text: // timer.cc -- helper class for time accounting
  
  // Copyright (C) 2009-2020 Free Software Foundation, Inc.
  // Written by Rafael Avila de Espindola <espindola@google.com>.
  
  // This file is part of gold.
  
  // 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; either version 3 of the License, or
  // (at your option) any later version.
  
  // 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 "gold.h"
  
  #include <unistd.h>
  
  #ifdef HAVE_TIMES
  #include <sys/times.h>
  #endif
  
  #include "libiberty.h"
  
  #include "timer.h"
  
  namespace gold
  {
  
  // Class Timer
  
  Timer::Timer()
  {
    this->start_time_.wall = 0;
    this->start_time_.user = 0;
    this->start_time_.sys = 0;
  }
  
  // Start counting the time.
  void
  Timer::start()
  {
    this->get_time(&this->start_time_);
  }
  
  // Record the time used by pass N (0 <= N <= 2).
  void
  Timer::stamp(int n)
  {
    gold_assert(n >= 0 && n <= 2);
    TimeStats& thispass = this->pass_times_[n];
    this->get_time(&thispass);
  }
  
  #if HAVE_SYSCONF && defined _SC_CLK_TCK
  # define TICKS_PER_SECOND sysconf (_SC_CLK_TCK) /* POSIX 1003.1-1996 */
  #else
  # ifdef CLK_TCK
  #  define TICKS_PER_SECOND CLK_TCK /* POSIX 1003.1-1988; obsolescent */
  # else
  #  ifdef HZ
  #   define TICKS_PER_SECOND HZ  /* traditional UNIX */
  #  else
  #   define TICKS_PER_SECOND 100 /* often the correct value */
  #  endif
  # endif
  #endif
  
  // times returns statistics in clock_t units.  This variable will hold the
  // conversion factor to seconds.  We use a variable that is initialized once
  // because sysconf can be slow.
  static long ticks_per_sec;
  class Timer_init
  {
   public:
    Timer_init()
    {
      ticks_per_sec = TICKS_PER_SECOND;
    }
  };
  Timer_init timer_init;
  
  // Write the current time information.
  void
  Timer::get_time(TimeStats *now)
  {
  #ifdef HAVE_TIMES
    tms t;
    now->wall = (times(&t) * 1000) / ticks_per_sec;
    now->user = (t.tms_utime * 1000) / ticks_per_sec;
    now->sys  = (t.tms_stime * 1000) / ticks_per_sec;
  #else
    now->wall = get_run_time() / 1000;
    now->user = 0;
    now->sys = 0;
  #endif
  }
  
  // Return the stats since start was called.
  Timer::TimeStats
  Timer::get_elapsed_time()
  {
    TimeStats now;
    this->get_time(&now);
    TimeStats delta;
    delta.wall = now.wall - this->start_time_.wall;
    delta.user = now.user - this->start_time_.user;
    delta.sys = now.sys - this->start_time_.sys;
    return delta;
  }
  
  // Return the stats for pass N (0 <= N <= 2).
  Timer::TimeStats
  Timer::get_pass_time(int n)
  {
    gold_assert(n >= 0 && n <= 2);
    TimeStats thispass = this->pass_times_[n];
    TimeStats& lastpass = n > 0 ? this->pass_times_[n-1] : this->start_time_;
    thispass.wall -= lastpass.wall;
    thispass.user -= lastpass.user;
    thispass.sys -= lastpass.sys;
    return thispass;
  }
  
  }
  