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 // Copyright (c) 2012 The Chromium Authors. All rights reserved.

 // Use of this source code is governed by a BSD-style license that can be

 // found in the LICENSE file.

 // Time represents an absolute point in time, internally represented as

 // microseconds (s/1,000,000) since the Windows epoch (1601-01-01 00:00:00 UTC)

 // (See http://crbug.com/14734).  System-dependent clock interface routines are

 // defined in time_PLATFORM.cc.

 //

 // TimeDelta represents a duration of time, internally represented in

 // microseconds.

 //

 // TimeTicks represents an abstract time that is most of the time incrementing

 // for use in measuring time durations. It is internally represented in

 // microseconds.  It can not be converted to a human-readable time, but is

 // guaranteed not to decrease (if the user changes the computer clock,

 // Time::Now() may actually decrease or jump).  But note that TimeTicks may

 // "stand still", for example if the computer suspended.

 //

 // These classes are represented as only a 64-bit value, so they can be

 // efficiently passed by value.

 #ifndef BASE_TIME_TIME_H_

 #define BASE_TIME_TIME_H_

 #include <time.h>

 #include "base/base_export.h"

 #include "base/basictypes.h"

 #include "build/build_config.h"

 #if defined(OS_MACOSX)

 #include <CoreFoundation/CoreFoundation.h>

 // Avoid Mac system header macro leak.

 #undef TYPE_BOOL

 #endif

 #if defined(OS_POSIX)

 #include <unistd.h>

 #include <sys/time.h>

 #endif

 #if defined(OS_WIN)

 // For FILETIME in FromFileTime, until it moves to a new converter class.

 // See TODO(iyengar) below.

 #include <windows.h>

 #endif

 #include <limits>

 namespace base {

 class Time;

 class TimeTicks;

 // TimeDelta ------------------------------------------------------------------

 class BASE_EXPORT TimeDelta {

  public:

   TimeDelta() : delta_(0) {

   }

   // Converts units of time to TimeDeltas.

   static TimeDelta FromDays(int64 days);

   static TimeDelta FromHours(int64 hours);

   static TimeDelta FromMinutes(int64 minutes);

   static TimeDelta FromSeconds(int64 secs);

   static TimeDelta FromMilliseconds(int64 ms);

   static TimeDelta FromMicroseconds(int64 us);

 #if defined(OS_WIN)

   static TimeDelta FromQPCValue(LONGLONG qpc_value);

 #endif

   // Converts an integer value representing TimeDelta to a class. This is used

   // when deserializing a |TimeDelta| structure, using a value known to be

   // compatible. It is not provided as a constructor because the integer type

   // may be unclear from the perspective of a caller.

   static TimeDelta FromInternalValue(int64 delta) {

     return TimeDelta(delta);

   }

   // Returns the internal numeric value of the TimeDelta object. Please don't

   // use this and do arithmetic on it, as it is more error prone than using the

   // provided operators.

   // For serializing, use FromInternalValue to reconstitute.

   int64 ToInternalValue() const {

     return delta_;

   }

 #if defined(OS_POSIX)

   struct timespec ToTimeSpec() const;

 #endif

   // Returns the time delta in some unit. The F versions return a floating

   // point value, the "regular" versions return a rounded-down value.

   //

   // InMillisecondsRoundedUp() instead returns an integer that is rounded up

   // to the next full millisecond.

   int InDays() const;

   int InHours() const;

   int InMinutes() const;

   double InSecondsF() const;

   int64 InSeconds() const;

   double InMillisecondsF() const;

   int64 InMilliseconds() const;

   int64 InMillisecondsRoundedUp() const;

   int64 InMicroseconds() const;

   TimeDelta& operator=(TimeDelta other) {

     delta_ = other.delta_;

     return *this;

   }

   // Computations with other deltas.

   TimeDelta operator+(TimeDelta other) const {

     return TimeDelta(delta_ + other.delta_);

   }

   TimeDelta operator-(TimeDelta other) const {

     return TimeDelta(delta_ - other.delta_);

   }

   TimeDelta& operator+=(TimeDelta other) {

     delta_ += other.delta_;

     return *this;

   }

   TimeDelta& operator-=(TimeDelta other) {

     delta_ -= other.delta_;

     return *this;

   }

   TimeDelta operator-() const {

     return TimeDelta(-delta_);

   }

   // Computations with ints, note that we only allow multiplicative operations

   // with ints, and additive operations with other deltas.

   TimeDelta operator*(int64 a) const {

     return TimeDelta(delta_ * a);

   }

   TimeDelta operator/(int64 a) const {

     return TimeDelta(delta_ / a);

   }

   TimeDelta& operator*=(int64 a) {

     delta_ *= a;

     return *this;

   }

   TimeDelta& operator/=(int64 a) {

     delta_ /= a;

     return *this;

   }

   int64 operator/(TimeDelta a) const {

     return delta_ / a.delta_;

   }

   // Defined below because it depends on the definition of the other classes.

   Time operator+(Time t) const;

   TimeTicks operator+(TimeTicks t) const;

   // Comparison operators.

   bool operator==(TimeDelta other) const {

     return delta_ == other.delta_;

   }

   bool operator!=(TimeDelta other) const {

     return delta_ != other.delta_;

   }

   bool operator<(TimeDelta other) const {

     return delta_ < other.delta_;

   }

   bool operator<=(TimeDelta other) const {

     return delta_ <= other.delta_;

   }

   bool operator>(TimeDelta other) const {

     return delta_ > other.delta_;

   }

   bool operator>=(TimeDelta other) const {

     return delta_ >= other.delta_;

   }

  private:

   friend class Time;

   friend class TimeTicks;

   friend TimeDelta operator*(int64 a, TimeDelta td);

   // Constructs a delta given the duration in microseconds. This is private

   // to avoid confusion by callers with an integer constructor. Use

   // FromSeconds, FromMilliseconds, etc. instead.

   explicit TimeDelta(int64 delta_us) : delta_(delta_us) {

   }

   // Delta in microseconds.

   int64 delta_;

 };

 inline TimeDelta operator*(int64 a, TimeDelta td) {

   return TimeDelta(a * td.delta_);

 }

 // Time -----------------------------------------------------------------------

 // Represents a wall clock time.

 class BASE_EXPORT Time {

  public:

   static const int64 kMillisecondsPerSecond = 1000;

   static const int64 kMicrosecondsPerMillisecond = 1000;

   static const int64 kMicrosecondsPerSecond = kMicrosecondsPerMillisecond *

                                               kMillisecondsPerSecond;

   static const int64 kMicrosecondsPerMinute = kMicrosecondsPerSecond * 60;

   static const int64 kMicrosecondsPerHour = kMicrosecondsPerMinute * 60;

   static const int64 kMicrosecondsPerDay = kMicrosecondsPerHour * 24;

   static const int64 kMicrosecondsPerWeek = kMicrosecondsPerDay * 7;

   static const int64 kNanosecondsPerMicrosecond = 1000;

   static const int64 kNanosecondsPerSecond = kNanosecondsPerMicrosecond *

                                              kMicrosecondsPerSecond;

 #if !defined(OS_WIN)

   // On Mac & Linux, this value is the delta from the Windows epoch of 1601 to

   // the Posix delta of 1970. This is used for migrating between the old

   // 1970-based epochs to the new 1601-based ones. It should be removed from

   // this global header and put in the platform-specific ones when we remove the

   // migration code.

   static const int64 kWindowsEpochDeltaMicroseconds;

 #endif

   // Represents an exploded time that can be formatted nicely. This is kind of

   // like the Win32 SYSTEMTIME structure or the Unix "struct tm" with a few

   // additions and changes to prevent errors.

   struct BASE_EXPORT Exploded {

     int year;          // Four digit year "2007"

     int month;         // 1-based month (values 1 = January, etc.)

     int day_of_week;   // 0-based day of week (0 = Sunday, etc.)

     int day_of_month;  // 1-based day of month (1-31)

     int hour;          // Hour within the current day (0-23)

     int minute;        // Minute within the current hour (0-59)

     int second;        // Second within the current minute (0-59 plus leap

                        //   seconds which may take it up to 60).

     int millisecond;   // Milliseconds within the current second (0-999)

     // A cursory test for whether the data members are within their

     // respective ranges. A 'true' return value does not guarantee the

     // Exploded value can be successfully converted to a Time value.

     bool HasValidValues() const;

   };

   // Contains the NULL time. Use Time::Now() to get the current time.

   Time() : us_(0) {

   }

   // Returns true if the time object has not been initialized.

   bool is_null() const {

     return us_ == 0;

   }

   // Returns true if the time object is the maximum time.

   bool is_max() const {

     return us_ == std::numeric_limits<int64>::max();

   }

   // Returns the time for epoch in Unix-like system (Jan 1, 1970).

   static Time UnixEpoch();

   // Returns the current time. Watch out, the system might adjust its clock

   // in which case time will actually go backwards. We don't guarantee that

   // times are increasing, or that two calls to Now() won't be the same.

   static Time Now();

   // Returns the maximum time, which should be greater than any reasonable time

   // with which we might compare it.

   static Time Max();

   // Returns the current time. Same as Now() except that this function always

   // uses system time so that there are no discrepancies between the returned

   // time and system time even on virtual environments including our test bot.

   // For timing sensitive unittests, this function should be used.

   static Time NowFromSystemTime();

   // Converts to/from time_t in UTC and a Time class.

   // TODO(brettw) this should be removed once everybody starts using the |Time|

   // class.

   static Time FromTimeT(time_t tt);

   time_t ToTimeT() const;

   // Converts time to/from a double which is the number of seconds since epoch

   // (Jan 1, 1970).  Webkit uses this format to represent time.

   // Because WebKit initializes double time value to 0 to indicate "not

   // initialized", we map it to empty Time object that also means "not

   // initialized".

   static Time FromDoubleT(double dt);

   double ToDoubleT() const;

 #if defined(OS_POSIX)

   // Converts the timespec structure to time. MacOS X 10.8.3 (and tentatively,

   // earlier versions) will have the |ts|'s tv_nsec component zeroed out,

   // having a 1 second resolution, which agrees with

   // https://developer.apple.com/legacy/library/#technotes/tn/tn1150.html#HFSPlusDates.

   static Time FromTimeSpec(const timespec& ts);

 #endif

   // Converts to/from the Javascript convention for times, a number of

   // milliseconds since the epoch:

   // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/getTime.

   static Time FromJsTime(double ms_since_epoch);

   double ToJsTime() const;

   // Converts to Java convention for times, a number of

   // milliseconds since the epoch.

   int64 ToJavaTime() const;

 #if defined(OS_POSIX)

   static Time FromTimeVal(struct timeval t);

   struct timeval ToTimeVal() const;

 #endif

 #if defined(OS_MACOSX)

   static Time FromCFAbsoluteTime(CFAbsoluteTime t);

   CFAbsoluteTime ToCFAbsoluteTime() const;

 #endif

 #if defined(OS_WIN)

   static Time FromFileTime(FILETIME ft);

   FILETIME ToFileTime() const;

   // The minimum time of a low resolution timer.  This is basically a windows

   // constant of ~15.6ms.  While it does vary on some older OS versions, we'll

   // treat it as static across all windows versions.

   static const int kMinLowResolutionThresholdMs = 16;

   // Enable or disable Windows high resolution timer. If the high resolution

   // timer is not enabled, calls to ActivateHighResolutionTimer will fail.

   // When disabling the high resolution timer, this function will not cause

   // the high resolution timer to be deactivated, but will prevent future

   // activations.

   // Must be called from the main thread.

   // For more details see comments in time_win.cc.

   static void EnableHighResolutionTimer(bool enable);

   // Activates or deactivates the high resolution timer based on the |activate|

   // flag.  If the HighResolutionTimer is not Enabled (see

   // EnableHighResolutionTimer), this function will return false.  Otherwise

   // returns true.  Each successful activate call must be paired with a

   // subsequent deactivate call.

   // All callers to activate the high resolution timer must eventually call

   // this function to deactivate the high resolution timer.

   static bool ActivateHighResolutionTimer(bool activate);

   // Returns true if the high resolution timer is both enabled and activated.

   // This is provided for testing only, and is not tracked in a thread-safe

   // way.

   static bool IsHighResolutionTimerInUse();

 #endif

   // Converts an exploded structure representing either the local time or UTC

   // into a Time class.

   static Time FromUTCExploded(const Exploded& exploded) {

     return FromExploded(false, exploded);

   }

   static Time FromLocalExploded(const Exploded& exploded) {

     return FromExploded(true, exploded);

   }

   // Converts an integer value representing Time to a class. This is used

   // when deserializing a |Time| structure, using a value known to be

   // compatible. It is not provided as a constructor because the integer type

   // may be unclear from the perspective of a caller.

   static Time FromInternalValue(int64 us) {

     return Time(us);

   }

   // Converts a string representation of time to a Time object.

   // An example of a time string which is converted is as below:-

   // "Tue, 15 Nov 1994 12:45:26 GMT". If the timezone is not specified

   // in the input string, FromString assumes local time and FromUTCString

   // assumes UTC. A timezone that cannot be parsed (e.g. "UTC" which is not

   // specified in RFC822) is treated as if the timezone is not specified.

   // TODO(iyengar) Move the FromString/FromTimeT/ToTimeT/FromFileTime to

   // a new time converter class.

   static bool FromString(const char* time_string, Time* parsed_time) {

     return FromStringInternal(time_string, true, parsed_time);

   }

   static bool FromUTCString(const char* time_string, Time* parsed_time) {

     return FromStringInternal(time_string, false, parsed_time);

   }

   // For serializing, use FromInternalValue to reconstitute. Please don't use

   // this and do arithmetic on it, as it is more error prone than using the

   // provided operators.

   int64 ToInternalValue() const {

     return us_;

   }

   // Fills the given exploded structure with either the local time or UTC from

   // this time structure (containing UTC).

   void UTCExplode(Exploded* exploded) const {

     return Explode(false, exploded);

   }

   void LocalExplode(Exploded* exploded) const {

     return Explode(true, exploded);

   }

   // Rounds this time down to the nearest day in local time. It will represent

   // midnight on that day.

   Time LocalMidnight() const;

   Time& operator=(Time other) {

     us_ = other.us_;

     return *this;

   }

   // Compute the difference between two times.

   TimeDelta operator-(Time other) const {

     return TimeDelta(us_ - other.us_);

   }

   // Modify by some time delta.

   Time& operator+=(TimeDelta delta) {

     us_ += delta.delta_;

     return *this;

   }

   Time& operator-=(TimeDelta delta) {

     us_ -= delta.delta_;

     return *this;

   }

   // Return a new time modified by some delta.

   Time operator+(TimeDelta delta) const {

     return Time(us_ + delta.delta_);

   }

   Time operator-(TimeDelta delta) const {

     return Time(us_ - delta.delta_);

   }

   // Comparison operators

   bool operator==(Time other) const {

     return us_ == other.us_;

   }

   bool operator!=(Time other) const {

     return us_ != other.us_;

   }

   bool operator<(Time other) const {

     return us_ < other.us_;

   }

   bool operator<=(Time other) const {

     return us_ <= other.us_;

   }

   bool operator>(Time other) const {

     return us_ > other.us_;

   }

   bool operator>=(Time other) const {

     return us_ >= other.us_;

   }

  private:

   friend class TimeDelta;

   explicit Time(int64 us) : us_(us) {

   }

   // Explodes the given time to either local time |is_local = true| or UTC

   // |is_local = false|.

   void Explode(bool is_local, Exploded* exploded) const;

   // Unexplodes a given time assuming the source is either local time

   // |is_local = true| or UTC |is_local = false|.

   static Time FromExploded(bool is_local, const Exploded& exploded);

   // Converts a string representation of time to a Time object.

   // An example of a time string which is converted is as below:-

   // "Tue, 15 Nov 1994 12:45:26 GMT". If the timezone is not specified

   // in the input string, local time |is_local = true| or

   // UTC |is_local = false| is assumed. A timezone that cannot be parsed

   // (e.g. "UTC" which is not specified in RFC822) is treated as if the

   // timezone is not specified.

   static bool FromStringInternal(const char* time_string,

                                  bool is_local,

                                  Time* parsed_time);

   // The representation of Jan 1, 1970 UTC in microseconds since the

   // platform-dependent epoch.

   static const int64 kTimeTToMicrosecondsOffset;

 #if defined(OS_WIN)

   // Indicates whether fast timers are usable right now.  For instance,

   // when using battery power, we might elect to prevent high speed timers

   // which would draw more power.

   static bool high_resolution_timer_enabled_;

   // Count of activations on the high resolution timer.  Only use in tests

   // which are single threaded.

   static int high_resolution_timer_activated_;

 #endif

   // Time in microseconds in UTC.

   int64 us_;

 };

 // Inline the TimeDelta factory methods, for fast TimeDelta construction.

 // static

 inline TimeDelta TimeDelta::FromDays(int64 days) {

   return TimeDelta(days * Time::kMicrosecondsPerDay);

 }

 // static

 inline TimeDelta TimeDelta::FromHours(int64 hours) {

   return TimeDelta(hours * Time::kMicrosecondsPerHour);

 }

 // static

 inline TimeDelta TimeDelta::FromMinutes(int64 minutes) {

   return TimeDelta(minutes * Time::kMicrosecondsPerMinute);

 }

 // static

 inline TimeDelta TimeDelta::FromSeconds(int64 secs) {

   return TimeDelta(secs * Time::kMicrosecondsPerSecond);

 }

 // static

 inline TimeDelta TimeDelta::FromMilliseconds(int64 ms) {

   return TimeDelta(ms * Time::kMicrosecondsPerMillisecond);

 }

 // static

 inline TimeDelta TimeDelta::FromMicroseconds(int64 us) {

   return TimeDelta(us);

 }

 inline Time TimeDelta::operator+(Time t) const {

   return Time(t.us_ + delta_);

 }

 // TimeTicks ------------------------------------------------------------------

 class BASE_EXPORT TimeTicks {

  public:

   TimeTicks() : ticks_(0) {

   }

   // Platform-dependent tick count representing "right now."

   // The resolution of this clock is ~1-15ms.  Resolution varies depending

   // on hardware/operating system configuration.

   static TimeTicks Now();

   // Returns a platform-dependent high-resolution tick count. Implementation

   // is hardware dependent and may or may not return sub-millisecond

   // resolution.  THIS CALL IS GENERALLY MUCH MORE EXPENSIVE THAN Now() AND

   // SHOULD ONLY BE USED WHEN IT IS REALLY NEEDED.

   static TimeTicks HighResNow();

   // Returns true if ThreadNow() is supported on this system.

   static bool IsThreadNowSupported() {

 #if defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)

     return true;

 #else

     return false;

 #endif

   }

   // Returns thread-specific CPU-time on systems that support this feature.

   // Needs to be guarded with a call to IsThreadNowSupported(). Use this timer

   // to (approximately) measure how much time the calling thread spent doing

   // actual work vs. being de-scheduled. May return bogus results if the thread

   // migrates to another CPU between two calls.

   static TimeTicks ThreadNow();

   // Returns the current system trace time or, if none is defined, the current

   // high-res time (i.e. HighResNow()). On systems where a global trace clock

   // is defined, timestamping TraceEvents's with this value guarantees

   // synchronization between events collected inside chrome and events

   // collected outside (e.g. kernel, X server).

   static TimeTicks NowFromSystemTraceTime();

 #if defined(OS_WIN)

   // Get the absolute value of QPC time drift. For testing.

   static int64 GetQPCDriftMicroseconds();

   static TimeTicks FromQPCValue(LONGLONG qpc_value);

   // Returns true if the high resolution clock is working on this system.

   // This is only for testing.

   static bool IsHighResClockWorking();

   // Enable high resolution time for TimeTicks::Now(). This function will

   // test for the availability of a working implementation of

   // QueryPerformanceCounter(). If one is not available, this function does

   // nothing and the resolution of Now() remains 1ms. Otherwise, all future

   // calls to TimeTicks::Now() will have the higher resolution provided by QPC.

   // Returns true if high resolution time was successfully enabled.

   static bool SetNowIsHighResNowIfSupported();

   // Returns a time value that is NOT rollover protected.

   static TimeTicks UnprotectedNow();

 #endif

   // Returns true if this object has not been initialized.

   bool is_null() const {

     return ticks_ == 0;

   }

   // Converts an integer value representing TimeTicks to a class. This is used

   // when deserializing a |TimeTicks| structure, using a value known to be

   // compatible. It is not provided as a constructor because the integer type

   // may be unclear from the perspective of a caller.

   static TimeTicks FromInternalValue(int64 ticks) {

     return TimeTicks(ticks);

   }

   // Returns the internal numeric value of the TimeTicks object.

   // For serializing, use FromInternalValue to reconstitute.

   int64 ToInternalValue() const {

     return ticks_;

   }

   TimeTicks& operator=(TimeTicks other) {

     ticks_ = other.ticks_;

     return *this;

   }

   // Compute the difference between two times.

   TimeDelta operator-(TimeTicks other) const {

     return TimeDelta(ticks_ - other.ticks_);

   }

   // Modify by some time delta.

   TimeTicks& operator+=(TimeDelta delta) {

     ticks_ += delta.delta_;

     return *this;

   }

   TimeTicks& operator-=(TimeDelta delta) {

     ticks_ -= delta.delta_;

     return *this;

   }

   // Return a new TimeTicks modified by some delta.

   TimeTicks operator+(TimeDelta delta) const {

     return TimeTicks(ticks_ + delta.delta_);

   }

   TimeTicks operator-(TimeDelta delta) const {

     return TimeTicks(ticks_ - delta.delta_);

   }

   // Comparison operators

   bool operator==(TimeTicks other) const {

     return ticks_ == other.ticks_;

   }

   bool operator!=(TimeTicks other) const {

     return ticks_ != other.ticks_;

   }

   bool operator<(TimeTicks other) const {

     return ticks_ < other.ticks_;

   }

   bool operator<=(TimeTicks other) const {

     return ticks_ <= other.ticks_;

   }

   bool operator>(TimeTicks other) const {

     return ticks_ > other.ticks_;

   }

   bool operator>=(TimeTicks other) const {

     return ticks_ >= other.ticks_;

   }

  protected:

   friend class TimeDelta;

   // Please use Now() to create a new object. This is for internal use

   // and testing. Ticks is in microseconds.

   explicit TimeTicks(int64 ticks) : ticks_(ticks) {

   }

   // Tick count in microseconds.

   int64 ticks_;

 #if defined(OS_WIN)

   typedef DWORD (*TickFunctionType)(void);

   static TickFunctionType SetMockTickFunction(TickFunctionType ticker);

 #endif

 };

 inline TimeTicks TimeDelta::operator+(TimeTicks t) const {

   return TimeTicks(t.ticks_ + delta_);

 }

 }  // namespace base

 #endif  // BASE_TIME_TIME_H_