timer.h

/*
 *  Copyright (C) 2004-2024 Edward F. Valeev
 *
 *  This file is part of Libint library.
 *
 *  Libint library 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 library 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 library.  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