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 * $Date$
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(converter: &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(converter: &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: &tv, tz: 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 suppress 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
128

source code of boost/boost/date_time/microsec_time_clock.hpp