Introduce kernel-probe locations
[lttng-tools.git] / include / lttng / session.h
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1239a312 1/*
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2 * Copyright (C) 2014 David Goulet <dgoulet@efficios.com>
3 * Copyright (C) 2019 Jérémie Galarneau <jeremie.galarneau@efficios.com>
1239a312 4 *
ab5be9fa 5 * SPDX-License-Identifier: LGPL-2.1-only
1239a312 6 *
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7 */
8
9#ifndef LTTNG_SESSION_H
10#define LTTNG_SESSION_H
11
12#ifdef __cplusplus
13extern "C" {
14#endif
15
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16#include <lttng/constant.h>
17
55c9e7ca 18struct lttng_handle;
b178f53e 19struct lttng_session_descriptor;
3e3665b8 20struct lttng_destruction_handle;
b178f53e 21
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22/*
23 * Basic session information.
24 *
25 * The "enabled" field is only used when listing the sessions which indicate if
26 * it's started or not.
27 *
28 * The structures should be initialized to zero before use.
29 */
e9af56b3 30#define LTTNG_SESSION_PADDING1 8
1239a312 31struct lttng_session {
36d2e35d 32 char name[LTTNG_NAME_MAX];
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33 /*
34 * Human-readable representation of the trace's destination.
35 * In the case of a local tracing session, a path is provided:
36 * /path/to/the/output
37 *
38 * In the case of a remote (network) tracing session, the string has
39 * the following format:
40 * net://hostname/path:ctrl_port [data: data_port]
41 */
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42 char path[PATH_MAX];
43 uint32_t enabled; /* enabled/started: 1, disabled/stopped: 0 */
44 uint32_t snapshot_mode;
45 unsigned int live_timer_interval; /* usec */
46
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47 /*
48 * End of public attributes.
49 * The remaining fields are used to deal with ABI management concerns.
50 */
51
52 /*
53 * 32-bit architectures are already naturally aligned on 4 bytes after
54 * 'live_timer_interval'. However, the offset does not result in a
55 * natural alignment on 64-bit architectures. Adding 4 bytes of
56 * padding here results in an aligned offset after 'alignement_padding'
57 * for both bitnesses.
58 *
59 * This was added since not all compilers appear to align unions in the
60 * same way. Some (e.g. MSVC) do not seem to impose an alignement
61 * constraint while others (e.g. gcc, clang, icc) seem to align it to
62 * ensure 'ptr' is naturally aligned.
63 */
64 char alignment_padding[4];
b178f53e 65 union {
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66 /*
67 * Ensure the 'extended' union has the same size for both
68 * 32-bit and 64-bit builds.
69 */
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70 char padding[LTTNG_SESSION_PADDING1];
71 void *ptr;
72 } extended;
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73};
74
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75/*
76 * Create a session on the session daemon from a session descriptor.
77 *
78 * See the session descriptor API description in session-descriptor.h
79 *
80 * Note that unspecified session descriptor parameters, such as a session's
81 * name, are updated in the session descriptor if the creation of the session
82 * succeeds. This allows users to query the session's auto-generated name
83 * after its creation. Note that other attributes can be queried using the
84 * session listing API.
85 *
86 * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
87 * return codes.
88 */
89extern enum lttng_error_code lttng_create_session_ext(
90 struct lttng_session_descriptor *session_descriptor);
91
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92/*
93 * Create a tracing session using a name and an optional URL.
94 *
95 * If _url_ is NULL, no consumer is created for the session. The name can't be
96 * NULL here.
97 *
98 * Return 0 on success else a negative LTTng error code.
99 */
100extern int lttng_create_session(const char *name, const char *url);
101
102/*
103 * Create a tracing session that will exclusively be used for snapshot meaning
104 * the session will be in no output mode and every channel enabled for that
105 * session will be set in overwrite mode and in mmap output since splice is not
106 * supported.
107 *
108 * Name can't be NULL. If an url is given, it will be used to create a default
109 * snapshot output using it as a destination. If NULL, no output will be
110 * defined and an add-output call will be needed.
111 *
112 * Return 0 on success else a negative LTTng error code.
113 */
114extern int lttng_create_session_snapshot(const char *name,
115 const char *snapshot_url);
116
117/*
118 * Create a session exclusively used for live reading.
119 *
120 * In this mode, the switch-timer parameter is forced for each UST channel, a
121 * live-switch-timer is enabled for kernel channels, manually setting
122 * switch-timer is forbidden. Synchronization beacons are sent to the relayd,
123 * indexes are sent and metadata is checked for each packet.
124 *
125 * Name can't be NULL. If no URL is given, the default is to send the data to
1aacaae2 126 * net://127.0.0.1. The timer_interval is in usec.
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127 *
128 * Return 0 on success else a negative LTTng error code.
129 */
130extern int lttng_create_session_live(const char *name, const char *url,
131 unsigned int timer_interval);
132
133/*
134 * Destroy a tracing session.
135 *
136 * The session will not be usable, tracing will be stopped thus buffers will be
137 * flushed.
138 *
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139 * This call will wait for data availability for each domain of the session,
140 * which can take an arbitrary amount of time. However, when returning the
141 * tracing data is guaranteed to be ready to be read and analyzed.
142 *
143 * lttng_destroy_session_no_wait() may be used if such a guarantee is not
144 * needed.
145 *
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146 * The name can't be NULL here.
147 *
780d4bb8 148 * Return 0 on success else a negative LTTng error code.
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149 */
150extern int lttng_destroy_session(const char *name);
151
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152/*
153 * Destroy a tracing session.
154 *
155 * Performs the same function as lttng_destroy_session(), but provides
156 * an lttng_destruction_handle which can be used to wait for the completion
157 * of the session's destruction. The lttng_destroy_handle can also be used
158 * obtain the status and archive location of any implicit session
83ed9e90 159 * rotation that may have occurred during the session's destruction.
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160 *
161 * Returns LTTNG_OK on success. The returned handle is owned by the caller
162 * and must be free'd using lttng_destruction_handle_destroy().
163 */
164extern enum lttng_error_code lttng_destroy_session_ext(const char *session_name,
165 struct lttng_destruction_handle **handle);
166
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167/*
168 * Behaves exactly like lttng_destroy_session but does not wait for data
169 * availability.
170 */
171extern int lttng_destroy_session_no_wait(const char *name);
172
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173/*
174 * List all the tracing sessions.
175 *
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176 * Return the number of entries of the "lttng_session" array. The caller
177 * must free the returned sessions array directly using free().
178 *
179 * On error, a negative LTTng error code is returned.
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180 */
181extern int lttng_list_sessions(struct lttng_session **sessions);
182
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183/*
184 * Get the creation time of an lttng_session object on the session daemon.
185 *
186 * This function must only be used with lttng_session objects returned
187 * by lttng_list_sessions() or lttng_session_create().
188 *
189 * The creation time returned is a UNIX timestamp; the number of seconds since
190 * Epoch (1970-01-01 00:00:00 +0000 (UTC)).
191 *
192 * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
193 * return codes.
194 */
195extern enum lttng_error_code lttng_session_get_creation_time(
196 const struct lttng_session *session, uint64_t *creation_time);
197
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198/*
199 * Set the shared memory path for a session.
200 *
201 * Sets the (optional) file system path where shared memory buffers will
202 * be created for the session. This is useful for buffer extraction on
203 * crash, when used with filesystems like pramfs.
204 *
205 * Return 0 on success else a negative LTTng error code.
206 */
207extern int lttng_set_session_shm_path(const char *session_name,
208 const char *shm_path);
209
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210#ifdef __cplusplus
211}
212#endif
213
214#endif /* LTTNG_SESSION_H */
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