tor-browser

time.h (14043B)

---

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
// 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"

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;

 // 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 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;

 // 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);

 explicit 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) {}
 TimeTicks(const TimeTicks&) = default;

 // 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 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_;
};

inline TimeTicks TimeDelta::operator+(TimeTicks t) const {
 return TimeTicks(t.ticks_ + delta_);
}

}  // namespace base

#endif  // BASE_TIME_H_