1 // Copyright (c) 2012 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/time.h"
6
7 #include <CoreFoundation/CFDate.h>
8 #include <CoreFoundation/CFTimeZone.h>
9 #include <mach/mach.h>
10 #include <mach/mach_time.h>
11 #include <stddef.h>
12 #include <stdint.h>
13 #include <sys/sysctl.h>
14 #include <sys/time.h>
15 #include <sys/types.h>
16 #include <time.h>
17
18 #include "base/logging.h"
19 #include "base/mac/mach_logging.h"
20 #include "base/mac/scoped_cftyperef.h"
21 #include "base/mac/scoped_mach_port.h"
22 #include "base/macros.h"
23 #include "base/numerics/safe_conversions.h"
24 #include "build/build_config.h"
25
26 namespace {
27
ComputeCurrentTicks()28 int64_t ComputeCurrentTicks() {
29 #if defined(OS_IOS)
30 // On iOS mach_absolute_time stops while the device is sleeping. Instead use
31 // now - KERN_BOOTTIME to get a time difference that is not impacted by clock
32 // changes. KERN_BOOTTIME will be updated by the system whenever the system
33 // clock change.
34 struct timeval boottime;
35 int mib[2] = {CTL_KERN, KERN_BOOTTIME};
36 size_t size = sizeof(boottime);
37 int kr = sysctl(mib, arraysize(mib), &boottime, &size, NULL, 0);
38 DCHECK_EQ(KERN_SUCCESS, kr);
39 base::TimeDelta time_difference = base::Time::Now() -
40 (base::Time::FromTimeT(boottime.tv_sec) +
41 base::TimeDelta::FromMicroseconds(boottime.tv_usec));
42 return time_difference.InMicroseconds();
43 #else
44 static mach_timebase_info_data_t timebase_info;
45 if (timebase_info.denom == 0) {
46 // Zero-initialization of statics guarantees that denom will be 0 before
47 // calling mach_timebase_info. mach_timebase_info will never set denom to
48 // 0 as that would be invalid, so the zero-check can be used to determine
49 // whether mach_timebase_info has already been called. This is
50 // recommended by Apple's QA1398.
51 kern_return_t kr = mach_timebase_info(&timebase_info);
52 MACH_DCHECK(kr == KERN_SUCCESS, kr) << "mach_timebase_info";
53 }
54
55 // mach_absolute_time is it when it comes to ticks on the Mac. Other calls
56 // with less precision (such as TickCount) just call through to
57 // mach_absolute_time.
58
59 // timebase_info converts absolute time tick units into nanoseconds. Convert
60 // to microseconds up front to stave off overflows.
61 base::CheckedNumeric<uint64_t> result(
62 mach_absolute_time() / base::Time::kNanosecondsPerMicrosecond);
63 result *= timebase_info.numer;
64 result /= timebase_info.denom;
65
66 // Don't bother with the rollover handling that the Windows version does.
67 // With numer and denom = 1 (the expected case), the 64-bit absolute time
68 // reported in nanoseconds is enough to last nearly 585 years.
69 return base::checked_cast<int64_t>(result.ValueOrDie());
70 #endif // defined(OS_IOS)
71 }
72
ComputeThreadTicks()73 int64_t ComputeThreadTicks() {
74 #if defined(OS_IOS)
75 NOTREACHED();
76 return 0;
77 #else
78 base::mac::ScopedMachSendRight thread(mach_thread_self());
79 mach_msg_type_number_t thread_info_count = THREAD_BASIC_INFO_COUNT;
80 thread_basic_info_data_t thread_info_data;
81
82 if (thread.get() == MACH_PORT_NULL) {
83 DLOG(ERROR) << "Failed to get mach_thread_self()";
84 return 0;
85 }
86
87 kern_return_t kr = thread_info(
88 thread.get(),
89 THREAD_BASIC_INFO,
90 reinterpret_cast<thread_info_t>(&thread_info_data),
91 &thread_info_count);
92 MACH_DCHECK(kr == KERN_SUCCESS, kr) << "thread_info";
93
94 base::CheckedNumeric<int64_t> absolute_micros(
95 thread_info_data.user_time.seconds);
96 absolute_micros *= base::Time::kMicrosecondsPerSecond;
97 absolute_micros += thread_info_data.user_time.microseconds;
98 return absolute_micros.ValueOrDie();
99 #endif // defined(OS_IOS)
100 }
101
102 } // namespace
103
104 namespace base {
105
106 // The Time routines in this file use Mach and CoreFoundation APIs, since the
107 // POSIX definition of time_t in Mac OS X wraps around after 2038--and
108 // there are already cookie expiration dates, etc., past that time out in
109 // the field. Using CFDate prevents that problem, and using mach_absolute_time
110 // for TimeTicks gives us nice high-resolution interval timing.
111
112 // Time -----------------------------------------------------------------------
113
114 // Core Foundation uses a double second count since 2001-01-01 00:00:00 UTC.
115 // The UNIX epoch is 1970-01-01 00:00:00 UTC.
116 // Windows uses a Gregorian epoch of 1601. We need to match this internally
117 // so that our time representations match across all platforms. See bug 14734.
118 // irb(main):010:0> Time.at(0).getutc()
119 // => Thu Jan 01 00:00:00 UTC 1970
120 // irb(main):011:0> Time.at(-11644473600).getutc()
121 // => Mon Jan 01 00:00:00 UTC 1601
122 static const int64_t kWindowsEpochDeltaSeconds = INT64_C(11644473600);
123
124 // static
125 const int64_t Time::kWindowsEpochDeltaMicroseconds =
126 kWindowsEpochDeltaSeconds * Time::kMicrosecondsPerSecond;
127
128 // Some functions in time.cc use time_t directly, so we provide an offset
129 // to convert from time_t (Unix epoch) and internal (Windows epoch).
130 // static
131 const int64_t Time::kTimeTToMicrosecondsOffset = kWindowsEpochDeltaMicroseconds;
132
133 // static
Now()134 Time Time::Now() {
135 return FromCFAbsoluteTime(CFAbsoluteTimeGetCurrent());
136 }
137
138 // static
FromCFAbsoluteTime(CFAbsoluteTime t)139 Time Time::FromCFAbsoluteTime(CFAbsoluteTime t) {
140 static_assert(std::numeric_limits<CFAbsoluteTime>::has_infinity,
141 "CFAbsoluteTime must have an infinity value");
142 if (t == 0)
143 return Time(); // Consider 0 as a null Time.
144 if (t == std::numeric_limits<CFAbsoluteTime>::infinity())
145 return Max();
146 return Time(static_cast<int64_t>((t + kCFAbsoluteTimeIntervalSince1970) *
147 kMicrosecondsPerSecond) +
148 kWindowsEpochDeltaMicroseconds);
149 }
150
ToCFAbsoluteTime() const151 CFAbsoluteTime Time::ToCFAbsoluteTime() const {
152 static_assert(std::numeric_limits<CFAbsoluteTime>::has_infinity,
153 "CFAbsoluteTime must have an infinity value");
154 if (is_null())
155 return 0; // Consider 0 as a null Time.
156 if (is_max())
157 return std::numeric_limits<CFAbsoluteTime>::infinity();
158 return (static_cast<CFAbsoluteTime>(us_ - kWindowsEpochDeltaMicroseconds) /
159 kMicrosecondsPerSecond) - kCFAbsoluteTimeIntervalSince1970;
160 }
161
162 // static
NowFromSystemTime()163 Time Time::NowFromSystemTime() {
164 // Just use Now() because Now() returns the system time.
165 return Now();
166 }
167
168 // static
FromExploded(bool is_local,const Exploded & exploded)169 Time Time::FromExploded(bool is_local, const Exploded& exploded) {
170 CFGregorianDate date;
171 date.second = exploded.second +
172 exploded.millisecond / static_cast<double>(kMillisecondsPerSecond);
173 date.minute = exploded.minute;
174 date.hour = exploded.hour;
175 date.day = exploded.day_of_month;
176 date.month = exploded.month;
177 date.year = exploded.year;
178
179 base::ScopedCFTypeRef<CFTimeZoneRef> time_zone(
180 is_local ? CFTimeZoneCopySystem() : NULL);
181 CFAbsoluteTime seconds = CFGregorianDateGetAbsoluteTime(date, time_zone) +
182 kCFAbsoluteTimeIntervalSince1970;
183 return Time(static_cast<int64_t>(seconds * kMicrosecondsPerSecond) +
184 kWindowsEpochDeltaMicroseconds);
185 }
186
Explode(bool is_local,Exploded * exploded) const187 void Time::Explode(bool is_local, Exploded* exploded) const {
188 // Avoid rounding issues, by only putting the integral number of seconds
189 // (rounded towards -infinity) into a |CFAbsoluteTime| (which is a |double|).
190 int64_t microsecond = us_ % kMicrosecondsPerSecond;
191 if (microsecond < 0)
192 microsecond += kMicrosecondsPerSecond;
193 CFAbsoluteTime seconds = ((us_ - microsecond) / kMicrosecondsPerSecond) -
194 kWindowsEpochDeltaSeconds -
195 kCFAbsoluteTimeIntervalSince1970;
196
197 base::ScopedCFTypeRef<CFTimeZoneRef> time_zone(
198 is_local ? CFTimeZoneCopySystem() : NULL);
199 CFGregorianDate date = CFAbsoluteTimeGetGregorianDate(seconds, time_zone);
200 // 1 = Monday, ..., 7 = Sunday.
201 int cf_day_of_week = CFAbsoluteTimeGetDayOfWeek(seconds, time_zone);
202
203 exploded->year = date.year;
204 exploded->month = date.month;
205 exploded->day_of_week = cf_day_of_week % 7;
206 exploded->day_of_month = date.day;
207 exploded->hour = date.hour;
208 exploded->minute = date.minute;
209 // Make sure seconds are rounded down towards -infinity.
210 exploded->second = floor(date.second);
211 // Calculate milliseconds ourselves, since we rounded the |seconds|, making
212 // sure to round towards -infinity.
213 exploded->millisecond =
214 (microsecond >= 0) ? microsecond / kMicrosecondsPerMillisecond :
215 (microsecond - kMicrosecondsPerMillisecond + 1) /
216 kMicrosecondsPerMillisecond;
217 }
218
219 // TimeTicks ------------------------------------------------------------------
220
221 // static
Now()222 TimeTicks TimeTicks::Now() {
223 return TimeTicks(ComputeCurrentTicks());
224 }
225
226 // static
IsHighResolution()227 bool TimeTicks::IsHighResolution() {
228 return true;
229 }
230
231 // static
Now()232 ThreadTicks ThreadTicks::Now() {
233 return ThreadTicks(ComputeThreadTicks());
234 }
235
236 } // namespace base
237