timer.h

/*
 *  Copyright (C) 2004-2021 Edward F. Valeev
 *
 *  This file is part of Libint.
 *
 *  Libint is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  Libint 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with Libint.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
 
#ifndef _libint2_src_lib_libint_timer_h_
#define _libint2_src_lib_libint_timer_h_
 
#ifdef __cplusplus
 
#include <libint2/util/cxxstd.h>
 
#if LIBINT2_CPLUSPLUS_STD >= 2011
 
#include <chrono>
 
namespace libint2 {
 
  template <size_t N>
  class Timers {
    public:
      typedef std::chrono::duration<double> dur_t;
      typedef std::chrono::high_resolution_clock clock_t;
      typedef std::chrono::time_point<clock_t> time_point_t;
 
      Timers() {
        clear();
        set_now_overhead(0);
      }
 
      static time_point_t now() {
        return clock_t::now();
      }
 
      void set_now_overhead(size_t ns) {
        overhead_ = std::chrono::nanoseconds(ns);
      }
 
      void start(size_t t) {
        tstart_[t] = now();
      }
      dur_t stop(size_t t) {
        const auto tstop = now();
        const dur_t result = (tstop - tstart_[t]) - overhead_;
        timers_[t] += result;
        return result;
      }
      double read(size_t t) const {
        return timers_[t].count();
      }
      void clear() {
        for(auto t=0; t!=ntimers; ++t) {
          timers_[t] = dur_t::zero();
          tstart_[t] = time_point_t();
        }
      }
 
    private:
      constexpr static auto ntimers = N;
      dur_t timers_[ntimers];
      time_point_t tstart_[ntimers];
      dur_t overhead_; // the duration of now() call ... use this to automatically adjust reported timings is you need fine-grained timing
  };
 
} // namespace libint2
 
#endif // C++11 or later
 
#endif  // defined(__cplusplus)
 
#endif // header guard