ceph/src/boost/libs/multiprecision/test/timer.hpp

   1 ///////////////////////////////////////////////////////////////
   2 //  Copyright Beman Dawes 1994-99.
   3 //  Copyright 2020 John Maddock. Distributed under the Boost
   4 //  Software License, Version 1.0. (See accompanying file
   5 //  LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
   6
   7 #include <ctime>
   8 #include <limits>
   9
  10 //
  11 // This file archives the old (now deprecated) Boost.Timer.
  12 // It is however, all that we need for a simple timeout.
  13 //
  14 // TODO: replace with std::chrono once we remove C++03
  15 // support in 2021.
  16 //
  17
  18 class timer
  19 {
  20  public:
  21    timer() { _start_time = std::clock(); }          // postcondition: elapsed()==0
  22                                                     //         timer( const timer& src );      // post: elapsed()==src.elapsed()
  23                                                     //        ~timer(){}
  24                                                     //  timer& operator=( const timer& src );  // post: elapsed()==src.elapsed()
  25    void   restart() { _start_time = std::clock(); } // post: elapsed()==0
  26    double elapsed() const                           // return elapsed time in seconds
  27    {
  28       return double(std::clock() - _start_time) / CLOCKS_PER_SEC;
  29    }
  30
  31    double elapsed_max() const // return estimated maximum value for elapsed()
  32    // Portability warning: elapsed_max() may return too high a value on systems
  33    // where std::clock_t overflows or resets at surprising values.
  34    {
  35       return (double((std::numeric_limits<std::clock_t>::max)()) - double(_start_time)) / double(CLOCKS_PER_SEC);
  36    }
  37
  38    double elapsed_min() const // return minimum value for elapsed()
  39    {
  40       return double(1) / double(CLOCKS_PER_SEC);
  41    }
  42
  43  private:
  44    std::clock_t _start_time;
  45 }; // timer