utils/timer.hpp

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// Copyright (c) 2014-2023, Lawrence Livermore National Security, LLC.
// Produced at the Lawrence Livermore National Laboratory.
// Written by the LBANN Research Team (B. Van Essen, et al.) listed in
// the CONTRIBUTORS file. <lbann-dev@llnl.gov>
//
// LLNL-CODE-697807.
// All rights reserved.
//
// This file is part of LBANN: Livermore Big Artificial Neural Network
// Toolkit. For details, see http://software.llnl.gov/LBANN or
// https://github.com/LLNL/LBANN.
//
// Licensed under the Apache License, Version 2.0 (the "Licensee"); you
// may not use this file except in compliance with the License.  You may
// obtain a copy of the License at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the license.
//
// lbann_timer .hpp - Wrapper around time functionality

#ifndef LBANN_UTILS_TIMER_HPP_INCLUDED
#define LBANN_UTILS_TIMER_HPP_INCLUDED

#include <chrono>

namespace lbann {

inline double get_time()
{
  using namespace std::chrono;
  return duration_cast<duration<double>>(steady_clock::now().time_since_epoch())
    .count();
}

class Timer
{
public:
  using ClockType = std::chrono::steady_clock;
  using TimePoint = typename ClockType::time_point;

public:
  Timer() = default;
  ~Timer() noexcept = default;
  Timer(Timer const&) = delete;
  Timer& operator=(Timer const&) = delete;
  Timer(Timer&&) = default;
  Timer& operator=(Timer&&) = default;

  void start() noexcept { m_start = ClockType::now(); }

  double stop() noexcept
  {
    auto elapsed_time = this->check();
    this->reset();
    return elapsed_time;
  }

  double check() const noexcept
  {
    using seconds_type = std::chrono::duration<double>;
    return running() ? seconds_type(ClockType::now() - m_start).count() : 0.;
  }

  void reset() noexcept { m_start = TimePoint{}; }

  bool running() const noexcept { return m_start != TimePoint{}; }

private:
  TimePoint m_start;

}; // class Timer

} // namespace lbann

#endif // LBANN_UTILS_TIMER_HPP_INCLUDED