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 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  * Reset the metadata cache.
  75  */
  76 static
  77 void metadata_cache_reset(struct consumer_metadata_cache *cache)
  78 {
  79         memset(cache->data, 0, cache->cache_alloc_size);
  80         cache->max_offset = 0;
  81 }
  82
  83 /*
  84  * Check if the metadata cache version changed.
  85  * If it did, reset the metadata cache.
  86  * The metadata cache lock MUST be held.
  87  *
  88  * Returns 0 on success, a negative value on error.
  89  */
  90 static
  91 int metadata_cache_check_version(struct consumer_metadata_cache *cache,
  92                 uint64_t version)
  93 {
  94         int ret = 0;
  95
  96         if (cache->version == version) {
  97                 goto end;
  98         }
  99
 100         DBG("Metadata cache version update to %" PRIu64, version);
 101         metadata_cache_reset(cache);
 102         cache->version = version;
 103
 104 end:
 105         return ret;
 106 }
 107
 108 /*
 109  * Write a character on the metadata poll pipe to wake the metadata thread.
 110  * Returns 0 on success, -1 on error.
 111  */
 112 int consumer_metadata_wakeup_pipe(const struct lttng_consumer_channel *channel)
 113 {
 114         int ret = 0;
 115         const char dummy = 'c';
 116
 117         if (channel->monitor && channel->metadata_stream) {
 118                 ssize_t write_ret;
 119
 120                 write_ret = lttng_write(channel->metadata_stream->ust_metadata_poll_pipe[1],
 121                                 &dummy, 1);
 122                 if (write_ret < 1) {
 123                         if (errno == EWOULDBLOCK) {
 124                                 /*
 125                                  * This is fine, the metadata poll thread
 126                                  * is having a hard time keeping-up, but
 127                                  * it will eventually wake-up and consume
 128                                  * the available data.
 129                                  */
 130                                 ret = 0;
 131                         } else {
 132                                 PERROR("Wake-up UST metadata pipe");
 133                                 ret = -1;
 134                                 goto end;
 135                         }
 136                 }
 137         }
 138
 139 end:
 140         return ret;
 141 }
 142
 143 /*
 144  * Write metadata to the cache, extend the cache if necessary. We support
 145  * overlapping updates, but they need to be contiguous. Send the
 146  * contiguous metadata in cache to the ring buffer. The metadata cache
 147  * lock MUST be acquired to write in the cache.
 148  *
 149  * Return 0 on success, a negative value on error.
 150  */
 151 int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
 152                 unsigned int offset, unsigned int len, uint64_t version,
 153                 char *data)
 154 {
 155         int ret = 0;
 156         struct consumer_metadata_cache *cache;
 157
 158         assert(channel);
 159         assert(channel->metadata_cache);
 160
 161         cache = channel->metadata_cache;
 162
 163         ret = metadata_cache_check_version(cache, version);
 164         if (ret < 0) {
 165                 goto end;
 166         }
 167
 168         DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
 169
 170         if (offset + len > cache->cache_alloc_size) {
 171                 ret = extend_metadata_cache(channel,
 172                                 len - cache->cache_alloc_size + offset);
 173                 if (ret < 0) {
 174                         ERR("Extending metadata cache");
 175                         goto end;
 176                 }
 177         }
 178
 179         memcpy(cache->data + offset, data, len);
 180         if (offset + len > cache->max_offset) {
 181                 cache->max_offset = offset + len;
 182                 ret = consumer_metadata_wakeup_pipe(channel);
 183         }
 184
 185 end:
 186         return ret;
 187 }
 188
 189 /*
 190  * Create the metadata cache, original allocated size: max_sb_size
 191  *
 192  * Return 0 on success, a negative value on error.
 193  */
 194 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
 195 {
 196         int ret;
 197
 198         assert(channel);
 199
 200         channel->metadata_cache = zmalloc(
 201                         sizeof(struct consumer_metadata_cache));
 202         if (!channel->metadata_cache) {
 203                 PERROR("zmalloc metadata cache struct");
 204                 ret = -1;
 205                 goto end;
 206         }
 207         ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
 208         if (ret != 0) {
 209                 PERROR("mutex init");
 210                 goto end_free_cache;
 211         }
 212
 213         channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
 214         channel->metadata_cache->data = zmalloc(
 215                         channel->metadata_cache->cache_alloc_size * sizeof(char));
 216         if (!channel->metadata_cache->data) {
 217                 PERROR("zmalloc metadata cache data");
 218                 ret = -1;
 219                 goto end_free_mutex;
 220         }
 221         DBG("Allocated metadata cache of %" PRIu64 " bytes",
 222                         channel->metadata_cache->cache_alloc_size);
 223
 224         ret = 0;
 225         goto end;
 226
 227 end_free_mutex:
 228         pthread_mutex_destroy(&channel->metadata_cache->lock);
 229 end_free_cache:
 230         free(channel->metadata_cache);
 231 end:
 232         return ret;
 233 }
 234
 235 /*
 236  * Destroy and free the metadata cache
 237  */
 238 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
 239 {
 240         if (!channel || !channel->metadata_cache) {
 241                 return;
 242         }
 243
 244         DBG("Destroying metadata cache");
 245
 246         pthread_mutex_destroy(&channel->metadata_cache->lock);
 247         free(channel->metadata_cache->data);
 248         free(channel->metadata_cache);
 249 }
 250
 251 /*
 252  * Check if the cache is flushed up to the offset passed in parameter.
 253  *
 254  * Return 0 if everything has been flushed, 1 if there is data not flushed.
 255  */
 256 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
 257                 uint64_t offset, int timer)
 258 {
 259         int ret = 0;
 260         struct lttng_consumer_stream *metadata_stream;
 261
 262         assert(channel);
 263         assert(channel->metadata_cache);
 264
 265         /*
 266          * If not called from a timer handler, we have to take the
 267          * channel lock to be mutually exclusive with channel teardown.
 268          * Timer handler does not need to take this lock because it is
 269          * already synchronized by timer stop (and, more importantly,
 270          * taking this lock in a timer handler would cause a deadlock).
 271          */
 272         if (!timer) {
 273                 pthread_mutex_lock(&channel->lock);
 274         }
 275         pthread_mutex_lock(&channel->timer_lock);
 276         metadata_stream = channel->metadata_stream;
 277         if (!metadata_stream) {
 278                 /*
 279                  * Having no metadata stream means the channel is being destroyed so there
 280                  * is no cache to flush anymore.
 281                  */
 282                 ret = 0;
 283                 goto end_unlock_channel;
 284         }
 285
 286         pthread_mutex_lock(&metadata_stream->lock);
 287         pthread_mutex_lock(&channel->metadata_cache->lock);
 288
 289         if (metadata_stream->ust_metadata_pushed >= offset) {
 290                 ret = 0;
 291         } else if (channel->metadata_stream->endpoint_status !=
 292                         CONSUMER_ENDPOINT_ACTIVE) {
 293                 /* An inactive endpoint means we don't have to flush anymore. */
 294                 ret = 0;
 295         } else {
 296                 /* Still not completely flushed. */
 297                 ret = 1;
 298         }
 299
 300         pthread_mutex_unlock(&channel->metadata_cache->lock);
 301         pthread_mutex_unlock(&metadata_stream->lock);
 302 end_unlock_channel:
 303         pthread_mutex_unlock(&channel->timer_lock);
 304         if (!timer) {
 305                 pthread_mutex_unlock(&channel->lock);
 306         }
 307
 308         return ret;
 309 }