timer.hh

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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_TIMER_HH
#define DUNE_TIMER_HH
 
#ifndef TIMER_USE_STD_CLOCK
// headers for std::chrono
#include <chrono>
#else
// headers for std::clock
#include <ctime>
#endif
 
namespace Dune {
 
  class Timer
  {
  public:
 
    Timer (bool startImmediately=true) noexcept
    {
      isRunning_ = startImmediately;
      reset();
    }
 
    void reset() noexcept
    {
      sumElapsed_ = 0.0;
      storedLastElapsed_ = 0.0;
      rawReset();
    }
 
 
    void start() noexcept
    {
      if (not (isRunning_))
      {
        rawReset();
        isRunning_ = true;
      }
    }
 
 
    double elapsed () const noexcept
    {
      // if timer is running add the time elapsed since last start to sum
      if (isRunning_)
        return sumElapsed_ + lastElapsed();
 
      return sumElapsed_;
    }
 
 
    double lastElapsed () const noexcept
    {
      // if timer is running return the current value
      if (isRunning_)
        return rawElapsed();
 
      // if timer is not running return stored value from last run
      return storedLastElapsed_;
    }
 
 
    double stop() noexcept
    {
      if (isRunning_)
      {
        // update storedLastElapsed_ and  sumElapsed_ and stop timer
        storedLastElapsed_ = lastElapsed();
        sumElapsed_ += storedLastElapsed_;
        isRunning_ = false;
      }
      return elapsed();
    }
 
 
  private:
 
    bool isRunning_;
    double sumElapsed_;
    double storedLastElapsed_;
 
 
#ifdef TIMER_USE_STD_CLOCK
    void rawReset() noexcept
    {
      cstart = std::clock();
    }
 
    double rawElapsed () const noexcept
    {
      return (std::clock()-cstart) / static_cast<double>(CLOCKS_PER_SEC);
    }
 
    std::clock_t cstart;
#else
    void rawReset() noexcept
    {
      cstart = std::chrono::high_resolution_clock::now();
    }
 
    double rawElapsed () const noexcept
    {
      std::chrono::high_resolution_clock::time_point now = std::chrono::high_resolution_clock::now();
      std::chrono::duration<double> time_span = std::chrono::duration_cast<std::chrono::duration<double> >(now - cstart);
      return time_span.count();
    }
 
    std::chrono::high_resolution_clock::time_point cstart;
#endif
  }; // end class Timer
 
} // end namespace
 
#endif