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      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 <sys/sysctl.h>
     12 #include <sys/time.h>
     13 #include <sys/types.h>
     14 #include <time.h>
     15 
     16 #include "base/basictypes.h"
     17 #include "base/logging.h"
     18 #include "base/mac/mach_logging.h"
     19 #include "base/mac/scoped_cftyperef.h"
     20 #include "base/mac/scoped_mach_port.h"
     21 
     22 namespace {
     23 
     24 uint64_t ComputeCurrentTicks() {
     25 #if defined(OS_IOS)
     26   // On iOS mach_absolute_time stops while the device is sleeping. Instead use
     27   // now - KERN_BOOTTIME to get a time difference that is not impacted by clock
     28   // changes. KERN_BOOTTIME will be updated by the system whenever the system
     29   // clock change.
     30   struct timeval boottime;
     31   int mib[2] = {CTL_KERN, KERN_BOOTTIME};
     32   size_t size = sizeof(boottime);
     33   int kr = sysctl(mib, arraysize(mib), &boottime, &size, NULL, 0);
     34   DCHECK_EQ(KERN_SUCCESS, kr);
     35   base::TimeDelta time_difference = base::Time::Now() -
     36       (base::Time::FromTimeT(boottime.tv_sec) +
     37        base::TimeDelta::FromMicroseconds(boottime.tv_usec));
     38   return time_difference.InMicroseconds();
     39 #else
     40   uint64_t absolute_micro;
     41 
     42   static mach_timebase_info_data_t timebase_info;
     43   if (timebase_info.denom == 0) {
     44     // Zero-initialization of statics guarantees that denom will be 0 before
     45     // calling mach_timebase_info.  mach_timebase_info will never set denom to
     46     // 0 as that would be invalid, so the zero-check can be used to determine
     47     // whether mach_timebase_info has already been called.  This is
     48     // recommended by Apple's QA1398.
     49     kern_return_t kr = mach_timebase_info(&timebase_info);
     50     MACH_DCHECK(kr == KERN_SUCCESS, kr) << "mach_timebase_info";
     51   }
     52 
     53   // mach_absolute_time is it when it comes to ticks on the Mac.  Other calls
     54   // with less precision (such as TickCount) just call through to
     55   // mach_absolute_time.
     56 
     57   // timebase_info converts absolute time tick units into nanoseconds.  Convert
     58   // to microseconds up front to stave off overflows.
     59   absolute_micro =
     60       mach_absolute_time() / base::Time::kNanosecondsPerMicrosecond *
     61       timebase_info.numer / timebase_info.denom;
     62 
     63   // Don't bother with the rollover handling that the Windows version does.
     64   // With numer and denom = 1 (the expected case), the 64-bit absolute time
     65   // reported in nanoseconds is enough to last nearly 585 years.
     66   return absolute_micro;
     67 #endif  // defined(OS_IOS)
     68 }
     69 
     70 uint64_t ComputeThreadTicks() {
     71 #if defined(OS_IOS)
     72   NOTREACHED();
     73   return 0;
     74 #else
     75   base::mac::ScopedMachSendRight thread(mach_thread_self());
     76   mach_msg_type_number_t thread_info_count = THREAD_BASIC_INFO_COUNT;
     77   thread_basic_info_data_t thread_info_data;
     78 
     79   if (thread.get() == MACH_PORT_NULL) {
     80     DLOG(ERROR) << "Failed to get mach_thread_self()";
     81     return 0;
     82   }
     83 
     84   kern_return_t kr = thread_info(
     85       thread,
     86       THREAD_BASIC_INFO,
     87       reinterpret_cast<thread_info_t>(&thread_info_data),
     88       &thread_info_count);
     89   MACH_DCHECK(kr == KERN_SUCCESS, kr) << "thread_info";
     90 
     91   return (thread_info_data.user_time.seconds *
     92               base::Time::kMicrosecondsPerSecond) +
     93          thread_info_data.user_time.microseconds;
     94 #endif  // defined(OS_IOS)
     95 }
     96 
     97 }  // namespace
     98 
     99 namespace base {
    100 
    101 // The Time routines in this file use Mach and CoreFoundation APIs, since the
    102 // POSIX definition of time_t in Mac OS X wraps around after 2038--and
    103 // there are already cookie expiration dates, etc., past that time out in
    104 // the field.  Using CFDate prevents that problem, and using mach_absolute_time
    105 // for TimeTicks gives us nice high-resolution interval timing.
    106 
    107 // Time -----------------------------------------------------------------------
    108 
    109 // Core Foundation uses a double second count since 2001-01-01 00:00:00 UTC.
    110 // The UNIX epoch is 1970-01-01 00:00:00 UTC.
    111 // Windows uses a Gregorian epoch of 1601.  We need to match this internally
    112 // so that our time representations match across all platforms.  See bug 14734.
    113 //   irb(main):010:0> Time.at(0).getutc()
    114 //   => Thu Jan 01 00:00:00 UTC 1970
    115 //   irb(main):011:0> Time.at(-11644473600).getutc()
    116 //   => Mon Jan 01 00:00:00 UTC 1601
    117 static const int64 kWindowsEpochDeltaSeconds = GG_INT64_C(11644473600);
    118 
    119 // static
    120 const int64 Time::kWindowsEpochDeltaMicroseconds =
    121     kWindowsEpochDeltaSeconds * Time::kMicrosecondsPerSecond;
    122 
    123 // Some functions in time.cc use time_t directly, so we provide an offset
    124 // to convert from time_t (Unix epoch) and internal (Windows epoch).
    125 // static
    126 const int64 Time::kTimeTToMicrosecondsOffset = kWindowsEpochDeltaMicroseconds;
    127 
    128 // static
    129 Time Time::Now() {
    130   return FromCFAbsoluteTime(CFAbsoluteTimeGetCurrent());
    131 }
    132 
    133 // static
    134 Time Time::FromCFAbsoluteTime(CFAbsoluteTime t) {
    135   COMPILE_ASSERT(std::numeric_limits<CFAbsoluteTime>::has_infinity,
    136                  numeric_limits_infinity_is_undefined_when_not_has_infinity);
    137   if (t == 0)
    138     return Time();  // Consider 0 as a null Time.
    139   if (t == std::numeric_limits<CFAbsoluteTime>::infinity())
    140     return Max();
    141   return Time(static_cast<int64>(
    142       (t + kCFAbsoluteTimeIntervalSince1970) * kMicrosecondsPerSecond) +
    143       kWindowsEpochDeltaMicroseconds);
    144 }
    145 
    146 CFAbsoluteTime Time::ToCFAbsoluteTime() const {
    147   COMPILE_ASSERT(std::numeric_limits<CFAbsoluteTime>::has_infinity,
    148                  numeric_limits_infinity_is_undefined_when_not_has_infinity);
    149   if (is_null())
    150     return 0;  // Consider 0 as a null Time.
    151   if (is_max())
    152     return std::numeric_limits<CFAbsoluteTime>::infinity();
    153   return (static_cast<CFAbsoluteTime>(us_ - kWindowsEpochDeltaMicroseconds) /
    154       kMicrosecondsPerSecond) - kCFAbsoluteTimeIntervalSince1970;
    155 }
    156 
    157 // static
    158 Time Time::NowFromSystemTime() {
    159   // Just use Now() because Now() returns the system time.
    160   return Now();
    161 }
    162 
    163 // static
    164 Time Time::FromExploded(bool is_local, const Exploded& exploded) {
    165   CFGregorianDate date;
    166   date.second = exploded.second +
    167       exploded.millisecond / static_cast<double>(kMillisecondsPerSecond);
    168   date.minute = exploded.minute;
    169   date.hour = exploded.hour;
    170   date.day = exploded.day_of_month;
    171   date.month = exploded.month;
    172   date.year = exploded.year;
    173 
    174   base::ScopedCFTypeRef<CFTimeZoneRef> time_zone(
    175       is_local ? CFTimeZoneCopySystem() : NULL);
    176   CFAbsoluteTime seconds = CFGregorianDateGetAbsoluteTime(date, time_zone) +
    177       kCFAbsoluteTimeIntervalSince1970;
    178   return Time(static_cast<int64>(seconds * kMicrosecondsPerSecond) +
    179       kWindowsEpochDeltaMicroseconds);
    180 }
    181 
    182 void Time::Explode(bool is_local, Exploded* exploded) const {
    183   // Avoid rounding issues, by only putting the integral number of seconds
    184   // (rounded towards -infinity) into a |CFAbsoluteTime| (which is a |double|).
    185   int64 microsecond = us_ % kMicrosecondsPerSecond;
    186   if (microsecond < 0)
    187     microsecond += kMicrosecondsPerSecond;
    188   CFAbsoluteTime seconds = ((us_ - microsecond) / kMicrosecondsPerSecond) -
    189                            kWindowsEpochDeltaSeconds -
    190                            kCFAbsoluteTimeIntervalSince1970;
    191 
    192   base::ScopedCFTypeRef<CFTimeZoneRef> time_zone(
    193       is_local ? CFTimeZoneCopySystem() : NULL);
    194   CFGregorianDate date = CFAbsoluteTimeGetGregorianDate(seconds, time_zone);
    195   // 1 = Monday, ..., 7 = Sunday.
    196   int cf_day_of_week = CFAbsoluteTimeGetDayOfWeek(seconds, time_zone);
    197 
    198   exploded->year = date.year;
    199   exploded->month = date.month;
    200   exploded->day_of_week = cf_day_of_week % 7;
    201   exploded->day_of_month = date.day;
    202   exploded->hour = date.hour;
    203   exploded->minute = date.minute;
    204   // Make sure seconds are rounded down towards -infinity.
    205   exploded->second = floor(date.second);
    206   // Calculate milliseconds ourselves, since we rounded the |seconds|, making
    207   // sure to round towards -infinity.
    208   exploded->millisecond =
    209       (microsecond >= 0) ? microsecond / kMicrosecondsPerMillisecond :
    210                            (microsecond - kMicrosecondsPerMillisecond + 1) /
    211                                kMicrosecondsPerMillisecond;
    212 }
    213 
    214 // TimeTicks ------------------------------------------------------------------
    215 
    216 // static
    217 TimeTicks TimeTicks::Now() {
    218   return TimeTicks(ComputeCurrentTicks());
    219 }
    220 
    221 // static
    222 TimeTicks TimeTicks::HighResNow() {
    223   return Now();
    224 }
    225 
    226 // static
    227 bool TimeTicks::IsHighResNowFastAndReliable() {
    228   return true;
    229 }
    230 
    231 // static
    232 TimeTicks TimeTicks::ThreadNow() {
    233   return TimeTicks(ComputeThreadTicks());
    234 }
    235 
    236 // static
    237 TimeTicks TimeTicks::NowFromSystemTraceTime() {
    238   return HighResNow();
    239 }
    240 
    241 }  // namespace base
    242