michael@0: // Copyright (c) 2008 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #include "base/time.h"
michael@0: 
michael@0: #include <CoreFoundation/CFDate.h>
michael@0: #include <CoreFoundation/CFTimeZone.h>
michael@0: #include <mach/mach_time.h>
michael@0: #include <sys/time.h>
michael@0: #include <time.h>
michael@0: 
michael@0: #include "base/basictypes.h"
michael@0: #include "base/logging.h"
michael@0: #include "base/scoped_cftyperef.h"
michael@0: 
michael@0: namespace base {
michael@0: 
michael@0: // The Time routines in this file use Mach and CoreFoundation APIs, since the
michael@0: // POSIX definition of time_t in Mac OS X wraps around after 2038--and
michael@0: // there are already cookie expiration dates, etc., past that time out in
michael@0: // the field.  Using CFDate prevents that problem, and using mach_absolute_time
michael@0: // for TimeTicks gives us nice high-resolution interval timing.
michael@0: 
michael@0: // Time -----------------------------------------------------------------------
michael@0: 
michael@0: // The internal representation of Time uses a 64-bit microsecond count
michael@0: // from 1970-01-01 00:00:00 UTC.  Core Foundation uses a double second count
michael@0: // since 2001-01-01 00:00:00 UTC.
michael@0: 
michael@0: // Some functions in time.cc use time_t directly, so we provide a zero offset
michael@0: // for them.  The epoch is 1970-01-01 00:00:00 UTC.
michael@0: // static
michael@0: const int64_t Time::kTimeTToMicrosecondsOffset = GG_INT64_C(0);
michael@0: 
michael@0: // static
michael@0: Time Time::Now() {
michael@0:   CFAbsoluteTime now =
michael@0:       CFAbsoluteTimeGetCurrent() + kCFAbsoluteTimeIntervalSince1970;
michael@0:   return Time(static_cast<int64_t>(now * kMicrosecondsPerSecond));
michael@0: }
michael@0: 
michael@0: // static
michael@0: Time Time::NowFromSystemTime() {
michael@0:   // Just use Now() because Now() returns the system time.
michael@0:   return Now();
michael@0: }
michael@0: 
michael@0: // static
michael@0: Time Time::FromExploded(bool is_local, const Exploded& exploded) {
michael@0:   CFGregorianDate date;
michael@0:   date.second = exploded.second +
michael@0:       exploded.millisecond / static_cast<double>(kMillisecondsPerSecond);
michael@0:   date.minute = exploded.minute;
michael@0:   date.hour = exploded.hour;
michael@0:   date.day = exploded.day_of_month;
michael@0:   date.month = exploded.month;
michael@0:   date.year = exploded.year;
michael@0: 
michael@0:   scoped_cftyperef<CFTimeZoneRef>
michael@0:       time_zone(is_local ? CFTimeZoneCopySystem() : NULL);
michael@0:   CFAbsoluteTime seconds = CFGregorianDateGetAbsoluteTime(date, time_zone) +
michael@0:       kCFAbsoluteTimeIntervalSince1970;
michael@0:   return Time(static_cast<int64_t>(seconds * kMicrosecondsPerSecond));
michael@0: }
michael@0: 
michael@0: void Time::Explode(bool is_local, Exploded* exploded) const {
michael@0:   CFAbsoluteTime seconds =
michael@0:       (static_cast<double>(us_) / kMicrosecondsPerSecond) -
michael@0:       kCFAbsoluteTimeIntervalSince1970;
michael@0: 
michael@0:   scoped_cftyperef<CFTimeZoneRef>
michael@0:       time_zone(is_local ? CFTimeZoneCopySystem() : NULL);
michael@0:   CFGregorianDate date = CFAbsoluteTimeGetGregorianDate(seconds, time_zone);
michael@0: 
michael@0:   exploded->year = date.year;
michael@0:   exploded->month = date.month;
michael@0:   exploded->day_of_month = date.day;
michael@0:   exploded->hour = date.hour;
michael@0:   exploded->minute = date.minute;
michael@0:   exploded->second = date.second;
michael@0:   exploded->millisecond  =
michael@0:       static_cast<int>(date.second * kMillisecondsPerSecond) %
michael@0:       kMillisecondsPerSecond;
michael@0: }
michael@0: 
michael@0: // TimeTicks ------------------------------------------------------------------
michael@0: 
michael@0: // static
michael@0: TimeTicks TimeTicks::Now() {
michael@0:   uint64_t absolute_micro;
michael@0: 
michael@0:   static mach_timebase_info_data_t timebase_info;
michael@0:   if (timebase_info.denom == 0) {
michael@0:     // Zero-initialization of statics guarantees that denom will be 0 before
michael@0:     // calling mach_timebase_info.  mach_timebase_info will never set denom to
michael@0:     // 0 as that would be invalid, so the zero-check can be used to determine
michael@0:     // whether mach_timebase_info has already been called.  This is
michael@0:     // recommended by Apple's QA1398.
michael@0:     kern_return_t kr = mach_timebase_info(&timebase_info);
michael@0:     DCHECK(kr == KERN_SUCCESS);
michael@0:   }
michael@0: 
michael@0:   // mach_absolute_time is it when it comes to ticks on the Mac.  Other calls
michael@0:   // with less precision (such as TickCount) just call through to
michael@0:   // mach_absolute_time.
michael@0: 
michael@0:   // timebase_info converts absolute time tick units into nanoseconds.  Convert
michael@0:   // to microseconds up front to stave off overflows.
michael@0:   absolute_micro = mach_absolute_time() / Time::kNanosecondsPerMicrosecond *
michael@0:                    timebase_info.numer / timebase_info.denom;
michael@0: 
michael@0:   // Don't bother with the rollover handling that the Windows version does.
michael@0:   // With numer and denom = 1 (the expected case), the 64-bit absolute time
michael@0:   // reported in nanoseconds is enough to last nearly 585 years.
michael@0: 
michael@0:   return TimeTicks(absolute_micro);
michael@0: }
michael@0: 
michael@0: // static
michael@0: TimeTicks TimeTicks::HighResNow() {
michael@0:   return Now();
michael@0: }
michael@0: 
michael@0: }  // namespace base