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*
* ---
* Author: Sanjay Ghemawat
*
* Module for CPU profiling based on periodic pc-sampling.
*
* For full(er) information, see doc/cpuprofile.html
*
* This module is linked into your program with
* no slowdown caused by this unless you activate the profiler
* using one of the following methods:
*
* 1. Before starting the program, set the environment variable
* "PROFILE" to be the name of the file to which the profile
* data should be written.
*
* 2. Programmatically, start and stop the profiler using the
* routines "ProfilerStart(filename)" and "ProfilerStop()".
*
*
* (Note: if using linux 2.4 or earlier, only the main thread may be
* profiled.)
*
* Use pprof to view the resulting profile output.
* % pprof <path_to_executable> <profile_file_name>
* % pprof --gv <path_to_executable> <profile_file_name>
*
* These functions are thread-safe.
*/
#ifndef BASE_PROFILER_H_
#define BASE_PROFILER_H_
#include <time.h> /* For time_t */
/* Annoying stuff for windows; makes sure clients can import these functions */
#ifndef PERFTOOLS_DLL_DECL
# ifdef _WIN32
# define PERFTOOLS_DLL_DECL __declspec(dllimport)
# else
# define PERFTOOLS_DLL_DECL
# endif
#endif
/* All this code should be usable from within C apps. */
#ifdef __cplusplus
extern "C" {
#endif
/* Profiler options, for use with ProfilerStartWithOptions. To use:
*
* struct ProfilerOptions options;
* memset(&options, 0, sizeof options);
*
* then fill in fields as needed.
*
* This structure is intended to be usable from C code, so no constructor
* is provided to initialize it. (Use memset as described above).
*/
struct ProfilerOptions {
/* Filter function and argument.
*
* If filter_in_thread is not NULL, when a profiling tick is delivered
* the profiler will call:
*
* (*filter_in_thread)(filter_in_thread_arg)
*
* If it returns nonzero, the sample will be included in the profile.
* Note that filter_in_thread runs in a signal handler, so must be
* async-signal-safe.
*
* A typical use would be to set up filter results for each thread
* in the system before starting the profiler, then to make
* filter_in_thread be a very simple function which retrieves those
* results in an async-signal-safe way. Retrieval could be done
* using thread-specific data, or using a shared data structure that
* supports async-signal-safe lookups.
*/
int (*filter_in_thread)(void *arg);
void *filter_in_thread_arg;
};
/* Start profiling and write profile info into fname, discarding any
* existing profiling data in that file.
*
* This is equivalent to calling ProfilerStartWithOptions(fname, NULL).
*/
PERFTOOLS_DLL_DECL int ProfilerStart(const char* fname);
/* Start profiling and write profile into fname, discarding any
* existing profiling data in that file.
*
* The profiler is configured using the options given by 'options'.
* Options which are not specified are given default values.
*
* 'options' may be NULL, in which case all are given default values.
*
* Returns nonzero if profiling was started sucessfully, or zero else.
*/
PERFTOOLS_DLL_DECL int ProfilerStartWithOptions(
const char *fname, const struct ProfilerOptions *options);
/* Stop profiling. Can be started again with ProfilerStart(), but
* the currently accumulated profiling data will be cleared.
*/
PERFTOOLS_DLL_DECL void ProfilerStop();
/* Flush any currently buffered profiling state to the profile file.
* Has no effect if the profiler has not been started.
*/
PERFTOOLS_DLL_DECL void ProfilerFlush();
/* DEPRECATED: these functions were used to enable/disable profiling
* in the current thread, but no longer do anything.
*/
PERFTOOLS_DLL_DECL void ProfilerEnable();
PERFTOOLS_DLL_DECL void ProfilerDisable();
/* Returns nonzero if profile is currently enabled, zero if it's not. */
PERFTOOLS_DLL_DECL int ProfilingIsEnabledForAllThreads();
/* Routine for registering new threads with the profiler.
*/
PERFTOOLS_DLL_DECL void ProfilerRegisterThread();
/* Stores state about profiler's current status into "*state". */
struct ProfilerState {
int enabled; /* Is profiling currently enabled? */
time_t start_time; /* If enabled, when was profiling started? */
char profile_name[1024]; /* Name of profile file being written, or '\0' */
int samples_gathered; /* Number of samples gathered so far (or 0) */
};
PERFTOOLS_DLL_DECL void ProfilerGetCurrentState(struct ProfilerState* state);
#ifdef __cplusplus
} // extern "C"
#endif
#endif /* BASE_PROFILER_H_ */