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 enum lttng_tracker_type {
  27         LTTNG_TRACKER_PID = 0,
  28         LTTNG_TRACKER_VPID = 1,
  29         LTTNG_TRACKER_UID = 2,
  30         LTTNG_TRACKER_GID = 3,
  31         LTTNG_TRACKER_VUID = 4,
  32         LTTNG_TRACKER_VGID = 5,
  33 };
  34
  35 enum lttng_tracker_id_type {
  36         LTTNG_ID_UNKNOWN = -1,
  37         LTTNG_ID_ALL = 0,
  38         LTTNG_ID_VALUE = 1,
  39         LTTNG_ID_STRING = 2,
  40 };
  41
  42 struct lttng_tracker_id {
  43         enum lttng_tracker_id_type type;
  44         int value;
  45         char *string;
  46 };
  47
  48 struct lttng_session_descriptor;
  49 struct lttng_destruction_handle;
  50
  51 /*
  52  * Basic session information.
  53  *
  54  * The "enabled" field is only used when listing the sessions which indicate if
  55  * it's started or not.
  56  *
  57  * The structures should be initialized to zero before use.
  58  */
  59 #define LTTNG_SESSION_PADDING1             8
  60 struct lttng_session {
  61         char name[LTTNG_NAME_MAX];
  62         /*
  63          * Human-readable representation of the trace's destination.
  64          * In the case of a local tracing session, a path is provided:
  65          *     /path/to/the/output
  66          *
  67          * In the case of a remote (network) tracing session, the string has
  68          * the following format:
  69          *     net://hostname/path:ctrl_port [data: data_port]
  70          */
  71         char path[PATH_MAX];
  72         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
  73         uint32_t snapshot_mode;
  74         unsigned int live_timer_interval;       /* usec */
  75
  76         /*
  77          * End of public attributes.
  78          * The remaining fields are used to deal with ABI management concerns.
  79          */
  80
  81         /*
  82          * 32-bit architectures are already naturally aligned on 4 bytes after
  83          * 'live_timer_interval'. However, the offset does not result in a
  84          * natural alignment on 64-bit architectures. Adding 4 bytes of
  85          * padding here results in an aligned offset after 'alignement_padding'
  86          * for both bitnesses.
  87          *
  88          * This was added since not all compilers appear to align unions in the
  89          * same way. Some (e.g. MSVC) do not seem to impose an alignement
  90          * constraint while others (e.g. gcc, clang, icc) seem to align it to
  91          * ensure 'ptr' is naturally aligned.
  92          */
  93         char alignment_padding[4];
  94         union {
  95                 /*
  96                  * Ensure the 'extended' union has the same size for both
  97                  * 32-bit and 64-bit builds.
  98                  */
  99                 char padding[LTTNG_SESSION_PADDING1];
 100                 void *ptr;
 101         } extended;
 102 };
 103
 104 /*
 105  * Create a session on the session daemon from a session descriptor.
 106  *
 107  * See the session descriptor API description in session-descriptor.h
 108  *
 109  * Note that unspecified session descriptor parameters, such as a session's
 110  * name, are updated in the session descriptor if the creation of the session
 111  * succeeds. This allows users to query the session's auto-generated name
 112  * after its creation. Note that other attributes can be queried using the
 113  * session listing API.
 114  *
 115  * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
 116  * return codes.
 117  */
 118 extern enum lttng_error_code lttng_create_session_ext(
 119                 struct lttng_session_descriptor *session_descriptor);
 120
 121 /*
 122  * Create a tracing session using a name and an optional URL.
 123  *
 124  * If _url_ is NULL, no consumer is created for the session. The name can't be
 125  * NULL here.
 126  *
 127  * Return 0 on success else a negative LTTng error code.
 128  */
 129 extern int lttng_create_session(const char *name, const char *url);
 130
 131 /*
 132  * Create a tracing session that will exclusively be used for snapshot meaning
 133  * the session will be in no output mode and every channel enabled for that
 134  * session will be set in overwrite mode and in mmap output since splice is not
 135  * supported.
 136  *
 137  * Name can't be NULL. If an url is given, it will be used to create a default
 138  * snapshot output using it as a destination. If NULL, no output will be
 139  * defined and an add-output call will be needed.
 140  *
 141  * Return 0 on success else a negative LTTng error code.
 142  */
 143 extern int lttng_create_session_snapshot(const char *name,
 144                 const char *snapshot_url);
 145
 146 /*
 147  * Create a session exclusively used for live reading.
 148  *
 149  * In this mode, the switch-timer parameter is forced for each UST channel, a
 150  * live-switch-timer is enabled for kernel channels, manually setting
 151  * switch-timer is forbidden. Synchronization beacons are sent to the relayd,
 152  * indexes are sent and metadata is checked for each packet.
 153  *
 154  * Name can't be NULL. If no URL is given, the default is to send the data to
 155  * net://127.0.0.1. The timer_interval is in usec.
 156  *
 157  * Return 0 on success else a negative LTTng error code.
 158  */
 159 extern int lttng_create_session_live(const char *name, const char *url,
 160                 unsigned int timer_interval);
 161
 162 /*
 163  * Destroy a tracing session.
 164  *
 165  * The session will not be usable, tracing will be stopped thus buffers will be
 166  * flushed.
 167  *
 168  * This call will wait for data availability for each domain of the session,
 169  * which can take an arbitrary amount of time. However, when returning the
 170  * tracing data is guaranteed to be ready to be read and analyzed.
 171  *
 172  * lttng_destroy_session_no_wait() may be used if such a guarantee is not
 173  * needed.
 174  *
 175  * The name can't be NULL here.
 176  *
 177  * Return 0 on success else a negative LTTng error code.
 178  */
 179 extern int lttng_destroy_session(const char *name);
 180
 181 /*
 182  * Destroy a tracing session.
 183  *
 184  * Performs the same function as lttng_destroy_session(), but provides
 185  * an lttng_destruction_handle which can be used to wait for the completion
 186  * of the session's destruction. The lttng_destroy_handle can also be used
 187  * obtain the status and archive location of any implicit session
 188  * rotation that may have occurred during the session's destruction.
 189  *
 190  * Returns LTTNG_OK on success. The returned handle is owned by the caller
 191  * and must be free'd using lttng_destruction_handle_destroy().
 192  */
 193 extern enum lttng_error_code lttng_destroy_session_ext(const char *session_name,
 194                 struct lttng_destruction_handle **handle);
 195
 196 /*
 197  * Behaves exactly like lttng_destroy_session but does not wait for data
 198  * availability.
 199  */
 200 extern int lttng_destroy_session_no_wait(const char *name);
 201
 202 /*
 203  * List all the tracing sessions.
 204  *
 205  * Return the number of entries of the "lttng_session" array. The caller
 206  * must free the returned sessions array directly using free().
 207  *
 208  * On error, a negative LTTng error code is returned.
 209  */
 210 extern int lttng_list_sessions(struct lttng_session **sessions);
 211
 212 /*
 213  * Get the creation time of an lttng_session object on the session daemon.
 214  *
 215  * This function must only be used with lttng_session objects returned
 216  * by lttng_list_sessions() or lttng_session_create().
 217  *
 218  * The creation time returned is a UNIX timestamp; the number of seconds since
 219  * Epoch (1970-01-01 00:00:00 +0000 (UTC)).
 220  *
 221  * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
 222  * return codes.
 223  */
 224 extern enum lttng_error_code lttng_session_get_creation_time(
 225                 const struct lttng_session *session, uint64_t *creation_time);
 226
 227 /*
 228  * Set the shared memory path for a session.
 229  *
 230  * Sets the (optional) file system path where shared memory buffers will
 231  * be created for the session. This is useful for buffer extraction on
 232  * crash, when used with filesystems like pramfs.
 233  *
 234  * Return 0 on success else a negative LTTng error code.
 235  */
 236 extern int lttng_set_session_shm_path(const char *session_name,
 237                 const char *shm_path);
 238
 239 /*
 240  * Add PID to session tracker.
 241  *
 242  * A pid argument >= 0 adds the PID to the session tracker.
 243  * A pid argument of -1 means "track all PIDs".
 244  *
 245  * Return 0 on success else a negative LTTng error code.
 246  */
 247 extern int lttng_track_pid(struct lttng_handle *handle, int pid);
 248
 249 /*
 250  * Remove PID from session tracker.
 251  *
 252  * A pid argument >= 0 removes the PID from the session tracker.
 253  * A pid argument of -1 means "untrack all PIDs".
 254  *
 255  * Return 0 on success else a negative LTTng error code.
 256  */
 257 extern int lttng_untrack_pid(struct lttng_handle *handle, int pid);
 258
 259 /*
 260  * List PIDs in the tracker.
 261  *
 262  * enabled is set to whether the PID tracker is enabled.
 263  * pids is set to an allocated array of PIDs currently tracked. On
 264  * success, pids must be freed by the caller.
 265  * nr_pids is set to the number of entries contained by the pids array.
 266  *
 267  * Returns 0 on success, else a negative LTTng error code.
 268  */
 269 extern int lttng_list_tracker_pids(struct lttng_handle *handle,
 270                 int *enabled, int32_t **pids, size_t *nr_pids);
 271
 272 #ifdef __cplusplus
 273 }
 274 #endif
 275
 276 #endif /* LTTNG_SESSION_H */