/* Return time used so far, in microseconds.
   Copyright (C) 1994, 1999 Free Software Foundation, Inc.

This file is part of the libiberty library.
Libiberty is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.

Libiberty 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with libiberty; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


/*
Mon May  9 15:57:53 CDT 2005

did not update license info here because
 (a) the original is still ok per GPL
 (b) the original is lifted from another package and it's better to preserve
 (c) this file is only used in swish-e binary, not libswish-e
 
*/


#include "acconfig.h"

/* For testing */
// #undef HAVE_GETRUSAGE
// #undef HAVE_SYS_RESOURCE_H
// #undef HAVE_TIMES

/* There are several ways to get elapsed execution time; unfortunately no
   single way is available for all host systems, nor are there reliable
   ways to find out which way is correct for a given host. */

#include "getruntime.h"
#include <time.h>

#if defined (HAVE_GETRUSAGE) && defined (HAVE_SYS_RESOURCE_H)
#include <sys/time.h>
#include <sys/resource.h>
#endif

#ifdef HAVE_TIMES
#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#include <sys/times.h>
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

/* This is a fallback; if wrong, it will likely make obviously wrong
   results. */

#ifndef CLOCKS_PER_SEC
#define CLOCKS_PER_SEC 1
#endif

#ifdef _SC_CLK_TCK
#define GNU_HZ  sysconf(_SC_CLK_TCK)
#else
#ifdef HZ
#define GNU_HZ  HZ
#else
#ifdef CLOCKS_PER_SEC
#define GNU_HZ  CLOCKS_PER_SEC
#endif
#endif
#endif

cpu_seconds 
get_cpu_secs ()
{
#if defined (HAVE_GETRUSAGE) && defined (HAVE_SYS_RESOURCE_H)
  struct rusage rusage;
  cpu_seconds secs;

  getrusage (0, &rusage);
  secs = (cpu_seconds)( rusage.ru_utime.tv_sec + rusage.ru_stime.tv_sec );

  if (  rusage.ru_utime.tv_usec > 500000 )
     secs++;
  if (  rusage.ru_stime.tv_usec > 500000 )
     secs++;

  return secs;


#else /* ! HAVE_GETRUSAGE */
#ifdef HAVE_TIMES

  /* This returns number of clock "ticks" since: */
  /* In linux since boot, in BSD since 1/1/1970 */
  /* Again, these are clock_t, which may overflow, but under linux it's 1/100 second so about 6000 hours */

  struct tms tms;

  times (&tms);

  return  (cpu_seconds)( (tms.tms_utime + tms.tms_stime) / GNU_HZ);


#else /* ! HAVE_TIMES */
  /* Fall back on clock and hope it's correctly implemented. */
  /* clock() returns clock_t, which seems to be a long.  On Linux CLOCKS_PER_SEC is 10^6 */
  /* so expect an overflow at about 35 minutes. */

  clock_t t = clock();
  if ( t < 0 )
      t = 0;

  return (cpu_seconds) (t / CLOCKS_PER_SEC );

#endif  /* HAVE_TIMES */
#endif  /* HAVE_GETRUSAGE */
}