com.alibaba.metrics

类 ExponentiallyDecayingReservoir

java.lang.Object

com.alibaba.metrics.ExponentiallyDecayingReservoir

所有已实现的接口:

Reservoir

public class ExponentiallyDecayingReservoir
extends Object
implements Reservoir

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.

另请参阅:

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)

构造器概要

构造器

构造器和说明
ExponentiallyDecayingReservoir() Creates a new ExponentiallyDecayingReservoir 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.
ExponentiallyDecayingReservoir(Clock clock)
ExponentiallyDecayingReservoir(int size, double alpha) Creates a new ExponentiallyDecayingReservoir.
ExponentiallyDecayingReservoir(int size, double alpha, Clock clock) Creates a new ExponentiallyDecayingReservoir.

方法概要

限定符和类型	方法和说明
Snapshot	getSnapshot()
int	size()
void	update(long value)
void	update(long value, long timestamp) Adds an old value with a fixed timestamp to the reservoir.

从类继承的方法 java.lang.Object

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

构造器详细资料

ExponentiallyDecayingReservoir

public ExponentiallyDecayingReservoir()

Creates a new ExponentiallyDecayingReservoir 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.

ExponentiallyDecayingReservoir

public ExponentiallyDecayingReservoir(Clock clock)

ExponentiallyDecayingReservoir

public ExponentiallyDecayingReservoir(int size,
                                      double alpha)

Creates a new ExponentiallyDecayingReservoir.

参数:

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

ExponentiallyDecayingReservoir

public ExponentiallyDecayingReservoir(int size,
                                      double alpha,
                                      Clock clock)

Creates a new ExponentiallyDecayingReservoir.

参数:

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 used to timestamp samples and track rescaling

方法详细资料

size

public int size()

指定者:

size 在接口中 Reservoir

update

public void update(long value)

指定者:

update 在接口中 Reservoir

update

public void update(long value,
                   long timestamp)

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

参数:

value - the value to be added

timestamp - the epoch timestamp of value in seconds

getSnapshot

public Snapshot getSnapshot()

指定者:

getSnapshot 在接口中 Reservoir