include/lttng/session.h

   1 /*
   2  * Copyright (C) 2014 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License, version 2.1 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This library is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  11  * for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18 #ifndef LTTNG_SESSION_H
  19 #define LTTNG_SESSION_H
  20
  21 #ifdef __cplusplus
  22 extern "C" {
  23 #endif
  24
  25 /*
  26  * Basic session information.
  27  *
  28  * The "enabled" field is only used when listing the sessions which indicate if
  29  * it's started or not.
  30  *
  31  * The structures should be initialized to zero before use.
  32  */
  33 #define LTTNG_SESSION_PADDING1             12
  34 struct lttng_session {
  35         char name[LTTNG_NAME_MAX];
  36         /* The path where traces are written */
  37         char path[PATH_MAX];
  38         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
  39         uint32_t snapshot_mode;
  40         unsigned int live_timer_interval;       /* usec */
  41
  42         char padding[LTTNG_SESSION_PADDING1];
  43 };
  44
  45 /*
  46  * Create a tracing session using a name and an optional URL.
  47  *
  48  * If _url_ is NULL, no consumer is created for the session. The name can't be
  49  * NULL here.
  50  *
  51  * Return 0 on success else a negative LTTng error code.
  52  */
  53 extern int lttng_create_session(const char *name, const char *url);
  54
  55 /*
  56  * Create a tracing session that will exclusively be used for snapshot meaning
  57  * the session will be in no output mode and every channel enabled for that
  58  * session will be set in overwrite mode and in mmap output since splice is not
  59  * supported.
  60  *
  61  * Name can't be NULL. If an url is given, it will be used to create a default
  62  * snapshot output using it as a destination. If NULL, no output will be
  63  * defined and an add-output call will be needed.
  64  *
  65  * Return 0 on success else a negative LTTng error code.
  66  */
  67 extern int lttng_create_session_snapshot(const char *name,
  68                 const char *snapshot_url);
  69
  70 /*
  71  * Create a session exclusively used for live reading.
  72  *
  73  * In this mode, the switch-timer parameter is forced for each UST channel, a
  74  * live-switch-timer is enabled for kernel channels, manually setting
  75  * switch-timer is forbidden. Synchronization beacons are sent to the relayd,
  76  * indexes are sent and metadata is checked for each packet.
  77  *
  78  * Name can't be NULL. If no URL is given, the default is to send the data to
  79  * net://127.0.0.1. The timer_interval is in usec and by default set to 1000000
  80  * (1 second).
  81  *
  82  * Return 0 on success else a negative LTTng error code.
  83  */
  84 extern int lttng_create_session_live(const char *name, const char *url,
  85                 unsigned int timer_interval);
  86
  87 /*
  88  * Destroy a tracing session.
  89  *
  90  * The session will not be usable, tracing will be stopped thus buffers will be
  91  * flushed.
  92  *
  93  * This call will wait for data availability for each domain of the session,
  94  * which can take an arbitrary amount of time. However, when returning the
  95  * tracing data is guaranteed to be ready to be read and analyzed.
  96  *
  97  * lttng_destroy_session_no_wait() may be used if such a guarantee is not
  98  * needed.
  99  *
 100  * The name can't be NULL here.
 101  *
 102  * Return 0 on success else a negative LTTng error code.
 103  */
 104 extern int lttng_destroy_session(const char *name);
 105
 106 /*
 107  * Behaves exactly like lttng_destroy_session but does not wait for data
 108  * availability.
 109  */
 110 extern int lttng_destroy_session_no_wait(const char *name);
 111
 112 /*
 113  * List all the tracing sessions.
 114  *
 115  * Return the size (number of entries) of the "lttng_session" array. Caller
 116  * must free sessions. On error, a negative LTTng error code is returned.
 117  */
 118 extern int lttng_list_sessions(struct lttng_session **sessions);
 119
 120 /*
 121  * Set the shared memory path for a session.
 122  *
 123  * Sets the (optional) file system path where shared memory buffers will
 124  * be created for the session. This is useful for buffer extraction on
 125  * crash, when used with filesystems like pramfs.
 126  *
 127  * Return 0 on success else a negative LTTng error code.
 128  */
 129 extern int lttng_set_session_shm_path(const char *session_name,
 130                 const char *shm_path);
 131
 132 /*
 133  * Add PID to session tracker.
 134  *
 135  * A pid argument >= 0 adds the PID to the session tracker.
 136  * A pid argument of -1 means "track all PIDs".
 137  *
 138  * Return 0 on success else a negative LTTng error code.
 139  */
 140 extern int lttng_track_pid(struct lttng_handle *handle, int pid);
 141
 142 /*
 143  * Remove PID from session tracker.
 144  *
 145  * A pid argument >= 0 removes the PID from the session tracker.
 146  * A pid argument of -1 means "untrack all PIDs".
 147  *
 148  * Return 0 on success else a negative LTTng error code.
 149  */
 150 extern int lttng_untrack_pid(struct lttng_handle *handle, int pid);
 151
 152 /*
 153  * List PIDs in the tracker.
 154  *
 155  * enabled is set to whether the PID tracker is enabled.
 156  * pids is set to an allocated array of PIDs currently tracked. On
 157  * success, pids must be freed by the caller.
 158  * nr_pids is set to the number of entries contained by the pids array.
 159  *
 160  * Returns 0 on success, else a negative LTTng error code.
 161  */
 162 extern int lttng_list_tracker_pids(struct lttng_handle *handle,
 163                 int *enabled, int32_t **pids, size_t *nr_pids);
 164
 165 #ifdef __cplusplus
 166 }
 167 #endif
 168
 169 #endif /* LTTNG_SESSION_H */