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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 coordinated universal time (UTC),
-// internally represented as microseconds (s/1,000,000) since the Windows epoch
-// (1601-01-01 00:00:00 UTC). System-dependent clock interface routines are
-// defined in time_PLATFORM.cc. Note that values for Time may skew and jump
-// around as the operating system makes adjustments to synchronize (e.g., with
-// NTP servers). Thus, client code that uses the Time class must account for
-// this.
-//
-// TimeDelta represents a duration of time, internally represented in
-// microseconds.
-//
-// TimeTicks and ThreadTicks represent an abstract time that is most of the time
-// incrementing, for use in measuring time durations. Internally, they are
-// represented in microseconds. They can not be converted to a human-readable
-// time, but are guaranteed not to decrease (unlike the Time class). Note that
-// TimeTicks may "stand still" (e.g., if the computer is suspended), and
-// ThreadTicks will "stand still" whenever the thread has been de-scheduled by
-// the operating system.
-//
-// All time classes are copyable, assignable, and occupy 64-bits per
-// instance. Thus, they can be efficiently passed by-value (as opposed to
-// by-reference).
-//
-// Definitions of operator<< are provided to make these types work with
-// DCHECK_EQ() and other log macros. For human-readable formatting, see
-// "base/i18n/time_formatting.h".
-//
-// So many choices! Which time class should you use? Examples:
-//
-// Time: Interpreting the wall-clock time provided by a remote
-// system. Detecting whether cached resources have
-// expired. Providing the user with a display of the current date
-// and time. Determining the amount of time between events across
-// re-boots of the machine.
-//
-// TimeTicks: Tracking the amount of time a task runs. Executing delayed
-// tasks at the right time. Computing presentation timestamps.
-// Synchronizing audio and video using TimeTicks as a common
-// reference clock (lip-sync). Measuring network round-trip
-// latency.
-//
-// ThreadTicks: Benchmarking how long the current thread has been doing actual
-// work.
-
-#ifndef BASE_TIME_TIME_H_
-#define BASE_TIME_TIME_H_
-
-#include <stdint.h>
-#include <time.h>
-
-#include <iosfwd>
-#include <limits>
-
-#include "base/base_export.h"
-#include "base/numerics/safe_math.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>
-
-#include "base/gtest_prod_util.h"
-#endif
-
-namespace base {
-
-class TimeDelta;
-
-// The functions in the time_internal namespace are meant to be used only by the
-// time classes and functions. Please use the math operators defined in the
-// time classes instead.
-namespace time_internal {
-
-// Add or subtract |value| from a TimeDelta. The int64_t argument and return
-// value are in terms of a microsecond timebase.
-BASE_EXPORT int64_t SaturatedAdd(TimeDelta delta, int64_t value);
-BASE_EXPORT int64_t SaturatedSub(TimeDelta delta, int64_t value);
-
-// Clamp |value| on overflow and underflow conditions. The int64_t argument and
-// return value are in terms of a microsecond timebase.
-BASE_EXPORT int64_t FromCheckedNumeric(const CheckedNumeric<int64_t> value);
-
-} // namespace time_internal
-
-// TimeDelta ------------------------------------------------------------------
-
-class BASE_EXPORT TimeDelta {
- public:
- TimeDelta() : delta_(0) {
- }
-
- // 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 FromSecondsD(double secs);
- static TimeDelta FromMillisecondsD(double ms);
- static TimeDelta FromMicroseconds(int64_t 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 the magnitude (absolute value) of this TimeDelta.
- TimeDelta magnitude() const {
- // Some toolchains provide an incomplete C++11 implementation and lack an
- // int64_t overload for std::abs(). The following is a simple branchless
- // implementation:
- const int64_t mask = delta_ >> (sizeof(delta_) * 8 - 1);
- return TimeDelta((delta_ + mask) ^ mask);
- }
-
- // Returns true if the time delta is zero.
- bool is_zero() const {
- return delta_ == 0;
- }
-
- // 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(time_internal::SaturatedAdd(*this, other.delta_));
- }
- TimeDelta operator-(TimeDelta other) const {
- return TimeDelta(time_internal::SaturatedSub(*this, other.delta_));
- }
-
- TimeDelta& operator+=(TimeDelta other) {
- return *this = (*this + other);
- }
- TimeDelta& operator-=(TimeDelta other) {
- return *this = (*this - other);
- }
- TimeDelta operator-() const {
- return TimeDelta(-delta_);
- }
-
- // Computations with numeric types.
- template<typename T>
- TimeDelta operator*(T a) const {
- CheckedNumeric<int64_t> rv(delta_);
- rv *= a;
- return TimeDelta(time_internal::FromCheckedNumeric(rv));
- }
- template<typename T>
- TimeDelta operator/(T a) const {
- CheckedNumeric<int64_t> rv(delta_);
- rv /= a;
- return TimeDelta(time_internal::FromCheckedNumeric(rv));
- }
- template<typename T>
- TimeDelta& operator*=(T a) {
- return *this = (*this * a);
- }
- template<typename T>
- TimeDelta& operator/=(T a) {
- return *this = (*this / a);
- }
-
- int64_t operator/(TimeDelta a) const { return delta_ / a.delta_; }
- TimeDelta operator%(TimeDelta a) const {
- return TimeDelta(delta_ % a.delta_);
- }
-
- // 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 int64_t time_internal::SaturatedAdd(TimeDelta delta, int64_t value);
- friend int64_t time_internal::SaturatedSub(TimeDelta delta, int64_t value);
-
- // 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) {}
-
- // Private method to build a delta from a double.
- static TimeDelta FromDouble(double value);
-
- // Delta in microseconds.
- int64_t delta_;
-};
-
-template<typename T>
-inline TimeDelta operator*(T a, TimeDelta td) {
- return td * a;
-}
-
-// For logging use only.
-BASE_EXPORT std::ostream& operator<<(std::ostream& os, TimeDelta time_delta);
-
-// Do not reference the time_internal::TimeBase template class directly. Please
-// use one of the time subclasses instead, and only reference the public
-// TimeBase members via those classes.
-namespace time_internal {
-
-// TimeBase--------------------------------------------------------------------
-
-// Provides value storage and comparison/math operations common to all time
-// classes. Each subclass provides for strong type-checking to ensure
-// semantically meaningful comparison/math of time values from the same clock
-// source or timeline.
-template<class TimeClass>
-class TimeBase {
- public:
- static const int64_t kHoursPerDay = 24;
- static const int64_t kMillisecondsPerSecond = 1000;
- static const int64_t kMillisecondsPerDay =
- kMillisecondsPerSecond * 60 * 60 * kHoursPerDay;
- 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 * kHoursPerDay;
- static const int64_t kMicrosecondsPerWeek = kMicrosecondsPerDay * 7;
- static const int64_t kNanosecondsPerMicrosecond = 1000;
- static const int64_t kNanosecondsPerSecond =
- kNanosecondsPerMicrosecond * kMicrosecondsPerSecond;
-
- // Returns true if this object has not been initialized.
- //
- // Warning: Be careful when writing code that performs math on time values,
- // since it's possible to produce a valid "zero" result that should not be
- // interpreted as a "null" value.
- bool is_null() const {
- return us_ == 0;
- }
-
- // Returns true if this object represents the maximum time.
- bool is_max() const { return us_ == std::numeric_limits<int64_t>::max(); }
-
- // For serializing only. 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_; }
-
- TimeClass& operator=(TimeClass other) {
- us_ = other.us_;
- return *(static_cast<TimeClass*>(this));
- }
-
- // Compute the difference between two times.
- TimeDelta operator-(TimeClass other) const {
- return TimeDelta::FromMicroseconds(us_ - other.us_);
- }
-
- // Return a new time modified by some delta.
- TimeClass operator+(TimeDelta delta) const {
- return TimeClass(time_internal::SaturatedAdd(delta, us_));
- }
- TimeClass operator-(TimeDelta delta) const {
- return TimeClass(-time_internal::SaturatedSub(delta, us_));
- }
-
- // Modify by some time delta.
- TimeClass& operator+=(TimeDelta delta) {
- return static_cast<TimeClass&>(*this = (*this + delta));
- }
- TimeClass& operator-=(TimeDelta delta) {
- return static_cast<TimeClass&>(*this = (*this - delta));
- }
-
- // Comparison operators
- bool operator==(TimeClass other) const {
- return us_ == other.us_;
- }
- bool operator!=(TimeClass other) const {
- return us_ != other.us_;
- }
- bool operator<(TimeClass other) const {
- return us_ < other.us_;
- }
- bool operator<=(TimeClass other) const {
- return us_ <= other.us_;
- }
- bool operator>(TimeClass other) const {
- return us_ > other.us_;
- }
- bool operator>=(TimeClass other) const {
- return us_ >= other.us_;
- }
-
- // Converts an integer value representing TimeClass to a class. This is used
- // when deserializing a |TimeClass| 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 TimeClass FromInternalValue(int64_t us) { return TimeClass(us); }
-
- protected:
- explicit TimeBase(int64_t us) : us_(us) {}
-
- // Time value in a microsecond timebase.
- int64_t us_;
-};
-
-} // namespace time_internal
-
-template<class TimeClass>
-inline TimeClass operator+(TimeDelta delta, TimeClass t) {
- return t + delta;
-}
-
-// Time -----------------------------------------------------------------------
-
-// Represents a wall clock time in UTC. Values are not guaranteed to be
-// monotonically non-decreasing and are subject to large amounts of skew.
-class BASE_EXPORT Time : public time_internal::TimeBase<Time> {
- public:
- // The representation of Jan 1, 1970 UTC in microseconds since the
- // platform-dependent epoch.
- static const int64_t kTimeTToMicrosecondsOffset;
-
-#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;
-#else
- // To avoid overflow in QPC to Microseconds calculations, since we multiply
- // by kMicrosecondsPerSecond, then the QPC value should not exceed
- // (2^63 - 1) / 1E6. If it exceeds that threshold, we divide then multiply.
- enum : int64_t{kQPCOverflowThreshold = 0x8637BD05AF7};
-#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() : TimeBase(0) {
- }
-
- // 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.
- 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);
- }
-
-#if !defined(MOZ_SANDBOX)
- // 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);
- }
-#endif
-
- // 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;
-
- private:
- friend class time_internal::TimeBase<Time>;
-
- explicit Time(int64_t us) : TimeBase(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);
-
-#if !defined(MOZ_SANDBOX)
- // 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);
-#endif
-};
-
-// Inline the TimeDelta factory methods, for fast TimeDelta construction.
-
-// static
-inline TimeDelta TimeDelta::FromDays(int days) {
- if (days == std::numeric_limits<int>::max())
- return Max();
- return TimeDelta(days * Time::kMicrosecondsPerDay);
-}
-
-// static
-inline TimeDelta TimeDelta::FromHours(int hours) {
- if (hours == std::numeric_limits<int>::max())
- return Max();
- return TimeDelta(hours * Time::kMicrosecondsPerHour);
-}
-
-// static
-inline TimeDelta TimeDelta::FromMinutes(int minutes) {
- if (minutes == std::numeric_limits<int>::max())
- return Max();
- 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::FromSecondsD(double secs) {
- return FromDouble(secs * Time::kMicrosecondsPerSecond);
-}
-
-// static
-inline TimeDelta TimeDelta::FromMillisecondsD(double ms) {
- return FromDouble(ms * Time::kMicrosecondsPerMillisecond);
-}
-
-// static
-inline TimeDelta TimeDelta::FromMicroseconds(int64_t us) {
- return TimeDelta(us);
-}
-
-// static
-inline TimeDelta TimeDelta::FromDouble(double value) {
- double max_magnitude = std::numeric_limits<int64_t>::max();
- TimeDelta delta = TimeDelta(static_cast<int64_t>(value));
- if (value > max_magnitude)
- delta = Max();
- else if (value < -max_magnitude)
- delta = -Max();
- return delta;
-}
-
-// For logging use only.
-BASE_EXPORT std::ostream& operator<<(std::ostream& os, Time time);
-
-// TimeTicks ------------------------------------------------------------------
-
-// Represents monotonically non-decreasing clock time.
-class BASE_EXPORT TimeTicks : public time_internal::TimeBase<TimeTicks> {
- public:
- TimeTicks() : TimeBase(0) {
- }
-
- // Platform-dependent tick count representing "right now." When
- // IsHighResolution() returns false, the resolution of the clock could be
- // as coarse as ~15.6ms. Otherwise, the resolution should be no worse than one
- // microsecond.
- static TimeTicks Now();
-
- // Returns true if the high resolution clock is working on this system and
- // Now() will return high resolution values. Note that, on systems where the
- // high resolution clock works but is deemed inefficient, the low resolution
- // clock will be used instead.
- static bool IsHighResolution();
-
-#if defined(OS_WIN)
- // Translates an absolute QPC timestamp into a TimeTicks value. The returned
- // value has the same origin as Now(). Do NOT attempt to use this if
- // IsHighResolution() returns false.
- static TimeTicks FromQPCValue(LONGLONG qpc_value);
-#endif
-
- // Get an estimate of the TimeTick value at the time of the UnixEpoch. Because
- // Time and TimeTicks respond differently to user-set time and NTP
- // adjustments, this number is only an estimate. Nevertheless, this can be
- // 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 |this| snapped to the next tick, given a |tick_phase| and
- // repeating |tick_interval| in both directions. |this| may be before,
- // after, or equal to the |tick_phase|.
- TimeTicks SnappedToNextTick(TimeTicks tick_phase,
- TimeDelta tick_interval) const;
-
-#if defined(OS_WIN)
- protected:
- typedef DWORD (*TickFunctionType)(void);
- static TickFunctionType SetMockTickFunction(TickFunctionType ticker);
-#endif
-
- private:
- friend class time_internal::TimeBase<TimeTicks>;
-
- // Please use Now() to create a new object. This is for internal use
- // and testing.
- explicit TimeTicks(int64_t us) : TimeBase(us) {}
-};
-
-// For logging use only.
-BASE_EXPORT std::ostream& operator<<(std::ostream& os, TimeTicks time_ticks);
-
-// ThreadTicks ----------------------------------------------------------------
-
-// Represents a clock, specific to a particular thread, than runs only while the
-// thread is running.
-class BASE_EXPORT ThreadTicks : public time_internal::TimeBase<ThreadTicks> {
- public:
- ThreadTicks() : TimeBase(0) {
- }
-
- // Returns true if ThreadTicks::Now() is supported on this system.
- static bool IsSupported() {
-#if (defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)) || \
- (defined(OS_MACOSX) && !defined(OS_IOS)) || defined(OS_ANDROID)
- return true;
-#elif defined(OS_WIN)
- return IsSupportedWin();
-#else
- return false;
-#endif
- }
-
- // Waits until the initialization is completed. Needs to be guarded with a
- // call to IsSupported().
- static void WaitUntilInitialized() {
-#if defined(OS_WIN)
- WaitUntilInitializedWin();
-#endif
- }
-
- // Returns thread-specific CPU-time on systems that support this feature.
- // Needs to be guarded with a call to IsSupported(). 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. Returns an empty ThreadTicks
- // object until the initialization is completed. If a clock reading is
- // absolutely needed, call WaitUntilInitialized() before this method.
- static ThreadTicks Now();
-
- private:
- friend class time_internal::TimeBase<ThreadTicks>;
-
- // Please use Now() to create a new object. This is for internal use
- // and testing.
- explicit ThreadTicks(int64_t us) : TimeBase(us) {}
-
-#if defined(OS_WIN)
- FRIEND_TEST_ALL_PREFIXES(TimeTicks, TSCTicksPerSecond);
-
- // Returns the frequency of the TSC in ticks per second, or 0 if it hasn't
- // been measured yet. Needs to be guarded with a call to IsSupported().
- // This method is declared here rather than in the anonymous namespace to
- // allow testing.
- static double TSCTicksPerSecond();
-
- static bool IsSupportedWin();
- static void WaitUntilInitializedWin();
-#endif
-};
-
-// For logging use only.
-BASE_EXPORT std::ostream& operator<<(std::ostream& os, ThreadTicks time_ticks);
-
-} // namespace base
-
-#endif // BASE_TIME_TIME_H_