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

   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 #ifndef CONSUMER_METADATA_CACHE_H
  10 #define CONSUMER_METADATA_CACHE_H
  11
  12 #include <common/consumer/consumer.h>
  13 #include <common/dynamic-buffer.h>
  14
  15 enum consumer_metadata_cache_write_status {
  16         CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR = -1,
  17         /*
  18          * New metadata content was appended to the cache successfully.
  19          * Previously available content remains valid.
  20          */
  21         CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT = 0,
  22         /*
  23          * The new content pushed to the cache invalidated the content that
  24          * was already present. The contents of the cache should be re-read.
  25          */
  26         CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED,
  27         /*
  28          * A metadata cache write can simply overwrite an already existing
  29          * section of the cache (and it should be a write-through with identical
  30          * data). From the caller's standpoint, there is no change to the state
  31          * of the cache.
  32          */
  33         CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE,
  34 };
  35
  36 struct consumer_metadata_cache {
  37         /* Current version of the metadata cache. */
  38         uint64_t version;
  39         /*
  40          * Size is the upper-limit of data written inside the buffer.
  41          * All cached data is contiguous.
  42          */
  43         struct lttng_dynamic_buffer contents;
  44         /*
  45          * Lock to update the metadata cache and push into the ring_buffer
  46          * (ustctl_write_metadata_to_channel).
  47          *
  48          * This is nested INSIDE the consumer_data lock.
  49          */
  50         pthread_mutex_t lock;
  51 };
  52
  53 enum consumer_metadata_cache_write_status
  54 consumer_metadata_cache_write(struct consumer_metadata_cache *cache,
  55                 unsigned int offset, unsigned int len, uint64_t version,
  56                 const char *data);
  57 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel);
  58 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel);
  59 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
  60                 uint64_t offset, int timer);
  61
  62 #endif /* CONSUMER_METADATA_CACHE_H */