text: /* Copyright (c) 2004, 2011, Oracle and/or its affiliates.
     Copyright (c) 2009-2011 Monty Program 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA */
  
  
  #include "mysys_priv.h"
  #include "my_static.h"
  
  #ifdef _WIN32
  #define OFFSET_TO_EPOC 116444736000000000LL
  static ulonglong query_performance_frequency;
  typedef void (WINAPI* get_system_time_as_filetime_t)(LPFILETIME);
  static get_system_time_as_filetime_t
    my_GetSystemTimePreciseAsFileTime= GetSystemTimeAsFileTime;
  #endif
  #ifdef HAVE_LINUX_UNISTD_H
  #include <linux/unistd.h>
  #endif
  
  /* For CYGWIN */
  #if !defined(CLOCK_THREAD_CPUTIME_ID) && defined(CLOCK_THREAD_CPUTIME)
  #define CLOCK_THREAD_CPUTIME_ID CLOCK_THREAD_CPUTIME
  #endif
  
  /*
    return number of nanoseconds since unspecified (but always the same)
    point in the past
  
    NOTE:
    Thus to get the current time we should use the system function
    with the highest possible resolution
  
    The value is not anchored to any specific point in time (e.g. epoch) nor
    is it subject to resetting or drifting by way of adjtime() or settimeofday(),
    and thus it is *NOT* appropriate for getting the current timestamp. It can be
    used for calculating time intervals, though.
  */
  
  ulonglong my_interval_timer()
  {
  #ifdef HAVE_CLOCK_GETTIME
    struct timespec tp;
    clock_gettime(CLOCK_MONOTONIC, &tp);
    return tp.tv_sec*1000000000ULL+tp.tv_nsec;
  #elif defined(HAVE_GETHRTIME)
    return gethrtime();
  #elif defined(_WIN32)
    LARGE_INTEGER t_cnt;
    if (query_performance_frequency)
    {
      QueryPerformanceCounter(&t_cnt);
      return (t_cnt.QuadPart / query_performance_frequency * 1000000000ULL) +
              ((t_cnt.QuadPart % query_performance_frequency) * 1000000000ULL /
               query_performance_frequency);
    }
    else
    {
      ulonglong newtime;
      my_GetSystemTimePreciseAsFileTime((FILETIME*)&newtime);
      return newtime*100ULL;
    }
  #else
    /* TODO: check for other possibilities for hi-res timestamping */
    struct timeval tv;
    gettimeofday(&tv,NULL);
    return tv.tv_sec*1000000000ULL+tv.tv_usec*1000ULL;
  #endif
  }
  
  
  /* Return current time in HRTIME_RESOLUTION (microseconds) since epoch */
  
  my_hrtime_t my_hrtime()
  {
    my_hrtime_t hrtime;
  #if defined(_WIN32)
    ulonglong newtime;
    my_GetSystemTimePreciseAsFileTime((FILETIME*)&newtime);
    hrtime.val= (newtime - OFFSET_TO_EPOC)/10;
  #elif defined(HAVE_CLOCK_GETTIME)
    struct timespec tp;
    clock_gettime(CLOCK_REALTIME, &tp);
    hrtime.val= tp.tv_sec*1000000ULL+tp.tv_nsec/1000ULL;
  #else
    struct timeval t;
    /* The following loop is here because gettimeofday may fail */
    while (gettimeofday(&t, NULL) != 0) {}
    hrtime.val= t.tv_sec*1000000ULL + t.tv_usec;
  #endif
    return hrtime;
  }
  
  #ifdef _WIN32
  
  /*
    Low accuracy, "coarse" timer.
    Has lower latency than my_hrtime(). Used in situations, where microsecond
    precision is not needed, e.g in Windows pthread_cond_timedwait, where POSIX 
    interface needs nanoseconds, yet the underlying Windows function only
    accepts millisecons.
  */
  my_hrtime_t my_hrtime_coarse()
  {
    my_hrtime_t hrtime;
    ulonglong t;
    GetSystemTimeAsFileTime((FILETIME*)&t);
    hrtime.val= (t - OFFSET_TO_EPOC)/10;
    return hrtime;
  }
  
  #endif
  
  void my_time_init()
  {
  #ifdef _WIN32
    compile_time_assert(sizeof(LARGE_INTEGER) ==
                        sizeof(query_performance_frequency));
    if (QueryPerformanceFrequency((LARGE_INTEGER *)&query_performance_frequency) == 0)
      query_performance_frequency= 0;
  
    get_system_time_as_filetime_t f= (get_system_time_as_filetime_t)
      GetProcAddress(GetModuleHandle("kernel32"),
                     "GetSystemTimePreciseAsFileTime");
    if (f)
      my_GetSystemTimePreciseAsFileTime= f;
  #endif
  }
  
  
  /*
    Return cpu time in 1/10th on a microsecond (1e-7 s)
  */
  
  ulonglong my_getcputime()
  {
  #ifdef CLOCK_THREAD_CPUTIME_ID
    struct timespec tp;
    if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &tp))
      return 0;
    return (ulonglong)tp.tv_sec*10000000+(ulonglong)tp.tv_nsec/100;
  #elif defined(__NR_clock_gettime)
    struct timespec tp;
    if (syscall(__NR_clock_gettime, CLOCK_THREAD_CPUTIME_ID, &tp))
      return 0;
    return (ulonglong)tp.tv_sec*10000000+(ulonglong)tp.tv_nsec/100;
  #endif /* CLOCK_THREAD_CPUTIME_ID */
    return 0;
  }
  