src/common/consumer-metadata-cache.c

   1 /*
   2  * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
   3  *                      David Goulet <dgoulet@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <assert.h>
  21 #include <pthread.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <sys/types.h>
  25 #include <unistd.h>
  26 #include <inttypes.h>
  27
  28 #include <common/common.h>
  29 #include <common/utils.h>
  30 #include <common/sessiond-comm/sessiond-comm.h>
  31 #include <common/ust-consumer/ust-consumer.h>
  32 #include <common/consumer.h>
  33
  34 #include "consumer-metadata-cache.h"
  35
  36 extern struct lttng_consumer_global_data consumer_data;
  37
  38 /*
  39  * Extend the allocated size of the metadata cache. Called only from
  40  * lttng_ustconsumer_write_metadata_cache.
  41  *
  42  * Return 0 on success, a negative value on error.
  43  */
  44 static int extend_metadata_cache(struct lttng_consumer_channel *channel,
  45                 unsigned int size)
  46 {
  47         int ret = 0;
  48         char *tmp_data_ptr;
  49         unsigned int new_size, old_size;
  50
  51         assert(channel);
  52         assert(channel->metadata_cache);
  53
  54         old_size = channel->metadata_cache->cache_alloc_size;
  55         new_size = max_t(unsigned int, old_size + size, old_size << 1);
  56         DBG("Extending metadata cache to %u", new_size);
  57         tmp_data_ptr = realloc(channel->metadata_cache->data, new_size);
  58         if (!tmp_data_ptr) {
  59                 ERR("Reallocating metadata cache");
  60                 free(channel->metadata_cache->data);
  61                 ret = -1;
  62                 goto end;
  63         }
  64         /* Zero newly allocated memory */
  65         memset(tmp_data_ptr + old_size, 0, new_size - old_size);
  66         channel->metadata_cache->data = tmp_data_ptr;
  67         channel->metadata_cache->cache_alloc_size = new_size;
  68
  69 end:
  70         return ret;
  71 }
  72
  73 /*
  74  * Write metadata to the cache, extend the cache if necessary. We support
  75  * non-contiguous updates but not overlapping ones. If there is contiguous
  76  * metadata in the cache, we send it to the ring buffer. The metadata cache
  77  * lock MUST be acquired to write in the cache.
  78  *
  79  * Return 0 on success, a negative value on error.
  80  */
  81 int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
  82                 unsigned int offset, unsigned int len, char *data)
  83 {
  84         int ret = 0;
  85         int size_ret;
  86         struct consumer_metadata_cache *cache;
  87
  88         assert(channel);
  89         assert(channel->metadata_cache);
  90
  91         cache = channel->metadata_cache;
  92         DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
  93
  94         if (offset + len > cache->cache_alloc_size) {
  95                 ret = extend_metadata_cache(channel,
  96                                 len - cache->cache_alloc_size + offset);
  97                 if (ret < 0) {
  98                         ERR("Extending metadata cache");
  99                         goto end;
 100                 }
 101         }
 102
 103         memcpy(cache->data + offset, data, len);
 104         cache->total_bytes_written += len;
 105         if (offset + len > cache->max_offset) {
 106                 cache->max_offset = offset + len;
 107         }
 108
 109         if (cache->max_offset == cache->total_bytes_written) {
 110                 char dummy = 'c';
 111
 112                 cache->contiguous = cache->max_offset;
 113                 if (channel->monitor) {
 114                         size_ret = lttng_write(channel->metadata_stream->ust_metadata_poll_pipe[1],
 115                                         &dummy, 1);
 116                         if (size_ret < 1) {
 117                                 ERR("Wakeup UST metadata pipe");
 118                                 ret = -1;
 119                                 goto end;
 120                         }
 121                 }
 122         }
 123
 124 end:
 125         return ret;
 126 }
 127
 128 /*
 129  * Create the metadata cache, original allocated size: max_sb_size
 130  *
 131  * Return 0 on success, a negative value on error.
 132  */
 133 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
 134 {
 135         int ret;
 136
 137         assert(channel);
 138
 139         channel->metadata_cache = zmalloc(
 140                         sizeof(struct consumer_metadata_cache));
 141         if (!channel->metadata_cache) {
 142                 PERROR("zmalloc metadata cache struct");
 143                 ret = -1;
 144                 goto end;
 145         }
 146         ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
 147         if (ret != 0) {
 148                 PERROR("mutex init");
 149                 goto end_free_cache;
 150         }
 151
 152         channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
 153         channel->metadata_cache->data = zmalloc(
 154                         channel->metadata_cache->cache_alloc_size * sizeof(char));
 155         if (!channel->metadata_cache->data) {
 156                 PERROR("zmalloc metadata cache data");
 157                 ret = -1;
 158                 goto end_free_mutex;
 159         }
 160         DBG("Allocated metadata cache of %" PRIu64 " bytes",
 161                         channel->metadata_cache->cache_alloc_size);
 162
 163         ret = 0;
 164         goto end;
 165
 166 end_free_mutex:
 167         pthread_mutex_destroy(&channel->metadata_cache->lock);
 168 end_free_cache:
 169         free(channel->metadata_cache);
 170 end:
 171         return ret;
 172 }
 173
 174 /*
 175  * Destroy and free the metadata cache
 176  */
 177 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
 178 {
 179         if (!channel || !channel->metadata_cache) {
 180                 return;
 181         }
 182
 183         DBG("Destroying metadata cache");
 184
 185         pthread_mutex_destroy(&channel->metadata_cache->lock);
 186         free(channel->metadata_cache->data);
 187         free(channel->metadata_cache);
 188 }
 189
 190 /*
 191  * Check if the cache is flushed up to the offset passed in parameter.
 192  *
 193  * Return 0 if everything has been flushed, 1 if there is data not flushed.
 194  */
 195 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
 196                 uint64_t offset, int timer)
 197 {
 198         int ret = 0;
 199         struct lttng_consumer_stream *metadata_stream;
 200
 201         assert(channel);
 202         assert(channel->metadata_cache);
 203
 204         /*
 205          * If not called from a timer handler, we have to take the
 206          * channel lock to be mutually exclusive with channel teardown.
 207          * Timer handler does not need to take this lock because it is
 208          * already synchronized by timer stop (and, more importantly,
 209          * taking this lock in a timer handler would cause a deadlock).
 210          */
 211         if (!timer) {
 212                 pthread_mutex_lock(&channel->lock);
 213         }
 214         pthread_mutex_lock(&channel->timer_lock);
 215         pthread_mutex_lock(&channel->metadata_cache->lock);
 216
 217         metadata_stream = channel->metadata_stream;
 218
 219         if (!metadata_stream) {
 220                 /*
 221                  * Having no metadata stream means the channel is being destroyed so there
 222                  * is no cache to flush anymore.
 223                  */
 224                 ret = 0;
 225         } else if (metadata_stream->ust_metadata_pushed >= offset) {
 226                 ret = 0;
 227         } else if (channel->metadata_stream->endpoint_status !=
 228                         CONSUMER_ENDPOINT_ACTIVE) {
 229                 /* An inactive endpoint means we don't have to flush anymore. */
 230                 ret = 0;
 231         } else {
 232                 /* Still not completely flushed. */
 233                 ret = 1;
 234         }
 235
 236         pthread_mutex_unlock(&channel->metadata_cache->lock);
 237         pthread_mutex_unlock(&channel->timer_lock);
 238         if (!timer) {
 239                 pthread_mutex_unlock(&channel->lock);
 240         }
 241
 242         return ret;
 243 }