~drizzle-trunk/drizzle/development

/* Copyright (C) 2004 MySQL AB

   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; version 2 of the License.

   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, write to the Free Software

   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/* get time since epoc in 100 nanosec units */

/* thus to get the current time we should use the system function

   with the highest possible resolution */

/* 

   TODO: in functions my_micro_time() and my_micro_time_and_time() there

   exists some common code that should be merged into a function.

*/

#include "mysys_priv.h"

#include "my_static.h"

ulonglong my_getsystime()

{

#ifdef HAVE_CLOCK_GETTIME

  struct timespec tp;

  clock_gettime(CLOCK_REALTIME, &tp);

  return (ulonglong)tp.tv_sec*10000000+(ulonglong)tp.tv_nsec/100;

#else

  /* TODO: check for other possibilities for hi-res timestamping */

  struct timeval tv;

  gettimeofday(&tv,NULL);

  return (ulonglong)tv.tv_sec*10000000+(ulonglong)tv.tv_usec*10;

#endif

}

/*

  Return current time

  SYNOPSIS

    my_time()

    flags	If MY_WME is set, write error if time call fails

*/

time_t my_time(myf flags __attribute__((unused)))

{

  time_t t;

#ifdef HAVE_GETHRTIME

  (void) my_micro_time_and_time(&t);

  return t;

#else

  /* The following loop is here beacuse time() may fail on some systems */

  while ((t= time(0)) == (time_t) -1)

  {

    if (flags & MY_WME)

      fprintf(stderr, "%s: Warning: time() call failed\n", my_progname);

  }

  return t;

#endif

}

/*

  Return time in micro seconds

  SYNOPSIS

    my_micro_time()

  NOTES

    This function is to be used to measure performance in micro seconds.

    As it's not defined whats the start time for the clock, this function

    us only useful to measure time between two moments.

    For windows platforms we need the frequency value of the CUP. This is

    initalized in my_init.c through QueryPerformanceFrequency().

    If Windows platform doesn't support QueryPerformanceFrequency() we will

    obtain the time via GetClockCount, which only supports milliseconds.

  RETURN

    Value in microseconds from some undefined point in time

*/

ulonglong my_micro_time()

{

#if defined(HAVE_GETHRTIME)

  return gethrtime()/1000;

#else

  ulonglong newtime;

  struct timeval t;

  /*

    The following loop is here because gettimeofday may fail on some systems

  */

  while (gettimeofday(&t, NULL) != 0)

  {}

  newtime= (ulonglong)t.tv_sec * 1000000 + t.tv_usec;

  return newtime;

#endif  /* defined(HAVE_GETHRTIME) */

}

/*

  Return time in seconds and timer in microseconds (not different start!)

  SYNOPSIS

    my_micro_time_and_time()

    time_arg		Will be set to seconds since epoch (00:00:00 UTC,

                        January 1, 1970)

  NOTES

    This function is to be useful when we need both the time and microtime.

    For example in MySQL this is used to get the query time start of a query

    and to measure the time of a query (for the slow query log)

  IMPLEMENTATION

    Value of time is as in time() call.

    Value of microtime is same as my_micro_time(), which may be totally

    unrealated to time()

  RETURN

    Value in microseconds from some undefined point in time

*/

#define DELTA_FOR_SECONDS LL(500000000)  /* Half a second */

ulonglong my_micro_time_and_time(time_t *time_arg)

{

#if defined(HAVE_GETHRTIME)

  /*

    Solaris has a very slow time() call. We optimize this by using the very

    fast gethrtime() call and only calling time() every 1/2 second

  */

  static hrtime_t prev_gethrtime= 0;

  static time_t cur_time= 0;

  hrtime_t cur_gethrtime;

  pthread_mutex_lock(&THR_LOCK_time);

  cur_gethrtime= gethrtime();

  if ((cur_gethrtime - prev_gethrtime) > DELTA_FOR_SECONDS)

  {

    cur_time= time(0);

    prev_gethrtime= cur_gethrtime;

  }

  *time_arg= cur_time;

  pthread_mutex_unlock(&THR_LOCK_time);

  return cur_gethrtime/1000;

#else

  ulonglong newtime;

  struct timeval t;

  /*

    The following loop is here because gettimeofday may fail on some systems

  */

  while (gettimeofday(&t, NULL) != 0)

  {}

  *time_arg= t.tv_sec;

  newtime= (ulonglong)t.tv_sec * 1000000 + t.tv_usec;

  return newtime;

#endif  /* defined(HAVE_GETHRTIME) */

}

/*

  Returns current time

  SYNOPSIS

    my_time_possible_from_micro()

    microtime		Value from very recent my_micro_time()

  NOTES

    This function returns the current time. The microtime argument is only used

    if my_micro_time() uses a function that can safely be converted to the

    current time.

  RETURN

    current time

*/

time_t my_time_possible_from_micro(ulonglong microtime __attribute__((unused)))

{

#if defined(HAVE_GETHRTIME)

  return my_time(0);                            /* Cached time */

#else

  return (time_t) (microtime / 1000000);

#endif  /* defined(HAVE_GETHRTIME) */

}