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/*
* Copyright (C) 2016 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef WTF_MonotonicTime_h
#define WTF_MonotonicTime_h
#include <wtf/ClockType.h>
#include <wtf/Seconds.h>
namespace WTF {
class WallTime;
class PrintStream;
// The current time according to a monotonic clock. Monotonic clocks don't go backwards and
// possibly don't count downtime. This uses floating point internally so that you can reason about
// infinity and other things that arise in math. It's acceptable to use this to wrap NaN times,
// negative times, and infinite times, so long as they are all relative to the same clock.
// Specifically, MonotonicTime should be used in agreement with the principle that
// MonotonicTime::now().secondsSinceEpoch().value() is the same as
// WTF::monotonicallyIncreasingTime().
class MonotonicTime {
public:
static const ClockType clockType = ClockType::Monotonic;
// This is the epoch. So, x.secondsSinceEpoch() should be the same as x - MonotonicTime().
constexpr MonotonicTime() { }
// Call this if you know for sure that the double represents time according to
// WTF::monotonicallyIncreasingTime(). It must be in seconds and it must be from the same time
// source.
static constexpr MonotonicTime fromRawSeconds(double value)
{
return MonotonicTime(value);
}
WTF_EXPORT_PRIVATE static MonotonicTime now();
static constexpr MonotonicTime infinity() { return fromRawSeconds(std::numeric_limits<double>::infinity()); }
static constexpr MonotonicTime nan() { return fromRawSeconds(std::numeric_limits<double>::quiet_NaN()); }
constexpr Seconds secondsSinceEpoch() const { return Seconds(m_value); }
MonotonicTime approximateMonotonicTime() const { return *this; }
WTF_EXPORT_PRIVATE WallTime approximateWallTime() const;
explicit constexpr operator bool() const { return !!m_value; }
constexpr MonotonicTime operator+(Seconds other) const
{
return fromRawSeconds(m_value + other.value());
}
constexpr MonotonicTime operator-(Seconds other) const
{
return fromRawSeconds(m_value - other.value());
}
Seconds operator%(Seconds other) const
{
return Seconds { fmod(m_value, other.value()) };
}
// Time is a scalar and scalars can be negated as this could arise from algebraic
// transformations. So, we allow it.
constexpr MonotonicTime operator-() const
{
return fromRawSeconds(-m_value);
}
MonotonicTime operator+=(Seconds other)
{
return *this = *this + other;
}
MonotonicTime operator-=(Seconds other)
{
return *this = *this - other;
}
constexpr Seconds operator-(MonotonicTime other) const
{
return Seconds(m_value - other.m_value);
}
constexpr bool operator==(MonotonicTime other) const
{
return m_value == other.m_value;
}
constexpr bool operator!=(MonotonicTime other) const
{
return m_value != other.m_value;
}
constexpr bool operator<(MonotonicTime other) const
{
return m_value < other.m_value;
}
constexpr bool operator>(MonotonicTime other) const
{
return m_value > other.m_value;
}
constexpr bool operator<=(MonotonicTime other) const
{
return m_value <= other.m_value;
}
constexpr bool operator>=(MonotonicTime other) const
{
return m_value >= other.m_value;
}
WTF_EXPORT_PRIVATE void dump(PrintStream&) const;
private:
constexpr MonotonicTime(double rawValue)
: m_value(rawValue)
{
}
double m_value { 0 };
};
} // namespace WTF
namespace std {
inline bool isnan(WTF::MonotonicTime time)
{
return std::isnan(time.secondsSinceEpoch().value());
}
inline bool isinf(WTF::MonotonicTime time)
{
return std::isinf(time.secondsSinceEpoch().value());
}
inline bool isfinite(WTF::MonotonicTime time)
{
return std::isfinite(time.secondsSinceEpoch().value());
}
} // namespace std
using WTF::MonotonicTime;
#endif // WTF_MonotonicTime_h