Fix: add UST context in the same order the user enabled them

This is to avoid having different field order in different traces for
the same contexts enabled in the same order by the user.

Signed-off-by: David Goulet <dgoulet@efficios.com>

diff --git a/src/bin/lttng-sessiond/context.c b/src/bin/lttng-sessiond/context.c
index b55254b4e398d0bfd55604c5fb8353dd3ba7f43a..6aacbad0ea1c96ad3375739ca908f765f1ba4370 100644 (file)
--- a/src/bin/lttng-sessiond/context.c
+++ b/src/bin/lttng-sessiond/context.c
@@ -132,6 +132,7 @@ static int add_uctx_to_channel(struct ltt_ust_session *usess, int domain,
        /* Add ltt UST context node to ltt UST channel */
        lttng_ht_add_unique_ulong(uchan->ctx, &uctx->node);
        rcu_read_unlock();
+       cds_list_add_tail(&uctx->list, &uchan->ctx_list);
 
        DBG("Context UST %d added to channel %s", uctx->ctx.ctx, uchan->name);
 

diff --git a/src/bin/lttng-sessiond/trace-ust.c b/src/bin/lttng-sessiond/trace-ust.c
index c80d5e772de8c48e913b5399f23be7af785241c5..8363ae2954912482900e2aa5f3eeeeb4cd7bd26f 100644 (file)
--- a/src/bin/lttng-sessiond/trace-ust.c
+++ b/src/bin/lttng-sessiond/trace-ust.c
@@ -289,6 +289,8 @@ struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan)
 
        /* Init node */
        lttng_ht_node_init_str(&luc->node, luc->name);
+       CDS_INIT_LIST_HEAD(&luc->ctx_list);
+
        /* Alloc hash tables */
        luc->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
        luc->ctx = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
@@ -463,6 +465,7 @@ struct ltt_ust_context *trace_ust_create_context(
 
        uctx->ctx.ctx = utype;
        lttng_ht_node_init_ulong(&uctx->node, (unsigned long) uctx->ctx.ctx);
+       CDS_INIT_LIST_HEAD(&uctx->list);
 
        return uctx;
 
@@ -491,11 +494,16 @@ static void destroy_contexts(struct lttng_ht *ht)
        int ret;
        struct lttng_ht_node_ulong *node;
        struct lttng_ht_iter iter;
+       struct ltt_ust_context *ctx;
 
        assert(ht);
 
        rcu_read_lock();
        cds_lfht_for_each_entry(ht->ht, &iter.iter, node, node) {
+               /* Remove from ordered list. */
+               ctx = caa_container_of(node, struct ltt_ust_context, node);
+               cds_list_del(&ctx->list);
+               /* Remove from channel's hash table. */
                ret = lttng_ht_del(ht, &iter);
                if (!ret) {
                        call_rcu(&node->head, destroy_context_rcu);

diff --git a/src/bin/lttng-sessiond/trace-ust.h b/src/bin/lttng-sessiond/trace-ust.h
index f4244fdefae8196a2dadfc092e844dc90a626f05..1c37b3f0f1bb977a49429f31f2ce9f47a7f74e2b 100644 (file)
--- a/src/bin/lttng-sessiond/trace-ust.h
+++ b/src/bin/lttng-sessiond/trace-ust.h
@@ -39,6 +39,7 @@ struct ltt_ust_ht_key {
 struct ltt_ust_context {
        struct lttng_ust_context ctx;
        struct lttng_ht_node_ulong node;
+       struct cds_list_head list;
 };
 
 /* UST event */
@@ -56,6 +57,7 @@ struct ltt_ust_channel {
        char name[LTTNG_UST_SYM_NAME_LEN];
        struct lttng_ust_channel_attr attr;
        struct lttng_ht *ctx;
+       struct cds_list_head ctx_list;
        struct lttng_ht *events;
        struct lttng_ht_node_str node;
        uint64_t tracefile_size;

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 9fe54835b656c69844599e3b0bd7b51f69db482f..5c4dc5ae85837ca24bbcef8cbb950fe0269e8376 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -364,6 +364,7 @@ void delete_ust_app_channel(int sock, struct ust_app_channel *ua_chan,
 
        /* Wipe context */
        cds_lfht_for_each_entry(ua_chan->ctx->ht, &iter.iter, ua_ctx, node.node) {
+               cds_list_del(&ua_ctx->list);
                ret = lttng_ht_del(ua_chan->ctx, &iter);
                assert(!ret);
                delete_ust_app_ctx(sock, ua_ctx);
@@ -825,6 +826,7 @@ struct ust_app_channel *alloc_ust_app_channel(char *name,
        lttng_ht_node_init_str(&ua_chan->node, ua_chan->name);
 
        CDS_INIT_LIST_HEAD(&ua_chan->streams.head);
+       CDS_INIT_LIST_HEAD(&ua_chan->ctx_list);
 
        /* Copy attributes */
        if (attr) {
@@ -916,6 +918,8 @@ struct ust_app_ctx *alloc_ust_app_ctx(struct lttng_ust_context *uctx)
                goto error;
        }
 
+       CDS_INIT_LIST_HEAD(&ua_ctx->list);
+
        if (uctx) {
                memcpy(&ua_ctx->ctx, uctx, sizeof(ua_ctx->ctx));
        }
@@ -1395,7 +1399,7 @@ static void shadow_copy_channel(struct ust_app_channel *ua_chan,
        ua_chan->enabled = uchan->enabled;
        ua_chan->tracing_channel_id = uchan->id;
 
-       cds_lfht_for_each_entry(uchan->ctx->ht, &iter.iter, uctx, node.node) {
+       cds_list_for_each_entry(uctx, &uchan->ctx_list, list) {
                ua_ctx = alloc_ust_app_ctx(&uctx->ctx);
                if (ua_ctx == NULL) {
                        continue;
@@ -1403,6 +1407,7 @@ static void shadow_copy_channel(struct ust_app_channel *ua_chan,
                lttng_ht_node_init_ulong(&ua_ctx->node,
                                (unsigned long) ua_ctx->ctx.ctx);
                lttng_ht_add_unique_ulong(ua_chan->ctx, &ua_ctx->node);
+               cds_list_add_tail(&ua_ctx->list, &ua_chan->ctx_list);
        }
 
        /* Copy all events from ltt ust channel to ust app channel */
@@ -1795,6 +1800,7 @@ int create_ust_app_channel_context(struct ust_app_session *ua_sess,
 
        lttng_ht_node_init_ulong(&ua_ctx->node, (unsigned long) ua_ctx->ctx.ctx);
        lttng_ht_add_unique_ulong(ua_chan->ctx, &ua_ctx->node);
+       cds_list_add_tail(&ua_ctx->list, &ua_chan->ctx_list);
 
        ret = create_ust_channel_context(ua_chan, ua_ctx, app);
        if (ret < 0) {
@@ -4052,7 +4058,7 @@ int ust_app_destroy_trace_all(struct ltt_ust_session *usess)
 void ust_app_global_update(struct ltt_ust_session *usess, int sock)
 {
        int ret = 0;
-       struct lttng_ht_iter iter, uiter, iter_ctx;
+       struct lttng_ht_iter iter, uiter;
        struct ust_app *app;
        struct ust_app_session *ua_sess = NULL;
        struct ust_app_channel *ua_chan;
@@ -4124,8 +4130,11 @@ void ust_app_global_update(struct ltt_ust_session *usess, int sock)
                        }
                }
 
-               cds_lfht_for_each_entry(ua_chan->ctx->ht, &iter_ctx.iter, ua_ctx,
-                               node.node) {
+               /*
+                * Add context using the list so they are enabled in the same order the
+                * user added them.
+                */
+               cds_list_for_each_entry(ua_ctx, &ua_chan->ctx_list, list) {
                        ret = create_ust_channel_context(ua_chan, ua_ctx, app);
                        if (ret < 0) {
                                goto error_unlock;

diff --git a/src/bin/lttng-sessiond/ust-app.h b/src/bin/lttng-sessiond/ust-app.h
index 11202ecaea5845a4ae8f354c7218a0a8d4a9b68c..a08cfd28928bdfbdfcaf3a01d2de65cc314608fb 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.h
+++ b/src/bin/lttng-sessiond/ust-app.h
@@ -102,6 +102,7 @@ struct ust_app_ctx {
        struct lttng_ust_context ctx;
        struct lttng_ust_object_data *obj;
        struct lttng_ht_node_ulong node;
+       struct cds_list_head list;
 };
 
 struct ust_app_event {
@@ -141,7 +142,14 @@ struct ust_app_channel {
        struct ust_app_stream_list streams;
        /* Session pointer that owns this object. */
        struct ust_app_session *session;
+       /*
+        * Contexts are kept in a hash table for fast lookup and in an ordered list
+        * so we are able to enable them on the tracer side in the same order the
+        * user added them.
+        */
        struct lttng_ht *ctx;
+       struct cds_list_head ctx_list;
+
        struct lttng_ht *events;
        uint64_t tracefile_size;
        uint64_t tracefile_count;

diff --git a/src/bin/lttng/commands/add_context.c b/src/bin/lttng/commands/add_context.c
index fad85b50aa5c263fa108f0faae44fa9936e4ed20..6286ed8a0a1838e49c4592e5770e02c4ab7f16df 100644 (file)
--- a/src/bin/lttng/commands/add_context.c
+++ b/src/bin/lttng/commands/add_context.c
@@ -480,7 +480,7 @@ int cmd_add_context(int argc, const char **argv)
                                ret = CMD_ERROR;
                                goto end;
                        } else {
-                               cds_list_add(&type->list, &ctx_type_list.head);
+                               cds_list_add_tail(&type->list, &ctx_type_list.head);
                        }
                        break;
                case OPT_USERSPACE: