getCPUTime.c

/*
 * Author:  David Robert Nadeau
 * Site:    http://NadeauSoftware.com/
 * License: Creative Commons Attribution 3.0 Unported License
 *          http://creativecommons.org/licenses/by/3.0/deed.en_US
 */
#if defined(_WIN32)
#include <Windows.h>

#elif defined(__unix__) || defined(__unix) || defined(unix) || (defined(__APPLE__) && defined(__MACH__))
#include <unistd.h>
#include <sys/resource.h>
#include <sys/times.h>
#include <time.h>

#else
#error "Unable to define getCPUTime( ) for an unknown OS."
#endif


/**
 * Returns the amount of CPU time used by the current process,
 * in seconds, or -1.0 if an error occurred.
 */
double getCPUTime() {
#if defined(_WIN32)
	/* Windows -------------------------------------------------- */
	FILETIME createTime;
	FILETIME exitTime;
	FILETIME kernelTime;
	FILETIME userTime;
	if (GetProcessTimes(GetCurrentProcess(), &createTime, &exitTime, &kernelTime, &userTime) != -1) {
		ULARGE_INTEGER li = {{userTime.dwLowDateTime, userTime.dwHighDateTime }};
        return li.QuadPart / 10000000.;
	}

#elif defined(__unix__) || defined(__unix) || defined(unix) || (defined(__APPLE__) && defined(__MACH__))
	/* AIX, BSD, Cygwin, HP-UX, Linux, OSX, and Solaris --------- */

#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0)
	/* Prefer high-res POSIX timers, when available. */
	{
		clockid_t id;
		struct timespec ts;
#if _POSIX_CPUTIME > 0
		/* Clock ids vary by OS.  Query the id, if possible. */
		if (clock_getcpuclockid(0, &id) == -1)
#endif
#if defined(CLOCK_PROCESS_CPUTIME_ID)
			/* Use known clock id for AIX, Linux, or Solaris. */
			id = CLOCK_PROCESS_CPUTIME_ID;
#elif defined(CLOCK_VIRTUAL)
		/* Use known clock id for BSD or HP-UX. */
		id = CLOCK_VIRTUAL;
#else
		id = (clockid_t) - 1;
#endif
		if (id != (clockid_t) - 1 && clock_gettime(id, &ts) != -1)
			return (double) ts.tv_sec + (double) ts.tv_nsec / 1000000000.0;
	}
#endif

#if defined(RUSAGE_SELF)
	{
		struct rusage rusage;
		if (getrusage(RUSAGE_SELF, &rusage) != -1)
			return (double) rusage.ru_utime.tv_sec + (double) rusage.ru_utime.tv_usec / 1000000.0;
	}
#endif

#if defined(_SC_CLK_TCK)
	{
		const double ticks = (double) sysconf(_SC_CLK_TCK);
		struct tms tms;
		if (times(&tms) != (clock_t) - 1)
			return (double) tms.tms_utime / ticks;
	}
#endif

#if defined(CLOCKS_PER_SEC)
	{
		clock_t cl = clock();
		if (cl != (clock_t) - 1)
			return (double) cl / (double) CLOCKS_PER_SEC;
	}
#endif

#endif
	
	return -1;        /* Failed. */
}