la_LDFLAGS = $(FORCE_SHARED_LIB_OPTIONS)
 
-libpause_sessiond_la_SOURCES = sessiond_testpoints.c
+libpause_sessiond_la_SOURCES = sessiond_testpoints.cpp
 libpause_sessiond_la_LIBADD = \
        $(top_builddir)/src/common/libcommon.la \
        $(top_builddir)/src/lib/lttng-ctl/liblttng-ctl.la \
diff --git a/tests/regression/tools/notification/consumer_testpoints.c b/tests/regression/tools/notification/consumer_testpoints.c
deleted file mode 100644 (file)
index 6294683..0000000
+++ /dev/null
@@ -1,139 +0,0 @@
-/*
- * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#include <common/compat/getenv.h>
-#include <common/consumer/consumer.h>
-#include <common/pipe.h>
-#include <common/error.h>
-#include <unistd.h>
-#include <stdbool.h>
-#include <lttng/constant.h>
-#include <lttng/lttng-export.h>
-#include <fcntl.h>
-#include <dlfcn.h>
-#include <stdio.h>
-
-static char *pause_pipe_path;
-static struct lttng_pipe *pause_pipe;
-static int *data_consumption_state;
-static enum lttng_consumer_type (*lttng_consumer_get_type)(void);
-
-int lttng_opt_verbose;
-int lttng_opt_mi;
-int lttng_opt_quiet;
-
-static
-void __attribute__((destructor)) pause_pipe_fini(void)
-{
-       int ret;
-
-       if (pause_pipe_path) {
-               ret = unlink(pause_pipe_path);
-               if (ret) {
-                       PERROR("unlink pause pipe");
-               }
-       }
-
-       free(pause_pipe_path);
-       lttng_pipe_destroy(pause_pipe);
-}
-
-/*
- * We use this testpoint, invoked at the start of the consumerd's data handling
- * thread to create a named pipe/FIFO which a test application can use to either
- * pause or resume the consumption of data.
- */
-LTTNG_EXPORT int __testpoint_consumerd_thread_data(void);
-int __testpoint_consumerd_thread_data(void)
-{
-       int ret = 0;
-       const char *pause_pipe_path_prefix, *domain;
-
-       pause_pipe_path_prefix = lttng_secure_getenv(
-                       "CONSUMER_PAUSE_PIPE_PATH");
-       if (!pause_pipe_path_prefix) {
-               ret = -1;
-               goto end;
-       }
-
-       /*
-        * These symbols are exclusive to the consumerd process, hence we can't
-        * rely on their presence in the sessiond. Not looking-up these symbols
-        * dynamically would not allow this shared object to be LD_PRELOAD-ed
-        * when launching the session daemon.
-        */
-       data_consumption_state = dlsym(NULL, "data_consumption_paused");
-       LTTNG_ASSERT(data_consumption_state);
-       lttng_consumer_get_type = dlsym(NULL, "lttng_consumer_get_type");
-       LTTNG_ASSERT(lttng_consumer_get_type);
-
-       switch (lttng_consumer_get_type()) {
-       case LTTNG_CONSUMER_KERNEL:
-               domain = "kernel";
-               break;
-       case LTTNG_CONSUMER32_UST:
-               domain = "ust32";
-               break;
-       case LTTNG_CONSUMER64_UST:
-               domain = "ust64";
-               break;
-       default:
-               abort();
-       }
-
-       ret = asprintf(&pause_pipe_path, "%s-%s", pause_pipe_path_prefix,
-                       domain);
-       if (ret < 1) {
-               ERR("Failed to allocate pause pipe path");
-               goto end;
-       }
-
-       DBG("Creating pause pipe at %s", pause_pipe_path);
-       pause_pipe = lttng_pipe_named_open(pause_pipe_path,
-                       S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP, O_NONBLOCK);
-       if (!pause_pipe) {
-               ERR("Failed to create pause pipe at %s", pause_pipe_path);
-               ret = -1;
-               goto end;
-       }
-
-       /* Only the read end of the pipe is useful to us. */
-       ret = lttng_pipe_write_close(pause_pipe);
-end:
-       return ret;
-}
-
-LTTNG_EXPORT int __testpoint_consumerd_thread_data_poll(void);
-int __testpoint_consumerd_thread_data_poll(void)
-{
-       int ret = 0;
-       uint8_t value;
-       bool value_read = false;
-
-       if (!pause_pipe) {
-               ret = -1;
-               goto end;
-       }
-
-       /* Purge pipe and only consider the freshest value. */
-       do {
-               ret = lttng_pipe_read(pause_pipe, &value, sizeof(value));
-               if (ret == sizeof(value)) {
-                       value_read = true;
-               }
-       } while (ret == sizeof(value));
-
-       ret = (errno == EAGAIN) ? 0 : -errno;
-
-       if (value_read) {
-               *data_consumption_state = !!value;
-               DBG("Message received on pause pipe: %s data consumption",
-                               *data_consumption_state ? "paused" : "resumed");
-       }
-end:
-       return ret;
-}
diff --git a/tests/regression/tools/notification/consumer_testpoints.cpp b/tests/regression/tools/notification/consumer_testpoints.cpp
new file mode 100644 (file)
index 0000000..07c855c
--- /dev/null
@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#include <common/compat/getenv.h>
+#include <common/consumer/consumer.h>
+#include <common/pipe.h>
+#include <common/error.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <lttng/constant.h>
+#include <lttng/lttng-export.h>
+#include <fcntl.h>
+#include <dlfcn.h>
+#include <stdio.h>
+
+static char *pause_pipe_path;
+static struct lttng_pipe *pause_pipe;
+static int *data_consumption_state;
+static enum lttng_consumer_type (*lttng_consumer_get_type)(void);
+
+int lttng_opt_verbose;
+int lttng_opt_mi;
+int lttng_opt_quiet;
+
+static
+void __attribute__((destructor)) pause_pipe_fini(void)
+{
+       int ret;
+
+       if (pause_pipe_path) {
+               ret = unlink(pause_pipe_path);
+               if (ret) {
+                       PERROR("unlink pause pipe");
+               }
+       }
+
+       free(pause_pipe_path);
+       lttng_pipe_destroy(pause_pipe);
+}
+
+/*
+ * We use this testpoint, invoked at the start of the consumerd's data handling
+ * thread to create a named pipe/FIFO which a test application can use to either
+ * pause or resume the consumption of data.
+ */
+extern "C" LTTNG_EXPORT int __testpoint_consumerd_thread_data(void);
+int __testpoint_consumerd_thread_data(void)
+{
+       int ret = 0;
+       const char *pause_pipe_path_prefix, *domain;
+
+       pause_pipe_path_prefix = lttng_secure_getenv(
+                       "CONSUMER_PAUSE_PIPE_PATH");
+       if (!pause_pipe_path_prefix) {
+               ret = -1;
+               goto end;
+       }
+
+       /*
+        * These symbols are exclusive to the consumerd process, hence we can't
+        * rely on their presence in the sessiond. Not looking-up these symbols
+        * dynamically would not allow this shared object to be LD_PRELOAD-ed
+        * when launching the session daemon.
+        */
+       data_consumption_state = (int *) dlsym(NULL, "data_consumption_paused");
+       LTTNG_ASSERT(data_consumption_state);
+       lttng_consumer_get_type = (lttng_consumer_type (*)()) dlsym(NULL, "lttng_consumer_get_type");
+       LTTNG_ASSERT(lttng_consumer_get_type);
+
+       switch (lttng_consumer_get_type()) {
+       case LTTNG_CONSUMER_KERNEL:
+               domain = "kernel";
+               break;
+       case LTTNG_CONSUMER32_UST:
+               domain = "ust32";
+               break;
+       case LTTNG_CONSUMER64_UST:
+               domain = "ust64";
+               break;
+       default:
+               abort();
+       }
+
+       ret = asprintf(&pause_pipe_path, "%s-%s", pause_pipe_path_prefix,
+                       domain);
+       if (ret < 1) {
+               ERR("Failed to allocate pause pipe path");
+               goto end;
+       }
+
+       DBG("Creating pause pipe at %s", pause_pipe_path);
+       pause_pipe = lttng_pipe_named_open(pause_pipe_path,
+                       S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP, O_NONBLOCK);
+       if (!pause_pipe) {
+               ERR("Failed to create pause pipe at %s", pause_pipe_path);
+               ret = -1;
+               goto end;
+       }
+
+       /* Only the read end of the pipe is useful to us. */
+       ret = lttng_pipe_write_close(pause_pipe);
+end:
+       return ret;
+}
+
+extern "C" LTTNG_EXPORT int __testpoint_consumerd_thread_data_poll(void);
+int __testpoint_consumerd_thread_data_poll(void)
+{
+       int ret = 0;
+       uint8_t value;
+       bool value_read = false;
+
+       if (!pause_pipe) {
+               ret = -1;
+               goto end;
+       }
+
+       /* Purge pipe and only consider the freshest value. */
+       do {
+               ret = lttng_pipe_read(pause_pipe, &value, sizeof(value));
+               if (ret == sizeof(value)) {
+                       value_read = true;
+               }
+       } while (ret == sizeof(value));
+
+       ret = (errno == EAGAIN) ? 0 : -errno;
+
+       if (value_read) {
+               *data_consumption_state = !!value;
+               DBG("Message received on pause pipe: %s data consumption",
+                               *data_consumption_state ? "paused" : "resumed");
+       }
+end:
+       return ret;
+}
diff --git a/tests/regression/tools/notification/sessiond_testpoints.c b/tests/regression/tools/notification/sessiond_testpoints.c
deleted file mode 100644 (file)
index 2bfd7ca..0000000
+++ /dev/null
@@ -1,112 +0,0 @@
-/*
- * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
- * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#include <common/compat/getenv.h>
-#include <common/consumer/consumer.h>
-#include <common/pipe.h>
-#include <common/error.h>
-#include <unistd.h>
-#include <stdbool.h>
-#include <lttng/constant.h>
-#include <lttng/lttng-export.h>
-#include <fcntl.h>
-#include <dlfcn.h>
-#include <stdio.h>
-
-static char *pause_pipe_path;
-static struct lttng_pipe *pause_pipe;
-static int *notifier_notif_consumption_state;;
-
-int lttng_opt_verbose;
-int lttng_opt_mi;
-int lttng_opt_quiet;
-
-static
-void __attribute__((destructor)) pause_pipe_fini(void)
-{
-       int ret;
-
-       if (pause_pipe_path) {
-               ret = unlink(pause_pipe_path);
-               if (ret) {
-                       PERROR("Failed to unlink pause pipe: path = %s",
-                                       pause_pipe_path);
-               }
-       }
-
-       free(pause_pipe_path);
-       lttng_pipe_destroy(pause_pipe);
-}
-
-LTTNG_EXPORT int __testpoint_sessiond_thread_notification(void);
-int __testpoint_sessiond_thread_notification(void)
-{
-       int ret = 0;
-       const char *pause_pipe_path_prefix;
-
-       pause_pipe_path_prefix = lttng_secure_getenv(
-                       "NOTIFIER_PAUSE_PIPE_PATH");
-       if (!pause_pipe_path_prefix) {
-               ret = -1;
-               goto end;
-       }
-
-       notifier_notif_consumption_state = dlsym(NULL, "notifier_consumption_paused");
-       LTTNG_ASSERT(notifier_notif_consumption_state);
-
-       ret = asprintf(&pause_pipe_path, "%s", pause_pipe_path_prefix);
-       if (ret < 1) {
-               ERR("Failed to allocate pause pipe path");
-               goto end;
-       }
-
-       DBG("Creating pause pipe at %s", pause_pipe_path);
-       pause_pipe = lttng_pipe_named_open(pause_pipe_path,
-                       S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP, O_NONBLOCK);
-       if (!pause_pipe) {
-               ERR("Failed to create pause pipe at %s", pause_pipe_path);
-               ret = -1;
-               goto end;
-       }
-
-       /* Only the read end of the pipe is useful to us. */
-       ret = lttng_pipe_write_close(pause_pipe);
-end:
-       return ret;
-}
-
-LTTNG_EXPORT int __testpoint_sessiond_handle_notifier_event_pipe(void);
-int __testpoint_sessiond_handle_notifier_event_pipe(void)
-{
-       int ret = 0;
-       uint8_t value;
-       bool value_read = false;
-
-       if (!pause_pipe) {
-               ret = -1;
-               goto end;
-       }
-
-       /* Purge pipe and only consider the freshest value. */
-       do {
-               ret = lttng_pipe_read(pause_pipe, &value, sizeof(value));
-               if (ret == sizeof(value)) {
-                       value_read = true;
-               }
-       } while (ret == sizeof(value));
-
-       ret = (errno == EAGAIN) ? 0 : -errno;
-
-       if (value_read) {
-               *notifier_notif_consumption_state = !!value;
-               DBG("Message received on pause pipe: %s data consumption",
-                               *notifier_notif_consumption_state ? "paused" : "resumed");
-       }
-end:
-       return ret;
-}
diff --git a/tests/regression/tools/notification/sessiond_testpoints.cpp b/tests/regression/tools/notification/sessiond_testpoints.cpp
new file mode 100644 (file)
index 0000000..fa3fe7f
--- /dev/null
@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#include <common/compat/getenv.h>
+#include <common/consumer/consumer.h>
+#include <common/pipe.h>
+#include <common/error.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <lttng/constant.h>
+#include <lttng/lttng-export.h>
+#include <fcntl.h>
+#include <dlfcn.h>
+#include <stdio.h>
+
+static char *pause_pipe_path;
+static struct lttng_pipe *pause_pipe;
+static int *notifier_notif_consumption_state;;
+
+int lttng_opt_verbose;
+int lttng_opt_mi;
+int lttng_opt_quiet;
+
+static
+void __attribute__((destructor)) pause_pipe_fini(void)
+{
+       int ret;
+
+       if (pause_pipe_path) {
+               ret = unlink(pause_pipe_path);
+               if (ret) {
+                       PERROR("Failed to unlink pause pipe: path = %s",
+                                       pause_pipe_path);
+               }
+       }
+
+       free(pause_pipe_path);
+       lttng_pipe_destroy(pause_pipe);
+}
+
+extern "C" LTTNG_EXPORT int __testpoint_sessiond_thread_notification(void);
+int __testpoint_sessiond_thread_notification(void)
+{
+       int ret = 0;
+       const char *pause_pipe_path_prefix;
+
+       pause_pipe_path_prefix = lttng_secure_getenv(
+                       "NOTIFIER_PAUSE_PIPE_PATH");
+       if (!pause_pipe_path_prefix) {
+               ret = -1;
+               goto end;
+       }
+
+       notifier_notif_consumption_state = (int *) dlsym(NULL, "notifier_consumption_paused");
+       LTTNG_ASSERT(notifier_notif_consumption_state);
+
+       ret = asprintf(&pause_pipe_path, "%s", pause_pipe_path_prefix);
+       if (ret < 1) {
+               ERR("Failed to allocate pause pipe path");
+               goto end;
+       }
+
+       DBG("Creating pause pipe at %s", pause_pipe_path);
+       pause_pipe = lttng_pipe_named_open(pause_pipe_path,
+                       S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP, O_NONBLOCK);
+       if (!pause_pipe) {
+               ERR("Failed to create pause pipe at %s", pause_pipe_path);
+               ret = -1;
+               goto end;
+       }
+
+       /* Only the read end of the pipe is useful to us. */
+       ret = lttng_pipe_write_close(pause_pipe);
+end:
+       return ret;
+}
+
+extern "C" LTTNG_EXPORT int __testpoint_sessiond_handle_notifier_event_pipe(void);
+int __testpoint_sessiond_handle_notifier_event_pipe(void)
+{
+       int ret = 0;
+       uint8_t value;
+       bool value_read = false;
+
+       if (!pause_pipe) {
+               ret = -1;
+               goto end;
+       }
+
+       /* Purge pipe and only consider the freshest value. */
+       do {
+               ret = lttng_pipe_read(pause_pipe, &value, sizeof(value));
+               if (ret == sizeof(value)) {
+                       value_read = true;
+               }
+       } while (ret == sizeof(value));
+
+       ret = (errno == EAGAIN) ? 0 : -errno;
+
+       if (value_read) {
+               *notifier_notif_consumption_state = !!value;
+               DBG("Message received on pause pipe: %s data consumption",
+                               *notifier_notif_consumption_state ? "paused" : "resumed");
+       }
+end:
+       return ret;
+}
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