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