Package jenkins.metrics.util

Class ExponentialLeakyBucket<T>

java.lang.Object

jenkins.metrics.util.ExponentialLeakyBucket<T>

public class ExponentialLeakyBucket<T>
extends Object

An exponentially-decaying random reservoir of longs. Uses Cormode et al's forward-decaying priority reservoir sampling method to produce a statistically representative sampling reservoir, exponentially biased towards newer entries.

See Also:

Cormode et al. Forward Decay: A Practical Time Decay Model for Streaming Systems. ICDE '09: Proceedings of the 2009 IEEE International Conference on Data Engineering (2009)

Constructor Summary

Constructors

Constructor	Description
ExponentialLeakyBucket()	Creates a new ExponentialLeakyBucket of 1028 elements, which offers a 99.9% confidence level with a 5% margin of error assuming a normal distribution, and an alpha factor of 0.015, which heavily biases the reservoir to the past 5 minutes of measurements.
ExponentialLeakyBucket(int size, double alpha)	Creates a new ExponentialLeakyBucket.
ExponentialLeakyBucket(int size, double alpha, com.codahale.metrics.Clock clock)	Creates a new ExponentialLeakyBucket.

Method Summary

Modifier and Type	Method	Description
void	add(T value)
void	add(T value, long timestamp)	Adds an old value with a fixed timestamp to the reservoir.
int	size()
List<T>	values()

Methods inherited from class java.lang.Object

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

Constructor Detail

ExponentialLeakyBucket

public ExponentialLeakyBucket()

Creates a new ExponentialLeakyBucket of 1028 elements, which offers a 99.9% confidence level with a 5% margin of error assuming a normal distribution, and an alpha factor of 0.015, which heavily biases the reservoir to the past 5 minutes of measurements.

ExponentialLeakyBucket

public ExponentialLeakyBucket(int size,
                              double alpha)

Creates a new ExponentialLeakyBucket.

Parameters:

size - the number of samples to keep in the sampling reservoir

alpha - the exponential decay factor; the higher this is, the more biased the reservoir will be towards newer values

ExponentialLeakyBucket

public ExponentialLeakyBucket(int size,
                              double alpha,
                              com.codahale.metrics.Clock clock)

Creates a new ExponentialLeakyBucket.

Parameters:

size - the number of samples to keep in the sampling reservoir

alpha - the exponential decay factor; the higher this is, the more biased the reservoir will be towards newer values

clock - the clock to use

Method Detail

size

public int size()

add

public void add(T value)

add

public void add(T value,
                long timestamp)

Adds an old value with a fixed timestamp to the reservoir.

Parameters:

value - the value to be added

timestamp - the epoch timestamp of value in seconds

values

public List<T> values()