/** @file
 * @brief Measure CPU time.
 */
/* Copyright (C) 2009,2015,2018,2020 Olly Betts
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see
 * <https://www.gnu.org/licenses/>.
 */

#include <config.h>

#include "cputimer.h"

#include "errno_to_string.h"
#include "testsuite.h"

#ifdef HAVE_GETRUSAGE
# include <sys/time.h>
# include <sys/resource.h>
#elif defined HAVE_TIMES
# include <sys/times.h>
# ifdef HAVE_SYSCONF
#  include "safeunistd.h"
# endif
#else
# include "realtime.h"
#endif

#include <cerrno>
#include <cstdlib>
#include <cstring>
#include <string>

using namespace std;

double
CPUTimer::get_current_cputime()
{
#ifdef XAPIAN_DEBUG_LOG
    SKIP_TEST("Skipping timed test because configured with --enable-log");
#else
    static bool skip = (getenv("AUTOMATED_TESTING") != NULL);
    if (skip) {
        SKIP_TEST("Skipping timed test because $AUTOMATED_TESTING is set");
    }

    double t = 0;
#ifdef HAVE_GETRUSAGE
    struct rusage r;
    if (getrusage(RUSAGE_SELF, &r) == -1) {
        FAIL_TEST("Couldn't measure CPU for self: " << errno_to_string(errno));
    }

    t = r.ru_utime.tv_sec + r.ru_stime.tv_sec;
    t += (r.ru_utime.tv_usec + r.ru_stime.tv_usec) * 0.000001;
#elif defined HAVE_TIMES
    struct tms b;
    if (times(&b) == clock_t(-1)) {
        FAIL_TEST("Couldn't measure CPU: " << errno_to_string(errno));
    }
    t = (double)(b.tms_utime + b.tms_stime);
# ifdef HAVE_SYSCONF
    t /= sysconf(_SC_CLK_TCK);
# else
    t /= CLK_TCK;
# endif
#else
    // FIXME: Fallback to just using wallclock time, which is probably only
    // going to be used on Microsoft Windows, where nobody has implemented
    // the code required to get the CPU time used by a process.
    t = RealTime::now();
#endif

    return t;
#endif
}
