Package org.agrona.concurrent

Class OffsetEpochNanoClock

java.lang.Object

org.agrona.concurrent.OffsetEpochNanoClock

All Implemented Interfaces:

EpochNanoClock

public class OffsetEpochNanoClock
extends Object
implements EpochNanoClock

An accurate, zero-gc, pure-java, EpochNanoClock that calculates an initial epoch nano time based on System.currentTimeMillis() and then uses that offset to adjust the return value of System.nanoTime() to the UNIX epoch.

The sample() method can be used in order to reset these initial values if your system clock gets updated.

This class can be used from multiple threads safely.

See Also:

• SystemEpochNanoClock

Constructor Summary

Constructors

Constructor	Description
OffsetEpochNanoClock()	Constructs the clock with default configuration.
OffsetEpochNanoClock(int maxMeasurementRetries, long measurementThresholdNs, long resampleIntervalNs)	Constructs the clock with custom configuration parameters.

Method Summary

Modifier and Type	Method	Description
boolean	isWithinThreshold()	Gets whether the clock sampled the initial time offset accurately.
long	nanoTime()	Time in nanoseconds since 1 Jan 1970 UTC.
void	sample()	Explicitly resample the initial seeds.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

OffsetEpochNanoClock

public OffsetEpochNanoClock()

Constructs the clock with default configuration.

OffsetEpochNanoClock

public OffsetEpochNanoClock(int maxMeasurementRetries,
 long measurementThresholdNs,
 long resampleIntervalNs)

Constructs the clock with custom configuration parameters.

Parameters:

maxMeasurementRetries - the maximum number of times that this clock will attempt to re-sample the initial time values.

measurementThresholdNs - the desired accuracy window for the initial clock samples.

resampleIntervalNs - the desired interval before the samples are automatically recalculated. The seed recalculation enables the system to minimise clock drift if the system clock is updated.

Method Details

sample

public void sample()

Explicitly resample the initial seeds.

nanoTime

public long nanoTime()

Time in nanoseconds since 1 Jan 1970 UTC.

Specified by:

nanoTime in interface EpochNanoClock

Returns:

the number of nanoseconds since 1 Jan 1970 UTC.

isWithinThreshold

public boolean isWithinThreshold()

Gets whether the clock sampled the initial time offset accurately.

Returns:

true if the clock sampled the initial time offset accurately.