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 #define _LGPL_SOURCE
  21 #include <assert.h>
  22 #include <pthread.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/types.h>
  26 #include <unistd.h>
  27 #include <inttypes.h>
  28
  29 #include <common/common.h>
  30 #include <common/utils.h>
  31 #include <common/sessiond-comm/sessiond-comm.h>
  32 #include <common/ust-consumer/ust-consumer.h>
  33 #include <common/consumer.h>
  34
  35 #include "consumer-metadata-cache.h"
  36
  37 extern struct lttng_consumer_global_data consumer_data;
  38
  39 /*
  40  * Extend the allocated size of the metadata cache. Called only from
  41  * lttng_ustconsumer_write_metadata_cache.
  42  *
  43  * Return 0 on success, a negative value on error.
  44  */
  45 static int extend_metadata_cache(struct lttng_consumer_channel *channel,
  46                 unsigned int size)
  47 {
  48         int ret = 0;
  49         char *tmp_data_ptr;
  50         unsigned int new_size, old_size;
  51
  52         assert(channel);
  53         assert(channel->metadata_cache);
  54
  55         old_size = channel->metadata_cache->cache_alloc_size;
  56         new_size = max_t(unsigned int, old_size + size, old_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         /* Zero newly allocated memory */
  66         memset(tmp_data_ptr + old_size, 0, new_size - old_size);
  67         channel->metadata_cache->data = tmp_data_ptr;
  68         channel->metadata_cache->cache_alloc_size = new_size;
  69
  70 end:
  71         return ret;
  72 }
  73
  74 /*
  75  * Write metadata to the cache, extend the cache if necessary. We support
  76  * overlapping updates, but they need to be contiguous. Send the
  77  * contiguous metadata in cache to the ring buffer. The metadata cache
  78  * lock MUST be acquired to write in the cache.
  79  *
  80  * Return 0 on success, a negative value on error.
  81  */
  82 int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
  83                 unsigned int offset, unsigned int len, char *data)
  84 {
  85         int ret = 0;
  86         int size_ret;
  87         struct consumer_metadata_cache *cache;
  88
  89         assert(channel);
  90         assert(channel->metadata_cache);
  91
  92         cache = channel->metadata_cache;
  93         DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
  94
  95         if (offset + len > cache->cache_alloc_size) {
  96                 ret = extend_metadata_cache(channel,
  97                                 len - cache->cache_alloc_size + offset);
  98                 if (ret < 0) {
  99                         ERR("Extending metadata cache");
 100                         goto end;
 101                 }
 102         }
 103
 104         memcpy(cache->data + offset, data, len);
 105         if (offset + len > cache->max_offset) {
 106                 char dummy = 'c';
 107
 108                 cache->max_offset = offset + len;
 109                 if (channel->monitor) {
 110                         size_ret = lttng_write(channel->metadata_stream->ust_metadata_poll_pipe[1],
 111                                         &dummy, 1);
 112                         if (size_ret < 1) {
 113                                 ERR("Wakeup UST metadata pipe");
 114                                 ret = -1;
 115                                 goto end;
 116                         }
 117                 }
 118         }
 119
 120 end:
 121         return ret;
 122 }
 123
 124 /*
 125  * Create the metadata cache, original allocated size: max_sb_size
 126  *
 127  * Return 0 on success, a negative value on error.
 128  */
 129 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
 130 {
 131         int ret;
 132
 133         assert(channel);
 134
 135         channel->metadata_cache = zmalloc(
 136                         sizeof(struct consumer_metadata_cache));
 137         if (!channel->metadata_cache) {
 138                 PERROR("zmalloc metadata cache struct");
 139                 ret = -1;
 140                 goto end;
 141         }
 142         ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
 143         if (ret != 0) {
 144                 PERROR("mutex init");
 145                 goto end_free_cache;
 146         }
 147
 148         channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
 149         channel->metadata_cache->data = zmalloc(
 150                         channel->metadata_cache->cache_alloc_size * sizeof(char));
 151         if (!channel->metadata_cache->data) {
 152                 PERROR("zmalloc metadata cache data");
 153                 ret = -1;
 154                 goto end_free_mutex;
 155         }
 156         DBG("Allocated metadata cache of %" PRIu64 " bytes",
 157                         channel->metadata_cache->cache_alloc_size);
 158
 159         ret = 0;
 160         goto end;
 161
 162 end_free_mutex:
 163         pthread_mutex_destroy(&channel->metadata_cache->lock);
 164 end_free_cache:
 165         free(channel->metadata_cache);
 166 end:
 167         return ret;
 168 }
 169
 170 /*
 171  * Destroy and free the metadata cache
 172  */
 173 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
 174 {
 175         if (!channel || !channel->metadata_cache) {
 176                 return;
 177         }
 178
 179         DBG("Destroying metadata cache");
 180
 181         pthread_mutex_destroy(&channel->metadata_cache->lock);
 182         free(channel->metadata_cache->data);
 183         free(channel->metadata_cache);
 184 }
 185
 186 /*
 187  * Check if the cache is flushed up to the offset passed in parameter.
 188  *
 189  * Return 0 if everything has been flushed, 1 if there is data not flushed.
 190  */
 191 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
 192                 uint64_t offset, int timer)
 193 {
 194         int ret = 0;
 195         struct lttng_consumer_stream *metadata_stream;
 196
 197         assert(channel);
 198         assert(channel->metadata_cache);
 199
 200         /*
 201          * If not called from a timer handler, we have to take the
 202          * channel lock to be mutually exclusive with channel teardown.
 203          * Timer handler does not need to take this lock because it is
 204          * already synchronized by timer stop (and, more importantly,
 205          * taking this lock in a timer handler would cause a deadlock).
 206          */
 207         if (!timer) {
 208                 pthread_mutex_lock(&channel->lock);
 209         }
 210         pthread_mutex_lock(&channel->timer_lock);
 211         pthread_mutex_lock(&channel->metadata_cache->lock);
 212
 213         metadata_stream = channel->metadata_stream;
 214
 215         if (!metadata_stream) {
 216                 /*
 217                  * Having no metadata stream means the channel is being destroyed so there
 218                  * is no cache to flush anymore.
 219                  */
 220                 ret = 0;
 221         } else if (metadata_stream->ust_metadata_pushed >= offset) {
 222                 ret = 0;
 223         } else if (channel->metadata_stream->endpoint_status !=
 224                         CONSUMER_ENDPOINT_ACTIVE) {
 225                 /* An inactive endpoint means we don't have to flush anymore. */
 226                 ret = 0;
 227         } else {
 228                 /* Still not completely flushed. */
 229                 ret = 1;
 230         }
 231
 232         pthread_mutex_unlock(&channel->metadata_cache->lock);
 233         pthread_mutex_unlock(&channel->timer_lock);
 234         if (!timer) {
 235                 pthread_mutex_unlock(&channel->lock);
 236         }
 237
 238         return ret;
 239 }