org.apache.beam.runners.samza.runtime

Interface FutureCollector<OutT>

Type Parameters:

OutT - type of the output element

public interface FutureCollector<OutT>

A future collector that buffers the output from the users DoFn and propagates the result future to downstream operators only after finish() is invoked.

Method Summary

Modifier and Type	Method and Description
void	add(java.util.concurrent.CompletionStage<org.apache.beam.sdk.util.WindowedValue<OutT>> element) Outputs the element to the collector.
void	addAll(java.util.concurrent.CompletionStage<java.util.Collection<org.apache.beam.sdk.util.WindowedValue<OutT>>> elements) Outputs a collection of elements to the collector.
void	discard() Discards the elements within the collector.
java.util.concurrent.CompletionStage<java.util.Collection<org.apache.beam.sdk.util.WindowedValue<OutT>>>	finish() Seals this FutureCollector, returning a CompletionStage containing all of the elements that were added to it.
void	prepare() Prepares the FutureCollector to accept output elements.

Method Detail

add

void add(java.util.concurrent.CompletionStage<org.apache.beam.sdk.util.WindowedValue<OutT>> element)

Outputs the element to the collector.

Parameters:

element - to add to the collector

addAll

void addAll(java.util.concurrent.CompletionStage<java.util.Collection<org.apache.beam.sdk.util.WindowedValue<OutT>>> elements)

Outputs a collection of elements to the collector.

Parameters:

elements - to add to the collector

discard

void discard()

Discards the elements within the collector. Once the elements have been discarded, callers need to prepare the collector again before invoking add(CompletionStage).

finish

java.util.concurrent.CompletionStage<java.util.Collection<org.apache.beam.sdk.util.WindowedValue<OutT>>> finish()

Seals this FutureCollector, returning a CompletionStage containing all of the elements that were added to it. The add(CompletionStage) method will throw an IllegalStateException if called after a call to finish.

The FutureCollector needs to be started again to collect newer batch of output.

prepare

void prepare()

Prepares the FutureCollector to accept output elements. The add(CompletionStage) method will throw an IllegalStateException if called without preparing the collector.