1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 // Copyright (c) 2008 The Chromium Authors. All rights reserved.
4 // Use of this source code is governed by a BSD-style license that can be
5 // found in the LICENSE file.
6
7 #include "base/time.h"
8
9 #include <CoreFoundation/CFDate.h>
10 #include <CoreFoundation/CFTimeZone.h>
11 #include <mach/mach_time.h>
12 #include <sys/time.h>
13 #include <time.h>
14
15 #include "base/basictypes.h"
16 #include "base/logging.h"
17 #include "base/scoped_cftyperef.h"
18
19 namespace base {
20
21 // The Time routines in this file use Mach and CoreFoundation APIs, since the
22 // POSIX definition of time_t in Mac OS X wraps around after 2038--and
23 // there are already cookie expiration dates, etc., past that time out in
24 // the field. Using CFDate prevents that problem, and using mach_absolute_time
25 // for TimeTicks gives us nice high-resolution interval timing.
26
27 // Time -----------------------------------------------------------------------
28
29 // The internal representation of Time uses a 64-bit microsecond count
30 // from 1970-01-01 00:00:00 UTC. Core Foundation uses a double second count
31 // since 2001-01-01 00:00:00 UTC.
32
33 // Some functions in time.cc use time_t directly, so we provide a zero offset
34 // for them. The epoch is 1970-01-01 00:00:00 UTC.
35 // static
36 const int64_t Time::kTimeTToMicrosecondsOffset = GG_INT64_C(0);
37
38 // static
Now()39 Time Time::Now() {
40 CFAbsoluteTime now =
41 CFAbsoluteTimeGetCurrent() + kCFAbsoluteTimeIntervalSince1970;
42 return Time(static_cast<int64_t>(now * kMicrosecondsPerSecond));
43 }
44
45 // static
NowFromSystemTime()46 Time Time::NowFromSystemTime() {
47 // Just use Now() because Now() returns the system time.
48 return Now();
49 }
50
51 // static
FromExploded(bool is_local,const Exploded & exploded)52 Time Time::FromExploded(bool is_local, const Exploded& exploded) {
53 CFGregorianDate date;
54 date.second =
55 exploded.second +
56 exploded.millisecond / static_cast<double>(kMillisecondsPerSecond);
57 date.minute = exploded.minute;
58 date.hour = exploded.hour;
59 date.day = exploded.day_of_month;
60 date.month = exploded.month;
61 date.year = exploded.year;
62
63 scoped_cftyperef<CFTimeZoneRef> time_zone(is_local ? CFTimeZoneCopySystem()
64 : NULL);
65 CFAbsoluteTime seconds = CFGregorianDateGetAbsoluteTime(date, time_zone) +
66 kCFAbsoluteTimeIntervalSince1970;
67 return Time(static_cast<int64_t>(seconds * kMicrosecondsPerSecond));
68 }
69
Explode(bool is_local,Exploded * exploded) const70 void Time::Explode(bool is_local, Exploded* exploded) const {
71 CFAbsoluteTime seconds = (static_cast<double>(us_) / kMicrosecondsPerSecond) -
72 kCFAbsoluteTimeIntervalSince1970;
73
74 scoped_cftyperef<CFTimeZoneRef> time_zone(is_local ? CFTimeZoneCopySystem()
75 : NULL);
76 CFGregorianDate date = CFAbsoluteTimeGetGregorianDate(seconds, time_zone);
77
78 exploded->year = date.year;
79 exploded->month = date.month;
80 exploded->day_of_month = date.day;
81 exploded->hour = date.hour;
82 exploded->minute = date.minute;
83 exploded->second = date.second;
84 exploded->millisecond =
85 static_cast<int>(date.second * kMillisecondsPerSecond) %
86 kMillisecondsPerSecond;
87 }
88
89 // TimeTicks ------------------------------------------------------------------
90
91 // static
Now()92 TimeTicks TimeTicks::Now() {
93 uint64_t absolute_micro;
94
95 static mach_timebase_info_data_t timebase_info;
96 if (timebase_info.denom == 0) {
97 // Zero-initialization of statics guarantees that denom will be 0 before
98 // calling mach_timebase_info. mach_timebase_info will never set denom to
99 // 0 as that would be invalid, so the zero-check can be used to determine
100 // whether mach_timebase_info has already been called. This is
101 // recommended by Apple's QA1398.
102 kern_return_t kr = mach_timebase_info(&timebase_info);
103 DCHECK(kr == KERN_SUCCESS);
104 }
105
106 // mach_absolute_time is it when it comes to ticks on the Mac. Other calls
107 // with less precision (such as TickCount) just call through to
108 // mach_absolute_time.
109
110 // timebase_info converts absolute time tick units into nanoseconds. Convert
111 // to microseconds up front to stave off overflows.
112 absolute_micro = mach_absolute_time() / Time::kNanosecondsPerMicrosecond *
113 timebase_info.numer / timebase_info.denom;
114
115 // Don't bother with the rollover handling that the Windows version does.
116 // With numer and denom = 1 (the expected case), the 64-bit absolute time
117 // reported in nanoseconds is enough to last nearly 585 years.
118
119 return TimeTicks(absolute_micro);
120 }
121
122 } // namespace base
123