configure: add '-Wundef' to warning flags
[lttng-tools.git] / src / common / trace-chunk-registry.h
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2c5ff4e4 1/*
ab5be9fa 2 * Copyright (C) 2019 Jérémie Galarneau <jeremie.galarneau@efficios.com>
2c5ff4e4 3 *
ab5be9fa 4 * SPDX-License-Identifier: LGPL-2.1-only
2c5ff4e4 5 *
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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
17struct 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 Trace chunks are unpublished when their last reference is released.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 */
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34struct lttng_trace_chunk_registry *lttng_trace_chunk_registry_create(void);
35
36/*
37 * Destroy an lttng trace chunk registry. The registry must be emptied
38 * (i.e. all references to the trace chunks it contains must be released) before
39 * it is destroyed.
40 */
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41void lttng_trace_chunk_registry_destroy(
42 struct lttng_trace_chunk_registry *registry);
43
44/*
45 * Publish a trace chunk for a given session id.
46 * A reference is acquired on behalf of the caller.
47 *
48 * The trace chunk that is returned is the published version of the trace
49 * chunk. The chunk provided should be discarded on success and it's
50 * published version used in its place.
51 *
52 * See the documentation of lttng_trace_chunk for more information on
53 * the usage of the various parameters.
54 *
55 * Returns an lttng_trace_chunk on success, NULL on error.
56 */
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57struct lttng_trace_chunk *lttng_trace_chunk_registry_publish_chunk(
58 struct lttng_trace_chunk_registry *registry,
59 uint64_t session_id, struct lttng_trace_chunk *chunk);
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60/*
61 * Adds the `previously_published` parameter which allows the caller
62 * to know if a trace chunk equivalent to `chunk` was previously published.
63 *
64 * The registry holds a reference to the published trace chunks it contains.
65 * Trace chunks automatically unpublish themselves from their registry on
66 * destruction.
67 *
68 * This information is necessary to drop the reference of newly published
69 * chunks when a user doesn't wish to explicitly maintain all references
70 * to a given trace chunk.
71 *
72 * For instance, the relay daemon doesn't need the registry to hold a
73 * reference since it controls the lifetime of its trace chunks.
74 * Conversely, the consumer daemons rely on the session daemon to inform
75 * them of the end of life of a trace chunk and the trace chunks don't
76 * belong to a specific top-level object: they are always retrieved from
77 * the registry by `id`.
78 */
79struct lttng_trace_chunk *lttng_trace_chunk_registry_publish_chunk(
80 struct lttng_trace_chunk_registry *registry,
81 uint64_t session_id, struct lttng_trace_chunk *chunk,
82 bool *previously_published);
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83
84/*
85 * Look-up a trace chunk by session_id and chunk_id.
86 * A reference is acquired on behalf of the caller.
87 *
88 * Returns an lttng_trace_chunk on success, NULL if the chunk does not exist.
89 */
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90struct lttng_trace_chunk *
91lttng_trace_chunk_registry_find_chunk(
92 const struct lttng_trace_chunk_registry *registry,
93 uint64_t session_id, uint64_t chunk_id);
94
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95/*
96 * Query the existence of a trace chunk by session_id and chunk_id.
97 *
98 * Returns 0 on success, a negative value on error.
99 */
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100int lttng_trace_chunk_registry_chunk_exists(
101 const struct lttng_trace_chunk_registry *registry,
102 uint64_t session_id, uint64_t chunk_id, bool *chunk_exists);
103
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104/*
105 * Look-up an anonymous trace chunk by session_id.
106 * A reference is acquired on behalf of the caller.
107 *
108 * Returns an lttng_trace_chunk on success, NULL if the chunk does not exist.
109 */
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110struct lttng_trace_chunk *
111lttng_trace_chunk_registry_find_anonymous_chunk(
112 const struct lttng_trace_chunk_registry *registry,
113 uint64_t session_id);
114
e10aec8f 115unsigned int lttng_trace_chunk_registry_put_each_chunk(
8ced4811 116 const struct lttng_trace_chunk_registry *registry);
e10aec8f 117
2c5ff4e4 118#endif /* LTTNG_TRACE_CHUNK_REGISTRY_H */
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