1  /* gethrxtime -- get high resolution real time
       2  
       3     Copyright (C) 2005-2007, 2009-2021 Free Software Foundation, Inc.
       4  
       5     This program is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU General Public License as published by
       7     the Free Software Foundation; either version 3 of the License, or
       8     (at your option) any later version.
       9  
      10     This program is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13     GNU General Public License for more details.
      14  
      15     You should have received a copy of the GNU General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  /* Written by Paul Eggert.  */
      19  
      20  #include <config.h>
      21  
      22  #define GETHRXTIME_INLINE _GL_EXTERN_INLINE
      23  #include "gethrxtime.h"
      24  
      25  #if ! (HAVE_ARITHMETIC_HRTIME_T && HAVE_DECL_GETHRTIME)
      26  
      27  #include <sys/time.h>
      28  #include "timespec.h"
      29  
      30  /* Get the current time, as a count of the number of nanoseconds since
      31     an arbitrary epoch (e.g., the system boot time).  Prefer a
      32     high-resolution clock that is not subject to resetting or
      33     drifting.  */
      34  
      35  xtime_t
      36  gethrxtime (void)
      37  {
      38  # if HAVE_NANOUPTIME
      39    {
      40      struct timespec ts;
      41      nanouptime (&ts);
      42      return xtime_make (ts.tv_sec, ts.tv_nsec);
      43    }
      44  # else
      45  
      46  #  if defined CLOCK_MONOTONIC && HAVE_CLOCK_GETTIME
      47    {
      48      struct timespec ts;
      49      if (clock_gettime (CLOCK_MONOTONIC, &ts) == 0)
      50        return xtime_make (ts.tv_sec, ts.tv_nsec);
      51    }
      52  #  endif
      53  
      54  #  if HAVE_MICROUPTIME
      55    {
      56      struct timeval tv;
      57      microuptime (&tv);
      58      return xtime_make (tv.tv_sec, 1000 * tv.tv_usec);
      59    }
      60  
      61  #  else
      62    /* No monotonically increasing clocks are available; fall back on a
      63       clock that might jump backwards, since it's the best we can do.  */
      64    {
      65      struct timespec ts;
      66      gettime (&ts);
      67      return xtime_make (ts.tv_sec, ts.tv_nsec);
      68    }
      69  #  endif
      70  # endif
      71  }
      72  
      73  #endif