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  * non-contiguous updates but not overlapping ones. If there is contiguous
  77  * metadata in the cache, we send it 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         cache->total_bytes_written += len;
 106         if (offset + len > cache->max_offset) {
 107                 cache->max_offset = offset + len;
 108         }
 109
 110         if (cache->max_offset == cache->total_bytes_written) {
 111                 char dummy = 'c';
 112
 113                 cache->contiguous = cache->max_offset;
 114                 if (channel->monitor) {
 115                         size_ret = lttng_write(channel->metadata_stream->ust_metadata_poll_pipe[1],
 116                                         &dummy, 1);
 117                         if (size_ret < 1) {
 118                                 ERR("Wakeup UST metadata pipe");
 119                                 ret = -1;
 120                                 goto end;
 121                         }
 122                 }
 123         }
 124
 125 end:
 126         return ret;
 127 }
 128
 129 /*
 130  * Create the metadata cache, original allocated size: max_sb_size
 131  *
 132  * Return 0 on success, a negative value on error.
 133  */
 134 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
 135 {
 136         int ret;
 137
 138         assert(channel);
 139
 140         channel->metadata_cache = zmalloc(
 141                         sizeof(struct consumer_metadata_cache));
 142         if (!channel->metadata_cache) {
 143                 PERROR("zmalloc metadata cache struct");
 144                 ret = -1;
 145                 goto end;
 146         }
 147         ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
 148         if (ret != 0) {
 149                 PERROR("mutex init");
 150                 goto end_free_cache;
 151         }
 152
 153         channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
 154         channel->metadata_cache->data = zmalloc(
 155                         channel->metadata_cache->cache_alloc_size * sizeof(char));
 156         if (!channel->metadata_cache->data) {
 157                 PERROR("zmalloc metadata cache data");
 158                 ret = -1;
 159                 goto end_free_mutex;
 160         }
 161         DBG("Allocated metadata cache of %" PRIu64 " bytes",
 162                         channel->metadata_cache->cache_alloc_size);
 163
 164         ret = 0;
 165         goto end;
 166
 167 end_free_mutex:
 168         pthread_mutex_destroy(&channel->metadata_cache->lock);
 169 end_free_cache:
 170         free(channel->metadata_cache);
 171 end:
 172         return ret;
 173 }
 174
 175 /*
 176  * Destroy and free the metadata cache
 177  */
 178 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
 179 {
 180         if (!channel || !channel->metadata_cache) {
 181                 return;
 182         }
 183
 184         DBG("Destroying metadata cache");
 185
 186         pthread_mutex_destroy(&channel->metadata_cache->lock);
 187         free(channel->metadata_cache->data);
 188         free(channel->metadata_cache);
 189 }
 190
 191 /*
 192  * Check if the cache is flushed up to the offset passed in parameter.
 193  *
 194  * Return 0 if everything has been flushed, 1 if there is data not flushed.
 195  */
 196 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
 197                 uint64_t offset, int timer)
 198 {
 199         int ret = 0;
 200         struct lttng_consumer_stream *metadata_stream;
 201
 202         assert(channel);
 203         assert(channel->metadata_cache);
 204
 205         /*
 206          * If not called from a timer handler, we have to take the
 207          * channel lock to be mutually exclusive with channel teardown.
 208          * Timer handler does not need to take this lock because it is
 209          * already synchronized by timer stop (and, more importantly,
 210          * taking this lock in a timer handler would cause a deadlock).
 211          */
 212         if (!timer) {
 213                 pthread_mutex_lock(&channel->lock);
 214         }
 215         pthread_mutex_lock(&channel->timer_lock);
 216         pthread_mutex_lock(&channel->metadata_cache->lock);
 217
 218         metadata_stream = channel->metadata_stream;
 219
 220         if (!metadata_stream) {
 221                 /*
 222                  * Having no metadata stream means the channel is being destroyed so there
 223                  * is no cache to flush anymore.
 224                  */
 225                 ret = 0;
 226         } else if (metadata_stream->ust_metadata_pushed >= offset) {
 227                 ret = 0;
 228         } else if (channel->metadata_stream->endpoint_status !=
 229                         CONSUMER_ENDPOINT_ACTIVE) {
 230                 /* An inactive endpoint means we don't have to flush anymore. */
 231                 ret = 0;
 232         } else {
 233                 /* Still not completely flushed. */
 234                 ret = 1;
 235         }
 236
 237         pthread_mutex_unlock(&channel->metadata_cache->lock);
 238         pthread_mutex_unlock(&channel->timer_lock);
 239         if (!timer) {
 240                 pthread_mutex_unlock(&channel->lock);
 241         }
 242
 243         return ret;
 244 }