Clean-up: sessiond: cmd_enable_channel_internal
[lttng-tools.git] / src / bin / lttng-relayd / viewer-session.h
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1#ifndef _VIEWER_SESSION_H
2#define _VIEWER_SESSION_H
3
4/*
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5 * Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
6 * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
7 * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
7591bab1 8 *
ab5be9fa 9 * SPDX-License-Identifier: GPL-2.0-only
7591bab1 10 *
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11 */
12
13#include <limits.h>
14#include <inttypes.h>
15#include <pthread.h>
16#include <urcu/list.h>
17#include <urcu/ref.h>
18
19#include <common/hashtable/hashtable.h>
b66a15d1 20#include <common/trace-chunk.h>
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21
22#include "session.h"
ac497a37 23#include "lttng-viewer-abi.h"
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24
25struct relay_viewer_session {
26 /*
27 * Session list. Updates are protected by the session_list_lock.
28 * Traversals are protected by RCU.
29 * This list limits the design to having the sessions in at most
30 * one viewer session.
31 */
32 struct cds_list_head session_list; /* RCU list. */
33 pthread_mutex_t session_list_lock; /* Protects list updates. */
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34 /*
35 * The viewer session's current trace chunk is initially set, when
36 * a viewer attaches to the viewer session, to a copy the corresponding
37 * relay_session's current trace chunk.
38 *
39 * A live session always attempts to "catch-up" to the newest available
40 * trace chunk. This means that when a viewer reaches the end of a
41 * trace chunk, the viewer session may not transition to the "next" one:
42 * it jumps to the most recent trace chunk available (the one being
43 * produced by the relay_session). Hence, if the producer performs
44 * multiple rotations before a viewer completes the consumption of a
45 * trace chunk, it will skip over those "intermediary" trace chunks.
46 *
47 * A viewer session updates its current trace chunk when:
48 * 1) new viewer streams are created,
49 * 2) a new index is requested,
50 * 3) metadata is requested.
51 *
52 * Hence, as a general principle, the viewer session will reference the
53 * most recent trace chunk available _even if its streams do not point to
54 * it_. It indicates which trace chunk viewer streams should transition
55 * to when the end of their current trace chunk is reached.
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56 *
57 * Note that a viewer session's trace chunk points to the session's
58 * output directory. The sub-directories in which the various stream files
59 * are created are considered as being a part of their name.
8aeeba8f 60 */
b66a15d1 61 struct lttng_trace_chunk *current_trace_chunk;
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62};
63
64struct relay_viewer_session *viewer_session_create(void);
65void viewer_session_destroy(struct relay_viewer_session *vsession);
66void viewer_session_close(struct relay_viewer_session *vsession);
67
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68enum lttng_viewer_attach_return_code viewer_session_attach(
69 struct relay_viewer_session *vsession,
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70 struct relay_session *session);
71int viewer_session_is_attached(struct relay_viewer_session *vsession,
72 struct relay_session *session);
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73void viewer_session_close_one_session(struct relay_viewer_session *vsession,
74 struct relay_session *session);
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75int viewer_session_set_trace_chunk_copy(struct relay_viewer_session *vsession,
76 struct lttng_trace_chunk *relay_session_trace_chunk);
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77
78#endif /* _VIEWER_SESSION_H */
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