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 struct lttng_session_descriptor;
  26
  27 /*
  28  * Basic session information.
  29  *
  30  * The "enabled" field is only used when listing the sessions which indicate if
  31  * it's started or not.
  32  *
  33  * The structures should be initialized to zero before use.
  34  */
  35 #define LTTNG_SESSION_PADDING1             12
  36 struct lttng_session {
  37         char name[LTTNG_NAME_MAX];
  38         /*
  39          * Human-readable representation of the trace's destination.
  40          * In the case of a local tracing session, a path is provided:
  41          *     /path/to/the/output
  42          *
  43          * In the case of a remote (network) tracing session, the string has
  44          * the following format:
  45          *     net://hostname/path:ctrl_port [data: data_port]
  46          */
  47         char path[PATH_MAX];
  48         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
  49         uint32_t snapshot_mode;
  50         unsigned int live_timer_interval;       /* usec */
  51
  52         union {
  53                 char padding[LTTNG_SESSION_PADDING1];
  54                 void *ptr;
  55         } extended;
  56 };
  57
  58 /*
  59  * Create a session on the session daemon from a session descriptor.
  60  *
  61  * See the session descriptor API description in session-descriptor.h
  62  *
  63  * Note that unspecified session descriptor parameters, such as a session's
  64  * name, are updated in the session descriptor if the creation of the session
  65  * succeeds. This allows users to query the session's auto-generated name
  66  * after its creation. Note that other attributes can be queried using the
  67  * session listing API.
  68  *
  69  * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
  70  * return codes.
  71  */
  72 extern enum lttng_error_code lttng_create_session_ext(
  73                 struct lttng_session_descriptor *session_descriptor);
  74
  75 /*
  76  * Create a tracing session using a name and an optional URL.
  77  *
  78  * If _url_ is NULL, no consumer is created for the session. The name can't be
  79  * NULL here.
  80  *
  81  * Return 0 on success else a negative LTTng error code.
  82  */
  83 extern int lttng_create_session(const char *name, const char *url);
  84
  85 /*
  86  * Create a tracing session that will exclusively be used for snapshot meaning
  87  * the session will be in no output mode and every channel enabled for that
  88  * session will be set in overwrite mode and in mmap output since splice is not
  89  * supported.
  90  *
  91  * Name can't be NULL. If an url is given, it will be used to create a default
  92  * snapshot output using it as a destination. If NULL, no output will be
  93  * defined and an add-output call will be needed.
  94  *
  95  * Return 0 on success else a negative LTTng error code.
  96  */
  97 extern int lttng_create_session_snapshot(const char *name,
  98                 const char *snapshot_url);
  99
 100 /*
 101  * Create a session exclusively used for live reading.
 102  *
 103  * In this mode, the switch-timer parameter is forced for each UST channel, a
 104  * live-switch-timer is enabled for kernel channels, manually setting
 105  * switch-timer is forbidden. Synchronization beacons are sent to the relayd,
 106  * indexes are sent and metadata is checked for each packet.
 107  *
 108  * Name can't be NULL. If no URL is given, the default is to send the data to
 109  * net://127.0.0.1. The timer_interval is in usec.
 110  *
 111  * Return 0 on success else a negative LTTng error code.
 112  */
 113 extern int lttng_create_session_live(const char *name, const char *url,
 114                 unsigned int timer_interval);
 115
 116 /*
 117  * Destroy a tracing session.
 118  *
 119  * The session will not be usable, tracing will be stopped thus buffers will be
 120  * flushed.
 121  *
 122  * This call will wait for data availability for each domain of the session,
 123  * which can take an arbitrary amount of time. However, when returning the
 124  * tracing data is guaranteed to be ready to be read and analyzed.
 125  *
 126  * lttng_destroy_session_no_wait() may be used if such a guarantee is not
 127  * needed.
 128  *
 129  * The name can't be NULL here.
 130  *
 131  * Return 0 on success else a negative LTTng error code.
 132  */
 133 extern int lttng_destroy_session(const char *name);
 134
 135 /*
 136  * Behaves exactly like lttng_destroy_session but does not wait for data
 137  * availability.
 138  */
 139 extern int lttng_destroy_session_no_wait(const char *name);
 140
 141 /*
 142  * List all the tracing sessions.
 143  *
 144  * Return the number of entries of the "lttng_session" array. The caller
 145  * must free the returned sessions array directly using free().
 146  *
 147  * On error, a negative LTTng error code is returned.
 148  */
 149 extern int lttng_list_sessions(struct lttng_session **sessions);
 150
 151 /*
 152  * Get the creation time of an lttng_session object on the session daemon.
 153  *
 154  * This function must only be used with lttng_session objects returned
 155  * by lttng_list_sessions() or lttng_session_create().
 156  *
 157  * The creation time returned is a UNIX timestamp; the number of seconds since
 158  * Epoch (1970-01-01 00:00:00 +0000 (UTC)).
 159  *
 160  * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
 161  * return codes.
 162  */
 163 extern enum lttng_error_code lttng_session_get_creation_time(
 164                 const struct lttng_session *session, uint64_t *creation_time);
 165
 166 /*
 167  * Set the shared memory path for a session.
 168  *
 169  * Sets the (optional) file system path where shared memory buffers will
 170  * be created for the session. This is useful for buffer extraction on
 171  * crash, when used with filesystems like pramfs.
 172  *
 173  * Return 0 on success else a negative LTTng error code.
 174  */
 175 extern int lttng_set_session_shm_path(const char *session_name,
 176                 const char *shm_path);
 177
 178 /*
 179  * Add PID to session tracker.
 180  *
 181  * A pid argument >= 0 adds the PID to the session tracker.
 182  * A pid argument of -1 means "track all PIDs".
 183  *
 184  * Return 0 on success else a negative LTTng error code.
 185  */
 186 extern int lttng_track_pid(struct lttng_handle *handle, int pid);
 187
 188 /*
 189  * Remove PID from session tracker.
 190  *
 191  * A pid argument >= 0 removes the PID from the session tracker.
 192  * A pid argument of -1 means "untrack all PIDs".
 193  *
 194  * Return 0 on success else a negative LTTng error code.
 195  */
 196 extern int lttng_untrack_pid(struct lttng_handle *handle, int pid);
 197
 198 /*
 199  * List PIDs in the tracker.
 200  *
 201  * enabled is set to whether the PID tracker is enabled.
 202  * pids is set to an allocated array of PIDs currently tracked. On
 203  * success, pids must be freed by the caller.
 204  * nr_pids is set to the number of entries contained by the pids array.
 205  *
 206  * Returns 0 on success, else a negative LTTng error code.
 207  */
 208 extern int lttng_list_tracker_pids(struct lttng_handle *handle,
 209                 int *enabled, int32_t **pids, size_t *nr_pids);
 210
 211 #ifdef __cplusplus
 212 }
 213 #endif
 214
 215 #endif /* LTTNG_SESSION_H */