128 lines
5.0 KiB
C++
128 lines
5.0 KiB
C++
#ifndef DATE_TIME_HIGHRES_TIME_CLOCK_HPP___
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#define DATE_TIME_HIGHRES_TIME_CLOCK_HPP___
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/* Copyright (c) 2002,2003,2005 CrystalClear Software, Inc.
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* Use, modification and distribution is subject to the
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* Boost Software License, Version 1.0. (See accompanying
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* file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
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* Author: Jeff Garland, Bart Garst
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* $Date: 2010-05-10 02:15:48 -0700 (Mon, 10 May 2010) $
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*/
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/*! @file microsec_time_clock.hpp
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This file contains a high resolution time clock implementation.
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*/
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#include <boost/cstdint.hpp>
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#include <boost/shared_ptr.hpp>
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#include <boost/detail/workaround.hpp>
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#include <boost/date_time/compiler_config.hpp>
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#include <boost/date_time/c_time.hpp>
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#include <boost/date_time/time_clock.hpp>
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#include <boost/date_time/filetime_functions.hpp>
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#ifdef BOOST_DATE_TIME_HAS_HIGH_PRECISION_CLOCK
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namespace boost {
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namespace date_time {
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//! A clock providing microsecond level resolution
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/*! A high precision clock that measures the local time
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* at a resolution up to microseconds and adjusts to the
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* resolution of the time system. For example, for the
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* a library configuration with nano second resolution,
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* the last 3 places of the fractional seconds will always
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* be 000 since there are 1000 nano-seconds in a micro second.
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*/
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template<class time_type>
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class microsec_clock
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{
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private:
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//! Type for the function used to convert time_t to tm
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typedef std::tm* (*time_converter)(const std::time_t*, std::tm*);
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public:
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typedef typename time_type::date_type date_type;
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typedef typename time_type::time_duration_type time_duration_type;
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typedef typename time_duration_type::rep_type resolution_traits_type;
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//! return a local time object for the given zone, based on computer clock
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//JKG -- looks like we could rewrite this against universal_time
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template<class time_zone_type>
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static time_type local_time(shared_ptr<time_zone_type> tz_ptr)
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{
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typedef typename time_type::utc_time_type utc_time_type;
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typedef second_clock<utc_time_type> second_clock;
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// we'll need to know the utc_offset this machine has
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// in order to get a utc_time_type set to utc
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utc_time_type utc_time = second_clock::universal_time();
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time_duration_type utc_offset = second_clock::local_time() - utc_time;
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// use micro clock to get a local time with sub seconds
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// and adjust it to get a true utc time reading with sub seconds
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utc_time = microsec_clock<utc_time_type>::local_time() - utc_offset;
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return time_type(utc_time, tz_ptr);
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}
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//! Returns the local time based on computer clock settings
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static time_type local_time()
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{
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return create_time(&c_time::localtime);
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}
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//! Returns the UTC time based on computer settings
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static time_type universal_time()
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{
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return create_time(&c_time::gmtime);
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}
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private:
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static time_type create_time(time_converter converter)
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{
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#ifdef BOOST_HAS_GETTIMEOFDAY
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timeval tv;
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gettimeofday(&tv, 0); //gettimeofday does not support TZ adjust on Linux.
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std::time_t t = tv.tv_sec;
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boost::uint32_t sub_sec = tv.tv_usec;
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#elif defined(BOOST_HAS_FTIME)
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winapi::file_time ft;
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winapi::get_system_time_as_file_time(ft);
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uint64_t micros = winapi::file_time_to_microseconds(ft); // it will not wrap, since ft is the current time
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// and cannot be before 1970-Jan-01
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std::time_t t = static_cast<std::time_t>(micros / 1000000UL); // seconds since epoch
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// microseconds -- static casts supress warnings
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boost::uint32_t sub_sec = static_cast<boost::uint32_t>(micros % 1000000UL);
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#else
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#error Internal Boost.DateTime error: BOOST_DATE_TIME_HAS_HIGH_PRECISION_CLOCK is defined, however neither gettimeofday nor FILETIME support is detected.
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#endif
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std::tm curr;
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std::tm* curr_ptr = converter(&t, &curr);
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date_type d(static_cast< typename date_type::year_type::value_type >(curr_ptr->tm_year + 1900),
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static_cast< typename date_type::month_type::value_type >(curr_ptr->tm_mon + 1),
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static_cast< typename date_type::day_type::value_type >(curr_ptr->tm_mday));
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//The following line will adjust the fractional second tick in terms
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//of the current time system. For example, if the time system
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//doesn't support fractional seconds then res_adjust returns 0
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//and all the fractional seconds return 0.
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int adjust = static_cast< int >(resolution_traits_type::res_adjust() / 1000000);
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time_duration_type td(static_cast< typename time_duration_type::hour_type >(curr_ptr->tm_hour),
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static_cast< typename time_duration_type::min_type >(curr_ptr->tm_min),
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static_cast< typename time_duration_type::sec_type >(curr_ptr->tm_sec),
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sub_sec * adjust);
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return time_type(d,td);
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}
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};
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} } //namespace date_time
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#endif //BOOST_DATE_TIME_HAS_HIGH_PRECISION_CLOCK
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#endif
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