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 // Copyright (c) 2006-2008 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 a platform-dependent epoch.  Each

 // platform's epoch, along with other system-dependent clock interface

 // routines, is defined in time_PLATFORM.cc.

 //

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

 // microseconds.

 //

 // TimeTicks represents an abstract time that is always 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).

 //

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

 // efficiently passed by value.

 #ifndef BASE_TIME_H_

 #define BASE_TIME_H_

 #include <time.h>

 #include "base/basictypes.h"

 #if defined(OS_WIN)

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

 // See TODO(iyengar) below.

 #include <windows.h>

 #endif

 namespace base {

 class Time;

 class TimeTicks;

 // This unit test does a lot of manual time manipulation.

 class PageLoadTrackerUnitTest;

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

 class TimeDelta {

  public:

   TimeDelta() : delta_(0) {

   }

   // Converts units of time to TimeDeltas.

   static TimeDelta FromDays(int64_t days);

   static TimeDelta FromHours(int64_t hours);

   static TimeDelta FromMinutes(int64_t minutes);

   static TimeDelta FromSeconds(int64_t secs);

   static TimeDelta FromMilliseconds(int64_t ms);

   static TimeDelta FromMicroseconds(int64_t us);

   // 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.

   int64_t ToInternalValue() const {

     return delta_;

   }

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

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

   int InDays() const;

   int InHours() const;

   int InMinutes() const;

   double InSecondsF() const;

   int64_t InSeconds() const;

   double InMillisecondsF() const;

   int64_t InMilliseconds() const;

   int64_t 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_t a) const {

     return TimeDelta(delta_ * a);

   }

   TimeDelta operator/(int64_t a) const {

     return TimeDelta(delta_ / a);

   }

   TimeDelta& operator*=(int64_t a) {

     delta_ *= a;

     return *this;

   }

   TimeDelta& operator/=(int64_t a) {

     delta_ /= a;

     return *this;

   }

   int64_t 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_t 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_t delta_us) : delta_(delta_us) {

   }

   // Delta in microseconds.

   int64_t delta_;

 };

 inline TimeDelta operator*(int64_t a, TimeDelta td) {

   return TimeDelta(a * td.delta_);

 }

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

 // Represents a wall clock time.

 class Time {

  public:

   static const int64_t kMillisecondsPerSecond = 1000;

   static const int64_t kMicrosecondsPerMillisecond = 1000;

   static const int64_t kMicrosecondsPerSecond = kMicrosecondsPerMillisecond *

                                               kMillisecondsPerSecond;

   static const int64_t kMicrosecondsPerMinute = kMicrosecondsPerSecond * 60;

   static const int64_t kMicrosecondsPerHour = kMicrosecondsPerMinute * 60;

   static const int64_t kMicrosecondsPerDay = kMicrosecondsPerHour * 24;

   static const int64_t kMicrosecondsPerWeek = kMicrosecondsPerDay * 7;

   static const int64_t kNanosecondsPerMicrosecond = 1000;

   static const int64_t kNanosecondsPerSecond = kNanosecondsPerMicrosecond *

                                              kMicrosecondsPerSecond;

   // 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 Exploded {

     int year;                 // Four digit year "2007"

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

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

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

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

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

     signed char 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)

   };

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

   explicit Time() : us_(0) {

   }

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

   bool is_null() const {

     return us_ == 0;

   }

   // 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 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.

   static Time FromDoubleT(double dt);

   double ToDoubleT() const;

 #if defined(OS_WIN)

   static Time FromFileTime(FILETIME ft);

   FILETIME ToFileTime() const;

 #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_t 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, we assume local time.

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

   // a new time converter class.

   static bool FromString(const wchar_t* time_string, Time* 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_t 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 us_ + delta.delta_;

   }

   Time operator-(TimeDelta delta) const {

     return 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;

   // 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);

   Time(int64_t us) : us_(us) {

   }

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

   // platform-dependent epoch.

   static const int64_t kTimeTToMicrosecondsOffset;

   // Time in microseconds in UTC.

   int64_t us_;

 };

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

   return Time(t.us_ + delta_);

 }

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

 // static

 inline TimeDelta TimeDelta::FromDays(int64_t days) {

   return TimeDelta(days * Time::kMicrosecondsPerDay);

 }

 // static

 inline TimeDelta TimeDelta::FromHours(int64_t hours) {

   return TimeDelta(hours * Time::kMicrosecondsPerHour);

 }

 // static

 inline TimeDelta TimeDelta::FromMinutes(int64_t minutes) {

   return TimeDelta(minutes * Time::kMicrosecondsPerMinute);

 }

 // static

 inline TimeDelta TimeDelta::FromSeconds(int64_t secs) {

   return TimeDelta(secs * Time::kMicrosecondsPerSecond);

 }

 // static

 inline TimeDelta TimeDelta::FromMilliseconds(int64_t ms) {

   return TimeDelta(ms * Time::kMicrosecondsPerMillisecond);

 }

 // static

 inline TimeDelta TimeDelta::FromMicroseconds(int64_t us) {

   return TimeDelta(us);

 }

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

 class 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 this object has not been initialized.

   bool is_null() const {

     return ticks_ == 0;

   }

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

   int64_t 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;

   friend class PageLoadTrackerUnitTest;

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

   // and testing. Ticks is in microseconds.

   explicit TimeTicks(int64_t ticks) : ticks_(ticks) {

   }

   // Tick count in microseconds.

   int64_t 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_H_