ClickHouse/contrib/libpoco/Foundation/include/Poco/Clock.h
2016-06-07 11:23:15 +03:00

241 lines
4.9 KiB
C++

//
// Clock.h
//
// $Id: //poco/1.4/Foundation/include/Poco/Clock.h#2 $
//
// Library: Foundation
// Package: DateTime
// Module: Clock
//
// Definition of the Clock class.
//
// Copyright (c) 2013, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_Clock_INCLUDED
#define Foundation_Clock_INCLUDED
#include "Poco/Foundation.h"
namespace Poco {
class Foundation_API Clock
/// A Clock stores a monotonic* clock value
/// with (theoretical) microseconds resolution.
/// Clocks can be compared with each other
/// and simple arithmetics are supported.
///
/// [*] Note that Clock values are only monotonic if
/// the operating system provides a monotonic clock.
/// The monotonic() function can be used to check whether
/// the system's clock is monotonic.
///
/// Monotonic Clock is available on Windows, Linux, OS X
/// and on POSIX platforms supporting clock_gettime() with CLOCK_MONOTONIC.
///
/// Clock values are relative to a system-dependent epoch time
/// (usually the system's startup time) and have no relation
/// to the time of day.
{
public:
typedef Int64 ClockVal;
/// Monotonic clock value in microsecond resolution.
typedef Int64 ClockDiff;
/// Difference between two ClockVal values in microseconds.
static const ClockVal CLOCKVAL_MIN; /// Minimum clock value.
static const ClockVal CLOCKVAL_MAX; /// Maximum clock value.
Clock();
/// Creates a Clock with the current system clock value.
Clock(ClockVal tv);
/// Creates a Clock from the given clock value.
Clock(const Clock& other);
/// Copy constructor.
~Clock();
/// Destroys the Clock.
Clock& operator = (const Clock& other);
Clock& operator = (ClockVal tv);
void swap(Clock& clock);
/// Swaps the Clock with another one.
void update();
/// Updates the Clock with the current system clock.
bool operator == (const Clock& ts) const;
bool operator != (const Clock& ts) const;
bool operator > (const Clock& ts) const;
bool operator >= (const Clock& ts) const;
bool operator < (const Clock& ts) const;
bool operator <= (const Clock& ts) const;
Clock operator + (ClockDiff d) const;
Clock operator - (ClockDiff d) const;
ClockDiff operator - (const Clock& ts) const;
Clock& operator += (ClockDiff d);
Clock& operator -= (ClockDiff d);
ClockVal microseconds() const;
/// Returns the clock value expressed in microseconds
/// since the system-specific epoch time (usually system
/// startup).
ClockVal raw() const;
/// Returns the clock value expressed in microseconds
/// since the system-specific epoch time (usually system
/// startup).
///
/// Same as microseconds().
ClockDiff elapsed() const;
/// Returns the time elapsed since the time denoted by
/// the Clock instance. Equivalent to Clock() - *this.
bool isElapsed(ClockDiff interval) const;
/// Returns true iff the given interval has passed
/// since the time denoted by the Clock instance.
static ClockDiff resolution();
/// Returns the resolution in units per second.
/// Since the Clock clas has microsecond resolution,
/// the returned value is always 1000000.
static ClockDiff accuracy();
/// Returns the system's clock accuracy in microseconds.
static bool monotonic();
/// Returns true iff the system's clock is monotonic.
private:
ClockVal _clock;
};
//
// inlines
//
inline bool Clock::operator == (const Clock& ts) const
{
return _clock == ts._clock;
}
inline bool Clock::operator != (const Clock& ts) const
{
return _clock != ts._clock;
}
inline bool Clock::operator > (const Clock& ts) const
{
return _clock > ts._clock;
}
inline bool Clock::operator >= (const Clock& ts) const
{
return _clock >= ts._clock;
}
inline bool Clock::operator < (const Clock& ts) const
{
return _clock < ts._clock;
}
inline bool Clock::operator <= (const Clock& ts) const
{
return _clock <= ts._clock;
}
inline Clock Clock::operator + (Clock::ClockDiff d) const
{
return Clock(_clock + d);
}
inline Clock Clock::operator - (Clock::ClockDiff d) const
{
return Clock(_clock - d);
}
inline Clock::ClockDiff Clock::operator - (const Clock& ts) const
{
return _clock - ts._clock;
}
inline Clock& Clock::operator += (Clock::ClockDiff d)
{
_clock += d;
return *this;
}
inline Clock& Clock::operator -= (Clock::ClockDiff d)
{
_clock -= d;
return *this;
}
inline Clock::ClockVal Clock::microseconds() const
{
return _clock;
}
inline Clock::ClockDiff Clock::elapsed() const
{
Clock now;
return now - *this;
}
inline bool Clock::isElapsed(Clock::ClockDiff interval) const
{
Clock now;
Clock::ClockDiff diff = now - *this;
return diff >= interval;
}
inline Clock::ClockDiff Clock::resolution()
{
return 1000000;
}
inline void swap(Clock& s1, Clock& s2)
{
s1.swap(s2);
}
inline Clock::ClockVal Clock::raw() const
{
return _clock;
}
} // namespace Poco
#endif // Foundation_Clock_INCLUDED