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 #ifdef __cplusplus
  16 extern "C" {
  17 #endif
  18
  19 enum consumer_metadata_cache_write_status {
  20         CONSUMER_METADATA_CACHE_WRITE_STATUS_ERROR = -1,
  21         /*
  22          * New metadata content was appended to the cache successfully.
  23          * Previously available content remains valid.
  24          */
  25         CONSUMER_METADATA_CACHE_WRITE_STATUS_APPENDED_CONTENT = 0,
  26         /*
  27          * The new content pushed to the cache invalidated the content that
  28          * was already present. The contents of the cache should be re-read.
  29          */
  30         CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED,
  31         /*
  32          * A metadata cache write can simply overwrite an already existing
  33          * section of the cache (and it should be a write-through with identical
  34          * data). From the caller's standpoint, there is no change to the state
  35          * of the cache.
  36          */
  37         CONSUMER_METADATA_CACHE_WRITE_STATUS_NO_CHANGE,
  38 };
  39
  40 struct consumer_metadata_cache {
  41         /* Current version of the metadata cache. */
  42         uint64_t version;
  43         /*
  44          * Size is the upper-limit of data written inside the buffer.
  45          * All cached data is contiguous.
  46          */
  47         struct lttng_dynamic_buffer contents;
  48         /*
  49          * Lock to update the metadata cache and push into the ring_buffer
  50          * (lttng_ust_ctl_write_metadata_to_channel).
  51          *
  52          * This is nested INSIDE the consumer_data lock.
  53          */
  54         pthread_mutex_t lock;
  55 };
  56
  57 enum consumer_metadata_cache_write_status
  58 consumer_metadata_cache_write(struct consumer_metadata_cache *cache,
  59                 unsigned int offset, unsigned int len, uint64_t version,
  60                 const char *data);
  61 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel);
  62 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel);
  63 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
  64                 uint64_t offset, int timer);
  65
  66 #ifdef __cplusplus
  67 }
  68 #endif
  69
  70 #endif /* CONSUMER_METADATA_CACHE_H */