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                         PERROR("Wake-up UST metadata pipe");
 124                         ret = -1;
 125                         goto end;
 126                 }
 127         }
 128
 129 end:
 130         return ret;
 131 }
 132
 133 /*
 134  * Write metadata to the cache, extend the cache if necessary. We support
 135  * overlapping updates, but they need to be contiguous. Send the
 136  * contiguous metadata in cache to the ring buffer. The metadata cache
 137  * lock MUST be acquired to write in the cache.
 138  *
 139  * Return 0 on success, a negative value on error.
 140  */
 141 int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
 142                 unsigned int offset, unsigned int len, uint64_t version,
 143                 char *data)
 144 {
 145         int ret = 0;
 146         struct consumer_metadata_cache *cache;
 147
 148         assert(channel);
 149         assert(channel->metadata_cache);
 150
 151         cache = channel->metadata_cache;
 152
 153         ret = metadata_cache_check_version(cache, version);
 154         if (ret < 0) {
 155                 goto end;
 156         }
 157
 158         DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
 159
 160         if (offset + len > cache->cache_alloc_size) {
 161                 ret = extend_metadata_cache(channel,
 162                                 len - cache->cache_alloc_size + offset);
 163                 if (ret < 0) {
 164                         ERR("Extending metadata cache");
 165                         goto end;
 166                 }
 167         }
 168
 169         memcpy(cache->data + offset, data, len);
 170         if (offset + len > cache->max_offset) {
 171                 cache->max_offset = offset + len;
 172                 ret = consumer_metadata_wakeup_pipe(channel);
 173         }
 174
 175 end:
 176         return ret;
 177 }
 178
 179 /*
 180  * Create the metadata cache, original allocated size: max_sb_size
 181  *
 182  * Return 0 on success, a negative value on error.
 183  */
 184 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
 185 {
 186         int ret;
 187
 188         assert(channel);
 189
 190         channel->metadata_cache = zmalloc(
 191                         sizeof(struct consumer_metadata_cache));
 192         if (!channel->metadata_cache) {
 193                 PERROR("zmalloc metadata cache struct");
 194                 ret = -1;
 195                 goto end;
 196         }
 197         ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
 198         if (ret != 0) {
 199                 PERROR("mutex init");
 200                 goto end_free_cache;
 201         }
 202
 203         channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
 204         channel->metadata_cache->data = zmalloc(
 205                         channel->metadata_cache->cache_alloc_size * sizeof(char));
 206         if (!channel->metadata_cache->data) {
 207                 PERROR("zmalloc metadata cache data");
 208                 ret = -1;
 209                 goto end_free_mutex;
 210         }
 211         DBG("Allocated metadata cache of %" PRIu64 " bytes",
 212                         channel->metadata_cache->cache_alloc_size);
 213
 214         ret = 0;
 215         goto end;
 216
 217 end_free_mutex:
 218         pthread_mutex_destroy(&channel->metadata_cache->lock);
 219 end_free_cache:
 220         free(channel->metadata_cache);
 221 end:
 222         return ret;
 223 }
 224
 225 /*
 226  * Destroy and free the metadata cache
 227  */
 228 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
 229 {
 230         if (!channel || !channel->metadata_cache) {
 231                 return;
 232         }
 233
 234         DBG("Destroying metadata cache");
 235
 236         pthread_mutex_destroy(&channel->metadata_cache->lock);
 237         free(channel->metadata_cache->data);
 238         free(channel->metadata_cache);
 239 }
 240
 241 /*
 242  * Check if the cache is flushed up to the offset passed in parameter.
 243  *
 244  * Return 0 if everything has been flushed, 1 if there is data not flushed.
 245  */
 246 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
 247                 uint64_t offset, int timer)
 248 {
 249         int ret = 0;
 250         struct lttng_consumer_stream *metadata_stream;
 251
 252         assert(channel);
 253         assert(channel->metadata_cache);
 254
 255         /*
 256          * If not called from a timer handler, we have to take the
 257          * channel lock to be mutually exclusive with channel teardown.
 258          * Timer handler does not need to take this lock because it is
 259          * already synchronized by timer stop (and, more importantly,
 260          * taking this lock in a timer handler would cause a deadlock).
 261          */
 262         if (!timer) {
 263                 pthread_mutex_lock(&channel->lock);
 264         }
 265         pthread_mutex_lock(&channel->timer_lock);
 266         pthread_mutex_lock(&channel->metadata_cache->lock);
 267
 268         metadata_stream = channel->metadata_stream;
 269
 270         if (!metadata_stream) {
 271                 /*
 272                  * Having no metadata stream means the channel is being destroyed so there
 273                  * is no cache to flush anymore.
 274                  */
 275                 ret = 0;
 276         } else if (metadata_stream->ust_metadata_pushed >= offset) {
 277                 ret = 0;
 278         } else if (channel->metadata_stream->endpoint_status !=
 279                         CONSUMER_ENDPOINT_ACTIVE) {
 280                 /* An inactive endpoint means we don't have to flush anymore. */
 281                 ret = 0;
 282         } else {
 283                 /* Still not completely flushed. */
 284                 ret = 1;
 285         }
 286
 287         pthread_mutex_unlock(&channel->metadata_cache->lock);
 288         pthread_mutex_unlock(&channel->timer_lock);
 289         if (!timer) {
 290                 pthread_mutex_unlock(&channel->lock);
 291         }
 292
 293         return ret;
 294 }