src/common/consumer/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 _LGPL_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/consumer.h>
  33
  34 #include "consumer-metadata-cache.h"
  35
  36 enum metadata_cache_update_version_status {
  37         METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED,
  38         METADATA_CACHE_UPDATE_STATUS_VERSION_NOT_UPDATED,
  39 };
  40
  41 extern struct lttng_consumer_global_data consumer_data;
  42
  43 /*
  44  * Extend the allocated size of the metadata cache. Called only from
  45  * lttng_ustconsumer_write_metadata_cache.
  46  *
  47  * Return 0 on success, a negative value on error.
  48  */
  49 static int extend_metadata_cache(struct lttng_consumer_channel *channel,
  50                 unsigned int size)
  51 {
  52         int ret = 0;
  53         char *tmp_data_ptr;
  54         unsigned int new_size, old_size;
  55
  56         assert(channel);
  57         assert(channel->metadata_cache);
  58
  59         old_size = channel->metadata_cache->cache_alloc_size;
  60         new_size = max_t(unsigned int, old_size + size, old_size << 1);
  61         DBG("Extending metadata cache to %u", new_size);
  62         tmp_data_ptr = realloc(channel->metadata_cache->data, new_size);
  63         if (!tmp_data_ptr) {
  64                 ERR("Reallocating metadata cache");
  65                 free(channel->metadata_cache->data);
  66                 ret = -1;
  67                 goto end;
  68         }
  69         /* Zero newly allocated memory */
  70         memset(tmp_data_ptr + old_size, 0, new_size - old_size);
  71         channel->metadata_cache->data = tmp_data_ptr;
  72         channel->metadata_cache->cache_alloc_size = new_size;
  73
  74 end:
  75         return ret;
  76 }
  77
  78 /*
  79  * Reset the metadata cache.
  80  */
  81 static
  82 void metadata_cache_reset(struct consumer_metadata_cache *cache)
  83 {
  84         memset(cache->data, 0, cache->cache_alloc_size);
  85         cache->max_offset = 0;
  86 }
  87
  88 /*
  89  * Check if the metadata cache version changed.
  90  * If it did, reset the metadata cache.
  91  * The metadata cache lock MUST be held.
  92  */
  93 static enum metadata_cache_update_version_status metadata_cache_update_version(
  94                 struct consumer_metadata_cache *cache, uint64_t version)
  95 {
  96         enum metadata_cache_update_version_status status;
  97
  98         if (cache->version == version) {
  99                 status = METADATA_CACHE_UPDATE_STATUS_VERSION_NOT_UPDATED;
 100                 goto end;
 101         }
 102
 103         DBG("Metadata cache version update to %" PRIu64, version);
 104         cache->version = version;
 105         status = METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED;
 106
 107 end:
 108         return status;
 109 }
 110
 111 /*
 112  * Write metadata to the cache, extend the cache if necessary. We support
 113  * overlapping updates, but they need to be contiguous. Send the
 114  * contiguous metadata in cache to the ring buffer. The metadata cache
 115  * lock MUST be acquired to write in the cache.
 116  *
 117  * See `enum consumer_metadata_cache_write_status` for the meaning of the
 118  * various returned status codes.
 119  */
 120 enum consumer_metadata_cache_write_status
 121 consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
 122                 unsigned int offset, unsigned int len, uint64_t version,
 123                 char *data)
 124 {
 125         int ret = 0;
 126         struct consumer_metadata_cache *cache;
 127         enum consumer_metadata_cache_write_status status;
 128         bool cache_is_invalidated = false;
 129         uint64_t original_max_offset;
 130
 131         assert(channel);
 132         assert(channel->metadata_cache);
 133
 134         cache = channel->metadata_cache;
 135         ASSERT_LOCKED(cache->lock);
 136         original_max_offset = cache->max_offset;
 137
 138         if (metadata_cache_update_version(cache, version) ==
 139                         METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED) {
 140                 metadata_cache_reset(cache);
 141                 cache_is_invalidated = true;
 142         }
 143
 144         DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
 145
 146         if (offset + len > cache->cache_alloc_size) {
 147                 ret = extend_metadata_cache(channel,
 148                                 len - cache->cache_alloc_size + offset);
 149                 if (ret < 0) {
 150                         ERR("Extending metadata cache");
 151                         status = CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR;
 152                         goto end;
 153                 }
 154         }
 155
 156         memcpy(cache->data + offset, data, len);
 157         cache->max_offset = max(cache->max_offset, offset + len);
 158
 159         if (cache_is_invalidated) {
 160                 status = CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED;
 161         } else if (cache->max_offset > original_max_offset) {
 162                 status = CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT;
 163         } else {
 164                 status = CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE;
 165                 assert(cache->max_offset == original_max_offset);
 166         }
 167
 168 end:
 169         return status;
 170 }
 171
 172 /*
 173  * Create the metadata cache, original allocated size: max_sb_size
 174  *
 175  * Return 0 on success, a negative value on error.
 176  */
 177 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
 178 {
 179         int ret;
 180
 181         assert(channel);
 182
 183         channel->metadata_cache = zmalloc(
 184                         sizeof(struct consumer_metadata_cache));
 185         if (!channel->metadata_cache) {
 186                 PERROR("zmalloc metadata cache struct");
 187                 ret = -1;
 188                 goto end;
 189         }
 190         ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
 191         if (ret != 0) {
 192                 PERROR("mutex init");
 193                 goto end_free_cache;
 194         }
 195
 196         channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
 197         channel->metadata_cache->data = zmalloc(
 198                         channel->metadata_cache->cache_alloc_size * sizeof(char));
 199         if (!channel->metadata_cache->data) {
 200                 PERROR("zmalloc metadata cache data");
 201                 ret = -1;
 202                 goto end_free_mutex;
 203         }
 204         DBG("Allocated metadata cache of %" PRIu64 " bytes",
 205                         channel->metadata_cache->cache_alloc_size);
 206
 207         ret = 0;
 208         goto end;
 209
 210 end_free_mutex:
 211         pthread_mutex_destroy(&channel->metadata_cache->lock);
 212 end_free_cache:
 213         free(channel->metadata_cache);
 214 end:
 215         return ret;
 216 }
 217
 218 /*
 219  * Destroy and free the metadata cache
 220  */
 221 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
 222 {
 223         if (!channel || !channel->metadata_cache) {
 224                 return;
 225         }
 226
 227         DBG("Destroying metadata cache");
 228
 229         pthread_mutex_destroy(&channel->metadata_cache->lock);
 230         free(channel->metadata_cache->data);
 231         free(channel->metadata_cache);
 232 }
 233
 234 /*
 235  * Check if the cache is flushed up to the offset passed in parameter.
 236  *
 237  * Return 0 if everything has been flushed, 1 if there is data not flushed.
 238  */
 239 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
 240                 uint64_t offset, int timer)
 241 {
 242         int ret = 0;
 243         struct lttng_consumer_stream *metadata_stream;
 244
 245         assert(channel);
 246         assert(channel->metadata_cache);
 247
 248         /*
 249          * If not called from a timer handler, we have to take the
 250          * channel lock to be mutually exclusive with channel teardown.
 251          * Timer handler does not need to take this lock because it is
 252          * already synchronized by timer stop (and, more importantly,
 253          * taking this lock in a timer handler would cause a deadlock).
 254          */
 255         if (!timer) {
 256                 pthread_mutex_lock(&channel->lock);
 257         }
 258         pthread_mutex_lock(&channel->timer_lock);
 259         metadata_stream = channel->metadata_stream;
 260         if (!metadata_stream) {
 261                 /*
 262                  * Having no metadata stream means the channel is being destroyed so there
 263                  * is no cache to flush anymore.
 264                  */
 265                 ret = 0;
 266                 goto end_unlock_channel;
 267         }
 268
 269         pthread_mutex_lock(&metadata_stream->lock);
 270         pthread_mutex_lock(&channel->metadata_cache->lock);
 271
 272         if (metadata_stream->ust_metadata_pushed >= offset) {
 273                 ret = 0;
 274         } else if (channel->metadata_stream->endpoint_status !=
 275                         CONSUMER_ENDPOINT_ACTIVE) {
 276                 /* An inactive endpoint means we don't have to flush anymore. */
 277                 ret = 0;
 278         } else {
 279                 /* Still not completely flushed. */
 280                 ret = 1;
 281         }
 282
 283         pthread_mutex_unlock(&channel->metadata_cache->lock);
 284         pthread_mutex_unlock(&metadata_stream->lock);
 285 end_unlock_channel:
 286         pthread_mutex_unlock(&channel->timer_lock);
 287         if (!timer) {
 288                 pthread_mutex_unlock(&channel->lock);
 289         }
 290
 291         return ret;
 292 }