Package org.apache.hadoop.hbase.util

Class ExponentialMovingAverage<T>

java.lang.Object

org.apache.hadoop.hbase.util.MovingAverage<T>

org.apache.hadoop.hbase.util.WindowMovingAverage<T>

org.apache.hadoop.hbase.util.ExponentialMovingAverage<T>

@Private
public class ExponentialMovingAverage<T>
extends WindowMovingAverage<T>

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	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	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	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, getMostRecentPosition, getNumberOfStatistics, getStatisticsAtIndex, moveForwardMostRecentPosition

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 Details

alpha

private double alpha

previousAverage

private double previousAverage

currentAverage

private double currentAverage

Constructor Details

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 Details

updateMostRecentTime

public void updateMostRecentTime(long elapsed)

Description copied from class: MovingAverage

Update the most recent data.

Overrides:

updateMostRecentTime in class WindowMovingAverage<T>

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<T>

Returns:

average time in ns

getPrevious

double getPrevious()