// 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 coordinated universal time (UTC),

// 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 BUTIL_TIME_TIME_H_

#define BUTIL_TIME_TIME_H_

#include <time.h>

#include "butil/base_export.h"

#include "butil/basictypes.h"

#include "butil/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>

#ifdef BAIDU_INTERNAL

// gejun: Force inclusion of ul_def.h and undef conflict macros

#include <ul_def.h>

#undef Uchar

#undef Ushort

#undef Uint

#undef Max

#undef Min

#undef Exchange

#endif // BAIDU_INTERNAL

namespace butil {

class Time;

class TimeTicks;

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

class BUTIL_EXPORT TimeDelta {

 public:

  TimeDelta() : delta_(0) {

  }

  // Required by clang++ 11 on MacOS catalina

  TimeDelta(const TimeDelta& other) : delta_(other.delta_) {}

  // Converts units of time to TimeDeltas.

  static TimeDelta FromDays(int days);

  static TimeDelta FromHours(int hours);

  static TimeDelta FromMinutes(int minutes);

  static TimeDelta FromSeconds(int64_t secs);

  static TimeDelta FromMilliseconds(int64_t ms);

  static TimeDelta FromMicroseconds(int64_t us);

  static TimeDelta FromSecondsD(double secs);

  static TimeDelta FromMillisecondsD(double ms);

  static TimeDelta FromMicrosecondsD(double 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_t delta) {

    return TimeDelta(delta);

  }

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

  // time delta we might compare it to. Adding or subtracting the maximum time

  // delta to a time or another time delta has an undefined result.

  static TimeDelta Max();

  // 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_t ToInternalValue() const {

    return delta_;

  }

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

  bool is_max() const {

    return delta_ == std::numeric_limits<int64_t>::max();

  }

#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_t InSeconds() const;

  double InMillisecondsF() const;

  int64_t InMilliseconds() const;

  int64_t InMillisecondsRoundedUp() 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 in UTC.

class BUTIL_EXPORT 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;

#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_t 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 BUTIL_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) {

  }

  // Required by clang++ 11 on MacOS catalina

  Time(const Time& other) : us_(other.us_) {}

  // 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_t>::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_t 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_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, 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_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 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_t 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_t 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_t us_;

};

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

// static

inline TimeDelta TimeDelta::FromDays(int days) {

  // Preserve max to prevent overflow.

  if (days == std::numeric_limits<int>::max())

    return Max();

  return TimeDelta(days * Time::kMicrosecondsPerDay);

}

// static

inline TimeDelta TimeDelta::FromHours(int hours) {

  // Preserve max to prevent overflow.

  if (hours == std::numeric_limits<int>::max())

    return Max();

  return TimeDelta(hours * Time::kMicrosecondsPerHour);

}

// static

inline TimeDelta TimeDelta::FromMinutes(int minutes) {

  // Preserve max to prevent overflow.

  if (minutes == std::numeric_limits<int>::max())

    return Max();

  return TimeDelta(minutes * Time::kMicrosecondsPerMinute);

}

// static

inline TimeDelta TimeDelta::FromSeconds(int64_t secs) {

  // Preserve max to prevent overflow.

  if (secs == std::numeric_limits<int64_t>::max())

    return Max();

  return TimeDelta(secs * Time::kMicrosecondsPerSecond);

}

// static

inline TimeDelta TimeDelta::FromMilliseconds(int64_t ms) {

  // Preserve max to prevent overflow.

  if (ms == std::numeric_limits<int64_t>::max())

    return Max();

  return TimeDelta(ms * Time::kMicrosecondsPerMillisecond);

}

// static

inline TimeDelta TimeDelta::FromSecondsD(double secs) {

  // Preserve max to prevent overflow.

  if (secs == std::numeric_limits<double>::infinity())

    return Max();

  return TimeDelta((int64_t)(secs * Time::kMicrosecondsPerSecond));

}

// static

inline TimeDelta TimeDelta::FromMillisecondsD(double ms) {

  // Preserve max to prevent overflow.

  if (ms == std::numeric_limits<double>::infinity())

    return Max();

  return TimeDelta((int64_t)(ms * Time::kMicrosecondsPerMillisecond));

}

// static

inline TimeDelta TimeDelta::FromMicroseconds(int64_t us) {

  // Preserve max to prevent overflow.

  if (us == std::numeric_limits<int64_t>::max())

    return Max();

  return TimeDelta(us);

}

// static

inline TimeDelta TimeDelta::FromMicrosecondsD(double us) {

  // Preserve max to prevent overflow.

  if (us == std::numeric_limits<double>::infinity())

    return Max();

  return TimeDelta((int64_t)us);

}

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

  return Time(t.us_ + delta_);

}

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

class BUTIL_EXPORT TimeTicks {

 public:

  // We define this even without OS_CHROMEOS for seccomp sandbox testing.

#if defined(OS_LINUX)

  // Force definition of the system trace clock; it is a chromeos-only api

  // at the moment and surfacing it in the right place requires mucking

  // with glibc et al.

  static const clockid_t kClockSystemTrace = 11;

#endif

  TimeTicks() : ticks_(0) {

  }

  // Required by clang++ 11 on MacOS catalina

  TimeTicks(const TimeTicks& other) : ticks_(other.ticks_) {}

  // 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();

  static bool IsHighResNowFastAndReliable();

  // FIXME(gejun): CLOCK_THREAD_CPUTIME_ID behaves differently in different

  // glibc. To avoid potential bug, disable ThreadNow() always.

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

  static bool IsThreadNowSupported() {

      return false;

  }

  // 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_t 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_t ticks) {

    return TimeTicks(ticks);

  }

  // Get the TimeTick value at the time of the UnixEpoch. This is useful when

  // you need to relate the value of TimeTicks to a real time and date.

  // Note: Upon first invocation, this function takes a snapshot of the realtime

  // clock to establish a reference point.  This function will return the same

  // value for the duration of the application, but will be different in future

  // application runs.

  static TimeTicks UnixEpoch();

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

  // For serializing, use FromInternalValue to reconstitute.

  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;

  // 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 butil

#endif  // BUTIL_TIME_TIME_H_