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Diffstat (limited to 'trace2.h')
| -rw-r--r-- | trace2.h | 584 |
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diff --git a/trace2.h b/trace2.h new file mode 100644 index 0000000..4ced30c --- /dev/null +++ b/trace2.h @@ -0,0 +1,584 @@ +#ifndef TRACE2_H +#define TRACE2_H + +/** + * The Trace2 API can be used to print debug, performance, and telemetry + * information to stderr or a file. The Trace2 feature is inactive unless + * explicitly enabled by enabling one or more Trace2 Targets. + * + * The Trace2 API is intended to replace the existing (Trace1) + * printf-style tracing provided by the existing `GIT_TRACE` and + * `GIT_TRACE_PERFORMANCE` facilities. During initial implementation, + * Trace2 and Trace1 may operate in parallel. + * + * The Trace2 API defines a set of high-level messages with known fields, + * such as (`start`: `argv`) and (`exit`: {`exit-code`, `elapsed-time`}). + * + * Trace2 instrumentation throughout the Git code base sends Trace2 + * messages to the enabled Trace2 Targets. Targets transform these + * messages content into purpose-specific formats and write events to + * their data streams. In this manner, the Trace2 API can drive + * many different types of analysis. + * + * Targets are defined using a VTable allowing easy extension to other + * formats in the future. This might be used to define a binary format, + * for example. + * + * Trace2 is controlled using `trace2.*` config values in the system and + * global config files and `GIT_TRACE2*` environment variables. Trace2 does + * not read from repo local or worktree config files or respect `-c` + * command line config settings. + * + * For more info about: trace2 targets, conventions for public functions and + * macros, trace2 target formats and examples on trace2 API usage refer to + * Documentation/technical/api-trace2.txt + * + */ + +struct child_process; +struct repository; +struct json_writer; + +/* + * The public TRACE2 routines are grouped into the following groups: + * + * [] trace2_initialize -- initialization. + * [] trace2_cmd_* -- emit command/control messages. + * [] trace2_child* -- emit child start/stop messages. + * [] trace2_exec* -- emit exec start/stop messages. + * [] trace2_thread* -- emit thread start/stop messages. + * [] trace2_def* -- emit definition/parameter mesasges. + * [] trace2_region* -- emit region nesting messages. + * [] trace2_data* -- emit region/thread/repo data messages. + * [] trace2_printf* -- legacy trace[1] messages. + * [] trace2_timer* -- stopwatch timers (messages are deferred). + * [] trace2_counter* -- global counters (messages are deferred). + */ + +/* + * Initialize the TRACE2 clock and do nothing else, in particular + * no mallocs, no system inspection, and no environment inspection. + * + * This should be called at the very top of main() to capture the + * process start time. This is intended to reduce chicken-n-egg + * bootstrap pressure. + * + * It is safe to call this more than once. This allows capturing + * absolute startup costs on Windows which uses a little trickery + * to do setup work before common-main.c:main() is called. + * + * The main trace2_initialize_fl() may be called a little later + * after more infrastructure is established. + */ +void trace2_initialize_clock(void); + +/* + * Initialize TRACE2 tracing facility if any of the builtin TRACE2 + * targets are enabled in the system config or the environment. + * This emits a 'version' message containing the version of git + * and the Trace2 protocol. + * + * This function should be called from `main()` as early as possible in + * the life of the process after essential process initialization. + * + * Cleanup/Termination is handled automatically by a registered + * atexit() routine. + */ +void trace2_initialize_fl(const char *file, int line); + +#define trace2_initialize() trace2_initialize_fl(__FILE__, __LINE__) + +/* + * Return 1 if trace2 is enabled (at least one target is active). + */ +int trace2_is_enabled(void); + +/* + * Emit a 'start' event with the original (unmodified) argv. + */ +void trace2_cmd_start_fl(const char *file, int line, const char **argv); + +#define trace2_cmd_start(argv) trace2_cmd_start_fl(__FILE__, __LINE__, (argv)) + +/* + * Emit an 'exit' event. + */ +void trace2_cmd_exit_fl(const char *file, int line, int code); + +#define trace2_cmd_exit(code) (trace2_cmd_exit_fl(__FILE__, __LINE__, (code))) + +/* + * Emit an 'error' event. + * + * Write an error message to the TRACE2 targets. + */ +void trace2_cmd_error_va_fl(const char *file, int line, const char *fmt, + va_list ap); + +#define trace2_cmd_error_va(fmt, ap) \ + trace2_cmd_error_va_fl(__FILE__, __LINE__, (fmt), (ap)) + +/* + * Emit a 'pathname' event with the canonical pathname of the current process + * This gives post-processors a simple field to identify the command without + * having to parse the argv. For example, to distinguish invocations from + * installed versus debug executables. + */ +void trace2_cmd_path_fl(const char *file, int line, const char *pathname); + +#define trace2_cmd_path(p) trace2_cmd_path_fl(__FILE__, __LINE__, (p)) + +/* + * Emit an 'ancestry' event with the process name of the current process's + * parent process. + * This gives post-processors a way to determine what invoked the command and + * learn more about usage patterns. + */ +void trace2_cmd_ancestry_fl(const char *file, int line, const char **parent_names); + +#define trace2_cmd_ancestry(v) trace2_cmd_ancestry_fl(__FILE__, __LINE__, (v)) + +/* + * Emit a 'cmd_name' event with the canonical name of the command. + * This gives post-processors a simple field to identify the command + * without having to parse the argv. + */ +void trace2_cmd_name_fl(const char *file, int line, const char *name); + +#define trace2_cmd_name(v) trace2_cmd_name_fl(__FILE__, __LINE__, (v)) + +/* + * Emit a 'cmd_mode' event to further describe the command being run. + * For example, "checkout" can checkout a single file or can checkout a + * different branch. This gives post-processors a simple field to compare + * equivalent commands without having to parse the argv. + */ +void trace2_cmd_mode_fl(const char *file, int line, const char *mode); + +#define trace2_cmd_mode(sv) trace2_cmd_mode_fl(__FILE__, __LINE__, (sv)) + +/* + * Emits an "alias" message containing the alias used and the argument + * expansion. + */ +void trace2_cmd_alias_fl(const char *file, int line, const char *alias, + const char **argv); + +#define trace2_cmd_alias(alias, argv) \ + trace2_cmd_alias_fl(__FILE__, __LINE__, (alias), (argv)) + +/* + * Emit one or more 'def_param' events for "important" configuration + * settings. + * + * Use the TR2_SYSENV_CFG_PARAM setting to register a comma-separated + * list of patterns configured important. For example: + * git config --system trace2.configParams 'core.*,remote.*.url' + * or: + * GIT_TRACE2_CONFIG_PARAMS=core.*,remote.*.url" + * + * Note: this routine does a read-only iteration on the config data + * (using read_early_config()), so it must not be called until enough + * of the process environment has been established. This includes the + * location of the git and worktree directories, expansion of any "-c" + * and "-C" command line options, and etc. + */ +void trace2_cmd_list_config_fl(const char *file, int line); + +#define trace2_cmd_list_config() trace2_cmd_list_config_fl(__FILE__, __LINE__) + +/* + * Emit one or more 'def_param' events for "important" environment variables. + * + * Use the TR2_SYSENV_ENV_VARS setting to register a comma-separated list of + * environment variables considered important. For example: + * git config --system trace2.envVars 'GIT_HTTP_USER_AGENT,GIT_CONFIG' + * or: + * GIT_TRACE2_ENV_VARS="GIT_HTTP_USER_AGENT,GIT_CONFIG" + */ +void trace2_cmd_list_env_vars_fl(const char *file, int line); + +#define trace2_cmd_list_env_vars() trace2_cmd_list_env_vars_fl(__FILE__, __LINE__) + +/* + * Emit a "def_param" event for the given config key/value pair IF + * we consider the key to be "important". + * + * Use this for new/updated config settings created/updated after + * trace2_cmd_list_config() is called. + */ +void trace2_cmd_set_config_fl(const char *file, int line, const char *key, + const char *value); + +#define trace2_cmd_set_config(k, v) \ + trace2_cmd_set_config_fl(__FILE__, __LINE__, (k), (v)) + +/** + * Emits a "child_start" message containing the "child-id", + * "child-argv", and "child-classification". + * + * Before calling optionally set "cmd->trace2_child_class" to a string + * describing the type of the child process. For example, "editor" or + * "pager". + * + * This function assigns a unique "child-id" to `cmd->trace2_child_id`. + * This field is used later during the "child_exit" message to associate + * it with the "child_start" message. + * + * This function should be called before spawning the child process. + */ +void trace2_child_start_fl(const char *file, int line, + struct child_process *cmd); + +#define trace2_child_start(cmd) trace2_child_start_fl(__FILE__, __LINE__, (cmd)) + +/** + * Emits a "child_exit" message containing the "child-id", + * the child's elapsed time and exit-code. + * + * The reported elapsed time includes the process creation overhead and + * time spend waiting for it to exit, so it may be slightly longer than + * the time reported by the child itself. + * + * This function should be called after reaping the child process. + */ +void trace2_child_exit_fl(const char *file, int line, struct child_process *cmd, + int child_exit_code); + +#define trace2_child_exit(cmd, code) \ + trace2_child_exit_fl(__FILE__, __LINE__, (cmd), (code)) + +/** + * Emits a "child_ready" message containing the "child-id" and a flag + * indicating whether the child was considered "ready" when we + * released it. + * + * This function should be called after starting a daemon process in + * the background (and after giving it sufficient time to boot + * up) to indicate that we no longer control or own it. + * + * The "ready" argument should contain one of { "ready", "timeout", + * "error" } to indicate the state of the running daemon when we + * released it. + * + * If the daemon process fails to start or it exits or is terminated + * while we are still waiting for it, the caller should emit a + * regular "child_exit" to report the normal process exit information. + * + */ +void trace2_child_ready_fl(const char *file, int line, + struct child_process *cmd, + const char *ready); + +#define trace2_child_ready(cmd, ready) \ + trace2_child_ready_fl(__FILE__, __LINE__, (cmd), (ready)) + +/** + * Emit an 'exec' event prior to calling one of exec(), execv(), + * execvp(), and etc. On Unix-derived systems, this will be the + * last event emitted for the current process, unless the exec + * fails. On Windows, exec() behaves like 'child_start' and a + * waitpid(), so additional events may be emitted. + * + * Returns a unique "exec-id". This value is used later + * if the exec() fails and a "exec-result" message is necessary. + */ +int trace2_exec_fl(const char *file, int line, const char *exe, + const char **argv); + +#define trace2_exec(exe, argv) trace2_exec_fl(__FILE__, __LINE__, (exe), (argv)) + +/** + * Emit an 'exec_result' when possible. On Unix-derived systems, + * this should be called after exec() returns (which only happens + * when there is an error starting the new process). On Windows, + * this should be called after the waitpid(). + * + * The "exec_id" should be the value returned from trace2_exec(). + */ +void trace2_exec_result_fl(const char *file, int line, int exec_id, int code); + +#define trace2_exec_result(id, code) \ + trace2_exec_result_fl(__FILE__, __LINE__, (id), (code)) + +/* + * Emit a 'thread_start' event. This must be called from inside the + * thread-proc to allow the thread to create its own thread-local + * storage. + * + * The thread base name should be descriptive, like "preload_index" or + * taken from the thread-proc function. A unique thread name will be + * created from the given base name and the thread id automatically. + */ +void trace2_thread_start_fl(const char *file, int line, + const char *thread_base_name); + +#define trace2_thread_start(thread_base_name) \ + trace2_thread_start_fl(__FILE__, __LINE__, (thread_base_name)) + +/* + * Emit a 'thread_exit' event. This must be called from inside the + * thread-proc so that the thread can access and clean up its + * thread-local storage. + */ +void trace2_thread_exit_fl(const char *file, int line); + +#define trace2_thread_exit() trace2_thread_exit_fl(__FILE__, __LINE__) + +/* + * Emits a "def_param" message containing a key/value pair. + * + * This message is intended to report some global aspect of the current + * command, such as a configuration setting or command line switch that + * significantly affects program performance or behavior, such as + * `core.abbrev`, `status.showUntrackedFiles`, or `--no-ahead-behind`. + */ +void trace2_def_param_fl(const char *file, int line, const char *param, + const char *value); + +#define trace2_def_param(param, value) \ + trace2_def_param_fl(__FILE__, __LINE__, (param), (value)) + +/* + * Tell trace2 about a newly instantiated repo object and assign + * a trace2-repo-id to be used in subsequent activity events. + * + * Emits a 'worktree' event for this repo instance. + * + * Region and data messages may refer to this repo-id. + * + * The main/top-level repository will have repo-id value 1 (aka "r1"). + * + * The repo-id field is in anticipation of future in-proc submodule + * repositories. + */ +void trace2_def_repo_fl(const char *file, int line, struct repository *repo); + +#define trace2_def_repo(repo) trace2_def_repo_fl(__FILE__, __LINE__, repo) + +/** + * Emit a 'region_enter' event for <category>.<label> with optional + * repo-id and printf message. + * + * This function pushes a new region nesting stack level on the current + * thread and starts a clock for the new stack frame. + * + * The `category` field is an arbitrary category name used to classify + * regions by feature area, such as "status" or "index". At this time + * it is only just printed along with the rest of the message. It may + * be used in the future to filter messages. + * + * The `label` field is an arbitrary label used to describe the activity + * being started, such as "read_recursive" or "do_read_index". + * + * The `repo` field, if set, will be used to get the "repo-id", so that + * recursive operations can be attributed to the correct repository. + */ +void trace2_region_enter_fl(const char *file, int line, const char *category, + const char *label, const struct repository *repo, ...); + +#define trace2_region_enter(category, label, repo) \ + trace2_region_enter_fl(__FILE__, __LINE__, (category), (label), (repo)) + +void trace2_region_enter_printf_va_fl(const char *file, int line, + const char *category, const char *label, + const struct repository *repo, + const char *fmt, va_list ap); + +#define trace2_region_enter_printf_va(category, label, repo, fmt, ap) \ + trace2_region_enter_printf_va_fl(__FILE__, __LINE__, (category), \ + (label), (repo), (fmt), (ap)) + +void trace2_region_enter_printf_fl(const char *file, int line, + const char *category, const char *label, + const struct repository *repo, + const char *fmt, ...); + +#define trace2_region_enter_printf(category, label, repo, ...) \ + trace2_region_enter_printf_fl(__FILE__, __LINE__, (category), (label), \ + (repo), __VA_ARGS__) + +/** + * Emit a 'region_leave' event for <category>.<label> with optional + * repo-id and printf message. + * + * Leave current nesting level and report the elapsed time spent + * in this nesting level. + * + * The `category`, `label`, and `repo` fields are the same as + * trace2_region_enter_fl. The `category` and `label` do not + * need to match the corresponding "region_enter" message, + * but it makes the data stream easier to understand. + */ +void trace2_region_leave_fl(const char *file, int line, const char *category, + const char *label, const struct repository *repo, ...); + +#define trace2_region_leave(category, label, repo) \ + trace2_region_leave_fl(__FILE__, __LINE__, (category), (label), (repo)) + +void trace2_region_leave_printf_va_fl(const char *file, int line, + const char *category, const char *label, + const struct repository *repo, + const char *fmt, va_list ap); + +#define trace2_region_leave_printf_va(category, label, repo, fmt, ap) \ + trace2_region_leave_printf_va_fl(__FILE__, __LINE__, (category), \ + (label), (repo), (fmt), (ap)) + +void trace2_region_leave_printf_fl(const char *file, int line, + const char *category, const char *label, + const struct repository *repo, + const char *fmt, ...); + +#define trace2_region_leave_printf(category, label, repo, ...) \ + trace2_region_leave_printf_fl(__FILE__, __LINE__, (category), (label), \ + (repo), __VA_ARGS__) + +/** + * Emit a key-value pair 'data' event of the form <category>.<key> = <value>. + * This event implicitly contains information about thread, nesting region, + * and optional repo-id. + * This could be used to print the number of files in a directory during + * a multi-threaded recursive tree walk. + * + * On event-based TRACE2 targets, this generates a 'data' event suitable + * for post-processing. On printf-based TRACE2 targets, this is converted + * into a fixed-format printf message. + */ +void trace2_data_string_fl(const char *file, int line, const char *category, + const struct repository *repo, const char *key, + const char *value); + +#define trace2_data_string(category, repo, key, value) \ + trace2_data_string_fl(__FILE__, __LINE__, (category), (repo), (key), \ + (value)) + +void trace2_data_intmax_fl(const char *file, int line, const char *category, + const struct repository *repo, const char *key, + intmax_t value); + +#define trace2_data_intmax(category, repo, key, value) \ + trace2_data_intmax_fl(__FILE__, __LINE__, (category), (repo), (key), \ + (value)) + +void trace2_data_json_fl(const char *file, int line, const char *category, + const struct repository *repo, const char *key, + const struct json_writer *jw); + +#define trace2_data_json(category, repo, key, value) \ + trace2_data_json_fl(__FILE__, __LINE__, (category), (repo), (key), \ + (value)) + +/* + * Emit a 'printf' event. + * + * Write an arbitrary formatted message to the TRACE2 targets. These + * text messages should be considered as human-readable strings without + * any formatting guidelines. Post-processors may choose to ignore + * them. + */ +void trace2_printf_va_fl(const char *file, int line, const char *fmt, + va_list ap); + +#define trace2_printf_va(fmt, ap) \ + trace2_printf_va_fl(__FILE__, __LINE__, (fmt), (ap)) + +void trace2_printf_fl(const char *file, int line, const char *fmt, ...); + +#define trace2_printf(...) trace2_printf_fl(__FILE__, __LINE__, __VA_ARGS__) + +/* + * Define the set of stopwatch timers. + * + * We can add more at any time, but they must be defined at compile + * time (to avoid the need to dynamically allocate and synchronize + * them between different threads). + * + * These must start at 0 and be contiguous (because we use them + * elsewhere as array indexes). + * + * Any values added to this enum must also be added to the + * `tr2_timer_metadata[]` in `trace2/tr2_tmr.c`. + */ +enum trace2_timer_id { + /* + * Define two timers for testing. See `t/helper/test-trace2.c`. + * These can be used for ad hoc testing, but should not be used + * for permanent analysis code. + */ + TRACE2_TIMER_ID_TEST1 = 0, /* emits summary event only */ + TRACE2_TIMER_ID_TEST2, /* emits summary and thread events */ + + /* Add additional timer definitions before here. */ + TRACE2_NUMBER_OF_TIMERS +}; + +/* + * Start/Stop the indicated stopwatch timer in the current thread. + * + * The time spent by the current thread between the _start and _stop + * calls will be added to the thread's partial sum for this timer. + * + * Timer events are emitted at thread and program exit. + * + * Note: Since the stopwatch API routines do not generate individual + * events, they do not take (file, line) arguments. Similarly, the + * category and timer name values are defined at compile-time in the + * timer definitions array, so they are not needed here in the API. + */ +void trace2_timer_start(enum trace2_timer_id tid); +void trace2_timer_stop(enum trace2_timer_id tid); + +/* + * Define the set of global counters. + * + * We can add more at any time, but they must be defined at compile + * time (to avoid the need to dynamically allocate and synchronize + * them between different threads). + * + * These must start at 0 and be contiguous (because we use them + * elsewhere as array indexes). + * + * Any values added to this enum be also be added to the + * `tr2_counter_metadata[]` in `trace2/tr2_tr2_ctr.c`. + */ +enum trace2_counter_id { + /* + * Define two counters for testing. See `t/helper/test-trace2.c`. + * These can be used for ad hoc testing, but should not be used + * for permanent analysis code. + */ + TRACE2_COUNTER_ID_TEST1 = 0, /* emits summary event only */ + TRACE2_COUNTER_ID_TEST2, /* emits summary and thread events */ + + /* Add additional counter definitions before here. */ + TRACE2_NUMBER_OF_COUNTERS +}; + +/* + * Increase the named global counter by value. + * + * Note that this adds `value` to the current thread's partial sum for + * this counter (without locking) and that the complete sum is not + * available until all threads have exited, so it does not return the + * new value of the counter. + */ +void trace2_counter_add(enum trace2_counter_id cid, uint64_t value); + +/* + * Optional platform-specific code to dump information about the + * current and any parent process(es). This is intended to allow + * post-processors to know who spawned this git instance and anything + * else that the platform may be able to tell us about the current process. + */ + +enum trace2_process_info_reason { + TRACE2_PROCESS_INFO_STARTUP, + TRACE2_PROCESS_INFO_EXIT, +}; + +void trace2_collect_process_info(enum trace2_process_info_reason reason); + +const char *trace2_session_id(void); + +#endif /* TRACE2_H */ |