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