include/lttng/session.h

   1 /*
   2  * Copyright (C) 2014 - David Goulet <dgoulet@efficios.com>
   3  * Copyright (C) 2019 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4  *
   5  * This library is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU Lesser General Public License, version 2.1 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This library is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  12  * for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public License
  15  * along with this library; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 #ifndef LTTNG_SESSION_H
  20 #define LTTNG_SESSION_H
  21
  22 #ifdef __cplusplus
  23 extern "C" {
  24 #endif
  25
  26 struct lttng_session_descriptor;
  27 struct lttng_destruction_handle;
  28
  29 /*
  30  * Basic session information.
  31  *
  32  * The "enabled" field is only used when listing the sessions which indicate if
  33  * it's started or not.
  34  *
  35  * The structures should be initialized to zero before use.
  36  */
  37 #define LTTNG_SESSION_PADDING1             12
  38 struct lttng_session {
  39         char name[LTTNG_NAME_MAX];
  40         /*
  41          * Human-readable representation of the trace's destination.
  42          * In the case of a local tracing session, a path is provided:
  43          *     /path/to/the/output
  44          *
  45          * In the case of a remote (network) tracing session, the string has
  46          * the following format:
  47          *     net://hostname/path:ctrl_port [data: data_port]
  48          */
  49         char path[PATH_MAX];
  50         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
  51         uint32_t snapshot_mode;
  52         unsigned int live_timer_interval;       /* usec */
  53
  54         union {
  55                 char padding[LTTNG_SESSION_PADDING1];
  56                 void *ptr;
  57         } extended;
  58 };
  59
  60 /*
  61  * Create a session on the session daemon from a session descriptor.
  62  *
  63  * See the session descriptor API description in session-descriptor.h
  64  *
  65  * Note that unspecified session descriptor parameters, such as a session's
  66  * name, are updated in the session descriptor if the creation of the session
  67  * succeeds. This allows users to query the session's auto-generated name
  68  * after its creation. Note that other attributes can be queried using the
  69  * session listing API.
  70  *
  71  * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
  72  * return codes.
  73  */
  74 extern enum lttng_error_code lttng_create_session_ext(
  75                 struct lttng_session_descriptor *session_descriptor);
  76
  77 /*
  78  * Create a tracing session using a name and an optional URL.
  79  *
  80  * If _url_ is NULL, no consumer is created for the session. The name can't be
  81  * NULL here.
  82  *
  83  * Return 0 on success else a negative LTTng error code.
  84  */
  85 extern int lttng_create_session(const char *name, const char *url);
  86
  87 /*
  88  * Create a tracing session that will exclusively be used for snapshot meaning
  89  * the session will be in no output mode and every channel enabled for that
  90  * session will be set in overwrite mode and in mmap output since splice is not
  91  * supported.
  92  *
  93  * Name can't be NULL. If an url is given, it will be used to create a default
  94  * snapshot output using it as a destination. If NULL, no output will be
  95  * defined and an add-output call will be needed.
  96  *
  97  * Return 0 on success else a negative LTTng error code.
  98  */
  99 extern int lttng_create_session_snapshot(const char *name,
 100                 const char *snapshot_url);
 101
 102 /*
 103  * Create a session exclusively used for live reading.
 104  *
 105  * In this mode, the switch-timer parameter is forced for each UST channel, a
 106  * live-switch-timer is enabled for kernel channels, manually setting
 107  * switch-timer is forbidden. Synchronization beacons are sent to the relayd,
 108  * indexes are sent and metadata is checked for each packet.
 109  *
 110  * Name can't be NULL. If no URL is given, the default is to send the data to
 111  * net://127.0.0.1. The timer_interval is in usec.
 112  *
 113  * Return 0 on success else a negative LTTng error code.
 114  */
 115 extern int lttng_create_session_live(const char *name, const char *url,
 116                 unsigned int timer_interval);
 117
 118 /*
 119  * Destroy a tracing session.
 120  *
 121  * The session will not be usable, tracing will be stopped thus buffers will be
 122  * flushed.
 123  *
 124  * This call will wait for data availability for each domain of the session,
 125  * which can take an arbitrary amount of time. However, when returning the
 126  * tracing data is guaranteed to be ready to be read and analyzed.
 127  *
 128  * lttng_destroy_session_no_wait() may be used if such a guarantee is not
 129  * needed.
 130  *
 131  * The name can't be NULL here.
 132  *
 133  * Return 0 on success else a negative LTTng error code.
 134  */
 135 extern int lttng_destroy_session(const char *name);
 136
 137 /*
 138  * Destroy a tracing session.
 139  *
 140  * Performs the same function as lttng_destroy_session(), but provides
 141  * an lttng_destruction_handle which can be used to wait for the completion
 142  * of the session's destruction. The lttng_destroy_handle can also be used
 143  * obtain the status and archive location of any implicit session
 144  * rotation that may have occured during the session's destruction.
 145  *
 146  * Returns LTTNG_OK on success. The returned handle is owned by the caller
 147  * and must be free'd using lttng_destruction_handle_destroy().
 148  */
 149 extern enum lttng_error_code lttng_destroy_session_ext(const char *session_name,
 150                 struct lttng_destruction_handle **handle);
 151
 152 /*
 153  * Behaves exactly like lttng_destroy_session but does not wait for data
 154  * availability.
 155  */
 156 extern int lttng_destroy_session_no_wait(const char *name);
 157
 158 /*
 159  * List all the tracing sessions.
 160  *
 161  * Return the number of entries of the "lttng_session" array. The caller
 162  * must free the returned sessions array directly using free().
 163  *
 164  * On error, a negative LTTng error code is returned.
 165  */
 166 extern int lttng_list_sessions(struct lttng_session **sessions);
 167
 168 /*
 169  * Get the creation time of an lttng_session object on the session daemon.
 170  *
 171  * This function must only be used with lttng_session objects returned
 172  * by lttng_list_sessions() or lttng_session_create().
 173  *
 174  * The creation time returned is a UNIX timestamp; the number of seconds since
 175  * Epoch (1970-01-01 00:00:00 +0000 (UTC)).
 176  *
 177  * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
 178  * return codes.
 179  */
 180 extern enum lttng_error_code lttng_session_get_creation_time(
 181                 const struct lttng_session *session, uint64_t *creation_time);
 182
 183 /*
 184  * Set the shared memory path for a session.
 185  *
 186  * Sets the (optional) file system path where shared memory buffers will
 187  * be created for the session. This is useful for buffer extraction on
 188  * crash, when used with filesystems like pramfs.
 189  *
 190  * Return 0 on success else a negative LTTng error code.
 191  */
 192 extern int lttng_set_session_shm_path(const char *session_name,
 193                 const char *shm_path);
 194
 195 /*
 196  * Add PID to session tracker.
 197  *
 198  * A pid argument >= 0 adds the PID to the session tracker.
 199  * A pid argument of -1 means "track all PIDs".
 200  *
 201  * Return 0 on success else a negative LTTng error code.
 202  */
 203 extern int lttng_track_pid(struct lttng_handle *handle, int pid);
 204
 205 /*
 206  * Remove PID from session tracker.
 207  *
 208  * A pid argument >= 0 removes the PID from the session tracker.
 209  * A pid argument of -1 means "untrack all PIDs".
 210  *
 211  * Return 0 on success else a negative LTTng error code.
 212  */
 213 extern int lttng_untrack_pid(struct lttng_handle *handle, int pid);
 214
 215 /*
 216  * List PIDs in the tracker.
 217  *
 218  * enabled is set to whether the PID tracker is enabled.
 219  * pids is set to an allocated array of PIDs currently tracked. On
 220  * success, pids must be freed by the caller.
 221  * nr_pids is set to the number of entries contained by the pids array.
 222  *
 223  * Returns 0 on success, else a negative LTTng error code.
 224  */
 225 extern int lttng_list_tracker_pids(struct lttng_handle *handle,
 226                 int *enabled, int32_t **pids, size_t *nr_pids);
 227
 228 #ifdef __cplusplus
 229 }
 230 #endif
 231
 232 #endif /* LTTNG_SESSION_H */