/*
  RealClock  -  convenience front-end to access the system clock

  Copyright (C)         Lumiera.org
    2012,               Hermann Vosseler <Ichthyostega@web.de>

  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 2 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., 675 Mass Ave, Cambridge, MA 02139, USA.

* *****************************************************/


/** @file real-clock.cpp
 ** Implementation of simplified access to current system time.
 ** Actually, a _steady clock_ is employed, with an unspecified base time,
 ** typically starting anew at each system boot. The micro-tick value will
 ** increase monotonously, without gaps at NTP corrections, but also without
 ** any relation to an external world time.
 */


#include "vault/real-clock.hpp"

#include <chrono>


using lib::time::FSecs;
using std::chrono::steady_clock;
using std::chrono::microseconds;
using std::chrono::floor;

namespace vault {
  
  
  
  /** events during the last ms are considered "recent" for the purpose of testing */
  const Offset RealClock::CONSIDERED_RECENT{FSecs {1,1000}};

  
  TimeValue
  RealClock::_readSystemTime()
  {
    auto now = steady_clock::now();
    auto microTicks = floor<microseconds> (now.time_since_epoch())
                        .count();
    
    ENSURE (microTicks == _raw(TimeValue{microTicks}));
    return TimeValue::buildRaw_(microTicks);        // bypassing the limit check
  }
  
  
  
} // namespace vault