src/common/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.h>
  23
  24 struct consumer_metadata_cache {
  25         char *data;
  26         uint64_t cache_alloc_size;
  27         /*
  28          * How many bytes from the cache were already sent to the ring buffer.
  29          */
  30         uint64_t rb_pushed;
  31         /*
  32          * How many bytes are written in the buffer (excluding the wholes).
  33          */
  34         uint64_t total_bytes_written;
  35         /*
  36          * The upper-limit of data written inside the buffer.
  37          *
  38          * With the total_bytes_written it allows us to keep track of when the
  39          * cache contains contiguous metadata ready to be sent to the RB.
  40          * The metadata cache updates must not overlap.
  41          */
  42         uint64_t max_offset;
  43         /*
  44          * Lock to update the metadata cache and push into the ring_buffer
  45          * (ustctl_write_metadata_to_channel).
  46          *
  47          * This is nested INSIDE the consumer_data lock.
  48          */
  49         pthread_mutex_t lock;
  50 };
  51
  52 int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
  53                 unsigned int offset, unsigned int len, char *data);
  54 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel);
  55 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel);
  56 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
  57                 uint64_t offset);
  58
  59 #endif /* CONSUMER_METADATA_CACHE_H */