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 #include <lttng/constant.h>
  27
  28 enum lttng_tracker_type {
  29         LTTNG_TRACKER_PID = 0,
  30         LTTNG_TRACKER_VPID = 1,
  31         LTTNG_TRACKER_UID = 2,
  32         LTTNG_TRACKER_GID = 3,
  33         LTTNG_TRACKER_VUID = 4,
  34         LTTNG_TRACKER_VGID = 5,
  35 };
  36
  37 enum lttng_tracker_id_type {
  38         LTTNG_ID_UNKNOWN = -1,
  39         LTTNG_ID_ALL = 0,
  40         LTTNG_ID_VALUE = 1,
  41         LTTNG_ID_STRING = 2,
  42 };
  43
  44 struct lttng_tracker_id {
  45         enum lttng_tracker_id_type type;
  46         int value;
  47         char *string;
  48 };
  49
  50 struct lttng_handle;
  51 struct lttng_session_descriptor;
  52 struct lttng_destruction_handle;
  53
  54 /*
  55  * Basic session information.
  56  *
  57  * The "enabled" field is only used when listing the sessions which indicate if
  58  * it's started or not.
  59  *
  60  * The structures should be initialized to zero before use.
  61  */
  62 #define LTTNG_SESSION_PADDING1             8
  63 struct lttng_session {
  64         char name[LTTNG_NAME_MAX];
  65         /*
  66          * Human-readable representation of the trace's destination.
  67          * In the case of a local tracing session, a path is provided:
  68          *     /path/to/the/output
  69          *
  70          * In the case of a remote (network) tracing session, the string has
  71          * the following format:
  72          *     net://hostname/path:ctrl_port [data: data_port]
  73          */
  74         char path[PATH_MAX];
  75         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
  76         uint32_t snapshot_mode;
  77         unsigned int live_timer_interval;       /* usec */
  78
  79         /*
  80          * End of public attributes.
  81          * The remaining fields are used to deal with ABI management concerns.
  82          */
  83
  84         /*
  85          * 32-bit architectures are already naturally aligned on 4 bytes after
  86          * 'live_timer_interval'. However, the offset does not result in a
  87          * natural alignment on 64-bit architectures. Adding 4 bytes of
  88          * padding here results in an aligned offset after 'alignement_padding'
  89          * for both bitnesses.
  90          *
  91          * This was added since not all compilers appear to align unions in the
  92          * same way. Some (e.g. MSVC) do not seem to impose an alignement
  93          * constraint while others (e.g. gcc, clang, icc) seem to align it to
  94          * ensure 'ptr' is naturally aligned.
  95          */
  96         char alignment_padding[4];
  97         union {
  98                 /*
  99                  * Ensure the 'extended' union has the same size for both
 100                  * 32-bit and 64-bit builds.
 101                  */
 102                 char padding[LTTNG_SESSION_PADDING1];
 103                 void *ptr;
 104         } extended;
 105 };
 106
 107 /*
 108  * Create a session on the session daemon from a session descriptor.
 109  *
 110  * See the session descriptor API description in session-descriptor.h
 111  *
 112  * Note that unspecified session descriptor parameters, such as a session's
 113  * name, are updated in the session descriptor if the creation of the session
 114  * succeeds. This allows users to query the session's auto-generated name
 115  * after its creation. Note that other attributes can be queried using the
 116  * session listing API.
 117  *
 118  * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
 119  * return codes.
 120  */
 121 extern enum lttng_error_code lttng_create_session_ext(
 122                 struct lttng_session_descriptor *session_descriptor);
 123
 124 /*
 125  * Create a tracing session using a name and an optional URL.
 126  *
 127  * If _url_ is NULL, no consumer is created for the session. The name can't be
 128  * NULL here.
 129  *
 130  * Return 0 on success else a negative LTTng error code.
 131  */
 132 extern int lttng_create_session(const char *name, const char *url);
 133
 134 /*
 135  * Create a tracing session that will exclusively be used for snapshot meaning
 136  * the session will be in no output mode and every channel enabled for that
 137  * session will be set in overwrite mode and in mmap output since splice is not
 138  * supported.
 139  *
 140  * Name can't be NULL. If an url is given, it will be used to create a default
 141  * snapshot output using it as a destination. If NULL, no output will be
 142  * defined and an add-output call will be needed.
 143  *
 144  * Return 0 on success else a negative LTTng error code.
 145  */
 146 extern int lttng_create_session_snapshot(const char *name,
 147                 const char *snapshot_url);
 148
 149 /*
 150  * Create a session exclusively used for live reading.
 151  *
 152  * In this mode, the switch-timer parameter is forced for each UST channel, a
 153  * live-switch-timer is enabled for kernel channels, manually setting
 154  * switch-timer is forbidden. Synchronization beacons are sent to the relayd,
 155  * indexes are sent and metadata is checked for each packet.
 156  *
 157  * Name can't be NULL. If no URL is given, the default is to send the data to
 158  * net://127.0.0.1. The timer_interval is in usec.
 159  *
 160  * Return 0 on success else a negative LTTng error code.
 161  */
 162 extern int lttng_create_session_live(const char *name, const char *url,
 163                 unsigned int timer_interval);
 164
 165 /*
 166  * Destroy a tracing session.
 167  *
 168  * The session will not be usable, tracing will be stopped thus buffers will be
 169  * flushed.
 170  *
 171  * This call will wait for data availability for each domain of the session,
 172  * which can take an arbitrary amount of time. However, when returning the
 173  * tracing data is guaranteed to be ready to be read and analyzed.
 174  *
 175  * lttng_destroy_session_no_wait() may be used if such a guarantee is not
 176  * needed.
 177  *
 178  * The name can't be NULL here.
 179  *
 180  * Return 0 on success else a negative LTTng error code.
 181  */
 182 extern int lttng_destroy_session(const char *name);
 183
 184 /*
 185  * Destroy a tracing session.
 186  *
 187  * Performs the same function as lttng_destroy_session(), but provides
 188  * an lttng_destruction_handle which can be used to wait for the completion
 189  * of the session's destruction. The lttng_destroy_handle can also be used
 190  * obtain the status and archive location of any implicit session
 191  * rotation that may have occurred during the session's destruction.
 192  *
 193  * Returns LTTNG_OK on success. The returned handle is owned by the caller
 194  * and must be free'd using lttng_destruction_handle_destroy().
 195  */
 196 extern enum lttng_error_code lttng_destroy_session_ext(const char *session_name,
 197                 struct lttng_destruction_handle **handle);
 198
 199 /*
 200  * Behaves exactly like lttng_destroy_session but does not wait for data
 201  * availability.
 202  */
 203 extern int lttng_destroy_session_no_wait(const char *name);
 204
 205 /*
 206  * List all the tracing sessions.
 207  *
 208  * Return the number of entries of the "lttng_session" array. The caller
 209  * must free the returned sessions array directly using free().
 210  *
 211  * On error, a negative LTTng error code is returned.
 212  */
 213 extern int lttng_list_sessions(struct lttng_session **sessions);
 214
 215 /*
 216  * Get the creation time of an lttng_session object on the session daemon.
 217  *
 218  * This function must only be used with lttng_session objects returned
 219  * by lttng_list_sessions() or lttng_session_create().
 220  *
 221  * The creation time returned is a UNIX timestamp; the number of seconds since
 222  * Epoch (1970-01-01 00:00:00 +0000 (UTC)).
 223  *
 224  * Returns LTTNG_OK on success. See lttng-error.h for the meaning of the other
 225  * return codes.
 226  */
 227 extern enum lttng_error_code lttng_session_get_creation_time(
 228                 const struct lttng_session *session, uint64_t *creation_time);
 229
 230 /*
 231  * Set the shared memory path for a session.
 232  *
 233  * Sets the (optional) file system path where shared memory buffers will
 234  * be created for the session. This is useful for buffer extraction on
 235  * crash, when used with filesystems like pramfs.
 236  *
 237  * Return 0 on success else a negative LTTng error code.
 238  */
 239 extern int lttng_set_session_shm_path(const char *session_name,
 240                 const char *shm_path);
 241
 242 /*
 243  * Add ID to session tracker.
 244  *
 245  * tracker_type is the type of tracker.
 246  * id the id to track.
 247  *
 248  * Return 0 on success else a negative LTTng error code.
 249  */
 250 extern int lttng_track_id(struct lttng_handle *handle,
 251                 enum lttng_tracker_type tracker_type,
 252                 const struct lttng_tracker_id *id);
 253
 254 /*
 255  * Remove ID from session tracker.
 256  *
 257  * tracker_type is the type of tracker.
 258  * id the id to untrack.
 259  *
 260  * Return 0 on success else a negative LTTng error code.
 261  */
 262 extern int lttng_untrack_id(struct lttng_handle *handle,
 263                 enum lttng_tracker_type tracker_type,
 264                 const struct lttng_tracker_id *id);
 265
 266 /*
 267  * List IDs in the tracker.
 268  *
 269  * tracker_type is the type of tracker.
 270  * ids is set to an allocated array of IDs currently tracked. On
 271  * success, ids and the strings it contains must be freed by the
 272  * caller.
 273  * nr_ids is set to the number of entries contained by the ids array.
 274  *
 275  * Returns 0 on success, else a negative LTTng error code.
 276  */
 277 extern int lttng_list_tracker_ids(struct lttng_handle *handle,
 278                 enum lttng_tracker_type tracker_type,
 279                 struct lttng_tracker_id **ids,
 280                 size_t *nr_ids);
 281
 282 /*
 283  * Add PID to session tracker.
 284  *
 285  * A pid argument >= 0 adds the PID to the session tracker.
 286  * A pid argument of -1 means "track all PIDs".
 287  *
 288  * Return 0 on success else a negative LTTng error code.
 289  */
 290 extern int lttng_track_pid(struct lttng_handle *handle, int pid);
 291
 292 /*
 293  * Remove PID from session tracker.
 294  *
 295  * A pid argument >= 0 removes the PID from the session tracker.
 296  * A pid argument of -1 means "untrack all PIDs".
 297  *
 298  * Return 0 on success else a negative LTTng error code.
 299  */
 300 extern int lttng_untrack_pid(struct lttng_handle *handle, int pid);
 301
 302 /*
 303  * List PIDs in the tracker.
 304  *
 305  * enabled is set to whether the PID tracker is enabled.
 306  * pids is set to an allocated array of PIDs currently tracked. On
 307  * success, pids must be freed by the caller.
 308  * nr_pids is set to the number of entries contained by the pids array.
 309  *
 310  * Returns 0 on success, else a negative LTTng error code.
 311  */
 312 extern int lttng_list_tracker_pids(struct lttng_handle *handle,
 313                 int *enabled, int32_t **pids, size_t *nr_pids);
 314
 315 #ifdef __cplusplus
 316 }
 317 #endif
 318
 319 #endif /* LTTNG_SESSION_H */