org.apache.fluo.recipes.core.combine

Class SummingCombiner<K>

java.lang.Object

org.apache.fluo.recipes.core.combine.SummingCombiner<K>

All Implemented Interfaces:

Combiner<K,Long>

public class SummingCombiner<K>
extends Object
implements Combiner<K,Long>

Sums long values and returns Optional.empty() when the sum is zero.

Since:

1.1.0

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.fluo.recipes.core.combine.Combiner

Combiner.Input<KI,VI>

Constructor Summary

Constructors

Constructor and Description
SummingCombiner()

Method Summary

Modifier and Type	Method and Description
Optional<Long>	combine(Combiner.Input<K,Long> input) This function is called to combine the current value of a key with updates that were queued for the key.

Methods inherited from class java.lang.Object

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

Constructor Detail

SummingCombiner

public SummingCombiner()

Method Detail

combine

public Optional<Long> combine(Combiner.Input<K,Long> input)

Description copied from interface: Combiner

This function is called to combine the current value of a key with updates that were queued for the key. See the collision free map project level documentation for more information.

Specified by:

combine in interface Combiner<K,Long>

Returns:

Then new value for the key. Returning Optional.empty() will cause the key to be deleted.