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Diffstat (limited to 'security/sandbox/chromium/base/time/time.h')
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diff --git a/security/sandbox/chromium/base/time/time.h b/security/sandbox/chromium/base/time/time.h new file mode 100644 index 000000000..ea19d7ed9 --- /dev/null +++ b/security/sandbox/chromium/base/time/time.h @@ -0,0 +1,768 @@ +// 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_ |