src/common/trace-chunk-registry.h

   1 /*
   2  * Copyright (C) 2019 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #ifndef LTTNG_TRACE_CHUNK_REGISTRY_H
   9 #define LTTNG_TRACE_CHUNK_REGISTRY_H
  10
  11 #include <stddef.h>
  12 #include <stdint.h>
  13 #include <stdbool.h>
  14 #include <common/macros.h>
  15 #include <common/trace-chunk.h>
  16
  17 struct lttng_trace_chunk_registry;
  18
  19 /*
  20  * Create an lttng_trace_chunk registry.
  21  *
  22  * A trace chunk registry maintains an association between a
  23  * (session_id, chunk_id) tuple and a trace chunk object. The chunk_id can
  24  * be "unset" in the case of an anonymous trace chunk.
  25  *
  26  * Note that a trace chunk registry holds no ownership of its trace
  27  * chunks. Trace chunks are unpublished when their last reference is released.
  28  * See the documentation of lttng_trace_chunk.
  29  *
  30  * Returns a trace chunk registry on success, NULL on error.
  31  *
  32  * Note that a trace chunk registry may only be accessed by an RCU thread.
  33  */
  34 LTTNG_HIDDEN
  35 struct lttng_trace_chunk_registry *lttng_trace_chunk_registry_create(void);
  36
  37 /*
  38  * Destroy an lttng trace chunk registry. The registry must be emptied
  39  * (i.e. all references to the trace chunks it contains must be released) before
  40  * it is destroyed.
  41  */
  42 LTTNG_HIDDEN
  43 void lttng_trace_chunk_registry_destroy(
  44                 struct lttng_trace_chunk_registry *registry);
  45
  46 /*
  47  * Publish a trace chunk for a given session id.
  48  * A reference is acquired on behalf of the caller.
  49  *
  50  * The trace chunk that is returned is the published version of the trace
  51  * chunk. The chunk provided should be discarded on success and it's
  52  * published version used in its place.
  53  *
  54  * See the documentation of lttng_trace_chunk for more information on
  55  * the usage of the various parameters.
  56  *
  57  * Returns an lttng_trace_chunk on success, NULL on error.
  58  */
  59 LTTNG_HIDDEN
  60 struct lttng_trace_chunk *lttng_trace_chunk_registry_publish_chunk(
  61                 struct lttng_trace_chunk_registry *registry,
  62                 uint64_t session_id, struct lttng_trace_chunk *chunk);
  63
  64 /*
  65  * Adds the `previously_published` parameter which allows the caller
  66  * to know if a trace chunk equivalent to `chunk` was previously published.
  67  *
  68  * The registry holds a reference to the published trace chunks it contains.
  69  * Trace chunks automatically unpublish themselves from their registry on
  70  * destruction.
  71  *
  72  * This information is necessary to drop the reference of newly published
  73  * chunks when a user doesn't wish to explicitly maintain all references
  74  * to a given trace chunk.
  75  *
  76  * For instance, the relay daemon doesn't need the registry to hold a
  77  * reference since it controls the lifetime of its trace chunks.
  78  * Conversely, the consumer daemons rely on the session daemon to inform
  79  * them of the end of life of a trace chunk and the trace chunks don't
  80  * belong to a specific top-level object: they are always retrieved from
  81  * the registry by `id`.
  82  */
  83 struct lttng_trace_chunk *lttng_trace_chunk_registry_publish_chunk_published(
  84                 struct lttng_trace_chunk_registry *registry,
  85                 uint64_t session_id, struct lttng_trace_chunk *chunk,
  86                 bool *previously_published);
  87
  88 /*
  89  * Look-up a trace chunk by session_id and chunk_id.
  90  * A reference is acquired on behalf of the caller.
  91  *
  92  * Returns an lttng_trace_chunk on success, NULL if the chunk does not exist.
  93  */
  94 LTTNG_HIDDEN
  95 struct lttng_trace_chunk *
  96 lttng_trace_chunk_registry_find_chunk(
  97                 const struct lttng_trace_chunk_registry *registry,
  98                 uint64_t session_id, uint64_t chunk_id);
  99
 100 /*
 101  * Query the existence of a trace chunk by session_id and chunk_id.
 102  *
 103  * Returns 0 on success, a negative value on error.
 104  */
 105 LTTNG_HIDDEN
 106 int lttng_trace_chunk_registry_chunk_exists(
 107                 const struct lttng_trace_chunk_registry *registry,
 108                 uint64_t session_id, uint64_t chunk_id, bool *chunk_exists);
 109
 110 /*
 111  * Look-up an anonymous trace chunk by session_id.
 112  * A reference is acquired on behalf of the caller.
 113  *
 114  * Returns an lttng_trace_chunk on success, NULL if the chunk does not exist.
 115  */
 116 LTTNG_HIDDEN
 117 struct lttng_trace_chunk *
 118 lttng_trace_chunk_registry_find_anonymous_chunk(
 119                 const struct lttng_trace_chunk_registry *registry,
 120                 uint64_t session_id);
 121
 122 LTTNG_HIDDEN
 123 unsigned int lttng_trace_chunk_registry_put_each_chunk(
 124                 const struct lttng_trace_chunk_registry *registry);
 125
 126 #endif /* LTTNG_TRACE_CHUNK_REGISTRY_H */