1 // boost timer.hpp header file ---------------------------------------------// 2 3 // Copyright Beman Dawes 1994-99. Distributed under the Boost 4 // Software License, Version 1.0. (See accompanying file 5 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6 7 // See http://www.boost.org/libs/timer for documentation. 8 9 // Revision History 10 // 01 Apr 01 Modified to use new <boost/limits.hpp> header. (JMaddock) 11 // 12 Jan 01 Change to inline implementation to allow use without library 12 // builds. See docs for more rationale. (Beman Dawes) 13 // 25 Sep 99 elapsed_max() and elapsed_min() added (John Maddock) 14 // 16 Jul 99 Second beta 15 // 6 Jul 99 Initial boost version 16 17 #ifndef BOOST_TIMER_HPP 18 #define BOOST_TIMER_HPP 19 20 #include <boost/config.hpp> 21 #include <ctime> 22 #include <boost/limits.hpp> 23 24 # ifdef BOOST_NO_STDC_NAMESPACE 25 namespace std { using ::clock_t; using ::clock; } 26 # endif 27 28 29 namespace boost { 30 31 // timer -------------------------------------------------------------------// 32 33 // A timer object measures elapsed time. 34 35 // It is recommended that implementations measure wall clock rather than CPU 36 // time since the intended use is performance measurement on systems where 37 // total elapsed time is more important than just process or CPU time. 38 39 // Warnings: The maximum measurable elapsed time may well be only 596.5+ hours 40 // due to implementation limitations. The accuracy of timings depends on the 41 // accuracy of timing information provided by the underlying platform, and 42 // this varies a great deal from platform to platform. 43 44 class timer 45 { 46 public: timer()47 timer() { _start_time = std::clock(); } // postcondition: elapsed()==0 48 // timer( const timer& src ); // post: elapsed()==src.elapsed() 49 // ~timer(){} 50 // timer& operator=( const timer& src ); // post: elapsed()==src.elapsed() restart()51 void restart() { _start_time = std::clock(); } // post: elapsed()==0 elapsed() const52 double elapsed() const // return elapsed time in seconds 53 { return double(std::clock() - _start_time) / CLOCKS_PER_SEC; } 54 elapsed_max() const55 double elapsed_max() const // return estimated maximum value for elapsed() 56 // Portability warning: elapsed_max() may return too high a value on systems 57 // where std::clock_t overflows or resets at surprising values. 58 { 59 return (double((std::numeric_limits<std::clock_t>::max)()) 60 - double(_start_time)) / double(CLOCKS_PER_SEC); 61 } 62 elapsed_min() const63 double elapsed_min() const // return minimum value for elapsed() 64 { return double(1)/double(CLOCKS_PER_SEC); } 65 66 private: 67 std::clock_t _start_time; 68 }; // timer 69 70 } // namespace boost 71 72 #endif // BOOST_TIMER_HPP 73