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 extern struct lttng_consumer_global_data consumer_data;
  27
  28 /*
  29  * Extend the allocated size of the metadata cache. Called only from
  30  * lttng_ustconsumer_write_metadata_cache.
  31  *
  32  * Return 0 on success, a negative value on error.
  33  */
  34 static int extend_metadata_cache(struct lttng_consumer_channel *channel,
  35                 unsigned int size)
  36 {
  37         int ret = 0;
  38         char *tmp_data_ptr;
  39         unsigned int new_size, old_size;
  40
  41         assert(channel);
  42         assert(channel->metadata_cache);
  43
  44         old_size = channel->metadata_cache->cache_alloc_size;
  45         new_size = max_t(unsigned int, old_size + size, old_size << 1);
  46         DBG("Extending metadata cache to %u", new_size);
  47         tmp_data_ptr = realloc(channel->metadata_cache->data, new_size);
  48         if (!tmp_data_ptr) {
  49                 ERR("Reallocating metadata cache");
  50                 free(channel->metadata_cache->data);
  51                 ret = -1;
  52                 goto end;
  53         }
  54         /* Zero newly allocated memory */
  55         memset(tmp_data_ptr + old_size, 0, new_size - old_size);
  56         channel->metadata_cache->data = tmp_data_ptr;
  57         channel->metadata_cache->cache_alloc_size = new_size;
  58
  59 end:
  60         return ret;
  61 }
  62
  63 /*
  64  * Reset the metadata cache.
  65  */
  66 static
  67 void metadata_cache_reset(struct consumer_metadata_cache *cache)
  68 {
  69         memset(cache->data, 0, cache->cache_alloc_size);
  70         cache->max_offset = 0;
  71 }
  72
  73 /*
  74  * Check if the metadata cache version changed.
  75  * If it did, reset the metadata cache.
  76  * The metadata cache lock MUST be held.
  77  *
  78  * Returns 0 on success, a negative value on error.
  79  */
  80 static
  81 int metadata_cache_check_version(struct consumer_metadata_cache *cache,
  82                 uint64_t version)
  83 {
  84         int ret = 0;
  85
  86         if (cache->version == version) {
  87                 goto end;
  88         }
  89
  90         DBG("Metadata cache version update to %" PRIu64, version);
  91         metadata_cache_reset(cache);
  92         cache->version = version;
  93
  94 end:
  95         return ret;
  96 }
  97
  98 /*
  99  * Write a character on the metadata poll pipe to wake the metadata thread.
 100  * Returns 0 on success, -1 on error.
 101  */
 102 int consumer_metadata_wakeup_pipe(const struct lttng_consumer_channel *channel)
 103 {
 104         int ret = 0;
 105         const char dummy = 'c';
 106
 107         if (channel->monitor && channel->metadata_stream) {
 108                 ssize_t write_ret;
 109
 110                 write_ret = lttng_write(channel->metadata_stream->ust_metadata_poll_pipe[1],
 111                                 &dummy, 1);
 112                 if (write_ret < 1) {
 113                         if (errno == EWOULDBLOCK) {
 114                                 /*
 115                                  * This is fine, the metadata poll thread
 116                                  * is having a hard time keeping-up, but
 117                                  * it will eventually wake-up and consume
 118                                  * the available data.
 119                                  */
 120                                 ret = 0;
 121                         } else {
 122                                 PERROR("Wake-up UST metadata pipe");
 123                                 ret = -1;
 124                                 goto end;
 125                         }
 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                 const 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         metadata_stream = channel->metadata_stream;
 267         if (!metadata_stream) {
 268                 /*
 269                  * Having no metadata stream means the channel is being destroyed so there
 270                  * is no cache to flush anymore.
 271                  */
 272                 ret = 0;
 273                 goto end_unlock_channel;
 274         }
 275
 276         pthread_mutex_lock(&metadata_stream->lock);
 277         pthread_mutex_lock(&channel->metadata_cache->lock);
 278
 279         if (metadata_stream->ust_metadata_pushed >= offset) {
 280                 ret = 0;
 281         } else if (channel->metadata_stream->endpoint_status !=
 282                         CONSUMER_ENDPOINT_ACTIVE) {
 283                 /* An inactive endpoint means we don't have to flush anymore. */
 284                 ret = 0;
 285         } else {
 286                 /* Still not completely flushed. */
 287                 ret = 1;
 288         }
 289
 290         pthread_mutex_unlock(&channel->metadata_cache->lock);
 291         pthread_mutex_unlock(&metadata_stream->lock);
 292 end_unlock_channel:
 293         pthread_mutex_unlock(&channel->timer_lock);
 294         if (!timer) {
 295                 pthread_mutex_unlock(&channel->lock);
 296         }
 297
 298         return ret;
 299 }