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

   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 #ifndef CONSUMER_METADATA_CACHE_H
  20 #define CONSUMER_METADATA_CACHE_H
  21
  22 #include <common/consumer/consumer.h>
  23
  24 enum consumer_metadata_cache_write_status {
  25         CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR = -1,
  26         /*
  27          * New metadata content was appended to the cache successfully.
  28          * Previously available content remains valid.
  29          */
  30         CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT = 0,
  31         /*
  32          * The new content pushed to the cache invalidated the content that
  33          * was already present. The contents of the cache should be re-read.
  34          */
  35         CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED,
  36         /*
  37          * A metadata cache write can simply overwrite an already existing
  38          * section of the cache (and it should be a write-through with identical
  39          * data). From the caller's standpoint, there is no change to the state
  40          * of the cache.
  41          */
  42         CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE,
  43 };
  44
  45 struct consumer_metadata_cache {
  46         char *data;
  47         uint64_t cache_alloc_size;
  48         /*
  49          * Current version of the metadata cache.
  50          */
  51         uint64_t version;
  52         /*
  53          * The upper-limit of data written inside the buffer.
  54          *
  55          * With the total_bytes_written it allows us to keep track of when the
  56          * cache contains contiguous metadata ready to be sent to the RB.
  57          * All cached data is contiguous.
  58          */
  59         uint64_t max_offset;
  60         /*
  61          * Lock to update the metadata cache and push into the ring_buffer
  62          * (ustctl_write_metadata_to_channel).
  63          *
  64          * This is nested INSIDE the consumer_data lock.
  65          */
  66         pthread_mutex_t lock;
  67 };
  68
  69 enum consumer_metadata_cache_write_status
  70 consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
  71                 unsigned int offset, unsigned int len, uint64_t version,
  72                 char *data);
  73 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel);
  74 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel);
  75 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
  76                 uint64_t offset, int timer);
  77
  78 #endif /* CONSUMER_METADATA_CACHE_H */