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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 cannot 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.
// As a result, prefer passing them by value:
// void MyFunction(TimeDelta arg);
// If circumstances require, you may also pass by const reference:
// void MyFunction(const TimeDelta& arg); // Not preferred.
//
// 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/compiler_specific.h"
#include "base/logging.h"
#include "base/numerics/safe_math.h"
#include "build/build_config.h"
#if defined(OS_FUCHSIA)
#include <zircon/types.h>
#endif
#if defined(OS_MACOSX)
#include <CoreFoundation/CoreFoundation.h>
// Avoid Mac system header macro leak.
#undef TYPE_BOOL
#endif
#if defined(OS_ANDROID)
#include <jni.h>
#endif
#if defined(OS_POSIX) || defined(OS_FUCHSIA)
#include <unistd.h>
#include <sys/time.h>
#endif
#if defined(OS_WIN)
#include "base/gtest_prod_util.h"
#include "base/win/windows_types.h"
#endif
namespace ABI {
namespace Windows {
namespace Foundation {
struct DateTime;
} // namespace Foundation
} // namespace Windows
} // namespace ABI
namespace base {
class PlatformThreadHandle;
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 a TimeDelta from |value|. TimeDelta::Min()/Max() are treated
// as infinity and will always saturate the return value (infinity math applies
// if |value| also is at either limit of its spectrum). The int64_t argument and
// return value are in terms of a microsecond timebase.
BASE_EXPORT constexpr int64_t SaturatedAdd(int64_t value, TimeDelta delta);
BASE_EXPORT constexpr int64_t SaturatedSub(int64_t value, TimeDelta delta);
} // namespace time_internal
// TimeDelta ------------------------------------------------------------------
class BASE_EXPORT TimeDelta {
public:
constexpr TimeDelta() : delta_(0) {}
// Converts units of time to TimeDeltas.
// WARNING: Floating point arithmetic is such that FromXXXD(t.InXXXF()) may
// not precisely equal |t|. Hence, floating point values should not be used
// for storage.
static constexpr TimeDelta FromDays(int days);
static constexpr TimeDelta FromHours(int hours);
static constexpr TimeDelta FromMinutes(int minutes);
static constexpr TimeDelta FromSeconds(int64_t secs);
static constexpr TimeDelta FromMilliseconds(int64_t ms);
static constexpr TimeDelta FromMicroseconds(int64_t us);
static constexpr TimeDelta FromNanoseconds(int64_t ns);
static constexpr TimeDelta FromSecondsD(double secs);
static constexpr TimeDelta FromMillisecondsD(double ms);
static constexpr TimeDelta FromMicrosecondsD(double us);
static constexpr TimeDelta FromNanosecondsD(double ns);
#if defined(OS_WIN)
static TimeDelta FromQPCValue(LONGLONG qpc_value);
// TODO(crbug.com/989694): Avoid base::TimeDelta factory functions
// based on absolute time
static TimeDelta FromFileTime(FILETIME ft);
static TimeDelta FromWinrtDateTime(ABI::Windows::Foundation::DateTime dt);
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
static TimeDelta FromTimeSpec(const timespec& ts);
#endif
#if defined(OS_FUCHSIA)
static TimeDelta FromZxDuration(zx_duration_t nanos);
#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 constexpr 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 constexpr TimeDelta Max();
// Returns the minimum time delta, which should be less than than any
// reasonable time delta we might compare it to. Adding or subtracting the
// minimum time delta to a time or another time delta has an undefined result.
static constexpr TimeDelta Min();
// 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.
//
constexpr int64_t ToInternalValue() const { return delta_; }
// Returns the magnitude (absolute value) of this TimeDelta.
constexpr 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.
constexpr bool is_zero() const { return delta_ == 0; }
// Returns true if the time delta is the maximum/minimum time delta.
constexpr bool is_max() const {
return delta_ == std::numeric_limits<int64_t>::max();
}
constexpr bool is_min() const {
return delta_ == std::numeric_limits<int64_t>::min();
}
#if defined(OS_POSIX) || defined(OS_FUCHSIA)
struct timespec ToTimeSpec() const;
#endif
#if defined(OS_FUCHSIA)
zx_duration_t ToZxDuration() const;
#endif
#if defined(OS_WIN)
ABI::Windows::Foundation::DateTime ToWinrtDateTime() const;
#endif
// Returns the time delta in some unit. The InXYZF versions return a floating
// point value. The InXYZ versions return a truncated value (aka rounded
// towards zero, std::trunc() behavior). The InXYZFloored() versions round to
// lesser integers (std::floor() behavior). The XYZRoundedUp() versions round
// up to greater integers (std::ceil() behavior).
// WARNING: Floating point arithmetic is such that FromXXXD(t.InXXXF()) may
// not precisely equal |t|. Hence, floating point values should not be used
// for storage.
int InDays() const;
int InDaysFloored() 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;
constexpr int64_t InMicroseconds() const { return delta_; }
double InMicrosecondsF() const;
int64_t InNanoseconds() const;
// Computations with other deltas.
constexpr TimeDelta operator+(TimeDelta other) const {
return TimeDelta(time_internal::SaturatedAdd(delta_, other));
}
constexpr TimeDelta operator-(TimeDelta other) const {
return TimeDelta(time_internal::SaturatedSub(delta_, other));
}
constexpr TimeDelta& operator+=(TimeDelta other) {
return *this = (*this + other);
}
constexpr TimeDelta& operator-=(TimeDelta other) {
return *this = (*this - other);
}
constexpr TimeDelta operator-() const { return TimeDelta(-delta_); }
// Computations with numeric types.
template <typename T>
constexpr TimeDelta operator*(T a) const {
CheckedNumeric<int64_t> rv(delta_);
rv *= a;
if (rv.IsValid())
return TimeDelta(rv.ValueOrDie());
// Matched sign overflows. Mismatched sign underflows.
if ((delta_ < 0) ^ (a < 0))
return TimeDelta(std::numeric_limits<int64_t>::min());
return TimeDelta(std::numeric_limits<int64_t>::max());
}
template <typename T>
constexpr TimeDelta operator/(T a) const {
CheckedNumeric<int64_t> rv(delta_);
rv /= a;
if (rv.IsValid())
return TimeDelta(rv.ValueOrDie());
// Matched sign overflows. Mismatched sign underflows.
// Special case to catch divide by zero.
if ((delta_ < 0) ^ (a <= 0))
return TimeDelta(std::numeric_limits<int64_t>::min());
return TimeDelta(std::numeric_limits<int64_t>::max());
}
template <typename T>
constexpr TimeDelta& operator*=(T a) {
return *this = (*this * a);
}
template <typename T>
constexpr TimeDelta& operator/=(T a) {
return *this = (*this / a);
}
constexpr int64_t operator/(TimeDelta a) const { return delta_ / a.delta_; }
constexpr TimeDelta operator%(TimeDelta a) const {
return TimeDelta(delta_ % a.delta_);
}
TimeDelta& operator%=(TimeDelta other) { return *this = (*this % other); }
// Comparison operators.
constexpr bool operator==(TimeDelta other) const {
return delta_ == other.delta_;
}
constexpr bool operator!=(TimeDelta other) const {
return delta_ != other.delta_;
}
constexpr bool operator<(TimeDelta other) const {
return delta_ < other.delta_;
}
constexpr bool operator<=(TimeDelta other) const {
return delta_ <= other.delta_;
}
constexpr bool operator>(TimeDelta other) const {
return delta_ > other.delta_;
}
constexpr bool operator>=(TimeDelta other) const {
return delta_ >= other.delta_;
}
private:
friend constexpr int64_t time_internal::SaturatedAdd(int64_t value,
TimeDelta delta);
friend constexpr int64_t time_internal::SaturatedSub(int64_t value,
TimeDelta delta);
// 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.
constexpr explicit TimeDelta(int64_t delta_us) : delta_(delta_us) {}
// Private method to build a delta from a double.
static constexpr TimeDelta FromDouble(double value);
// Private method to build a delta from the product of a user-provided value
// and a known-positive value.
static constexpr TimeDelta FromProduct(int64_t value, int64_t positive_value);
// Delta in microseconds.
int64_t delta_;
};
template <typename T>
constexpr 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 {
constexpr int64_t SaturatedAdd(int64_t value, TimeDelta delta) {
// Treat Min/Max() as +/- infinity (additions involving two infinities are
// only valid if signs match).
if (delta.is_max()) {
CHECK_GT(value, std::numeric_limits<int64_t>::min());
return std::numeric_limits<int64_t>::max();
} else if (delta.is_min()) {
CHECK_LT(value, std::numeric_limits<int64_t>::max());
return std::numeric_limits<int64_t>::min();
}
return base::ClampAdd(value, delta.delta_);
}
constexpr int64_t SaturatedSub(int64_t value, TimeDelta delta) {
// Treat Min/Max() as +/- infinity (subtractions involving two infinities are
// only valid if signs are opposite).
if (delta.is_max()) {
CHECK_LT(value, std::numeric_limits<int64_t>::max());
return std::numeric_limits<int64_t>::min();
} else if (delta.is_min()) {
CHECK_GT(value, std::numeric_limits<int64_t>::min());
return std::numeric_limits<int64_t>::max();
}
return base::ClampSub(value, delta.delta_);
}
// 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 constexpr int64_t kHoursPerDay = 24;
static constexpr int64_t kSecondsPerMinute = 60;
static constexpr int64_t kSecondsPerHour = 60 * kSecondsPerMinute;
static constexpr int64_t kMillisecondsPerSecond = 1000;
static constexpr int64_t kMillisecondsPerDay =
kMillisecondsPerSecond * 60 * 60 * kHoursPerDay;
static constexpr int64_t kMicrosecondsPerMillisecond = 1000;
static constexpr int64_t kMicrosecondsPerSecond =
kMicrosecondsPerMillisecond * kMillisecondsPerSecond;
static constexpr int64_t kMicrosecondsPerMinute = kMicrosecondsPerSecond * 60;
static constexpr int64_t kMicrosecondsPerHour = kMicrosecondsPerMinute * 60;
static constexpr int64_t kMicrosecondsPerDay =
kMicrosecondsPerHour * kHoursPerDay;
static constexpr int64_t kMicrosecondsPerWeek = kMicrosecondsPerDay * 7;
static constexpr int64_t kNanosecondsPerMicrosecond = 1000;
static constexpr 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.
constexpr bool is_null() const { return us_ == 0; }
// Returns true if this object represents the maximum/minimum time.
constexpr bool is_max() const {
return us_ == std::numeric_limits<int64_t>::max();
}
constexpr bool is_min() const {
return us_ == std::numeric_limits<int64_t>::min();
}
// Returns the maximum/minimum times, which should be greater/less than than
// any reasonable time with which we might compare it.
static constexpr TimeClass Max() {
return TimeClass(std::numeric_limits<int64_t>::max());
}
static constexpr TimeClass Min() {
return TimeClass(std::numeric_limits<int64_t>::min());
}
// 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.
//
// DEPRECATED - Do not use in new code. For serializing Time values, prefer
constexpr int64_t ToInternalValue() const { return us_; }
// The amount of time since the origin (or "zero") point. This is a syntactic
// convenience to aid in code readability, mainly for debugging/testing use
// cases.
//
// Warning: While the Time subclass has a fixed origin point, the origin for
// the other subclasses can vary each time the application is restarted.
constexpr TimeDelta since_origin() const {
return TimeDelta::FromMicroseconds(us_);
}
constexpr TimeClass& operator=(TimeClass other) {
us_ = other.us_;
return *(static_cast<TimeClass*>(this));
}
// Compute the difference between two times.
constexpr TimeDelta operator-(TimeClass other) const {
return TimeDelta::FromMicroseconds(us_ - other.us_);
}
// Return a new time modified by some delta.
constexpr TimeClass operator+(TimeDelta delta) const {
return TimeClass(time_internal::SaturatedAdd(us_, delta));
}
constexpr TimeClass operator-(TimeDelta delta) const {
return TimeClass(time_internal::SaturatedSub(us_, delta));
}
// Modify by some time delta.
constexpr TimeClass& operator+=(TimeDelta delta) {
return static_cast<TimeClass&>(*this = (*this + delta));
}
constexpr TimeClass& operator-=(TimeDelta delta) {
return static_cast<TimeClass&>(*this = (*this - delta));
}
// Comparison operators
constexpr bool operator==(TimeClass other) const { return us_ == other.us_; }
constexpr bool operator!=(TimeClass other) const { return us_ != other.us_; }
constexpr bool operator<(TimeClass other) const { return us_ < other.us_; }
constexpr bool operator<=(TimeClass other) const { return us_ <= other.us_; }
constexpr bool operator>(TimeClass other) const { return us_ > other.us_; }
constexpr bool operator>=(TimeClass other) const { return us_ >= other.us_; }
protected:
constexpr explicit TimeBase(int64_t us) : us_(us) {}
// Time value in a microsecond timebase.
int64_t us_;
};
} // namespace time_internal
template <class TimeClass>
inline constexpr 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.
// Time is stored internally as microseconds since the Windows epoch (1601).
class BASE_EXPORT Time : public time_internal::TimeBase<Time> {
public:
// Offset of UNIX epoch (1970-01-01 00:00:00 UTC) from Windows FILETIME epoch
// (1601-01-01 00:00:00 UTC), in microseconds. This value is derived from the
// following: ((1970-1601)*365+89)*24*60*60*1000*1000, where 89 is the number
// of leap year days between 1601 and 1970: (1970-1601)/4 excluding 1700,
// 1800, and 1900.
static constexpr int64_t kTimeTToMicrosecondsOffset =
INT64_C(11644473600000000);
#if defined(OS_WIN)
// 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.
static constexpr int64_t kQPCOverflowThreshold = INT64_C(0x8637BD05AF7);
#endif
// kExplodedMinYear and kExplodedMaxYear define the platform-specific limits
// for values passed to FromUTCExploded() and FromLocalExploded(). Those
// functions will return false if passed values outside these limits. The limits
// are inclusive, meaning that the API should support all dates within a given
// limit year.
#if defined(OS_WIN)
static constexpr int kExplodedMinYear = 1601;
static constexpr int kExplodedMaxYear = 30827;
#elif defined(OS_IOS) && !__LP64__
static constexpr int kExplodedMinYear = std::numeric_limits<int>::min();
static constexpr int kExplodedMaxYear = std::numeric_limits<int>::max();
#elif defined(OS_MACOSX)
static constexpr int kExplodedMinYear = 1902;
static constexpr int kExplodedMaxYear = std::numeric_limits<int>::max();
#elif defined(OS_ANDROID)
// Though we use 64-bit time APIs on both 32 and 64 bit Android, some OS
// versions like KitKat (ARM but not x86 emulator) can't handle some early
// dates (e.g. before 1170). So we set min conservatively here.
static constexpr int kExplodedMinYear = 1902;
static constexpr int kExplodedMaxYear = std::numeric_limits<int>::max();
#else
static constexpr int kExplodedMinYear =
(sizeof(time_t) == 4 ? 1902 : std::numeric_limits<int>::min());
static constexpr int kExplodedMaxYear =
(sizeof(time_t) == 4 ? 2037 : std::numeric_limits<int>::max());
#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.
constexpr 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 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 TimeDeltas relative to the Windows epoch (1601-01-01
// 00:00:00 UTC). Prefer these methods for opaque serialization and
// deserialization of time values, e.g.
//
// // Serialization:
// base::Time last_updated = ...;
// SaveToDatabase(last_updated.ToDeltaSinceWindowsEpoch().InMicroseconds());
//
// // Deserialization:
// base::Time last_updated = base::Time::FromDeltaSinceWindowsEpoch(
// base::TimeDelta::FromMicroseconds(LoadFromDatabase()));
static Time FromDeltaSinceWindowsEpoch(TimeDelta delta);
TimeDelta ToDeltaSinceWindowsEpoch() const;
// Converts to/from time_t in UTC and a 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) || defined(OS_FUCHSIA)
// 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
static Time FromTimeSpec(const timespec& ts);
#endif
// Converts to/from the Javascript convention for times, a number of
// milliseconds since the epoch:
//
// Don't use ToJsTime() in new code, since it contains a subtle hack (only
// exactly 1601-01-01 00:00 UTC is represented as 1970-01-01 00:00 UTC), and
// that is not appropriate for general use. Try to use ToJsTimeIgnoringNull()
// unless you have a very good reason to use ToJsTime().
static Time FromJsTime(double ms_since_epoch);
double ToJsTime() const;
double ToJsTimeIgnoringNull() const;
// Converts to/from Java convention for times, a number of milliseconds since
// the epoch. Because the Java format has less resolution, converting to Java
// time is a lossy operation.
static Time FromJavaTime(int64_t ms_since_epoch);
int64_t ToJavaTime() const;
#if defined(OS_POSIX) || defined(OS_FUCHSIA)
static Time FromTimeVal(struct timeval t);
struct timeval ToTimeVal() const;
#endif
#if defined(OS_FUCHSIA)
static Time FromZxTime(zx_time_t time);
zx_time_t ToZxTime() 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);
// Read the minimum timer interval from the feature list. This should be
// called once after the feature list is initialized. This is needed for
static void ReadMinTimerIntervalLowResMs();
// 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();
// The following two functions are used to report the fraction of elapsed time
// that the high resolution timer is activated.
// ResetHighResolutionTimerUsage() resets the cumulative usage and starts the
// measurement interval and GetHighResolutionTimerUsage() returns the
// percentage of time since the reset that the high resolution timer was
// activated.
// ResetHighResolutionTimerUsage() must be called at least once before calling
// GetHighResolutionTimerUsage(); otherwise the usage result would be
// undefined.
static void ResetHighResolutionTimerUsage();
static double GetHighResolutionTimerUsage();
#endif // defined(OS_WIN)
// Converts an exploded structure representing either the local time or UTC
// into a Time class. Returns false on a failure when, for example, a day of
// month is set to 31 on a 28-30 day month. Returns Time(0) on overflow.
static bool FromUTCExploded(const Exploded& exploded,
Time* time) WARN_UNUSED_RESULT {
return FromExploded(false, exploded, time);
}
static bool FromLocalExploded(const Exploded& exploded,
Time* time) WARN_UNUSED_RESULT {
return FromExploded(true, exploded, time);
}
// 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.
//
// WARNING: the underlying converter is very permissive. For example: it is
// not checked whether a given day of the week matches the date; Feb 29
// silently becomes Mar 1 in non-leap years; under certain conditions, whole
// English sentences may be parsed successfully and yield unexpected results.
//
// TODO(iyengar) Move the FromString/FromTimeT/ToTimeT/FromFileTime to
// a new time converter class.
static bool FromString(const char* time_string,
Time* parsed_time) WARN_UNUSED_RESULT {
return FromStringInternal(time_string, true, parsed_time);
}
static bool FromUTCString(const char* time_string,
Time* parsed_time) WARN_UNUSED_RESULT {
return FromStringInternal(time_string, false, parsed_time);
}
// 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);
}
// The following two functions round down the time to the nearest day in
// either UTC or local time. It will represent midnight on that day.
Time UTCMidnight() const { return Midnight(false); }
Time LocalMidnight() const { return Midnight(true); }
// Converts an integer value representing Time to a class. This may be 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.
//
// DEPRECATED - Do not use in new code. For deserializing Time values, prefer
static constexpr Time FromInternalValue(int64_t us) { return Time(us); }
private:
friend class time_internal::TimeBase<Time>;
constexpr explicit Time(int64_t microseconds_since_win_epoch)
: TimeBase(microseconds_since_win_epoch) {}
// 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|. Function returns false on
// failure and sets |time| to Time(0). Otherwise returns true and sets |time|
// to non-exploded time.
static bool FromExploded(bool is_local,
const Exploded& exploded,
Time* time) WARN_UNUSED_RESULT;
// Rounds down the time to the nearest day in either local time
// |is_local = true| or UTC |is_local = false|.
Time Midnight(bool is_local) const;
// 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) WARN_UNUSED_RESULT;
// Comparison does not consider |day_of_week| when doing the operation.
static bool ExplodedMostlyEquals(const Exploded& lhs,
const Exploded& rhs) WARN_UNUSED_RESULT;
// Converts the provided time in milliseconds since the Unix epoch (1970) to a
// Time object, avoiding overflows.
static bool FromMillisecondsSinceUnixEpoch(int64_t unix_milliseconds,
Time* time) WARN_UNUSED_RESULT;
// Returns the milliseconds since the Unix epoch (1970), rounding the
// microseconds towards -infinity.
int64_t ToRoundedDownMillisecondsSinceUnixEpoch() const;
};
// static
constexpr TimeDelta TimeDelta::FromDays(int days) {
return days == std::numeric_limits<int>::max()
? Max()
: TimeDelta(days * Time::kMicrosecondsPerDay);
}
// static
constexpr TimeDelta TimeDelta::FromHours(int hours) {
return hours == std::numeric_limits<int>::max()
? Max()
: TimeDelta(hours * Time::kMicrosecondsPerHour);
}
// static
constexpr TimeDelta TimeDelta::FromMinutes(int minutes) {
return minutes == std::numeric_limits<int>::max()
? Max()
: TimeDelta(minutes * Time::kMicrosecondsPerMinute);
}
// static
constexpr TimeDelta TimeDelta::FromSeconds(int64_t secs) {
return FromProduct(secs, Time::kMicrosecondsPerSecond);
}
// static
constexpr TimeDelta TimeDelta::FromMilliseconds(int64_t ms) {
return FromProduct(ms, Time::kMicrosecondsPerMillisecond);
}
// static
constexpr TimeDelta TimeDelta::FromMicroseconds(int64_t us) {
return TimeDelta(us);
}
// static
constexpr TimeDelta TimeDelta::FromNanoseconds(int64_t ns) {
return TimeDelta(ns / Time::kNanosecondsPerMicrosecond);
}
// static
constexpr TimeDelta TimeDelta::FromSecondsD(double secs) {
return FromDouble(secs * Time::kMicrosecondsPerSecond);
}
// static
constexpr TimeDelta TimeDelta::FromMillisecondsD(double ms) {
return FromDouble(ms * Time::kMicrosecondsPerMillisecond);
}
// static
constexpr TimeDelta TimeDelta::FromMicrosecondsD(double us) {
return FromDouble(us);
}
// static
constexpr TimeDelta TimeDelta::FromNanosecondsD(double ns) {
return FromDouble(ns / Time::kNanosecondsPerMicrosecond);
}
// static
constexpr TimeDelta TimeDelta::Max() {
return TimeDelta(std::numeric_limits<int64_t>::max());
}
// static
constexpr TimeDelta TimeDelta::Min() {
return TimeDelta(std::numeric_limits<int64_t>::min());
}
// static
constexpr TimeDelta TimeDelta::FromDouble(double value) {
return TimeDelta(saturated_cast<int64_t>(value));
}
// static
constexpr TimeDelta TimeDelta::FromProduct(int64_t value,
int64_t positive_value) {
DCHECK(positive_value > 0); // NOLINT, DCHECK_GT isn't constexpr.
return value > std::numeric_limits<int64_t>::max() / positive_value
? Max()
: value < std::numeric_limits<int64_t>::min() / positive_value
? Min()
: TimeDelta(value * positive_value);
}
// 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:
// The underlying clock used to generate new TimeTicks.
enum class Clock {
FUCHSIA_ZX_CLOCK_MONOTONIC,
LINUX_CLOCK_MONOTONIC,
IOS_CF_ABSOLUTE_TIME_MINUS_KERN_BOOTTIME,
MAC_MACH_ABSOLUTE_TIME,
WIN_QPC,
WIN_ROLLOVER_PROTECTED_TIME_GET_TIME
};
constexpr 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() WARN_UNUSED_RESULT;
// Returns true if TimeTicks is consistent across processes, meaning that
// timestamps taken on different processes can be safely compared with one
// another. (Note that, even on platforms where this returns true, time values
// from different threads that are within one tick of each other must be
// considered to have an ambiguous ordering.)
static bool IsConsistentAcrossProcesses() WARN_UNUSED_RESULT;
#if defined(OS_FUCHSIA)
// Converts between TimeTicks and an ZX_CLOCK_MONOTONIC zx_time_t value.
static TimeTicks FromZxTime(zx_time_t nanos_since_boot);
zx_time_t ToZxTime() const;
#endif
#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
#if defined(OS_MACOSX) && !defined(OS_IOS)
static TimeTicks FromMachAbsoluteTime(uint64_t mach_absolute_time);
#endif // defined(OS_MACOSX) && !defined(OS_IOS)
#if defined(OS_ANDROID) || defined(OS_CHROMEOS)
// Converts to TimeTicks the value obtained from SystemClock.uptimeMillis().
// Note: this convertion may be non-monotonic in relation to previously
// obtained TimeTicks::Now() values because of the truncation (to
// milliseconds) performed by uptimeMillis().
static TimeTicks FromUptimeMillis(int64_t uptime_millis_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;
// Returns an enum indicating the underlying clock being used to generate
// TimeTicks timestamps. This function should only be used for debugging and
// logging purposes.
static Clock GetClock();
// Converts an integer value representing TimeTicks to a class. This may be
// 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.
//
// DEPRECATED - Do not use in new code. For deserializing TimeTicks values,
static constexpr TimeTicks FromInternalValue(int64_t us) {
return TimeTicks(us);
}
protected:
#if defined(OS_WIN)
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.
constexpr 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:
constexpr ThreadTicks() : TimeBase(0) {}
// Returns true if ThreadTicks::Now() is supported on this system.
static bool IsSupported() WARN_UNUSED_RESULT {
#if (defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)) || \
(defined(OS_MACOSX) && !defined(OS_IOS)) || defined(OS_ANDROID) || \
defined(OS_FUCHSIA)
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();
#if defined(OS_WIN)
// Similar to Now() above except this returns thread-specific CPU time for an
// arbitrary thread. All comments for Now() method above apply apply to this
// method as well.
static ThreadTicks GetForThread(const PlatformThreadHandle& thread_handle);
#endif
// Converts an integer value representing ThreadTicks to a class. This may be
// used when deserializing a |ThreadTicks| 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.
//
// DEPRECATED - Do not use in new code. For deserializing ThreadTicks values,
static constexpr ThreadTicks FromInternalValue(int64_t us) {
return ThreadTicks(us);
}
private:
friend class time_internal::TimeBase<ThreadTicks>;
// Please use Now() or GetForThread() to create a new object. This is for
// internal use and testing.
constexpr explicit ThreadTicks(int64_t us) : TimeBase(us) {}
#if defined(OS_WIN)
FRIEND_TEST_ALL_PREFIXES(TimeTicks, TSCTicksPerSecond);
#if defined(ARCH_CPU_ARM64)
// TSCTicksPerSecond is not supported on Windows on Arm systems because the
// cycle-counting methods use the actual CPU cycle count, and not a consistent
// incrementing counter.
#else
// 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();
#endif
static bool IsSupportedWin() WARN_UNUSED_RESULT;
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_