boost/date_time/microsec_time_clock.hpp
#ifndef DATE_TIME_HIGHRES_TIME_CLOCK_HPP___ #define DATE_TIME_HIGHRES_TIME_CLOCK_HPP___ /* Copyright (c) 2002,2003,2005 CrystalClear Software, Inc. * Use, modification and distribution is subject to the * Boost Software License, Version 1.0. (See accompanying * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) * Author: Jeff Garland, Bart Garst * $Date$ */ /*! @file microsec_time_clock.hpp This file contains a high resolution time clock implementation. */ #include <boost/cstdint.hpp> #include <boost/shared_ptr.hpp> #include <boost/detail/workaround.hpp> #include <boost/date_time/compiler_config.hpp> #include <boost/date_time/c_time.hpp> #include <boost/date_time/time_clock.hpp> #if defined(BOOST_HAS_FTIME) #include <boost/winapi/time.hpp> #endif #ifdef BOOST_DATE_TIME_HAS_HIGH_PRECISION_CLOCK namespace boost { namespace date_time { //! A clock providing microsecond level resolution /*! A high precision clock that measures the local time * at a resolution up to microseconds and adjusts to the * resolution of the time system. For example, for the * a library configuration with nano second resolution, * the last 3 places of the fractional seconds will always * be 000 since there are 1000 nano-seconds in a micro second. */ template<class time_type> class microsec_clock { private: //! Type for the function used to convert time_t to tm typedef std::tm* (*time_converter)(const std::time_t*, std::tm*); public: typedef typename time_type::date_type date_type; typedef typename time_type::time_duration_type time_duration_type; typedef typename time_duration_type::rep_type resolution_traits_type; //! return a local time object for the given zone, based on computer clock //JKG -- looks like we could rewrite this against universal_time template<class time_zone_type> static time_type local_time(shared_ptr<time_zone_type> tz_ptr) { typedef typename time_type::utc_time_type utc_time_type; typedef second_clock<utc_time_type> second_clock; // we'll need to know the utc_offset this machine has // in order to get a utc_time_type set to utc utc_time_type utc_time = second_clock::universal_time(); time_duration_type utc_offset = second_clock::local_time() - utc_time; // use micro clock to get a local time with sub seconds // and adjust it to get a true utc time reading with sub seconds utc_time = microsec_clock<utc_time_type>::local_time() - utc_offset; return time_type(utc_time, tz_ptr); } //! Returns the local time based on computer clock settings static time_type local_time() { return create_time(&c_time::localtime); } //! Returns the UTC time based on computer settings static time_type universal_time() { return create_time(&c_time::gmtime); } private: static time_type create_time(time_converter converter) { #ifdef BOOST_HAS_GETTIMEOFDAY timeval tv; gettimeofday(&tv, 0); //gettimeofday does not support TZ adjust on Linux. std::time_t t = tv.tv_sec; boost::uint32_t sub_sec = tv.tv_usec; #elif defined(BOOST_HAS_FTIME) boost::winapi::FILETIME_ ft; boost::winapi::GetSystemTimeAsFileTime(&ft); #if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3205)) // Some runtime library implementations expect local times as the norm for ctime functions. { boost::winapi::FILETIME_ local_ft; boost::winapi::FileTimeToLocalFileTime(&ft, &local_ft); ft = local_ft; } #endif boost::uint64_t micros = file_time_to_microseconds(ft); // it will not wrap, since ft is the current time // and cannot be before 1970-Jan-01 std::time_t t = static_cast<std::time_t>(micros / 1000000UL); // seconds since epoch // microseconds -- static casts suppress warnings boost::uint32_t sub_sec = static_cast<boost::uint32_t>(micros % 1000000UL); #else #error Internal Boost.DateTime error: BOOST_DATE_TIME_HAS_HIGH_PRECISION_CLOCK is defined, however neither gettimeofday nor FILETIME support is detected. #endif std::tm curr; std::tm* curr_ptr = converter(&t, &curr); date_type d(static_cast< typename date_type::year_type::value_type >(curr_ptr->tm_year + 1900), static_cast< typename date_type::month_type::value_type >(curr_ptr->tm_mon + 1), static_cast< typename date_type::day_type::value_type >(curr_ptr->tm_mday)); //The following line will adjust the fractional second tick in terms //of the current time system. For example, if the time system //doesn't support fractional seconds then res_adjust returns 0 //and all the fractional seconds return 0. int adjust = static_cast< int >(resolution_traits_type::res_adjust() / 1000000); time_duration_type td(static_cast< typename time_duration_type::hour_type >(curr_ptr->tm_hour), static_cast< typename time_duration_type::min_type >(curr_ptr->tm_min), static_cast< typename time_duration_type::sec_type >(curr_ptr->tm_sec), sub_sec * adjust); return time_type(d,td); } #if defined(BOOST_HAS_FTIME) /*! * The function converts file_time into number of microseconds elapsed since 1970-Jan-01 * * \note Only dates after 1970-Jan-01 are supported. Dates before will be wrapped. */ static boost::uint64_t file_time_to_microseconds(boost::winapi::FILETIME_ const& ft) { // shift is difference between 1970-Jan-01 & 1601-Jan-01 // in 100-nanosecond units const boost::uint64_t shift = 116444736000000000ULL; // (27111902 << 32) + 3577643008 // 100-nanos since 1601-Jan-01 boost::uint64_t ft_as_integer = (static_cast< boost::uint64_t >(ft.dwHighDateTime) << 32) | static_cast< boost::uint64_t >(ft.dwLowDateTime); ft_as_integer -= shift; // filetime is now 100-nanos since 1970-Jan-01 return (ft_as_integer / 10U); // truncate to microseconds } #endif }; } } //namespace date_time #endif //BOOST_DATE_TIME_HAS_HIGH_PRECISION_CLOCK #endif