1 // Copyright (c) 2008 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/time.h" 6 7 #include <CoreFoundation/CFDate.h> 8 #include <CoreFoundation/CFTimeZone.h> 9 #include <mach/mach_time.h> 10 #include <sys/time.h> 11 #include <time.h> 12 13 #include "base/basictypes.h" 14 #include "base/logging.h" 15 #include "base/scoped_cftyperef.h" 16 17 namespace base { 18 19 // The Time routines in this file use Mach and CoreFoundation APIs, since the 20 // POSIX definition of time_t in Mac OS X wraps around after 2038--and 21 // there are already cookie expiration dates, etc., past that time out in 22 // the field. Using CFDate prevents that problem, and using mach_absolute_time 23 // for TimeTicks gives us nice high-resolution interval timing. 24 25 // Time ----------------------------------------------------------------------- 26 27 // Core Foundation uses a double second count since 2001-01-01 00:00:00 UTC. 28 // The UNIX epoch is 1970-01-01 00:00:00 UTC. 29 // Windows uses a Gregorian epoch of 1601. We need to match this internally 30 // so that our time representations match across all platforms. See bug 14734. 31 // irb(main):010:0> Time.at(0).getutc() 32 // => Thu Jan 01 00:00:00 UTC 1970 33 // irb(main):011:0> Time.at(-11644473600).getutc() 34 // => Mon Jan 01 00:00:00 UTC 1601 35 static const int64 kWindowsEpochDeltaSeconds = GG_INT64_C(11644473600); 36 static const int64 kWindowsEpochDeltaMilliseconds = 37 kWindowsEpochDeltaSeconds * Time::kMillisecondsPerSecond; 38 39 // static 40 const int64 Time::kWindowsEpochDeltaMicroseconds = 41 kWindowsEpochDeltaSeconds * Time::kMicrosecondsPerSecond; 42 43 // Some functions in time.cc use time_t directly, so we provide an offset 44 // to convert from time_t (Unix epoch) and internal (Windows epoch). 45 // static 46 const int64 Time::kTimeTToMicrosecondsOffset = kWindowsEpochDeltaMicroseconds; 47 48 // static 49 Time Time::Now() { 50 CFAbsoluteTime now = 51 CFAbsoluteTimeGetCurrent() + kCFAbsoluteTimeIntervalSince1970; 52 return Time(static_cast<int64>(now * kMicrosecondsPerSecond) + 53 kWindowsEpochDeltaMicroseconds); 54 } 55 56 // static 57 Time Time::NowFromSystemTime() { 58 // Just use Now() because Now() returns the system time. 59 return Now(); 60 } 61 62 // static 63 Time Time::FromExploded(bool is_local, const Exploded& exploded) { 64 CFGregorianDate date; 65 date.second = exploded.second + 66 exploded.millisecond / static_cast<double>(kMillisecondsPerSecond); 67 date.minute = exploded.minute; 68 date.hour = exploded.hour; 69 date.day = exploded.day_of_month; 70 date.month = exploded.month; 71 date.year = exploded.year; 72 73 scoped_cftyperef<CFTimeZoneRef> 74 time_zone(is_local ? CFTimeZoneCopySystem() : NULL); 75 CFAbsoluteTime seconds = CFGregorianDateGetAbsoluteTime(date, time_zone) + 76 kCFAbsoluteTimeIntervalSince1970; 77 return Time(static_cast<int64>(seconds * kMicrosecondsPerSecond) + 78 kWindowsEpochDeltaMicroseconds); 79 } 80 81 void Time::Explode(bool is_local, Exploded* exploded) const { 82 CFAbsoluteTime seconds = 83 (static_cast<double>((us_ - kWindowsEpochDeltaMicroseconds) / 84 kMicrosecondsPerSecond) - kCFAbsoluteTimeIntervalSince1970); 85 86 scoped_cftyperef<CFTimeZoneRef> 87 time_zone(is_local ? CFTimeZoneCopySystem() : NULL); 88 CFGregorianDate date = CFAbsoluteTimeGetGregorianDate(seconds, time_zone); 89 90 exploded->year = date.year; 91 exploded->month = date.month; 92 exploded->day_of_month = date.day; 93 exploded->hour = date.hour; 94 exploded->minute = date.minute; 95 exploded->second = date.second; 96 exploded->millisecond = 97 static_cast<int>(date.second * kMillisecondsPerSecond) % 98 kMillisecondsPerSecond; 99 } 100 101 // TimeTicks ------------------------------------------------------------------ 102 103 // static 104 TimeTicks TimeTicks::Now() { 105 uint64_t absolute_micro; 106 107 static mach_timebase_info_data_t timebase_info; 108 if (timebase_info.denom == 0) { 109 // Zero-initialization of statics guarantees that denom will be 0 before 110 // calling mach_timebase_info. mach_timebase_info will never set denom to 111 // 0 as that would be invalid, so the zero-check can be used to determine 112 // whether mach_timebase_info has already been called. This is 113 // recommended by Apple's QA1398. 114 kern_return_t kr = mach_timebase_info(&timebase_info); 115 DCHECK(kr == KERN_SUCCESS); 116 } 117 118 // mach_absolute_time is it when it comes to ticks on the Mac. Other calls 119 // with less precision (such as TickCount) just call through to 120 // mach_absolute_time. 121 122 // timebase_info converts absolute time tick units into nanoseconds. Convert 123 // to microseconds up front to stave off overflows. 124 absolute_micro = mach_absolute_time() / Time::kNanosecondsPerMicrosecond * 125 timebase_info.numer / timebase_info.denom; 126 127 // Don't bother with the rollover handling that the Windows version does. 128 // With numer and denom = 1 (the expected case), the 64-bit absolute time 129 // reported in nanoseconds is enough to last nearly 585 years. 130 131 return TimeTicks(absolute_micro); 132 } 133 134 // static 135 TimeTicks TimeTicks::HighResNow() { 136 return Now(); 137 } 138 139 } // namespace base 140