org.apache.samza.operators.functions

Interface FoldLeftFunction<M,WV>

All Superinterfaces:

ClosableFunction, InitableFunction, java.io.Serializable

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@InterfaceStability.Unstable
 @FunctionalInterface
public interface FoldLeftFunction<M,WV>
extends InitableFunction, ClosableFunction, java.io.Serializable

Incrementally updates the aggregated value as messages are added. Main usage is in Window operator.

Method Summary

Modifier and Type	Method and Description
WV	apply(M message, WV oldValue) Incrementally updates the aggregated value as messages are added.

Methods inherited from interface org.apache.samza.operators.functions.InitableFunction

init

Methods inherited from interface org.apache.samza.operators.functions.ClosableFunction

close

Method Detail

apply

WV apply(M message,
         WV oldValue)

Incrementally updates the aggregated value as messages are added.

Parameters:

message - the message being added to the aggregated value

oldValue - the previous value

Returns:

the new value