Package org.elasticsearch.common.util.concurrent

Class ListenableFuture<V>

java.lang.Object

org.elasticsearch.common.util.concurrent.BaseFuture<V>

org.elasticsearch.common.util.concurrent.ListenableFuture<V>

All Implemented Interfaces:

Future<V>, ActionListener<V>

public final class ListenableFuture<V>
extends BaseFuture<V>
implements ActionListener<V>

A future implementation that allows for the result to be passed to listeners waiting for notification. This is useful for cases where a computation is requested many times concurrently, but really only needs to be performed a single time. Once the computation has been performed the registered listeners will be notified by submitting a runnable for execution in the provided ExecutorService. If the computation has already been performed, a request to add a listener will simply result in execution of the listener on the calling thread.

Nested Class Summary

Nested classes/interfaces inherited from interface org.elasticsearch.action.ActionListener

ActionListener.Delegating<Response,DelegateResponse>, ActionListener.DelegatingActionListener<T>, ActionListener.DelegatingFailureActionListener<T,R>, ActionListener.MappedActionListener<Response,MappedResponse>, ActionListener.RunAfterActionListener<T>, ActionListener.RunBeforeActionListener<T>

Constructor Summary

Constructors

Constructor	Description
ListenableFuture()

Method Summary

Modifier and Type	Method	Description
void	addListener(ActionListener<V> listener)	Adds a listener to this future.
void	addListener(ActionListener<V> listener, ExecutorService executor, ThreadContext threadContext)	Adds a listener to this future.
protected void	done(boolean ignored)	Called when the BaseFuture is completed.
void	onFailure(Exception e)	A failure caused by an exception at some phase of the task.
void	onResponse(V v)	Handle action response.

Methods inherited from class org.elasticsearch.common.util.concurrent.BaseFuture

blockingAllowed, cancel, get, get, interruptTask, isCancelled, isDone, set, setException

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.elasticsearch.action.ActionListener

delegateFailure, delegateResponse, map

Constructor Details

ListenableFuture

public ListenableFuture()

Method Details

addListener

public void addListener(ActionListener<V> listener)

Adds a listener to this future. If the future has not yet completed, the listener will be notified of a response or exception on the thread completing this future. If the future has completed, the listener will be notified immediately without forking to a different thread.

addListener

public void addListener(ActionListener<V> listener,
 ExecutorService executor,
 ThreadContext threadContext)

Adds a listener to this future. If the future has not yet completed, the listener will be notified of a response or exception in a runnable submitted to the ExecutorService provided. If the future has completed, the listener will be notified immediately without forking to a different thread. It will apply the provided ThreadContext (if not null) when executing the listening.

done

protected void done(boolean ignored)

Description copied from class: BaseFuture

Called when the BaseFuture is completed. The success boolean indicates if the BaseFuture was successfully completed (the value is true). In the cases the BaseFuture was completed with an error or cancelled the value is false.

Overrides:

done in class BaseFuture<V>

Parameters:

ignored - indicates if the BaseFuture was completed with success (true); in other cases it equals to false

onResponse

public void onResponse(V v)

Description copied from interface: ActionListener

Handle action response. This response may constitute a failure or a success but it is up to the listener to make that decision.

Specified by:

onResponse in interface ActionListener<V>

onFailure

public void onFailure(Exception e)

Description copied from interface: ActionListener

A failure caused by an exception at some phase of the task.

Specified by:

onFailure in interface ActionListener<V>