ListenableFuture (server 6.4.2 API)

java.lang.Object
- org.elasticsearch.common.util.concurrent.BaseFuture<V>
- - org.elasticsearch.common.util.concurrent.ListenableFuture<V>

All Implemented Interfaces:

java.util.concurrent.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.

Constructor Summary

Constructors
Constructor Description

ListenableFuture()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`addListener(ActionListener<V> listener, java.util.concurrent.ExecutorService executor)`	Adds a listener to this future.
`protected void`	`done()`
`void`	`onFailure(java.lang.Exception e)`	A failure caused by an exception at some phase of the task.
`void`	`onResponse(V v)`	Handle action response.

Methods inherited from interface org.elasticsearch.action.ActionListener

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

- Constructor Detail
  - ListenableFuture
```
public ListenableFuture()
```
- Method Detail
  - addListener
```
public void addListener(ActionListener<V> listener,
                        java.util.concurrent.ExecutorService executor)
```
    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.
  - done
```
protected void done()
```
    Overrides:
    
    done in class BaseFuture<V>
  - 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(java.lang.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>