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         /*
  37          * Human-readable representation of the trace's destination.
  38          * In the case of a local tracing session, a path is provided:
  39          *     /path/to/the/output
  40          *
  41          * In the case of a remote (network) tracing session, the string has
  42          * the following format:
  43          *     net://hostname/path:ctrl_port [data: data_port]
  44          */
  45         char path[PATH_MAX];
  46         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
  47         uint32_t snapshot_mode;
  48         unsigned int live_timer_interval;       /* usec */
  49
  50         char padding[LTTNG_SESSION_PADDING1];
  51 };
  52
  53 /*
  54  * Create a tracing session using a name and an optional URL.
  55  *
  56  * If _url_ is NULL, no consumer is created for the session. The name can't be
  57  * NULL here.
  58  *
  59  * Return 0 on success else a negative LTTng error code.
  60  */
  61 extern int lttng_create_session(const char *name, const char *url);
  62
  63 /*
  64  * Create a tracing session that will exclusively be used for snapshot meaning
  65  * the session will be in no output mode and every channel enabled for that
  66  * session will be set in overwrite mode and in mmap output since splice is not
  67  * supported.
  68  *
  69  * Name can't be NULL. If an url is given, it will be used to create a default
  70  * snapshot output using it as a destination. If NULL, no output will be
  71  * defined and an add-output call will be needed.
  72  *
  73  * Return 0 on success else a negative LTTng error code.
  74  */
  75 extern int lttng_create_session_snapshot(const char *name,
  76                 const char *snapshot_url);
  77
  78 /*
  79  * Create a session exclusively used for live reading.
  80  *
  81  * In this mode, the switch-timer parameter is forced for each UST channel, a
  82  * live-switch-timer is enabled for kernel channels, manually setting
  83  * switch-timer is forbidden. Synchronization beacons are sent to the relayd,
  84  * indexes are sent and metadata is checked for each packet.
  85  *
  86  * Name can't be NULL. If no URL is given, the default is to send the data to
  87  * net://127.0.0.1. The timer_interval is in usec and by default set to 1000000
  88  * (1 second).
  89  *
  90  * Return 0 on success else a negative LTTng error code.
  91  */
  92 extern int lttng_create_session_live(const char *name, const char *url,
  93                 unsigned int timer_interval);
  94
  95 /*
  96  * Destroy a tracing session.
  97  *
  98  * The session will not be usable, tracing will be stopped thus buffers will be
  99  * flushed.
 100  *
 101  * This call will wait for data availability for each domain of the session,
 102  * which can take an arbitrary amount of time. However, when returning the
 103  * tracing data is guaranteed to be ready to be read and analyzed.
 104  *
 105  * lttng_destroy_session_no_wait() may be used if such a guarantee is not
 106  * needed.
 107  *
 108  * The name can't be NULL here.
 109  *
 110  * Return 0 on success else a negative LTTng error code.
 111  */
 112 extern int lttng_destroy_session(const char *name);
 113
 114 /*
 115  * Behaves exactly like lttng_destroy_session but does not wait for data
 116  * availability.
 117  */
 118 extern int lttng_destroy_session_no_wait(const char *name);
 119
 120 /*
 121  * List all the tracing sessions.
 122  *
 123  * Return the size (number of entries) of the "lttng_session" array. Caller
 124  * must free sessions. On error, a negative LTTng error code is returned.
 125  */
 126 extern int lttng_list_sessions(struct lttng_session **sessions);
 127
 128 /*
 129  * Set the shared memory path for a session.
 130  *
 131  * Sets the (optional) file system path where shared memory buffers will
 132  * be created for the session. This is useful for buffer extraction on
 133  * crash, when used with filesystems like pramfs.
 134  *
 135  * Return 0 on success else a negative LTTng error code.
 136  */
 137 extern int lttng_set_session_shm_path(const char *session_name,
 138                 const char *shm_path);
 139
 140 /*
 141  * Add PID to session tracker.
 142  *
 143  * A pid argument >= 0 adds the PID to the session tracker.
 144  * A pid argument of -1 means "track all PIDs".
 145  *
 146  * Return 0 on success else a negative LTTng error code.
 147  */
 148 extern int lttng_track_pid(struct lttng_handle *handle, int pid);
 149
 150 /*
 151  * Remove PID from session tracker.
 152  *
 153  * A pid argument >= 0 removes the PID from the session tracker.
 154  * A pid argument of -1 means "untrack all PIDs".
 155  *
 156  * Return 0 on success else a negative LTTng error code.
 157  */
 158 extern int lttng_untrack_pid(struct lttng_handle *handle, int pid);
 159
 160 /*
 161  * List PIDs in the tracker.
 162  *
 163  * enabled is set to whether the PID tracker is enabled.
 164  * pids is set to an allocated array of PIDs currently tracked. On
 165  * success, pids must be freed by the caller.
 166  * nr_pids is set to the number of entries contained by the pids array.
 167  *
 168  * Returns 0 on success, else a negative LTTng error code.
 169  */
 170 extern int lttng_list_tracker_pids(struct lttng_handle *handle,
 171                 int *enabled, int32_t **pids, size_t *nr_pids);
 172
 173 #ifdef __cplusplus
 174 }
 175 #endif
 176
 177 #endif /* LTTNG_SESSION_H */