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09b2c1c769
Add trace_performance and trace_performance_since macros that print a
duration and an optional printf-formatted text to the file specified in
environment variable GIT_TRACE_PERFORMANCE.
These macros, in conjunction with getnanotime(), are intended to simplify
performance measurements from within the application (i.e. profiling via
manual instrumentation, rather than using an external profiling tool).
Unless enabled via GIT_TRACE_PERFORMANCE, these macros have no noticeable
impact on performance, so that test code for well known time killers may
be shipped in release builds. Alternatively, a developer could provide an
additional performance patch (not meant for master) that allows reviewers
to reproduce performance tests more easily, e.g. on other platforms or
using their own repositories.
Usage examples:
Simple use case (measure one code section):
uint64_t start = getnanotime();
/* code section to measure */
trace_performance_since(start, "foobar");
Complex use case (measure repetitive code sections):
uint64_t t = 0;
for (;;) {
/* ignore */
t -= getnanotime();
/* code section to measure */
t += getnanotime();
/* ignore */
}
trace_performance(t, "frotz");
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
113 lines
3.5 KiB
C
113 lines
3.5 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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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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#define TRACE_KEY_INIT(name) { "GIT_TRACE_" #name, 0, 0, 0 }
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extern void trace_repo_setup(const char *prefix);
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extern int trace_want(struct trace_key *key);
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extern void trace_disable(struct trace_key *key);
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extern uint64_t getnanotime(void);
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#ifndef HAVE_VARIADIC_MACROS
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__attribute__((format (printf, 1, 2)))
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extern void trace_printf(const char *format, ...);
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__attribute__((format (printf, 2, 3)))
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extern void trace_printf_key(struct trace_key *key, const char *format, ...);
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__attribute__((format (printf, 2, 3)))
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extern void trace_argv_printf(const char **argv, const char *format, ...);
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extern void trace_strbuf(struct trace_key *key, const struct strbuf *data);
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/* Prints elapsed time (in nanoseconds) if GIT_TRACE_PERFORMANCE is enabled. */
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__attribute__((format (printf, 2, 3)))
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extern void trace_performance(uint64_t nanos, const char *format, ...);
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/* Prints elapsed time since 'start' if GIT_TRACE_PERFORMANCE is enabled. */
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__attribute__((format (printf, 2, 3)))
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extern void trace_performance_since(uint64_t start, 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(...) \
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trace_printf_key_fl(TRACE_CONTEXT, __LINE__, NULL, __VA_ARGS__)
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#define trace_printf_key(key, ...) \
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trace_printf_key_fl(TRACE_CONTEXT, __LINE__, key, __VA_ARGS__)
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#define trace_argv_printf(argv, ...) \
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trace_argv_printf_fl(TRACE_CONTEXT, __LINE__, argv, __VA_ARGS__)
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#define trace_strbuf(key, data) \
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trace_strbuf_fl(TRACE_CONTEXT, __LINE__, key, data)
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#define trace_performance(nanos, ...) \
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trace_performance_fl(TRACE_CONTEXT, __LINE__, nanos, __VA_ARGS__)
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#define trace_performance_since(start, ...) \
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trace_performance_fl(TRACE_CONTEXT, __LINE__, getnanotime() - (start), \
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__VA_ARGS__)
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/* backend functions, use non-*fl macros instead */
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__attribute__((format (printf, 4, 5)))
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extern 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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extern void trace_argv_printf_fl(const char *file, int line, const char **argv,
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const char *format, ...);
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extern 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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extern void trace_performance_fl(const char *file, int line,
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uint64_t nanos, const char *fmt, ...);
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#endif /* HAVE_VARIADIC_MACROS */
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#endif /* TRACE_H */
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