include/lttng/lttng.h

   1 /*
   2  * lttng.h
   3  *
   4  * Linux Trace Toolkit Control Library Header File
   5  *
   6  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   7  *
   8  * This library is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License, version 2.1 only,
  10  * as published by the Free Software Foundation.
  11  *
  12  * This library is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  15  * for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public License
  18  * along with this library; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #ifndef LTTNG_H
  23 #define LTTNG_H
  24
  25 #include <limits.h>
  26 #include <stdint.h>
  27 #include <sys/types.h>
  28
  29 /* Error codes that can be returned by API calls */
  30 #include <lttng/lttng-error.h>
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36 /*
  37  * Event symbol length. Copied from LTTng kernel ABI.
  38  */
  39 #define LTTNG_SYMBOL_NAME_LEN             256
  40
  41 /*
  42  * Every lttng_event_* structure both apply to kernel event and user-space
  43  * event.
  44  */
  45
  46 /*
  47  * Domain types: the different possible tracers.
  48  */
  49 enum lttng_domain_type {
  50         LTTNG_DOMAIN_KERNEL                   = 1,
  51         LTTNG_DOMAIN_UST                      = 2,
  52
  53         /*
  54          * For now, the domains below are not implemented. However, we keep them
  55          * here in order to retain their enum values for future development. Note
  56          * that it is on the roadmap to implement them.
  57          *
  58         LTTNG_DOMAIN_UST_EXEC_NAME            = 3,
  59         LTTNG_DOMAIN_UST_PID                  = 4,
  60         LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN  = 5,
  61         */
  62 };
  63
  64 /*
  65  * Instrumentation type of tracing event.
  66  */
  67 enum lttng_event_type {
  68         LTTNG_EVENT_ALL                       = -1,
  69         LTTNG_EVENT_TRACEPOINT                = 0,
  70         LTTNG_EVENT_PROBE                     = 1,
  71         LTTNG_EVENT_FUNCTION                  = 2,
  72         LTTNG_EVENT_FUNCTION_ENTRY            = 3,
  73         LTTNG_EVENT_NOOP                      = 4,
  74         LTTNG_EVENT_SYSCALL                   = 5,
  75 };
  76
  77 /*
  78  * Loglevel information.
  79  */
  80 enum lttng_loglevel_type {
  81         LTTNG_EVENT_LOGLEVEL_ALL              = 0,
  82         LTTNG_EVENT_LOGLEVEL_RANGE            = 1,
  83         LTTNG_EVENT_LOGLEVEL_SINGLE           = 2,
  84 };
  85
  86 /*
  87  * Available loglevels.
  88  */
  89 enum lttng_loglevel {
  90         LTTNG_LOGLEVEL_EMERG                  = 0,
  91         LTTNG_LOGLEVEL_ALERT                  = 1,
  92         LTTNG_LOGLEVEL_CRIT                   = 2,
  93         LTTNG_LOGLEVEL_ERR                    = 3,
  94         LTTNG_LOGLEVEL_WARNING                = 4,
  95         LTTNG_LOGLEVEL_NOTICE                 = 5,
  96         LTTNG_LOGLEVEL_INFO                   = 6,
  97         LTTNG_LOGLEVEL_DEBUG_SYSTEM           = 7,
  98         LTTNG_LOGLEVEL_DEBUG_PROGRAM          = 8,
  99         LTTNG_LOGLEVEL_DEBUG_PROCESS          = 9,
 100         LTTNG_LOGLEVEL_DEBUG_MODULE           = 10,
 101         LTTNG_LOGLEVEL_DEBUG_UNIT             = 11,
 102         LTTNG_LOGLEVEL_DEBUG_FUNCTION         = 12,
 103         LTTNG_LOGLEVEL_DEBUG_LINE             = 13,
 104         LTTNG_LOGLEVEL_DEBUG                  = 14,
 105 };
 106
 107 /*
 108  * LTTng consumer mode
 109  */
 110 enum lttng_event_output {
 111         LTTNG_EVENT_SPLICE                    = 0,
 112         LTTNG_EVENT_MMAP                      = 1,
 113 };
 114
 115 /* Event context possible type */
 116 enum lttng_event_context_type {
 117         LTTNG_EVENT_CONTEXT_PID               = 0,
 118         LTTNG_EVENT_CONTEXT_PERF_COUNTER      = 1,
 119         LTTNG_EVENT_CONTEXT_PROCNAME          = 2,
 120         LTTNG_EVENT_CONTEXT_PRIO              = 3,
 121         LTTNG_EVENT_CONTEXT_NICE              = 4,
 122         LTTNG_EVENT_CONTEXT_VPID              = 5,
 123         LTTNG_EVENT_CONTEXT_TID               = 6,
 124         LTTNG_EVENT_CONTEXT_VTID              = 7,
 125         LTTNG_EVENT_CONTEXT_PPID              = 8,
 126         LTTNG_EVENT_CONTEXT_VPPID             = 9,
 127         LTTNG_EVENT_CONTEXT_PTHREAD_ID        = 10,
 128         LTTNG_EVENT_CONTEXT_HOSTNAME          = 11,
 129         LTTNG_EVENT_CONTEXT_IP                = 12,
 130 };
 131
 132 enum lttng_calibrate_type {
 133         LTTNG_CALIBRATE_FUNCTION              = 0,
 134 };
 135
 136 /* Health component for the health check function. */
 137 enum lttng_health_component {
 138         LTTNG_HEALTH_CMD,
 139         LTTNG_HEALTH_APP_MANAGE,
 140         LTTNG_HEALTH_APP_REG,
 141         LTTNG_HEALTH_KERNEL,
 142         LTTNG_HEALTH_CONSUMER,
 143         LTTNG_HEALTH_HT_CLEANUP,
 144         LTTNG_HEALTH_APP_MANAGE_NOTIFY,
 145         LTTNG_HEALTH_APP_REG_DISPATCH,
 146         LTTNG_HEALTH_ALL,
 147 };
 148
 149 /* Buffer type for a specific domain. */
 150 enum lttng_buffer_type {
 151         LTTNG_BUFFER_PER_PID,   /* Only supported by UST being the default. */
 152         LTTNG_BUFFER_PER_UID,   /* Only supported by UST. */
 153         LTTNG_BUFFER_GLOBAL,    /* Only supported by the Kernel. */
 154 };
 155
 156 /*
 157  * The structures should be initialized to zero before use.
 158  */
 159 #define LTTNG_DOMAIN_PADDING1              12
 160 #define LTTNG_DOMAIN_PADDING2              LTTNG_SYMBOL_NAME_LEN + 32
 161 struct lttng_domain {
 162         enum lttng_domain_type type;
 163         enum lttng_buffer_type buf_type;
 164         char padding[LTTNG_DOMAIN_PADDING1];
 165
 166         union {
 167                 pid_t pid;
 168                 char exec_name[NAME_MAX];
 169                 char padding[LTTNG_DOMAIN_PADDING2];
 170         } attr;
 171 };
 172
 173 /*
 174  * Perf counter attributes
 175  *
 176  * The structures should be initialized to zero before use.
 177  */
 178 #define LTTNG_PERF_EVENT_PADDING1          16
 179 struct lttng_event_perf_counter_ctx {
 180         uint32_t type;
 181         uint64_t config;
 182         char name[LTTNG_SYMBOL_NAME_LEN];
 183
 184         char padding[LTTNG_PERF_EVENT_PADDING1];
 185 };
 186
 187 /*
 188  * Event/channel context
 189  *
 190  * The structures should be initialized to zero before use.
 191  */
 192 #define LTTNG_EVENT_CONTEXT_PADDING1       16
 193 #define LTTNG_EVENT_CONTEXT_PADDING2       LTTNG_SYMBOL_NAME_LEN + 32
 194 struct lttng_event_context {
 195         enum lttng_event_context_type ctx;
 196         char padding[LTTNG_EVENT_CONTEXT_PADDING1];
 197
 198         union {
 199                 struct lttng_event_perf_counter_ctx perf_counter;
 200                 char padding[LTTNG_EVENT_CONTEXT_PADDING2];
 201         } u;
 202 };
 203
 204 /*
 205  * Event probe.
 206  *
 207  * Either addr is used or symbol_name and offset.
 208  *
 209  * The structures should be initialized to zero before use.
 210  */
 211 #define LTTNG_EVENT_PROBE_PADDING1         16
 212 struct lttng_event_probe_attr {
 213         uint64_t addr;
 214
 215         uint64_t offset;
 216         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 217
 218         char padding[LTTNG_EVENT_PROBE_PADDING1];
 219 };
 220
 221 /*
 222  * Function tracer
 223  *
 224  * The structures should be initialized to zero before use.
 225  */
 226 #define LTTNG_EVENT_FUNCTION_PADDING1      16
 227 struct lttng_event_function_attr {
 228         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 229
 230         char padding[LTTNG_EVENT_FUNCTION_PADDING1];
 231 };
 232
 233 /*
 234  * Generic lttng event
 235  *
 236  * The structures should be initialized to zero before use.
 237  */
 238 #define LTTNG_EVENT_PADDING1               15
 239 #define LTTNG_EVENT_PADDING2               LTTNG_SYMBOL_NAME_LEN + 32
 240 struct lttng_event {
 241         enum lttng_event_type type;
 242         char name[LTTNG_SYMBOL_NAME_LEN];
 243
 244         enum lttng_loglevel_type loglevel_type;
 245         int loglevel;
 246
 247         int32_t enabled;        /* Does not apply: -1 */
 248         pid_t pid;
 249         unsigned char filter;   /* filter enabled ? */
 250
 251         char padding[LTTNG_EVENT_PADDING1];
 252
 253         /* Per event type configuration */
 254         union {
 255                 struct lttng_event_probe_attr probe;
 256                 struct lttng_event_function_attr ftrace;
 257
 258                 char padding[LTTNG_EVENT_PADDING2];
 259         } attr;
 260 };
 261
 262 enum lttng_event_field_type {
 263         LTTNG_EVENT_FIELD_OTHER                 = 0,
 264         LTTNG_EVENT_FIELD_INTEGER               = 1,
 265         LTTNG_EVENT_FIELD_ENUM                  = 2,
 266         LTTNG_EVENT_FIELD_FLOAT                 = 3,
 267         LTTNG_EVENT_FIELD_STRING                = 4,
 268 };
 269
 270 #define LTTNG_EVENT_FIELD_PADDING       LTTNG_SYMBOL_NAME_LEN + 32
 271 struct lttng_event_field {
 272         char field_name[LTTNG_SYMBOL_NAME_LEN];
 273         enum lttng_event_field_type type;
 274         char padding[LTTNG_EVENT_FIELD_PADDING];
 275         struct lttng_event event;
 276         int nowrite;
 277 };
 278
 279 /*
 280  * Tracer channel attributes. For both kernel and user-space.
 281  *
 282  * The structures should be initialized to zero before use.
 283  */
 284 #define LTTNG_CHANNEL_ATTR_PADDING1        LTTNG_SYMBOL_NAME_LEN + 12
 285 struct lttng_channel_attr {
 286         int overwrite;                      /* 1: overwrite, 0: discard */
 287         uint64_t subbuf_size;               /* bytes */
 288         uint64_t num_subbuf;                /* power of 2 */
 289         unsigned int switch_timer_interval; /* usec */
 290         unsigned int read_timer_interval;   /* usec */
 291         enum lttng_event_output output;     /* splice, mmap */
 292         /* LTTng 2.1 padding limit */
 293         uint64_t tracefile_size;            /* bytes */
 294         uint64_t tracefile_count;           /* number of tracefiles */
 295         /* LTTng 2.3 padding limit */
 296         unsigned int live_timer_interval;   /* usec */
 297
 298         char padding[LTTNG_CHANNEL_ATTR_PADDING1];
 299 };
 300
 301 /*
 302  * Channel information structure. For both kernel and user-space.
 303  *
 304  * The structures should be initialized to zero before use.
 305  */
 306 #define LTTNG_CHANNEL_PADDING1             16
 307 struct lttng_channel {
 308         char name[LTTNG_SYMBOL_NAME_LEN];
 309         uint32_t enabled;
 310         struct lttng_channel_attr attr;
 311
 312         char padding[LTTNG_CHANNEL_PADDING1];
 313 };
 314
 315 #define LTTNG_CALIBRATE_PADDING1           16
 316 struct lttng_calibrate {
 317         enum lttng_calibrate_type type;
 318
 319         char padding[LTTNG_CALIBRATE_PADDING1];
 320 };
 321
 322 /*
 323  * Basic session information.
 324  *
 325  * This is an 'output data' meaning that it only comes *from* the session
 326  * daemon *to* the lttng client. It's basically a 'human' representation of
 327  * tracing entities (here a session).
 328  *
 329  * The structures should be initialized to zero before use.
 330  */
 331 #define LTTNG_SESSION_PADDING1             12
 332 struct lttng_session {
 333         char name[NAME_MAX];
 334         /* The path where traces are written */
 335         char path[PATH_MAX];
 336         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
 337         uint32_t snapshot_mode;
 338         unsigned int live_timer_interval;       /* usec */
 339
 340         char padding[LTTNG_SESSION_PADDING1];
 341 };
 342
 343 /*
 344  * Handle used as a context for commands.
 345  *
 346  * The structures should be initialized to zero before use.
 347  */
 348 #define LTTNG_HANDLE_PADDING1              16
 349 struct lttng_handle {
 350         char session_name[NAME_MAX];
 351         struct lttng_domain domain;
 352
 353         char padding[LTTNG_HANDLE_PADDING1];
 354 };
 355
 356 /*
 357  * Public LTTng control API
 358  *
 359  * For functions having an lttng domain type as parameter, if a bad value is
 360  * given, NO default is applied and an error is returned.
 361  *
 362  * On success, all functions of the API return 0 or the size of the allocated
 363  * array (in bytes).
 364  *
 365  * On error, a negative value is returned being a specific lttng-tools error
 366  * code which can be humanly interpreted with lttng_strerror(err).
 367  *
 368  * Exceptions to this are noted below.
 369  */
 370
 371 /*
 372  * Create a handle used as a context for every request made to the library.
 373  *
 374  * This handle contains the session name and lttng domain on which the command
 375  * will be executed.
 376  * The returned pointer will be NULL in case of malloc() error.
 377  */
 378 extern struct lttng_handle *lttng_create_handle(const char *session_name,
 379                 struct lttng_domain *domain);
 380
 381 /*
 382  * Destroy an handle.
 383  *
 384  * It free(3) the data pointer returned by lttng_create_handle(), rendering it
 385  * unusable.
 386  */
 387 extern void lttng_destroy_handle(struct lttng_handle *handle);
 388
 389 /*
 390  * Create a tracing session using a name and an optional URL.
 391  *
 392  * If _url_ is NULL, no consumer is created for the session. The name can't be
 393  * NULL here.
 394  */
 395 extern int lttng_create_session(const char *name, const char *url);
 396
 397 /*
 398  * Create a tracing session that will exclusively be used for snapshot meaning
 399  * the session will be in no output mode and every channel enabled for that
 400  * session will be set in overwrite mode and in mmap output since splice is not
 401  * supported.
 402  *
 403  * If an url is given, it will be used to create a default snapshot output
 404  * using it as a destination. If NULL, no output will be defined and an
 405  * add-output call will be needed.
 406  *
 407  * Name can't be NULL.
 408  */
 409 extern int lttng_create_session_snapshot(const char *name,
 410                 const char *snapshot_url);
 411
 412 /*
 413  * Create a session exclusively used for live reading.
 414  *
 415  * In this mode, the switch-timer parameter is forced for each UST channel, a
 416  * live-switch-timer is enabled for kernel channels, manually setting
 417  * switch-timer is forbidden. Synchronization beacons are sent to the relayd,
 418  * indexes are sent and metadata is checked for each packet.
 419  *
 420  * Returns LTTNG_OK on success or a negative error code.
 421  */
 422 extern int lttng_create_session_live(const char *name, const char *url,
 423                 unsigned int timer_interval);
 424
 425 /*
 426  * Destroy a tracing session.
 427  *
 428  * The session will not be usable anymore, tracing will be stopped for all
 429  * registered traces, and the tracing buffers will be flushed.
 430  *
 431  * The name can't be NULL here.
 432  */
 433 extern int lttng_destroy_session(const char *name);
 434
 435 /*
 436  * List all the tracing sessions.
 437  *
 438  * Return the size (number of entries) of the "lttng_session" array. Caller
 439  * must free(3).
 440  */
 441 extern int lttng_list_sessions(struct lttng_session **sessions);
 442
 443 /*
 444  * List the registered domain(s) of a session.
 445  *
 446  * Return the size (number of entries) of the "lttng_domain" array. Caller
 447  * must free(3).
 448  */
 449 extern int lttng_list_domains(const char *session_name,
 450                 struct lttng_domain **domains);
 451
 452 /*
 453  * List the channel(s) of a session.
 454  *
 455  * Return the size (number of entries) of the "lttng_channel" array. Caller
 456  * must free(3).
 457  */
 458 extern int lttng_list_channels(struct lttng_handle *handle,
 459                 struct lttng_channel **channels);
 460
 461 /*
 462  * List the event(s) of a session channel.
 463  *
 464  * Return the size (number of entries) of the "lttng_event" array.
 465  * Caller must free(3).
 466  */
 467 extern int lttng_list_events(struct lttng_handle *handle,
 468                 const char *channel_name, struct lttng_event **events);
 469
 470 /*
 471  * List the available tracepoints of a specific lttng domain.
 472  *
 473  * Return the size (number of entries) of the "lttng_event" array.
 474  * Caller must free(3).
 475  */
 476 extern int lttng_list_tracepoints(struct lttng_handle *handle,
 477                 struct lttng_event **events);
 478
 479 /*
 480  * List the available tracepoints fields of a specific lttng domain.
 481  *
 482  * Return the size (number of entries) of the "lttng_event_field" array.
 483  * Caller must free(3).
 484  */
 485 extern int lttng_list_tracepoint_fields(struct lttng_handle *handle,
 486                 struct lttng_event_field **fields);
 487
 488 /*
 489  * Check if a session daemon is alive.
 490  *
 491  * Return 1 if alive or 0 if not. On error returns a negative value.
 492  */
 493 extern int lttng_session_daemon_alive(void);
 494
 495 /*
 496  * Set the tracing group for the *current* flow of execution.
 497  *
 498  * On success, returns 0 else a negative value on error being a lttng error
 499  * code found in lttng-error.h
 500  */
 501 extern int lttng_set_tracing_group(const char *name);
 502
 503 /*
 504  * Return a human-readable error message for an lttng-tools error code.
 505  *
 506  * Parameter MUST be a negative value or else you'll get a generic message.
 507  */
 508 extern const char *lttng_strerror(int code);
 509
 510 /*
 511  * This call registers an "outside consumer" for a session and an lttng domain.
 512  * No consumer will be spawned and all fds/commands will go through the socket
 513  * path given (socket_path).
 514  *
 515  * NOTE: At the moment, if you use the liblttng-kconsumer, you can only use the
 516  * command socket. The error socket is not supported yet for roaming consumers.
 517  */
 518 extern int lttng_register_consumer(struct lttng_handle *handle,
 519                 const char *socket_path);
 520
 521 /*
 522  * Start tracing for *all* registered traces (kernel and user-space).
 523  */
 524 extern int lttng_start_tracing(const char *session_name);
 525
 526 /*
 527  * Stop tracing for *all* registered traces (kernel and user-space).
 528  *
 529  * This call will wait for data availability for each domain of the session so
 530  * this can take an abritrary amount of time. However, when returning you have
 531  * the guarantee that the data is ready to be read and analyse. Use the
 532  * _no_wait call below to avoid this behavior.
 533  *
 534  * The session_name can't be NULL.
 535  */
 536 extern int lttng_stop_tracing(const char *session_name);
 537
 538 /*
 539  * Behave exactly like lttng_stop_tracing but does not wait for data
 540  * availability.
 541  */
 542 extern int lttng_stop_tracing_no_wait(const char *session_name);
 543
 544 /*
 545  * Add context to event(s) for a specific channel (or for all).
 546  *
 547  * If channel_name is NULL, a lookup of the event's channel is done. If both
 548  * are NULL, the context is applied to all events of all channels.
 549  *
 550  * Note that whatever event_name value is, a context can not be added to an
 551  * event, so we just ignore it for now.
 552  */
 553 extern int lttng_add_context(struct lttng_handle *handle,
 554                 struct lttng_event_context *ctx, const char *event_name,
 555                 const char *channel_name);
 556
 557 /*
 558  * Create or enable an event (or events) for a channel.
 559  *
 560  * If the event you are trying to enable does not exist, it will be created,
 561  * else it is enabled.
 562  * If channel_name is NULL, the default channel is used (channel0).
 563  *
 564  * The handle and ev params can not be NULL.
 565  */
 566 extern int lttng_enable_event(struct lttng_handle *handle,
 567                 struct lttng_event *ev, const char *channel_name);
 568
 569 /*
 570  * Create or enable an event with a specific filter.
 571  *
 572  * If the event you are trying to enable does not exist, it will be created,
 573  * else it is enabled.
 574  * If ev is NULL, all events are enabled with that filter.
 575  * If channel_name is NULL, the default channel is used (channel0) and created
 576  * if not found.
 577  * If filter_expression is NULL, an event without associated filter is
 578  * created.
 579  */
 580 extern int lttng_enable_event_with_filter(struct lttng_handle *handle,
 581                 struct lttng_event *event, const char *channel_name,
 582                 const char *filter_expression);
 583
 584 /*
 585  * Create or enable a channel.
 586  *
 587  * The chan and handle params can not be NULL.
 588  */
 589 extern int lttng_enable_channel(struct lttng_handle *handle,
 590                 struct lttng_channel *chan);
 591
 592 /*
 593  * Disable event(s) of a channel and domain.
 594  *
 595  * If name is NULL, all events are disabled.
 596  * If channel_name is NULL, the default channel is used (channel0).
 597  */
 598 extern int lttng_disable_event(struct lttng_handle *handle,
 599                 const char *name, const char *channel_name);
 600
 601 /*
 602  * Disable channel.
 603  *
 604  */
 605 extern int lttng_disable_channel(struct lttng_handle *handle,
 606                 const char *name);
 607
 608 /*
 609  * Calibrate LTTng overhead.
 610  *
 611  * The chan and handle params can not be NULL.
 612  */
 613 extern int lttng_calibrate(struct lttng_handle *handle,
 614                 struct lttng_calibrate *calibrate);
 615
 616 /*
 617  * Set the default channel attributes for a specific domain and an allocated
 618  * lttng_channel_attr pointer.
 619  *
 620  * If one or both arguments are NULL, nothing happens.
 621  */
 622 extern void lttng_channel_set_default_attr(struct lttng_domain *domain,
 623                 struct lttng_channel_attr *attr);
 624
 625 /*
 626  * Set URL for a consumer for a session and domain.
 627  *
 628  * Both data and control URL must be defined. If both URLs are the same, only
 629  * the control URL is used even for network streaming.
 630  *
 631  * Default port are 5342 and 5343 respectively for control and data which uses
 632  * the TCP protocol.
 633  */
 634 extern int lttng_set_consumer_url(struct lttng_handle *handle,
 635                 const char *control_url, const char *data_url);
 636
 637 /*
 638  * Enable the consumer for a session and domain.
 639  */
 640 extern LTTNG_DEPRECATED("This call is now obsolete.")
 641 int lttng_enable_consumer(struct lttng_handle *handle);
 642
 643 /*
 644  * Disable consumer for a session and domain.
 645  */
 646 extern LTTNG_DEPRECATED("This call is now obsolete.")
 647 int lttng_disable_consumer(struct lttng_handle *handle);
 648
 649 /*
 650  * Check session daemon health for a specific component.
 651  *
 652  * Return 0 if health is OK or 1 if BAD. A returned value of -1 indicate that
 653  * the control library was not able to connect to the session daemon health
 654  * socket.
 655  *
 656  * Any other positive value is an lttcomm error which can be translate with
 657  * lttng_strerror().
 658  *
 659  * Please see lttng-health-check(3) man page for more information.
 660  */
 661 extern int lttng_health_check(enum lttng_health_component c);
 662
 663 /*
 664  * For a given session name, this call checks if the data is ready to be read
 665  * or is still being extracted by the consumer(s) (pending) hence not ready to
 666  * be used by any readers.
 667  *
 668  * Return 0 if there is _no_ data pending in the buffers thus having a
 669  * guarantee that the data can be read safely. Else, return 1 if there is still
 670  * traced data is pending. On error, a negative value is returned and readable
 671  * by lttng_strerror().
 672  */
 673 extern int lttng_data_pending(const char *session_name);
 674
 675 #ifdef __cplusplus
 676 }
 677 #endif
 678
 679 #endif /* LTTNG_H */