src/common/consumer/consumer-metadata-cache.c

   1 /*
   2  * Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
   3  * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 #define _LGPL_SOURCE
  10 #include <assert.h>
  11 #include <pthread.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <sys/types.h>
  15 #include <unistd.h>
  16 #include <inttypes.h>
  17
  18 #include <common/common.h>
  19 #include <common/utils.h>
  20 #include <common/sessiond-comm/sessiond-comm.h>
  21 #include <common/ust-consumer/ust-consumer.h>
  22 #include <common/consumer/consumer.h>
  23
  24 #include "consumer-metadata-cache.h"
  25
  26 enum metadata_cache_update_version_status {
  27         METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED,
  28         METADATA_CACHE_UPDATE_STATUS_VERSION_NOT_UPDATED,
  29 };
  30
  31 extern struct lttng_consumer_global_data consumer_data;
  32
  33 /*
  34  * Extend the allocated size of the metadata cache. Called only from
  35  * lttng_ustconsumer_write_metadata_cache.
  36  *
  37  * Return 0 on success, a negative value on error.
  38  */
  39 static int extend_metadata_cache(struct lttng_consumer_channel *channel,
  40                 unsigned int size)
  41 {
  42         int ret = 0;
  43         char *tmp_data_ptr;
  44         unsigned int new_size, old_size;
  45
  46         assert(channel);
  47         assert(channel->metadata_cache);
  48
  49         old_size = channel->metadata_cache->cache_alloc_size;
  50         new_size = max_t(unsigned int, old_size + size, old_size << 1);
  51         DBG("Extending metadata cache to %u", new_size);
  52         tmp_data_ptr = realloc(channel->metadata_cache->data, new_size);
  53         if (!tmp_data_ptr) {
  54                 ERR("Reallocating metadata cache");
  55                 free(channel->metadata_cache->data);
  56                 ret = -1;
  57                 goto end;
  58         }
  59         /* Zero newly allocated memory */
  60         memset(tmp_data_ptr + old_size, 0, new_size - old_size);
  61         channel->metadata_cache->data = tmp_data_ptr;
  62         channel->metadata_cache->cache_alloc_size = new_size;
  63
  64 end:
  65         return ret;
  66 }
  67
  68 /*
  69  * Reset the metadata cache.
  70  */
  71 static
  72 void metadata_cache_reset(struct consumer_metadata_cache *cache)
  73 {
  74         memset(cache->data, 0, cache->cache_alloc_size);
  75         cache->max_offset = 0;
  76 }
  77
  78 /*
  79  * Check if the metadata cache version changed.
  80  * If it did, reset the metadata cache.
  81  * The metadata cache lock MUST be held.
  82  */
  83 static enum metadata_cache_update_version_status metadata_cache_update_version(
  84                 struct consumer_metadata_cache *cache, uint64_t version)
  85 {
  86         enum metadata_cache_update_version_status status;
  87
  88         if (cache->version == version) {
  89                 status = METADATA_CACHE_UPDATE_STATUS_VERSION_NOT_UPDATED;
  90                 goto end;
  91         }
  92
  93         DBG("Metadata cache version update to %" PRIu64, version);
  94         cache->version = version;
  95         status = METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED;
  96
  97 end:
  98         return status;
  99 }
 100
 101 /*
 102  * Write metadata to the cache, extend the cache if necessary. We support
 103  * overlapping updates, but they need to be contiguous. Send the
 104  * contiguous metadata in cache to the ring buffer. The metadata cache
 105  * lock MUST be acquired to write in the cache.
 106  *
 107  * See `enum consumer_metadata_cache_write_status` for the meaning of the
 108  * various returned status codes.
 109  */
 110 enum consumer_metadata_cache_write_status
 111 consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
 112                 unsigned int offset, unsigned int len, uint64_t version,
 113                 const char *data)
 114 {
 115         int ret = 0;
 116         struct consumer_metadata_cache *cache;
 117         enum consumer_metadata_cache_write_status status;
 118         bool cache_is_invalidated = false;
 119         uint64_t original_max_offset;
 120
 121         assert(channel);
 122         assert(channel->metadata_cache);
 123
 124         cache = channel->metadata_cache;
 125         ASSERT_LOCKED(cache->lock);
 126         original_max_offset = cache->max_offset;
 127
 128         if (metadata_cache_update_version(cache, version) ==
 129                         METADATA_CACHE_UPDATE_STATUS_VERSION_UPDATED) {
 130                 metadata_cache_reset(cache);
 131                 cache_is_invalidated = true;
 132         }
 133
 134         DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
 135
 136         if (offset + len > cache->cache_alloc_size) {
 137                 ret = extend_metadata_cache(channel,
 138                                 len - cache->cache_alloc_size + offset);
 139                 if (ret < 0) {
 140                         ERR("Extending metadata cache");
 141                         status = CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR;
 142                         goto end;
 143                 }
 144         }
 145
 146         memcpy(cache->data + offset, data, len);
 147         cache->max_offset = max(cache->max_offset, offset + len);
 148
 149         if (cache_is_invalidated) {
 150                 status = CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED;
 151         } else if (cache->max_offset > original_max_offset) {
 152                 status = CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT;
 153         } else {
 154                 status = CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE;
 155                 assert(cache->max_offset == original_max_offset);
 156         }
 157
 158 end:
 159         return status;
 160 }
 161
 162 /*
 163  * Create the metadata cache, original allocated size: max_sb_size
 164  *
 165  * Return 0 on success, a negative value on error.
 166  */
 167 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
 168 {
 169         int ret;
 170
 171         assert(channel);
 172
 173         channel->metadata_cache = zmalloc(
 174                         sizeof(struct consumer_metadata_cache));
 175         if (!channel->metadata_cache) {
 176                 PERROR("zmalloc metadata cache struct");
 177                 ret = -1;
 178                 goto end;
 179         }
 180         ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
 181         if (ret != 0) {
 182                 PERROR("mutex init");
 183                 goto end_free_cache;
 184         }
 185
 186         channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
 187         channel->metadata_cache->data = zmalloc(
 188                         channel->metadata_cache->cache_alloc_size * sizeof(char));
 189         if (!channel->metadata_cache->data) {
 190                 PERROR("zmalloc metadata cache data");
 191                 ret = -1;
 192                 goto end_free_mutex;
 193         }
 194         DBG("Allocated metadata cache of %" PRIu64 " bytes",
 195                         channel->metadata_cache->cache_alloc_size);
 196
 197         ret = 0;
 198         goto end;
 199
 200 end_free_mutex:
 201         pthread_mutex_destroy(&channel->metadata_cache->lock);
 202 end_free_cache:
 203         free(channel->metadata_cache);
 204 end:
 205         return ret;
 206 }
 207
 208 /*
 209  * Destroy and free the metadata cache
 210  */
 211 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
 212 {
 213         if (!channel || !channel->metadata_cache) {
 214                 return;
 215         }
 216
 217         DBG("Destroying metadata cache");
 218
 219         pthread_mutex_destroy(&channel->metadata_cache->lock);
 220         free(channel->metadata_cache->data);
 221         free(channel->metadata_cache);
 222 }
 223
 224 /*
 225  * Check if the cache is flushed up to the offset passed in parameter.
 226  *
 227  * Return 0 if everything has been flushed, 1 if there is data not flushed.
 228  */
 229 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
 230                 uint64_t offset, int timer)
 231 {
 232         int ret = 0;
 233         struct lttng_consumer_stream *metadata_stream;
 234
 235         assert(channel);
 236         assert(channel->metadata_cache);
 237
 238         /*
 239          * If not called from a timer handler, we have to take the
 240          * channel lock to be mutually exclusive with channel teardown.
 241          * Timer handler does not need to take this lock because it is
 242          * already synchronized by timer stop (and, more importantly,
 243          * taking this lock in a timer handler would cause a deadlock).
 244          */
 245         if (!timer) {
 246                 pthread_mutex_lock(&channel->lock);
 247         }
 248         pthread_mutex_lock(&channel->timer_lock);
 249         metadata_stream = channel->metadata_stream;
 250         if (!metadata_stream) {
 251                 /*
 252                  * Having no metadata stream means the channel is being destroyed so there
 253                  * is no cache to flush anymore.
 254                  */
 255                 ret = 0;
 256                 goto end_unlock_channel;
 257         }
 258
 259         pthread_mutex_lock(&metadata_stream->lock);
 260         pthread_mutex_lock(&channel->metadata_cache->lock);
 261
 262         if (metadata_stream->ust_metadata_pushed >= offset) {
 263                 ret = 0;
 264         } else if (channel->metadata_stream->endpoint_status !=
 265                         CONSUMER_ENDPOINT_ACTIVE) {
 266                 /* An inactive endpoint means we don't have to flush anymore. */
 267                 ret = 0;
 268         } else {
 269                 /* Still not completely flushed. */
 270                 ret = 1;
 271         }
 272
 273         pthread_mutex_unlock(&channel->metadata_cache->lock);
 274         pthread_mutex_unlock(&metadata_stream->lock);
 275 end_unlock_channel:
 276         pthread_mutex_unlock(&channel->timer_lock);
 277         if (!timer) {
 278                 pthread_mutex_unlock(&channel->lock);
 279         }
 280
 281         return ret;
 282 }