com.hazelcast.spi.merge

Class HyperLogLogMergePolicy

java.lang.Object

com.hazelcast.spi.merge.AbstractSplitBrainMergePolicy

com.hazelcast.spi.merge.HyperLogLogMergePolicy

All Implemented Interfaces:

DataSerializable, IdentifiedDataSerializable, SplitBrainMergePolicy

public class HyperLogLogMergePolicy
extends AbstractSplitBrainMergePolicy

Only available for HyperLogLog backed CardinalityEstimator.

Uses the default merge algorithm from HyperLogLog research, keeping the max register value of the two given instances. The result should be the union to the two HyperLogLog estimations.

Since:

3.10

Constructor Summary

Constructors

Constructor and Description
HyperLogLogMergePolicy()

Method Summary

Modifier and Type	Method and Description
int	getId() Returns type identifier for this class.
<V> V	merge(MergingValueHolder<V> mergingValue, MergingValueHolder<V> existingValue) Selects the value of either the merging or the existing MergingValueHolder which should be merged.

Methods inherited from class com.hazelcast.spi.merge.AbstractSplitBrainMergePolicy

checkInstanceOf, getFactoryId, readData, writeData

Methods inherited from class java.lang.Object

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

Constructor Detail

HyperLogLogMergePolicy

public HyperLogLogMergePolicy()

Method Detail

merge

public <V> V merge(MergingValueHolder<V> mergingValue,
                   MergingValueHolder<V> existingValue)

Description copied from interface: SplitBrainMergePolicy

Selects the value of either the merging or the existing MergingValueHolder which should be merged.

Note that the existing MergingValueHolder instance may be null if no matching data could be found to the merging MergingValueHolder.

Specified by:

merge in interface SplitBrainMergePolicy

Overrides:

merge in class AbstractSplitBrainMergePolicy

Type Parameters:

V - the type of the value

Parameters:

mergingValue - MergingValueHolder instance that has the merging data of the smaller sub-cluster

existingValue - MergingValueHolder instance that has the existing data or null if no matching data exists

Returns:

the selected value for merging

getId

public int getId()

Description copied from interface: IdentifiedDataSerializable

Returns type identifier for this class. It should be unique per DataSerializableFactory.

Returns:

type ID