| #ifndef TRACE_H |
| #define TRACE_H |
| |
| #include "git-compat-util.h" |
| #include "strbuf.h" |
| |
| /** |
| * The trace API can be used to print debug messages to stderr or a file. Trace |
| * code is inactive unless explicitly enabled by setting `GIT_TRACE*` environment |
| * variables. |
| * |
| * The trace implementation automatically adds `timestamp file:line ... \n` to |
| * all trace messages. E.g.: |
| * |
| * ------------ |
| * 23:59:59.123456 git.c:312 trace: built-in: git 'foo' |
| * 00:00:00.000001 builtin/foo.c:99 foo: some message |
| * ------------ |
| * |
| * Bugs & Caveats |
| * -------------- |
| * |
| * GIT_TRACE_* environment variables can be used to tell Git to show |
| * trace output to its standard error stream. Git can often spawn a pager |
| * internally to run its subcommand and send its standard output and |
| * standard error to it. |
| * |
| * Because GIT_TRACE_PERFORMANCE trace is generated only at the very end |
| * of the program with atexit(), which happens after the pager exits, it |
| * would not work well if you send its log to the standard error output |
| * and let Git spawn the pager at the same time. |
| * |
| * As a work around, you can for example use '--no-pager', or set |
| * GIT_TRACE_PERFORMANCE to another file descriptor which is redirected |
| * to stderr, or set GIT_TRACE_PERFORMANCE to a file specified by its |
| * absolute path. |
| * |
| * For example instead of the following command which by default may not |
| * print any performance information: |
| * |
| * ------------ |
| * GIT_TRACE_PERFORMANCE=2 git log -1 |
| * ------------ |
| * |
| * you may want to use: |
| * |
| * ------------ |
| * GIT_TRACE_PERFORMANCE=2 git --no-pager log -1 |
| * ------------ |
| * |
| * or: |
| * |
| * ------------ |
| * GIT_TRACE_PERFORMANCE=3 3>&2 git log -1 |
| * ------------ |
| * |
| * or: |
| * |
| * ------------ |
| * GIT_TRACE_PERFORMANCE=/path/to/log/file git log -1 |
| * ------------ |
| * |
| */ |
| |
| /** |
| * Defines a trace key (or category). The default (for API functions that |
| * don't take a key) is `GIT_TRACE`. |
| * |
| * E.g. to define a trace key controlled by environment variable `GIT_TRACE_FOO`: |
| * |
| * ------------ |
| * static struct trace_key trace_foo = TRACE_KEY_INIT(FOO); |
| * |
| * static void trace_print_foo(const char *message) |
| * { |
| * trace_printf_key(&trace_foo, "%s", message); |
| * } |
| * ------------ |
| * |
| * Note: don't use `const` as the trace implementation stores internal state in |
| * the `trace_key` structure. |
| */ |
| struct trace_key { |
| const char * const key; |
| int fd; |
| unsigned int initialized : 1; |
| unsigned int need_close : 1; |
| }; |
| |
| extern struct trace_key trace_default_key; |
| |
| #define TRACE_KEY_INIT(name) { .key = "GIT_TRACE_" #name } |
| extern struct trace_key trace_perf_key; |
| extern struct trace_key trace_setup_key; |
| |
| void trace_repo_setup(const char *prefix); |
| |
| /** |
| * Checks whether the trace key is enabled. Used to prevent expensive |
| * string formatting before calling one of the printing APIs. |
| */ |
| int trace_want(struct trace_key *key); |
| |
| /** |
| * Enables or disables tracing for the specified key, as if the environment |
| * variable was set to the given value. |
| */ |
| void trace_override_envvar(struct trace_key *key, const char *value); |
| |
| /** |
| * Disables tracing for the specified key, even if the environment variable |
| * was set. |
| */ |
| void trace_disable(struct trace_key *key); |
| |
| /** |
| * Returns nanoseconds since the epoch (01/01/1970), typically used |
| * for performance measurements. |
| * Currently there are high precision timer implementations for Linux (using |
| * `clock_gettime(CLOCK_MONOTONIC)`) and Windows (`QueryPerformanceCounter`). |
| * Other platforms use `gettimeofday` as time source. |
| */ |
| uint64_t getnanotime(void); |
| |
| void trace_command_performance(const char **argv); |
| void trace_verbatim(struct trace_key *key, const void *buf, unsigned len); |
| uint64_t trace_performance_enter(void); |
| |
| /* |
| * TRACE_CONTEXT may be set to __FUNCTION__ if the compiler supports it. The |
| * default is __FILE__, as it is consistent with assert(), and static function |
| * names are not necessarily unique. |
| * |
| * __FILE__ ":" __FUNCTION__ doesn't work with GNUC, as __FILE__ is supplied |
| * by the preprocessor as a string literal, and __FUNCTION__ is filled in by |
| * the compiler as a string constant. |
| */ |
| #ifndef TRACE_CONTEXT |
| # define TRACE_CONTEXT __FILE__ |
| #endif |
| |
| /** |
| * Macros to add the file:line of the calling code, instead of that of |
| * the trace function itself. |
| * |
| * Note: with C99 variadic macros, __VA_ARGS__ must include the last fixed |
| * parameter ('format' in this case). Otherwise, a call without variable |
| * arguments will have a surplus ','. E.g.: |
| * |
| * #define foo(format, ...) bar(format, __VA_ARGS__) |
| * foo("test"); |
| * |
| * will expand to |
| * |
| * bar("test",); |
| * |
| * which is invalid (note the ',)'). With GNUC, '##__VA_ARGS__' drops the |
| * comma, but this is non-standard. |
| */ |
| |
| /** |
| * trace_printf(), accepts "const char *format, ...". |
| * |
| * Prints a formatted message, similar to printf. |
| */ |
| #define trace_printf(...) trace_printf_key(&trace_default_key, __VA_ARGS__) |
| |
| /** |
| * trace_printf_key(), accepts "struct trace_key *key, const char *format, ...". |
| */ |
| #define trace_printf_key(key, ...) \ |
| do { \ |
| if (trace_pass_fl(key)) \ |
| trace_printf_key_fl(TRACE_CONTEXT, __LINE__, key, \ |
| __VA_ARGS__); \ |
| } while (0) |
| |
| /** |
| * trace_argv_printf(), accepts "struct trace_key *key, const char *format, ...)". |
| * |
| * Prints a formatted message, followed by a quoted list of arguments. |
| */ |
| #define trace_argv_printf(argv, ...) \ |
| do { \ |
| if (trace_pass_fl(&trace_default_key)) \ |
| trace_argv_printf_fl(TRACE_CONTEXT, __LINE__, \ |
| argv, __VA_ARGS__); \ |
| } while (0) |
| |
| /** |
| * trace_strbuf(), accepts "struct trace_key *key, const struct strbuf *data". |
| * |
| * Prints the strbuf, without additional formatting (i.e. doesn't |
| * choke on `%` or even `\0`). |
| */ |
| #define trace_strbuf(key, data) \ |
| do { \ |
| if (trace_pass_fl(key)) \ |
| trace_strbuf_fl(TRACE_CONTEXT, __LINE__, key, data);\ |
| } while (0) |
| |
| /** |
| * trace_performance(), accepts "uint64_t nanos, const char *format, ...". |
| * |
| * Prints elapsed time (in nanoseconds) if GIT_TRACE_PERFORMANCE is enabled. |
| * |
| * Example: |
| * ------------ |
| * uint64_t t = 0; |
| * for (;;) { |
| * // ignore |
| * t -= getnanotime(); |
| * // code section to measure |
| * t += getnanotime(); |
| * // ignore |
| * } |
| * trace_performance(t, "frotz"); |
| * ------------ |
| */ |
| #define trace_performance(nanos, ...) \ |
| do { \ |
| if (trace_pass_fl(&trace_perf_key)) \ |
| trace_performance_fl(TRACE_CONTEXT, __LINE__, nanos,\ |
| __VA_ARGS__); \ |
| } while (0) |
| |
| /** |
| * trace_performance_since(), accepts "uint64_t start, const char *format, ...". |
| * |
| * Prints elapsed time since 'start' if GIT_TRACE_PERFORMANCE is enabled. |
| * |
| * Example: |
| * ------------ |
| * uint64_t start = getnanotime(); |
| * // code section to measure |
| * trace_performance_since(start, "foobar"); |
| * ------------ |
| */ |
| #define trace_performance_since(start, ...) \ |
| do { \ |
| if (trace_pass_fl(&trace_perf_key)) \ |
| trace_performance_fl(TRACE_CONTEXT, __LINE__, \ |
| getnanotime() - (start), \ |
| __VA_ARGS__); \ |
| } while (0) |
| |
| /** |
| * trace_performance_leave(), accepts "const char *format, ...". |
| */ |
| #define trace_performance_leave(...) \ |
| do { \ |
| if (trace_pass_fl(&trace_perf_key)) \ |
| trace_performance_leave_fl(TRACE_CONTEXT, __LINE__, \ |
| getnanotime(), \ |
| __VA_ARGS__); \ |
| } while (0) |
| |
| /* backend functions, use non-*fl macros instead */ |
| __attribute__((format (printf, 4, 5))) |
| void trace_printf_key_fl(const char *file, int line, struct trace_key *key, |
| const char *format, ...); |
| __attribute__((format (printf, 4, 5))) |
| void trace_argv_printf_fl(const char *file, int line, const char **argv, |
| const char *format, ...); |
| void trace_strbuf_fl(const char *file, int line, struct trace_key *key, |
| const struct strbuf *data); |
| __attribute__((format (printf, 4, 5))) |
| void trace_performance_fl(const char *file, int line, |
| uint64_t nanos, const char *fmt, ...); |
| __attribute__((format (printf, 4, 5))) |
| void trace_performance_leave_fl(const char *file, int line, |
| uint64_t nanos, const char *fmt, ...); |
| static inline int trace_pass_fl(struct trace_key *key) |
| { |
| return key->fd || !key->initialized; |
| } |
| |
| #endif /* TRACE_H */ |