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/Src/Dependencies/Boost/boost/date_time/microsec_time_clock.hpp

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C++ Header | 127 lines | 72 code | 22 blank | 33 comment | 0 complexity | 93737a1b1acc17901cdb8798733731c1 MD5 | raw file
  1#ifndef DATE_TIME_HIGHRES_TIME_CLOCK_HPP___
  2#define DATE_TIME_HIGHRES_TIME_CLOCK_HPP___
  3
  4/* Copyright (c) 2002,2003,2005 CrystalClear Software, Inc.
  5 * Use, modification and distribution is subject to the
  6 * Boost Software License, Version 1.0. (See accompanying
  7 * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
  8 * Author: Jeff Garland, Bart Garst
  9 * $Date: 2010-05-10 19:15:48 +1000 (Mon, 10 May 2010) $
 10 */
 11
 12
 13/*! @file microsec_time_clock.hpp
 14  This file contains a high resolution time clock implementation.
 15*/
 16
 17#include <boost/cstdint.hpp>
 18#include <boost/shared_ptr.hpp>
 19#include <boost/detail/workaround.hpp>
 20#include <boost/date_time/compiler_config.hpp>
 21#include <boost/date_time/c_time.hpp>
 22#include <boost/date_time/time_clock.hpp>
 23#include <boost/date_time/filetime_functions.hpp>
 24
 25#ifdef BOOST_DATE_TIME_HAS_HIGH_PRECISION_CLOCK
 26
 27namespace boost {
 28namespace date_time {
 29
 30  //! A clock providing microsecond level resolution
 31  /*! A high precision clock that measures the local time
 32   *  at a resolution up to microseconds and adjusts to the
 33   *  resolution of the time system.  For example, for the
 34   *  a library configuration with nano second resolution,
 35   *  the last 3 places of the fractional seconds will always
 36   *  be 000 since there are 1000 nano-seconds in a micro second.
 37   */
 38  template<class time_type>
 39  class microsec_clock
 40  {
 41  private:
 42    //! Type for the function used to convert time_t to tm
 43    typedef std::tm* (*time_converter)(const std::time_t*, std::tm*);
 44
 45  public:
 46    typedef typename time_type::date_type date_type;
 47    typedef typename time_type::time_duration_type time_duration_type;
 48    typedef typename time_duration_type::rep_type resolution_traits_type;
 49
 50    //! return a local time object for the given zone, based on computer clock
 51    //JKG -- looks like we could rewrite this against universal_time
 52    template<class time_zone_type>
 53    static time_type local_time(shared_ptr<time_zone_type> tz_ptr)
 54    {
 55      typedef typename time_type::utc_time_type utc_time_type;
 56      typedef second_clock<utc_time_type> second_clock;
 57      // we'll need to know the utc_offset this machine has
 58      // in order to get a utc_time_type set to utc
 59      utc_time_type utc_time = second_clock::universal_time();
 60      time_duration_type utc_offset = second_clock::local_time() - utc_time;
 61      // use micro clock to get a local time with sub seconds
 62      // and adjust it to get a true utc time reading with sub seconds
 63      utc_time = microsec_clock<utc_time_type>::local_time() - utc_offset;
 64      return time_type(utc_time, tz_ptr);
 65    }
 66
 67    //! Returns the local time based on computer clock settings
 68    static time_type local_time()
 69    {
 70      return create_time(&c_time::localtime);
 71    }
 72
 73    //! Returns the UTC time based on computer settings
 74    static time_type universal_time()
 75    {
 76      return create_time(&c_time::gmtime);
 77    }
 78
 79  private:
 80    static time_type create_time(time_converter converter)
 81    {
 82#ifdef BOOST_HAS_GETTIMEOFDAY
 83      timeval tv;
 84      gettimeofday(&tv, 0); //gettimeofday does not support TZ adjust on Linux.
 85      std::time_t t = tv.tv_sec;
 86      boost::uint32_t sub_sec = tv.tv_usec;
 87#elif defined(BOOST_HAS_FTIME)
 88      winapi::file_time ft;
 89      winapi::get_system_time_as_file_time(ft);
 90      uint64_t micros = winapi::file_time_to_microseconds(ft); // it will not wrap, since ft is the current time
 91                                                               // and cannot be before 1970-Jan-01
 92      std::time_t t = static_cast<std::time_t>(micros / 1000000UL); // seconds since epoch
 93      // microseconds -- static casts supress warnings
 94      boost::uint32_t sub_sec = static_cast<boost::uint32_t>(micros % 1000000UL);
 95#else
 96#error Internal Boost.DateTime error: BOOST_DATE_TIME_HAS_HIGH_PRECISION_CLOCK is defined, however neither gettimeofday nor FILETIME support is detected.
 97#endif
 98
 99      std::tm curr;
100      std::tm* curr_ptr = converter(&t, &curr);
101      date_type d(static_cast< typename date_type::year_type::value_type >(curr_ptr->tm_year + 1900),
102                  static_cast< typename date_type::month_type::value_type >(curr_ptr->tm_mon + 1),
103                  static_cast< typename date_type::day_type::value_type >(curr_ptr->tm_mday));
104
105      //The following line will adjust the fractional second tick in terms
106      //of the current time system.  For example, if the time system
107      //doesn't support fractional seconds then res_adjust returns 0
108      //and all the fractional seconds return 0.
109      int adjust = static_cast< int >(resolution_traits_type::res_adjust() / 1000000);
110
111      time_duration_type td(static_cast< typename time_duration_type::hour_type >(curr_ptr->tm_hour),
112                            static_cast< typename time_duration_type::min_type >(curr_ptr->tm_min),
113                            static_cast< typename time_duration_type::sec_type >(curr_ptr->tm_sec),
114                            sub_sec * adjust);
115
116      return time_type(d,td);
117    }
118  };
119
120
121} } //namespace date_time
122
123#endif //BOOST_DATE_TIME_HAS_HIGH_PRECISION_CLOCK
124
125
126#endif
127