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/mac/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
Now()49 Time Time::Now() {
50 CFAbsoluteTime now =
51 CFAbsoluteTimeGetCurrent() + kCFAbsoluteTimeIntervalSince1970;
52 return Time(static_cast<int64>(now * kMicrosecondsPerSecond) +
53 kWindowsEpochDeltaMicroseconds);
54 }
55
56 // static
NowFromSystemTime()57 Time Time::NowFromSystemTime() {
58 // Just use Now() because Now() returns the system time.
59 return Now();
60 }
61
62 // static
FromExploded(bool is_local,const Exploded & exploded)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 base::mac::ScopedCFTypeRef<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
Explode(bool is_local,Exploded * exploded) const81 void Time::Explode(bool is_local, Exploded* exploded) const {
82 CFAbsoluteTime seconds =
83 ((static_cast<double>(us_) - kWindowsEpochDeltaMicroseconds) /
84 kMicrosecondsPerSecond) - kCFAbsoluteTimeIntervalSince1970;
85
86 base::mac::ScopedCFTypeRef<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
Now()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
HighResNow()135 TimeTicks TimeTicks::HighResNow() {
136 return Now();
137 }
138
139 } // namespace base
140