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 and 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

Methods

Modifier and Type	Method and 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

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()