2 * Copyright (C) 2014 David Goulet <dgoulet@efficios.com>
3 * Copyright (C) 2019 Jérémie Galarneau <jeremie.galarneau@efficios.com>
5 * SPDX-License-Identifier: LGPL-2.1-only
9 #ifndef LTTNG_SESSION_H
10 #define LTTNG_SESSION_H
16 #include <lttng/constant.h>
17 #include <lttng/lttng-export.h>
20 struct lttng_session_descriptor
;
21 struct lttng_destruction_handle
;
24 * Basic session information.
26 * The "enabled" field is only used when listing the sessions which indicate if
27 * it's started or not.
29 * The structures should be initialized to zero before use.
31 #define LTTNG_SESSION_PADDING1 8
32 struct lttng_session
{
33 char name
[LTTNG_NAME_MAX
];
35 * Human-readable representation of the trace's destination.
36 * In the case of a local tracing session, a path is provided:
39 * In the case of a remote (network) tracing session, the string has
40 * the following format:
41 * net://hostname/path:ctrl_port [data: data_port]
44 uint32_t enabled
; /* enabled/started: 1, disabled/stopped: 0 */
45 uint32_t snapshot_mode
;
46 unsigned int live_timer_interval
; /* usec */
49 * End of public attributes.
50 * The remaining fields are used to deal with ABI management concerns.
54 * 32-bit architectures are already naturally aligned on 4 bytes after
55 * 'live_timer_interval'. However, the offset does not result in a
56 * natural alignment on 64-bit architectures. Adding 4 bytes of
57 * padding here results in an aligned offset after 'alignement_padding'
60 * This was added since not all compilers appear to align unions in the
61 * same way. Some (e.g. MSVC) do not seem to impose an alignement
62 * constraint while others (e.g. gcc, clang, icc) seem to align it to
63 * ensure 'ptr' is naturally aligned.
65 char alignment_padding
[4];
68 * Ensure the 'extended' union has the same size for both
69 * 32-bit and 64-bit builds.
71 char padding
[LTTNG_SESSION_PADDING1
];
77 * Create a session on the session daemon from a session descriptor.
79 * See the session descriptor API description in session-descriptor.h
81 * Note that unspecified session descriptor parameters, such as a session's
82 * name, are updated in the session descriptor if the creation of the session
83 * succeeds. This allows users to query the session's auto-generated name
84 * after its creation. Note that other attributes can be queried using the
85 * session listing API.
87 * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
90 LTTNG_EXPORT
extern enum lttng_error_code
91 lttng_create_session_ext(struct lttng_session_descriptor
*session_descriptor
);
94 * Create a tracing session using a name and an optional URL.
96 * If _url_ is NULL, no consumer is created for the session. The name can't be
99 * Return 0 on success else a negative LTTng error code.
101 LTTNG_EXPORT
extern int lttng_create_session(const char *name
, const char *url
);
104 * Create a tracing session that will exclusively be used for snapshot meaning
105 * the session will be in no output mode and every channel enabled for that
106 * session will be set in overwrite mode and in mmap output since splice is not
109 * Name can't be NULL. If an url is given, it will be used to create a default
110 * snapshot output using it as a destination. If NULL, no output will be
111 * defined and an add-output call will be needed.
113 * Return 0 on success else a negative LTTng error code.
115 LTTNG_EXPORT
extern int lttng_create_session_snapshot(const char *name
, const char *snapshot_url
);
118 * Create a session exclusively used for live reading.
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.
125 * Name can't be NULL. If no URL is given, the default is to send the data to
126 * net://127.0.0.1. The timer_interval is in usec.
128 * Return 0 on success else a negative LTTng error code.
130 LTTNG_EXPORT
extern int
131 lttng_create_session_live(const char *name
, const char *url
, unsigned int timer_interval
);
134 * Destroy a tracing session.
136 * The session will not be usable, tracing will be stopped thus buffers will be
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.
143 * lttng_destroy_session_no_wait() may be used if such a guarantee is not
146 * The name can't be NULL here.
148 * Return 0 on success else a negative LTTng error code.
150 LTTNG_EXPORT
extern int lttng_destroy_session(const char *name
);
153 * Destroy a tracing session.
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
159 * rotation that may have occurred during the session's destruction.
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().
164 LTTNG_EXPORT
extern enum lttng_error_code
165 lttng_destroy_session_ext(const char *session_name
, struct lttng_destruction_handle
**handle
);
168 * Behaves exactly like lttng_destroy_session but does not wait for data
171 LTTNG_EXPORT
extern int lttng_destroy_session_no_wait(const char *name
);
174 * List all the tracing sessions.
176 * Return the number of entries of the "lttng_session" array. The caller
177 * must free the returned sessions array directly using free().
179 * On error, a negative LTTng error code is returned.
181 LTTNG_EXPORT
extern int lttng_list_sessions(struct lttng_session
**sessions
);
184 * Get the creation time of an lttng_session object on the session daemon.
186 * This function must only be used with lttng_session objects returned
187 * by lttng_list_sessions() or lttng_session_create().
189 * The creation time returned is a UNIX timestamp; the number of seconds since
190 * Epoch (1970-01-01 00:00:00 +0000 (UTC)).
192 * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
195 LTTNG_EXPORT
extern enum lttng_error_code
196 lttng_session_get_creation_time(const struct lttng_session
*session
, uint64_t *creation_time
);
199 * Set the shared memory path for a session.
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.
205 * Return 0 on success else a negative LTTng error code.
207 LTTNG_EXPORT
extern int lttng_set_session_shm_path(const char *session_name
, const char *shm_path
);
213 #endif /* LTTNG_SESSION_H */
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