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;
  50
  51         assert(channel);
  52         assert(channel->metadata_cache);
  53
  54         new_size = max_t(unsigned int,
  55                         channel->metadata_cache->cache_alloc_size + size,
  56                         channel->metadata_cache->cache_alloc_size << 1);
  57         DBG("Extending metadata cache to %u", new_size);
  58         tmp_data_ptr = realloc(channel->metadata_cache->data, new_size);
  59         if (!tmp_data_ptr) {
  60                 ERR("Reallocating metadata cache");
  61                 free(channel->metadata_cache->data);
  62                 ret = -1;
  63                 goto end;
  64         }
  65         channel->metadata_cache->data = tmp_data_ptr;
  66         channel->metadata_cache->cache_alloc_size = new_size;
  67
  68 end:
  69         return ret;
  70 }
  71
  72 /*
  73  * Write metadata to the cache, extend the cache if necessary. We support
  74  * non-contiguous updates but not overlapping ones. If there is contiguous
  75  * metadata in the cache, we send it to the ring buffer. The metadata cache
  76  * lock MUST be acquired to write in the cache.
  77  *
  78  * Return 0 on success, a negative value on error.
  79  */
  80 int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
  81                 unsigned int offset, unsigned int len, char *data)
  82 {
  83         int ret = 0;
  84         int size_ret;
  85         struct consumer_metadata_cache *cache;
  86
  87         assert(channel);
  88         assert(channel->metadata_cache);
  89
  90         cache = channel->metadata_cache;
  91         DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
  92
  93         if (offset + len > cache->cache_alloc_size) {
  94                 ret = extend_metadata_cache(channel,
  95                                 len - cache->cache_alloc_size + offset);
  96                 if (ret < 0) {
  97                         ERR("Extending metadata cache");
  98                         goto end;
  99                 }
 100         }
 101
 102         memcpy(cache->data + offset, data, len);
 103         cache->total_bytes_written += len;
 104         if (offset + len > cache->max_offset) {
 105                 cache->max_offset = offset + len;
 106         }
 107
 108         if (cache->max_offset == cache->total_bytes_written) {
 109                 char dummy = 'c';
 110
 111                 cache->contiguous = cache->max_offset;
 112                 if (channel->monitor) {
 113                         size_ret = lttng_write(channel->metadata_stream->ust_metadata_poll_pipe[1],
 114                                         &dummy, 1);
 115                         if (size_ret < 1) {
 116                                 ERR("Wakeup UST metadata pipe");
 117                                 ret = -1;
 118                                 goto end;
 119                         }
 120                 }
 121         }
 122
 123 end:
 124         return ret;
 125 }
 126
 127 /*
 128  * Create the metadata cache, original allocated size: max_sb_size
 129  *
 130  * Return 0 on success, a negative value on error.
 131  */
 132 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
 133 {
 134         int ret;
 135
 136         assert(channel);
 137
 138         channel->metadata_cache = zmalloc(
 139                         sizeof(struct consumer_metadata_cache));
 140         if (!channel->metadata_cache) {
 141                 PERROR("zmalloc metadata cache struct");
 142                 ret = -1;
 143                 goto end;
 144         }
 145         ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
 146         if (ret != 0) {
 147                 PERROR("mutex init");
 148                 goto end_free_cache;
 149         }
 150
 151         channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
 152         channel->metadata_cache->data = zmalloc(
 153                         channel->metadata_cache->cache_alloc_size * sizeof(char));
 154         if (!channel->metadata_cache->data) {
 155                 PERROR("zmalloc metadata cache data");
 156                 ret = -1;
 157                 goto end_free_mutex;
 158         }
 159         DBG("Allocated metadata cache of %" PRIu64 " bytes",
 160                         channel->metadata_cache->cache_alloc_size);
 161
 162         ret = 0;
 163         goto end;
 164
 165 end_free_mutex:
 166         pthread_mutex_destroy(&channel->metadata_cache->lock);
 167 end_free_cache:
 168         free(channel->metadata_cache);
 169 end:
 170         return ret;
 171 }
 172
 173 /*
 174  * Destroy and free the metadata cache
 175  */
 176 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
 177 {
 178         if (!channel || !channel->metadata_cache) {
 179                 return;
 180         }
 181
 182         DBG("Destroying metadata cache");
 183
 184         pthread_mutex_destroy(&channel->metadata_cache->lock);
 185         free(channel->metadata_cache->data);
 186         free(channel->metadata_cache);
 187 }
 188
 189 /*
 190  * Check if the cache is flushed up to the offset passed in parameter.
 191  *
 192  * Return 0 if everything has been flushed, 1 if there is data not flushed.
 193  */
 194 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
 195                 uint64_t offset, int timer)
 196 {
 197         int ret = 0;
 198         struct lttng_consumer_stream *metadata_stream;
 199
 200         assert(channel);
 201         assert(channel->metadata_cache);
 202
 203         /*
 204          * If not called from a timer handler, we have to take the
 205          * channel lock to be mutually exclusive with channel teardown.
 206          * Timer handler does not need to take this lock because it is
 207          * already synchronized by timer stop (and, more importantly,
 208          * taking this lock in a timer handler would cause a deadlock).
 209          */
 210         if (!timer) {
 211                 pthread_mutex_lock(&channel->lock);
 212         }
 213         pthread_mutex_lock(&channel->timer_lock);
 214         pthread_mutex_lock(&channel->metadata_cache->lock);
 215
 216         metadata_stream = channel->metadata_stream;
 217
 218         if (!metadata_stream) {
 219                 /*
 220                  * Having no metadata stream means the channel is being destroyed so there
 221                  * is no cache to flush anymore.
 222                  */
 223                 ret = 0;
 224         } else if (metadata_stream->ust_metadata_pushed >= offset) {
 225                 ret = 0;
 226         } else if (channel->metadata_stream->endpoint_status !=
 227                         CONSUMER_ENDPOINT_ACTIVE) {
 228                 /* An inactive endpoint means we don't have to flush anymore. */
 229                 ret = 0;
 230         } else {
 231                 /* Still not completely flushed. */
 232                 ret = 1;
 233         }
 234
 235         pthread_mutex_unlock(&channel->metadata_cache->lock);
 236         pthread_mutex_unlock(&channel->timer_lock);
 237         if (!timer) {
 238                 pthread_mutex_unlock(&channel->lock);
 239         }
 240
 241         return ret;
 242 }