Module org.elasticsearch.server

Package org.elasticsearch.common.metrics

Class ExponentialBucketHistogram

java.lang.Object

org.elasticsearch.common.metrics.ExponentialBucketHistogram

Direct Known Subclasses:

HandlingTimeTracker

public class ExponentialBucketHistogram
extends Object

A histogram with a fixed number of buckets of exponentially increasing width.

The bucket boundaries are defined by increasing powers of two, e.g. (-∞, 1), [1, 2), [2, 4), [4, 8), ..., [2^(bucketCount-2), ∞) There are bucketCount buckets.

Constructor Summary

Constructors

Constructor	Description
ExponentialBucketHistogram(int bucketCount)

Method Summary

Modifier and Type	Method	Description
void	addObservation(long observedValue)
int[]	calculateBucketUpperBounds()
void	clear()	Clear all values in the histogram (non-atomic)
static int[]	getBucketUpperBounds(int bucketCount)
long	getPercentile(float percentile)	Calculate the Nth percentile value
long	getPercentile(float percentile, long[] snapshot, int[] bucketUpperBounds)	Calculate the Nth percentile value
long[]	getSnapshot()

Methods inherited from class java.lang.Object

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

Constructor Details

ExponentialBucketHistogram

public ExponentialBucketHistogram(int bucketCount)

Method Details

getBucketUpperBounds

public static int[] getBucketUpperBounds(int bucketCount)

calculateBucketUpperBounds

public int[] calculateBucketUpperBounds()

addObservation

public void addObservation(long observedValue)

getSnapshot

public long[] getSnapshot()

Returns:

An array of frequencies of handling times in buckets with upper bounds as returned by calculateBucketUpperBounds(), plus an extra bucket for handling times longer than the longest upper bound.

getPercentile

public long getPercentile(float percentile)

Calculate the Nth percentile value

Parameters:

percentile - The percentile as a fraction (in [0, 1.0])

Returns:

A value greater than the specified fraction of values in the histogram

Throws:

IllegalArgumentException - if the requested percentile is invalid

getPercentile

public long getPercentile(float percentile,
 long[] snapshot,
 int[] bucketUpperBounds)

Calculate the Nth percentile value

Parameters:

percentile - The percentile as a fraction (in [0, 1.0])

snapshot - An array of frequencies of handling times in buckets with upper bounds as per calculateBucketUpperBounds()

bucketUpperBounds - The upper bounds of the buckets in the histogram, as per calculateBucketUpperBounds()

Returns:

A value greater than the specified fraction of values in the histogram

Throws:

IllegalArgumentException - if the requested percentile is invalid

clear

public void clear()

Clear all values in the histogram (non-atomic)