/*
 * Copyright 2006-2008 The FLWOR Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#pragma once
#ifndef ZORBA_UTIL_TIME_H
#define ZORBA_UTIL_TIME_H

/**
 * This header includes utility functions for certain timing-related
 * operations, namely getting current wall-clock time and current
 * CPU-used time values in a platform-dependent fashion, and computing
 * deltas for both types.
 *
 * Types:
 *   cputime - type representing CPU time utilized thus far by this process
 *   walltime - type representing wall-clock time since some
 *     platform-dependent epoch
 *
 * Function signatures:
 *   void get_current_cputime(cputime& t) - returns current CPU time
 *
 *   double get_cputime_elapsed(const cputime& t0, const cputime& t1) -
 *     calculates elapsed CPU time (in ms) between two cputimes
 *
 *   void get_current_walltime(walltime& t) - returns current wall-clock time
 *
 *   double get_walltime_elapsed(const walltime& t0, const walltime& t1) -
 *    calculates elapsed wall-clock time (in ms) between two walltimes
 */

/**
 * TODO These functions should probably be defined in a .cpp file
 * somewhere rather than here in time.h; as it is they will be
 * compiled into every .o that uses them. So far, though, this is only
 * zorbacmd and the implementation of fn:doc(), so it's not too bad.
 */

namespace zorba 
{

  namespace time
  {

    //
    //
    // Types and functions for CPU time
    //
    //

#if (defined(ZORBA_HAVE_CLOCKGETTIME_FUNCTION) & defined(_POSIX_CPUTIME))

#include <time.h>

    typedef struct timespec cputime;

    inline double get_cputime_elapsed (const cputime& t0, const cputime& t1)
    {
      return ((t1.tv_sec - t0.tv_sec) * 1000.0) +
        ((t1.tv_nsec - t0.tv_nsec) / 1000000.0);
    }

    inline void get_current_cputime (cputime& t)
    {
      clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &t);
    }

#elif defined(ZORBA_HAVE_RUSAGE_FUNCTION)

#include <sys/time.h>
#include <sys/resource.h>

    typedef struct timeval cputime;

    inline double get_cputime_elapsed (const cputime& t0, const cputime& t1) 
    {
      return ((t1.tv_sec - t0.tv_sec) * 1000.0) +
        ((t1.tv_usec - t0.tv_usec) / 1000.0);
    }

    inline void get_current_cputime (cputime& t) 
    {
      struct rusage ru;
      getrusage (RUSAGE_SELF, &ru);
      t = ru.ru_utime;
    }

#else /* no rusage, no clock_gettime */

#include <time.h>

    typedef clock_t cputime;

    inline double get_cputime_elapsed (const cputime& t0, const cputime& t1) 
    {
      return (double) (t1 - t0) / (CLOCKS_PER_SEC / 1000);
    }

    inline void get_current_cputime (cputime& t)
    {
      t = clock ();
    }

#endif /* ZORBA_HAVE_CLOCKGETTIME_FUNCTION */


    //
    //
    // Types and functions for wall-clock time
    //
    //

#if defined(ZORBA_HAVE_CLOCKGETTIME_FUNCTION)

#include <time.h>

    typedef struct timespec walltime;

    inline double get_walltime_elapsed (const walltime& t0, const walltime& t1)
    {
      return ((t1.tv_sec - t0.tv_sec) * 1000.0) +
        ((t1.tv_nsec - t0.tv_nsec) / 1000000.0);
    }

    inline void get_current_walltime (walltime& t)
    {
#ifdef _POSIX_MONOTONIC_CLOCK
      clock_gettime(CLOCK_MONOTONIC, &t);
#else
      clock_gettime(CLOCK_REALTIME, &t);
#endif
    }

    inline long get_walltime_in_millis(const walltime& t)
    {
      return t.tv_sec * 1000 + t.tv_nsec / 1000000;
    }

#elif defined(WIN32)

    // TODO: Should maybe use QueryPerformanceCounter() or
    // GetSystemTimeAsFileTime() for this, rather than ftime(), but I
    // don't know enough about any of these alternatives to choose
    // one. See http://msdn.microsoft.com/en-us/magazine/cc163996.aspx .

#include <sys/timeb.h>

#ifdef WINCE
    typedef struct timeb walltime;
#else
    typedef struct _timeb walltime;
#endif

    inline double get_walltime_elapsed (const walltime& t0, const walltime& t1) 
    {
      return ((t1.time - t0.time) * 1000.0) + (t1.millitm - t0.millitm);
    }

    inline void get_current_walltime (walltime& t) 
    {
#ifdef WINCE
      ftime(&t);
#else
      _ftime_s(&t);
#endif
    }
	
    inline long get_walltime_in_millis(const walltime& t)
    {
      return (long)(t.time * 1000 + t.millitm);
    }

#else /* not Windows, and no clock_gettime() */

#include <time.h>
#include <sys/time.h>

    typedef struct timeval walltime;

    inline double get_walltime_elapsed (const walltime& t0, const walltime& t1) 
    {
      return ((t1.tv_sec - t0.tv_sec) * 1000.0) +
        ((t1.tv_usec - t0.tv_usec) / 1000.0);
    }

    inline void get_current_walltime (walltime& t)
    {
      gettimeofday(&t, NULL);
    }
	
    inline long get_walltime_in_millis(const walltime& t)
    {
      return t.tv_sec * 1000 + t.tv_usec / 1000;
    }

#endif /* ZORBA_HAVE_CLOCKGETTIME_FUNCTION */

  }  // ::time

}  // ::zorba

#endif

/*
 * Local variables:
 * mode: c++
 * End:
 */
/* vim:set et sw=2 ts=2: */