trace2.h

   1 #ifndef TRACE2_H
   2 #define TRACE2_H
   3
   4 /**
   5  * The Trace2 API can be used to print debug, performance, and telemetry
   6  * information to stderr or a file.  The Trace2 feature is inactive unless
   7  * explicitly enabled by enabling one or more Trace2 Targets.
   8  *
   9  * The Trace2 API is intended to replace the existing (Trace1)
  10  * printf-style tracing provided by the existing `GIT_TRACE` and
  11  * `GIT_TRACE_PERFORMANCE` facilities.  During initial implementation,
  12  * Trace2 and Trace1 may operate in parallel.
  13  *
  14  * The Trace2 API defines a set of high-level messages with known fields,
  15  * such as (`start`: `argv`) and (`exit`: {`exit-code`, `elapsed-time`}).
  16  *
  17  * Trace2 instrumentation throughout the Git code base sends Trace2
  18  * messages to the enabled Trace2 Targets.  Targets transform these
  19  * messages content into purpose-specific formats and write events to
  20  * their data streams.  In this manner, the Trace2 API can drive
  21  * many different types of analysis.
  22  *
  23  * Targets are defined using a VTable allowing easy extension to other
  24  * formats in the future.  This might be used to define a binary format,
  25  * for example.
  26  *
  27  * Trace2 is controlled using `trace2.*` config values in the system and
  28  * global config files and `GIT_TRACE2*` environment variables.  Trace2 does
  29  * not read from repo local or worktree config files or respect `-c`
  30  * command line config settings.
  31  *
  32  * For more info about: trace2 targets, conventions for public functions and
  33  * macros, trace2 target formats and examples on trace2 API usage refer to
  34  * Documentation/technical/api-trace2.txt
  35  *
  36  */
  37
  38 struct child_process;
  39 struct repository;
  40 struct json_writer;
  41
  42 /*
  43  * The public TRACE2 routines are grouped into the following groups:
  44  *
  45  * [] trace2_initialize -- initialization.
  46  * [] trace2_cmd_*      -- emit command/control messages.
  47  * [] trace2_child*     -- emit child start/stop messages.
  48  * [] trace2_exec*      -- emit exec start/stop messages.
  49  * [] trace2_thread*    -- emit thread start/stop messages.
  50  * [] trace2_def*       -- emit definition/parameter mesasges.
  51  * [] trace2_region*    -- emit region nesting messages.
  52  * [] trace2_data*      -- emit region/thread/repo data messages.
  53  * [] trace2_printf*    -- legacy trace[1] messages.
  54  */
  55
  56 /*
  57  * Initialize the TRACE2 clock and do nothing else, in particular
  58  * no mallocs, no system inspection, and no environment inspection.
  59  *
  60  * This should be called at the very top of main() to capture the
  61  * process start time.  This is intended to reduce chicken-n-egg
  62  * bootstrap pressure.
  63  *
  64  * It is safe to call this more than once.  This allows capturing
  65  * absolute startup costs on Windows which uses a little trickery
  66  * to do setup work before common-main.c:main() is called.
  67  *
  68  * The main trace2_initialize_fl() may be called a little later
  69  * after more infrastructure is established.
  70  */
  71 void trace2_initialize_clock(void);
  72
  73 /*
  74  * Initialize TRACE2 tracing facility if any of the builtin TRACE2
  75  * targets are enabled in the system config or the environment.
  76  * This includes setting up the Trace2 thread local storage (TLS).
  77  * Emits a 'version' message containing the version of git
  78  * and the Trace2 protocol.
  79  *
  80  * This function should be called from `main()` as early as possible in
  81  * the life of the process after essential process initialization.
  82  *
  83  * Cleanup/Termination is handled automatically by a registered
  84  * atexit() routine.
  85  */
  86 void trace2_initialize_fl(const char *file, int line);
  87
  88 #define trace2_initialize() trace2_initialize_fl(__FILE__, __LINE__)
  89
  90 /*
  91  * Return 1 if trace2 is enabled (at least one target is active).
  92  */
  93 int trace2_is_enabled(void);
  94
  95 /*
  96  * Emit a 'start' event with the original (unmodified) argv.
  97  */
  98 void trace2_cmd_start_fl(const char *file, int line, const char **argv);
  99
 100 #define trace2_cmd_start(argv) trace2_cmd_start_fl(__FILE__, __LINE__, (argv))
 101
 102 /*
 103  * Emit an 'exit' event.
 104  */
 105 void trace2_cmd_exit_fl(const char *file, int line, int code);
 106
 107 #define trace2_cmd_exit(code) (trace2_cmd_exit_fl(__FILE__, __LINE__, (code)))
 108
 109 /*
 110  * Emit an 'error' event.
 111  *
 112  * Write an error message to the TRACE2 targets.
 113  */
 114 void trace2_cmd_error_va_fl(const char *file, int line, const char *fmt,
 115                             va_list ap);
 116
 117 #define trace2_cmd_error_va(fmt, ap) \
 118         trace2_cmd_error_va_fl(__FILE__, __LINE__, (fmt), (ap))
 119
 120 /*
 121  * Emit a 'pathname' event with the canonical pathname of the current process
 122  * This gives post-processors a simple field to identify the command without
 123  * having to parse the argv.  For example, to distinguish invocations from
 124  * installed versus debug executables.
 125  */
 126 void trace2_cmd_path_fl(const char *file, int line, const char *pathname);
 127
 128 #define trace2_cmd_path(p) trace2_cmd_path_fl(__FILE__, __LINE__, (p))
 129
 130 /*
 131  * Emit an 'ancestry' event with the process name of the current process's
 132  * parent process.
 133  * This gives post-processors a way to determine what invoked the command and
 134  * learn more about usage patterns.
 135  */
 136 void trace2_cmd_ancestry_fl(const char *file, int line, const char **parent_names);
 137
 138 #define trace2_cmd_ancestry(v) trace2_cmd_ancestry_fl(__FILE__, __LINE__, (v))
 139
 140 /*
 141  * Emit a 'cmd_name' event with the canonical name of the command.
 142  * This gives post-processors a simple field to identify the command
 143  * without having to parse the argv.
 144  */
 145 void trace2_cmd_name_fl(const char *file, int line, const char *name);
 146
 147 #define trace2_cmd_name(v) trace2_cmd_name_fl(__FILE__, __LINE__, (v))
 148
 149 /*
 150  * Emit a 'cmd_mode' event to further describe the command being run.
 151  * For example, "checkout" can checkout a single file or can checkout a
 152  * different branch.  This gives post-processors a simple field to compare
 153  * equivalent commands without having to parse the argv.
 154  */
 155 void trace2_cmd_mode_fl(const char *file, int line, const char *mode);
 156
 157 #define trace2_cmd_mode(sv) trace2_cmd_mode_fl(__FILE__, __LINE__, (sv))
 158
 159 /*
 160  * Emits an "alias" message containing the alias used and the argument
 161  * expansion.
 162  */
 163 void trace2_cmd_alias_fl(const char *file, int line, const char *alias,
 164                          const char **argv);
 165
 166 #define trace2_cmd_alias(alias, argv) \
 167         trace2_cmd_alias_fl(__FILE__, __LINE__, (alias), (argv))
 168
 169 /*
 170  * Emit one or more 'def_param' events for "important" configuration
 171  * settings.
 172  *
 173  * Use the TR2_SYSENV_CFG_PARAM setting to register a comma-separated
 174  * list of patterns configured important.  For example:
 175  *     git config --system trace2.configParams 'core.*,remote.*.url'
 176  * or:
 177  *     GIT_TRACE2_CONFIG_PARAMS=core.*,remote.*.url"
 178  *
 179  * Note: this routine does a read-only iteration on the config data
 180  * (using read_early_config()), so it must not be called until enough
 181  * of the process environment has been established.  This includes the
 182  * location of the git and worktree directories, expansion of any "-c"
 183  * and "-C" command line options, and etc.
 184  */
 185 void trace2_cmd_list_config_fl(const char *file, int line);
 186
 187 #define trace2_cmd_list_config() trace2_cmd_list_config_fl(__FILE__, __LINE__)
 188
 189 /*
 190  * Emit one or more 'def_param' events for "important" environment variables.
 191  *
 192  * Use the TR2_SYSENV_ENV_VARS setting to register a comma-separated list of
 193  * environment variables considered important.  For example:
 194  *     git config --system trace2.envVars 'GIT_HTTP_USER_AGENT,GIT_CONFIG'
 195  * or:
 196  *     GIT_TRACE2_ENV_VARS="GIT_HTTP_USER_AGENT,GIT_CONFIG"
 197  */
 198 void trace2_cmd_list_env_vars_fl(const char *file, int line);
 199
 200 #define trace2_cmd_list_env_vars() trace2_cmd_list_env_vars_fl(__FILE__, __LINE__)
 201
 202 /*
 203  * Emit a "def_param" event for the given config key/value pair IF
 204  * we consider the key to be "important".
 205  *
 206  * Use this for new/updated config settings created/updated after
 207  * trace2_cmd_list_config() is called.
 208  */
 209 void trace2_cmd_set_config_fl(const char *file, int line, const char *key,
 210                               const char *value);
 211
 212 #define trace2_cmd_set_config(k, v) \
 213         trace2_cmd_set_config_fl(__FILE__, __LINE__, (k), (v))
 214
 215 /**
 216  * Emits a "child_start" message containing the "child-id",
 217  * "child-argv", and "child-classification".
 218  *
 219  * Before calling optionally set "cmd->trace2_child_class" to a string
 220  * describing the type of the child process.  For example, "editor" or
 221  * "pager".
 222  *
 223  * This function assigns a unique "child-id" to `cmd->trace2_child_id`.
 224  * This field is used later during the "child_exit" message to associate
 225  * it with the "child_start" message.
 226  *
 227  * This function should be called before spawning the child process.
 228  */
 229 void trace2_child_start_fl(const char *file, int line,
 230                            struct child_process *cmd);
 231
 232 #define trace2_child_start(cmd) trace2_child_start_fl(__FILE__, __LINE__, (cmd))
 233
 234 /**
 235  * Emits a "child_exit" message containing the "child-id",
 236  * the child's elapsed time and exit-code.
 237  *
 238  * The reported elapsed time includes the process creation overhead and
 239  * time spend waiting for it to exit, so it may be slightly longer than
 240  * the time reported by the child itself.
 241  *
 242  * This function should be called after reaping the child process.
 243  */
 244 void trace2_child_exit_fl(const char *file, int line, struct child_process *cmd,
 245                           int child_exit_code);
 246
 247 #define trace2_child_exit(cmd, code) \
 248         trace2_child_exit_fl(__FILE__, __LINE__, (cmd), (code))
 249
 250 /**
 251  * Emits a "child_ready" message containing the "child-id" and a flag
 252  * indicating whether the child was considered "ready" when we
 253  * released it.
 254  *
 255  * This function should be called after starting a daemon process in
 256  * the background (and after giving it sufficient time to boot
 257  * up) to indicate that we no longer control or own it.
 258  *
 259  * The "ready" argument should contain one of { "ready", "timeout",
 260  * "error" } to indicate the state of the running daemon when we
 261  * released it.
 262  *
 263  * If the daemon process fails to start or it exits or is terminated
 264  * while we are still waiting for it, the caller should emit a
 265  * regular "child_exit" to report the normal process exit information.
 266  *
 267  */
 268 void trace2_child_ready_fl(const char *file, int line,
 269                            struct child_process *cmd,
 270                            const char *ready);
 271
 272 #define trace2_child_ready(cmd, ready) \
 273         trace2_child_ready_fl(__FILE__, __LINE__, (cmd), (ready))
 274
 275 /**
 276  * Emit an 'exec' event prior to calling one of exec(), execv(),
 277  * execvp(), and etc.  On Unix-derived systems, this will be the
 278  * last event emitted for the current process, unless the exec
 279  * fails.  On Windows, exec() behaves like 'child_start' and a
 280  * waitpid(), so additional events may be emitted.
 281  *
 282  * Returns a unique "exec-id".  This value is used later
 283  * if the exec() fails and a "exec-result" message is necessary.
 284  */
 285 int trace2_exec_fl(const char *file, int line, const char *exe,
 286                    const char **argv);
 287
 288 #define trace2_exec(exe, argv) trace2_exec_fl(__FILE__, __LINE__, (exe), (argv))
 289
 290 /**
 291  * Emit an 'exec_result' when possible.  On Unix-derived systems,
 292  * this should be called after exec() returns (which only happens
 293  * when there is an error starting the new process).  On Windows,
 294  * this should be called after the waitpid().
 295  *
 296  * The "exec_id" should be the value returned from trace2_exec().
 297  */
 298 void trace2_exec_result_fl(const char *file, int line, int exec_id, int code);
 299
 300 #define trace2_exec_result(id, code) \
 301         trace2_exec_result_fl(__FILE__, __LINE__, (id), (code))
 302
 303 /*
 304  * Emit a 'thread_start' event.  This must be called from inside the
 305  * thread-proc to set up the trace2 TLS data for the thread.
 306  *
 307  * Thread names should be descriptive, like "preload_index".
 308  * Thread names will be decorated with an instance number automatically.
 309  */
 310 void trace2_thread_start_fl(const char *file, int line,
 311                             const char *thread_name);
 312
 313 #define trace2_thread_start(thread_name) \
 314         trace2_thread_start_fl(__FILE__, __LINE__, (thread_name))
 315
 316 /*
 317  * Emit a 'thread_exit' event.  This must be called from inside the
 318  * thread-proc to report thread-specific data and cleanup TLS data
 319  * for the thread.
 320  */
 321 void trace2_thread_exit_fl(const char *file, int line);
 322
 323 #define trace2_thread_exit() trace2_thread_exit_fl(__FILE__, __LINE__)
 324
 325 /*
 326  * Emits a "def_param" message containing a key/value pair.
 327  *
 328  * This message is intended to report some global aspect of the current
 329  * command, such as a configuration setting or command line switch that
 330  * significantly affects program performance or behavior, such as
 331  * `core.abbrev`, `status.showUntrackedFiles`, or `--no-ahead-behind`.
 332  */
 333 void trace2_def_param_fl(const char *file, int line, const char *param,
 334                          const char *value);
 335
 336 #define trace2_def_param(param, value) \
 337         trace2_def_param_fl(__FILE__, __LINE__, (param), (value))
 338
 339 /*
 340  * Tell trace2 about a newly instantiated repo object and assign
 341  * a trace2-repo-id to be used in subsequent activity events.
 342  *
 343  * Emits a 'worktree' event for this repo instance.
 344  *
 345  * Region and data messages may refer to this repo-id.
 346  *
 347  * The main/top-level repository will have repo-id value 1 (aka "r1").
 348  *
 349  * The repo-id field is in anticipation of future in-proc submodule
 350  * repositories.
 351  */
 352 void trace2_def_repo_fl(const char *file, int line, struct repository *repo);
 353
 354 #define trace2_def_repo(repo) trace2_def_repo_fl(__FILE__, __LINE__, repo)
 355
 356 /**
 357  * Emit a 'region_enter' event for <category>.<label> with optional
 358  * repo-id and printf message.
 359  *
 360  * This function pushes a new region nesting stack level on the current
 361  * thread and starts a clock for the new stack frame.
 362  *
 363  * The `category` field is an arbitrary category name used to classify
 364  * regions by feature area, such as "status" or "index".  At this time
 365  * it is only just printed along with the rest of the message.  It may
 366  * be used in the future to filter messages.
 367  *
 368  * The `label` field is an arbitrary label used to describe the activity
 369  * being started, such as "read_recursive" or "do_read_index".
 370  *
 371  * The `repo` field, if set, will be used to get the "repo-id", so that
 372  * recursive operations can be attributed to the correct repository.
 373  */
 374 void trace2_region_enter_fl(const char *file, int line, const char *category,
 375                             const char *label, const struct repository *repo, ...);
 376
 377 #define trace2_region_enter(category, label, repo) \
 378         trace2_region_enter_fl(__FILE__, __LINE__, (category), (label), (repo))
 379
 380 void trace2_region_enter_printf_va_fl(const char *file, int line,
 381                                       const char *category, const char *label,
 382                                       const struct repository *repo,
 383                                       const char *fmt, va_list ap);
 384
 385 #define trace2_region_enter_printf_va(category, label, repo, fmt, ap)    \
 386         trace2_region_enter_printf_va_fl(__FILE__, __LINE__, (category), \
 387                                          (label), (repo), (fmt), (ap))
 388
 389 void trace2_region_enter_printf_fl(const char *file, int line,
 390                                    const char *category, const char *label,
 391                                    const struct repository *repo,
 392                                    const char *fmt, ...);
 393
 394 #define trace2_region_enter_printf(category, label, repo, ...)                 \
 395         trace2_region_enter_printf_fl(__FILE__, __LINE__, (category), (label), \
 396                                       (repo), __VA_ARGS__)
 397
 398 /**
 399  * Emit a 'region_leave' event for <category>.<label> with optional
 400  * repo-id and printf message.
 401  *
 402  * Leave current nesting level and report the elapsed time spent
 403  * in this nesting level.
 404  *
 405  * The `category`, `label`, and `repo` fields are the same as
 406  * trace2_region_enter_fl. The `category` and `label` do not
 407  * need to match the corresponding "region_enter" message,
 408  * but it makes the data stream easier to understand.
 409  */
 410 void trace2_region_leave_fl(const char *file, int line, const char *category,
 411                             const char *label, const struct repository *repo, ...);
 412
 413 #define trace2_region_leave(category, label, repo) \
 414         trace2_region_leave_fl(__FILE__, __LINE__, (category), (label), (repo))
 415
 416 void trace2_region_leave_printf_va_fl(const char *file, int line,
 417                                       const char *category, const char *label,
 418                                       const struct repository *repo,
 419                                       const char *fmt, va_list ap);
 420
 421 #define trace2_region_leave_printf_va(category, label, repo, fmt, ap)    \
 422         trace2_region_leave_printf_va_fl(__FILE__, __LINE__, (category), \
 423                                          (label), (repo), (fmt), (ap))
 424
 425 void trace2_region_leave_printf_fl(const char *file, int line,
 426                                    const char *category, const char *label,
 427                                    const struct repository *repo,
 428                                    const char *fmt, ...);
 429
 430 #define trace2_region_leave_printf(category, label, repo, ...)                 \
 431         trace2_region_leave_printf_fl(__FILE__, __LINE__, (category), (label), \
 432                                       (repo), __VA_ARGS__)
 433
 434 /**
 435  * Emit a key-value pair 'data' event of the form <category>.<key> = <value>.
 436  * This event implicitly contains information about thread, nesting region,
 437  * and optional repo-id.
 438  * This could be used to print the number of files in a directory during
 439  * a multi-threaded recursive tree walk.
 440  *
 441  * On event-based TRACE2 targets, this generates a 'data' event suitable
 442  * for post-processing.  On printf-based TRACE2 targets, this is converted
 443  * into a fixed-format printf message.
 444  */
 445 void trace2_data_string_fl(const char *file, int line, const char *category,
 446                            const struct repository *repo, const char *key,
 447                            const char *value);
 448
 449 #define trace2_data_string(category, repo, key, value)                       \
 450         trace2_data_string_fl(__FILE__, __LINE__, (category), (repo), (key), \
 451                               (value))
 452
 453 void trace2_data_intmax_fl(const char *file, int line, const char *category,
 454                            const struct repository *repo, const char *key,
 455                            intmax_t value);
 456
 457 #define trace2_data_intmax(category, repo, key, value)                       \
 458         trace2_data_intmax_fl(__FILE__, __LINE__, (category), (repo), (key), \
 459                               (value))
 460
 461 void trace2_data_json_fl(const char *file, int line, const char *category,
 462                          const struct repository *repo, const char *key,
 463                          const struct json_writer *jw);
 464
 465 #define trace2_data_json(category, repo, key, value)                       \
 466         trace2_data_json_fl(__FILE__, __LINE__, (category), (repo), (key), \
 467                             (value))
 468
 469 /*
 470  * Emit a 'printf' event.
 471  *
 472  * Write an arbitrary formatted message to the TRACE2 targets.  These
 473  * text messages should be considered as human-readable strings without
 474  * any formatting guidelines.  Post-processors may choose to ignore
 475  * them.
 476  */
 477 void trace2_printf_va_fl(const char *file, int line, const char *fmt,
 478                          va_list ap);
 479
 480 #define trace2_printf_va(fmt, ap) \
 481         trace2_printf_va_fl(__FILE__, __LINE__, (fmt), (ap))
 482
 483 void trace2_printf_fl(const char *file, int line, const char *fmt, ...);
 484
 485 #define trace2_printf(...) trace2_printf_fl(__FILE__, __LINE__, __VA_ARGS__)
 486
 487 /*
 488  * Optional platform-specific code to dump information about the
 489  * current and any parent process(es).  This is intended to allow
 490  * post-processors to know who spawned this git instance and anything
 491  * else that the platform may be able to tell us about the current process.
 492  */
 493
 494 enum trace2_process_info_reason {
 495         TRACE2_PROCESS_INFO_STARTUP,
 496         TRACE2_PROCESS_INFO_EXIT,
 497 };
 498
 499 void trace2_collect_process_info(enum trace2_process_info_reason reason);
 500
 501 const char *trace2_session_id(void);
 502
 503 #endif /* TRACE2_H */