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         struct consumer_metadata_cache *cache;
  85
  86         assert(channel);
  87         assert(channel->metadata_cache);
  88
  89         cache = channel->metadata_cache;
  90         DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
  91
  92         if (offset + len > cache->cache_alloc_size) {
  93                 ret = extend_metadata_cache(channel,
  94                                 len - cache->cache_alloc_size + offset);
  95                 if (ret < 0) {
  96                         ERR("Extending metadata cache");
  97                         goto end;
  98                 }
  99         }
 100
 101         memcpy(cache->data + offset, data, len);
 102         cache->total_bytes_written += len;
 103         if (offset + len > cache->max_offset) {
 104                 cache->max_offset = offset + len;
 105         }
 106
 107         if (cache->max_offset == cache->total_bytes_written) {
 108                 char dummy = 'c';
 109
 110                 cache->contiguous = cache->max_offset;
 111                 if (channel->monitor) {
 112                         ret = write(channel->metadata_stream->ust_metadata_poll_pipe[1],
 113                                         &dummy, 1);
 114                         if (ret < 1) {
 115                                 ERR("Wakeup UST metadata pipe");
 116                                 goto end;
 117                         }
 118                 }
 119         }
 120
 121 end:
 122         return ret;
 123 }
 124
 125 /*
 126  * Create the metadata cache, original allocated size: max_sb_size
 127  *
 128  * Return 0 on success, a negative value on error.
 129  */
 130 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
 131 {
 132         int ret;
 133
 134         assert(channel);
 135
 136         channel->metadata_cache = zmalloc(
 137                         sizeof(struct consumer_metadata_cache));
 138         if (!channel->metadata_cache) {
 139                 PERROR("zmalloc metadata cache struct");
 140                 ret = -1;
 141                 goto end;
 142         }
 143         ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
 144         if (ret != 0) {
 145                 PERROR("mutex init");
 146                 goto end_free_cache;
 147         }
 148
 149         channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
 150         channel->metadata_cache->data = zmalloc(
 151                         channel->metadata_cache->cache_alloc_size * sizeof(char));
 152         if (!channel->metadata_cache->data) {
 153                 PERROR("zmalloc metadata cache data");
 154                 ret = -1;
 155                 goto end_free_mutex;
 156         }
 157         DBG("Allocated metadata cache of %" PRIu64 " bytes",
 158                         channel->metadata_cache->cache_alloc_size);
 159
 160         ret = 0;
 161         goto end;
 162
 163 end_free_mutex:
 164         pthread_mutex_destroy(&channel->metadata_cache->lock);
 165 end_free_cache:
 166         free(channel->metadata_cache);
 167 end:
 168         return ret;
 169 }
 170
 171 /*
 172  * Destroy and free the metadata cache
 173  */
 174 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
 175 {
 176         if (!channel || !channel->metadata_cache) {
 177                 return;
 178         }
 179
 180         DBG("Destroying metadata cache");
 181
 182         pthread_mutex_destroy(&channel->metadata_cache->lock);
 183         free(channel->metadata_cache->data);
 184         free(channel->metadata_cache);
 185 }
 186
 187 /*
 188  * Check if the cache is flushed up to the offset passed in parameter.
 189  *
 190  * Return 0 if everything has been flushed, 1 if there is data not flushed.
 191  */
 192 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
 193                 uint64_t offset)
 194 {
 195         int ret = 0;
 196         struct lttng_consumer_stream *metadata_stream;
 197
 198         assert(channel);
 199         assert(channel->metadata_cache);
 200
 201         /*
 202          * XXX This consumer_data.lock should eventually be replaced by
 203          * a channel lock. It protects metadata_stream read and endpoint
 204          * status check.
 205          */
 206         pthread_mutex_lock(&consumer_data.lock);
 207         pthread_mutex_lock(&channel->lock);
 208         pthread_mutex_lock(&channel->metadata_cache->lock);
 209
 210         metadata_stream = channel->metadata_stream;
 211
 212         if (!metadata_stream) {
 213                 /*
 214                  * Having no metadata stream means the channel is being destroyed so there
 215                  * is no cache to flush anymore.
 216                  */
 217                 ret = 0;
 218         } else if (metadata_stream->ust_metadata_pushed >= offset) {
 219                 ret = 0;
 220         } else if (channel->metadata_stream->endpoint_status !=
 221                         CONSUMER_ENDPOINT_ACTIVE) {
 222                 /* An inactive endpoint means we don't have to flush anymore. */
 223                 ret = 0;
 224         } else {
 225                 /* Still not completely flushed. */
 226                 ret = 1;
 227         }
 228
 229         pthread_mutex_unlock(&channel->metadata_cache->lock);
 230         pthread_mutex_unlock(&channel->lock);
 231         pthread_mutex_unlock(&consumer_data.lock);
 232
 233         return ret;
 234 }