chromium/v8/src/base/platform/time.h

// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_BASE_PLATFORM_TIME_H_
#define V8_BASE_PLATFORM_TIME_H_

#include <stdint.h>

#include <ctime>
#include <iosfwd>
#include <limits>

#include "src/base/base-export.h"
#include "src/base/bits.h"
#include "src/base/macros.h"
#include "src/base/safe_conversions.h"
#if V8_OS_WIN
#include "src/base/win32-headers.h"
#endif

// Forward declarations.
extern "C" {
struct _FILETIME;
struct mach_timespec;
struct timespec;
struct timeval;
}

namespace v8 {
namespace base {

class Time;
class TimeDelta;
class TimeTicks;

namespace time_internal {
template<class TimeClass>
class TimeBase;
}  // namespace time_internal

class TimeConstants { … };

// -----------------------------------------------------------------------------
// TimeDelta
//
// This class represents a duration of time, internally represented in
// microseonds.

class V8_BASE_EXPORT TimeDelta final { … };

// static
constexpr TimeDelta TimeDelta::FromDouble(double value) { … }

// static
constexpr TimeDelta TimeDelta::Max() { … }

// static
constexpr TimeDelta TimeDelta::Min() { … }

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 TimeConstants { … };

}  // namespace time_internal


// -----------------------------------------------------------------------------
// Time
//
// This class represents an absolute point in time, internally represented as
// microseconds (s/1,000,000) since 00:00:00 UTC, January 1, 1970.

class V8_BASE_EXPORT Time final : public time_internal::TimeBase<Time> { … };

V8_BASE_EXPORT std::ostream& operator<<(std::ostream&, const Time&);

inline Time operator+(const TimeDelta& delta, const Time& time) { … }


// -----------------------------------------------------------------------------
// TimeTicks
//
// This class represents an abstract time that is most of the time incrementing
// for use in measuring time durations. It is internally represented in
// microseconds.  It can not be converted to a human-readable time, but is
// guaranteed not to decrease (if the user changes the computer clock,
// Time::Now() may actually decrease or jump).  But note that TimeTicks may
// "stand still", for example if the computer suspended.

class V8_BASE_EXPORT TimeTicks final
    : public time_internal::TimeBase<TimeTicks> { … };

inline TimeTicks operator+(const TimeDelta& delta, const TimeTicks& ticks) { … }


// ThreadTicks ----------------------------------------------------------------

// Represents a clock, specific to a particular thread, than runs only while the
// thread is running.
class V8_BASE_EXPORT ThreadTicks final
    : public time_internal::TimeBase<ThreadTicks> { … };

}  // namespace base
}  // namespace v8

#endif  // V8_BASE_PLATFORM_TIME_H_