org.apache.hadoop.hbase.util

Class ExponentialMovingAverage

java.lang.Object

org.apache.hadoop.hbase.util.MovingAverage

org.apache.hadoop.hbase.util.WindowMovingAverage

org.apache.hadoop.hbase.util.ExponentialMovingAverage

@InterfaceAudience.Private
public class ExponentialMovingAverage
extends WindowMovingAverage

EMA is similar to WeightedMovingAverage in weighted, but the weighting factor decrease exponentially. It brings benefits that it is more sensitive, and can see the trends easily.

Field Summary

Fields

Modifier and Type	Field and Description
private double	alpha
private double	currentAverage
private double	previousAverage

Fields inherited from class org.apache.hadoop.hbase.util.WindowMovingAverage

DEFAULT_SIZE, lastN, mostRecent, oneRound

Fields inherited from class org.apache.hadoop.hbase.util.MovingAverage

label

Constructor Summary

Constructors

Constructor and Description
ExponentialMovingAverage(String label)
ExponentialMovingAverage(String label, double alpha)
ExponentialMovingAverage(String label, int size)
ExponentialMovingAverage(String label, int size, double alpha)

Method Summary

Modifier and Type	Method and Description
double	getAverageTime() Get average execution time of the measured method.
(package private) double	getPrevious()
void	updateMostRecentTime(long elapsed) Update the most recent data.

Methods inherited from class org.apache.hadoop.hbase.util.WindowMovingAverage

enoughStatistics, getMostRecentPosistion, getNumberOfStatistics, getStatisticsAtIndex, moveForwardMostRecentPosistion

Methods inherited from class org.apache.hadoop.hbase.util.MovingAverage

measure, start, stop

Methods inherited from class java.lang.Object

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

Field Detail

alpha

private double alpha

previousAverage

private double previousAverage

currentAverage

private double currentAverage

Constructor Detail

ExponentialMovingAverage

public ExponentialMovingAverage(String label)

ExponentialMovingAverage

public ExponentialMovingAverage(String label,
                                double alpha)

ExponentialMovingAverage

public ExponentialMovingAverage(String label,
                                int size)

ExponentialMovingAverage

public ExponentialMovingAverage(String label,
                                int size,
                                double alpha)

Method Detail

updateMostRecentTime

public void updateMostRecentTime(long elapsed)

Description copied from class: MovingAverage

Update the most recent data.

Overrides:

updateMostRecentTime in class WindowMovingAverage

Parameters:

elapsed - elapsed time of the most recent measurement

getAverageTime

public double getAverageTime()

Description copied from class: MovingAverage

Get average execution time of the measured method.

Overrides:

getAverageTime in class WindowMovingAverage

Returns:

average time in ns

getPrevious

double getPrevious()