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229 lines
8.5 KiB
229 lines
8.5 KiB
// boost/chrono/system_clocks.hpp --------------------------------------------------------------// |
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// Copyright 2008 Howard Hinnant |
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// Copyright 2008 Beman Dawes |
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// Copyright 2009-2011 Vicente J. Botet Escriba |
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// Distributed under the Boost Software License, Version 1.0. |
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// See http://www.boost.org/LICENSE_1_0.txt |
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/* |
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This code was derived by Beman Dawes from Howard Hinnant's time2_demo prototype. |
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Many thanks to Howard for making his code available under the Boost license. |
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The original code was modified to conform to Boost conventions and to section |
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20.9 Time utilities [time] of the C++ committee's working paper N2798. |
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See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2798.pdf. |
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time2_demo contained this comment: |
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Much thanks to Andrei Alexandrescu, |
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Walter Brown, |
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Peter Dimov, |
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Jeff Garland, |
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Terry Golubiewski, |
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Daniel Krugler, |
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Anthony Williams. |
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*/ |
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/* |
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TODO: |
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* Fully implement error handling, with test cases. |
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* Use boost::throw_exception. (Currently not used because of an issue with Intel 11.0.) |
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* Consider issues raised by Michael Marcin: |
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> In the past I've seen QueryPerformanceCounter give incorrect results, |
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> especially with SpeedStep processors on laptops. This was many years ago and |
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> might have been fixed by service packs and drivers. |
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> |
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> Typically you check the results of QPC against GetTickCount to see if the |
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> results are reasonable. |
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> http://support.microsoft.com/kb/274323 |
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> |
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> I've also heard of problems with QueryPerformanceCounter in multi-processor |
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> systems. |
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> |
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> I know some people SetThreadAffinityMask to 1 for the current thread call |
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> their QueryPerformance* functions then restore SetThreadAffinityMask. This |
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> seems horrible to me because it forces your program to jump to another |
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> physical processor if it isn't already on cpu0 but they claim it worked well |
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> in practice because they called the timing functions infrequently. |
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> |
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> In the past I have chosen to use timeGetTime with timeBeginPeriod(1) for |
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> high resolution timers to avoid these issues. |
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*/ |
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#ifndef BOOST_CHRONO_SYSTEM_CLOCKS_HPP |
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#define BOOST_CHRONO_SYSTEM_CLOCKS_HPP |
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#include <boost/chrono/config.hpp> |
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#include <boost/chrono/duration.hpp> |
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#include <boost/chrono/time_point.hpp> |
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#if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING |
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#include <boost/chrono/detail/system.hpp> |
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#include <boost/system/error_code.hpp> |
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#endif |
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#include <boost/chrono/clock_string.hpp> |
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#include <ctime> |
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#ifdef BOOST_CHRONO_WINDOWS_API |
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// The system_clock tick is 100 nanoseconds |
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# define BOOST_SYSTEM_CLOCK_DURATION boost::chrono::duration<boost::int_least64_t, ratio<BOOST_RATIO_INTMAX_C(1), BOOST_RATIO_INTMAX_C(10000000)> > |
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#else |
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# define BOOST_SYSTEM_CLOCK_DURATION boost::chrono::nanoseconds |
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#endif |
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#ifndef BOOST_CHRONO_HEADER_ONLY |
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#include <boost/config/abi_prefix.hpp> // must be the last #include |
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#endif |
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//----------------------------------------------------------------------------// |
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// // |
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// 20.9 Time utilities [time] // |
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// synopsis // |
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// // |
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//----------------------------------------------------------------------------// |
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namespace boost { |
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namespace chrono { |
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// Clocks |
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class BOOST_CHRONO_DECL system_clock; |
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#ifdef BOOST_CHRONO_HAS_CLOCK_STEADY |
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class BOOST_CHRONO_DECL steady_clock; // as permitted by [time.clock.steady] |
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#endif |
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#ifdef BOOST_CHRONO_HAS_CLOCK_STEADY |
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typedef steady_clock high_resolution_clock; // as permitted by [time.clock.hires] |
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#else |
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typedef system_clock high_resolution_clock; // as permitted by [time.clock.hires] |
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#endif |
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//----------------------------------------------------------------------------// |
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// // |
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// 20.9.5 Clocks [time.clock] // |
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// // |
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//----------------------------------------------------------------------------// |
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// If you're porting, clocks are the system-specific (non-portable) part. |
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// You'll need to know how to get the current time and implement that under now(). |
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// You'll need to know what units (tick period) and representation makes the most |
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// sense for your clock and set those accordingly. |
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// If you know how to map this clock to time_t (perhaps your clock is std::time, which |
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// makes that trivial), then you can fill out system_clock's to_time_t() and from_time_t(). |
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//----------------------------------------------------------------------------// |
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// 20.9.5.1 Class system_clock [time.clock.system] // |
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//----------------------------------------------------------------------------// |
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class BOOST_CHRONO_DECL system_clock |
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{ |
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public: |
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typedef BOOST_SYSTEM_CLOCK_DURATION duration; |
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typedef duration::rep rep; |
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typedef duration::period period; |
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typedef chrono::time_point<system_clock> time_point; |
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BOOST_CHRONO_STATIC_CONSTEXPR bool is_steady = false; |
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static BOOST_CHRONO_INLINE time_point now() BOOST_CHRONO_NOEXCEPT; |
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#if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING |
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static BOOST_CHRONO_INLINE time_point now(system::error_code & ec); |
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#endif |
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static BOOST_CHRONO_INLINE std::time_t to_time_t(const time_point& t) BOOST_CHRONO_NOEXCEPT; |
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static BOOST_CHRONO_INLINE time_point from_time_t(std::time_t t) BOOST_CHRONO_NOEXCEPT; |
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}; |
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//----------------------------------------------------------------------------// |
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// 20.9.5.2 Class steady_clock [time.clock.steady] // |
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//----------------------------------------------------------------------------// |
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// As permitted by [time.clock.steady] |
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// The class steady_clock is conditionally supported. |
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#ifdef BOOST_CHRONO_HAS_CLOCK_STEADY |
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class BOOST_CHRONO_DECL steady_clock |
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{ |
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public: |
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typedef nanoseconds duration; |
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typedef duration::rep rep; |
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typedef duration::period period; |
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typedef chrono::time_point<steady_clock> time_point; |
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BOOST_CHRONO_STATIC_CONSTEXPR bool is_steady = true; |
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static BOOST_CHRONO_INLINE time_point now() BOOST_CHRONO_NOEXCEPT; |
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#if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING |
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static BOOST_CHRONO_INLINE time_point now(system::error_code & ec); |
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#endif |
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}; |
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#endif |
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//----------------------------------------------------------------------------// |
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// 20.9.5.3 Class high_resolution_clock [time.clock.hires] // |
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//----------------------------------------------------------------------------// |
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// As permitted, steady_clock or system_clock is a typedef for high_resolution_clock. |
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// See synopsis. |
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template<class CharT> |
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struct clock_string<system_clock, CharT> |
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{ |
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static std::basic_string<CharT> name() |
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{ |
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static const CharT u[] = |
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{ 's', 'y', 's', 't', 'e', 'm', '_', 'c', 'l', 'o', 'c', 'k' }; |
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static const std::basic_string<CharT> str(u, u + sizeof(u) |
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/ sizeof(u[0])); |
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return str; |
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} |
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static std::basic_string<CharT> since() |
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{ |
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static const CharT |
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u[] = |
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{ ' ', 's', 'i', 'n', 'c', 'e', ' ', 'J', 'a', 'n', ' ', '1', ',', ' ', '1', '9', '7', '0' }; |
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static const std::basic_string<CharT> str(u, u + sizeof(u) |
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/ sizeof(u[0])); |
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return str; |
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} |
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}; |
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#ifdef BOOST_CHRONO_HAS_CLOCK_STEADY |
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template<class CharT> |
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struct clock_string<steady_clock, CharT> |
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{ |
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static std::basic_string<CharT> name() |
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{ |
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static const CharT |
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u[] = |
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{ 's', 't', 'e', 'a', 'd', 'y', '_', 'c', 'l', 'o', 'c', 'k' }; |
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static const std::basic_string<CharT> str(u, u + sizeof(u) |
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/ sizeof(u[0])); |
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return str; |
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} |
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static std::basic_string<CharT> since() |
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{ |
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const CharT u[] = |
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{ ' ', 's', 'i', 'n', 'c', 'e', ' ', 'b', 'o', 'o', 't' }; |
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const std::basic_string<CharT> str(u, u + sizeof(u) / sizeof(u[0])); |
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return str; |
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} |
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}; |
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#endif |
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} // namespace chrono |
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} // namespace boost |
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#ifndef BOOST_CHRONO_HEADER_ONLY |
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#include <boost/config/abi_suffix.hpp> // pops abi_prefix.hpp pragmas |
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#else |
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#include <boost/chrono/detail/inlined/chrono.hpp> |
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#endif |
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#endif // BOOST_CHRONO_SYSTEM_CLOCKS_HPP
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