Timer.h

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/* -*- c++ -*-
 * Copyright (C) 2007-2015 Hypertable, Inc.
 *
 * This file is part of Hypertable.
 *
 * Hypertable 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 any later version.
 *
 * Hypertable 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.
 */

#ifndef Common_Timer_h
#define Common_Timer_h

#include <Common/fast_clock.h>

#include <cassert>
#include <chrono>
#include <cstring>

namespace Hypertable {

  class Timer {
  public:
  Timer(uint32_t millis, bool start_timer = false)
    : m_duration(std::chrono::milliseconds(millis)),
      m_remaining(std::chrono::milliseconds(millis)) {
      if (start_timer)
        start();
    }

    void start() {
      if (!m_running) {
        start_time = std::chrono::fast_clock::now();
        m_running = true;
        if (!m_started)
          m_started = true;
      }
    }

    void stop() {
      assert(m_started);
      auto adjustment = std::chrono::fast_clock::now() - start_time;
      m_remaining = (adjustment < m_remaining) ?
        m_remaining - adjustment :
        std::chrono::fast_clock::duration::zero();
      m_running = false;
    }

    void reset(bool start_timer = false) {
      m_running = false;
      m_started = false;
      m_remaining = m_duration;
      if (start_timer)
        start();
    }

    uint32_t remaining() {
      if (m_running) {
        stop();
        start();
      }
     return std::chrono::duration_cast<std::chrono::milliseconds>(m_remaining).count();
    }

    bool expired() {
      return remaining() == 0;
    }

    bool is_running() {
      return m_running;
    }

    uint32_t duration() {
      return (uint32_t)std::chrono::duration_cast<std::chrono::milliseconds>(m_duration).count();
    }


  private:

    std::chrono::fast_clock::time_point start_time;

    bool m_running {};

    bool m_started {};

    std::chrono::fast_clock::duration m_duration;

    std::chrono::fast_clock::duration m_remaining;
  };

}

#endif // Common_Timer_h