com.aquenos.epics.jackie.common.util

Class DelegatingListenableFuture<V>

java.lang.Object

com.aquenos.epics.jackie.common.util.DelegatingListenableFuture<V>

Type Parameters:

V - The result type returned by the future.

All Implemented Interfaces:

ListenableFuture<V>, java.util.concurrent.Future<V>

public class DelegatingListenableFuture<V>
extends java.lang.Object
implements ListenableFuture<V>

Listenable future implementation that simply delegates all method calls to another listenable future. While this implementation can be used on its own, it is most useful as a base class for implementations that want to intercept certain method calls while simply passing other ones through.

Author:

Sebastian Marsching

Field Summary

Fields

Modifier and Type	Field and Description
protected ListenableFuture<? extends V>	delegate Delegate to which all method calls are delegated.

Constructor Summary

Constructors

Constructor and Description
DelegatingListenableFuture(ListenableFuture<? extends V> delegate) Creates a listenable future that delegates all method calls to the specified listenable future.

Method Summary

Modifier and Type	Method and Description
boolean	addCompletionListener(FutureCompletionListener<? super V> listener) Registers a completion listener with this future.
boolean	cancel(boolean mayInterruptIfRunning)
V	get()
V	get(long timeout, java.util.concurrent.TimeUnit unit)
boolean	isCancelled()
boolean	isDone()
boolean	removeCompletionListener(FutureCompletionListener<? super V> listener) Removes the registration of a completion listener with this future.

Methods inherited from class java.lang.Object

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

Field Detail

delegate

protected ListenableFuture<? extends V> delegate

Delegate to which all method calls are delegated.

Constructor Detail

DelegatingListenableFuture

public DelegatingListenableFuture(ListenableFuture<? extends V> delegate)

Creates a listenable future that delegates all method calls to the specified listenable future.

Parameters:

delegate - listenable future that will receive all method calls that are made on this listenable future.

Method Detail

cancel

public boolean cancel(boolean mayInterruptIfRunning)

Specified by:

cancel in interface java.util.concurrent.Future<V>

isCancelled

public boolean isCancelled()

Specified by:

isCancelled in interface java.util.concurrent.Future<V>

isDone

public boolean isDone()

Specified by:

isDone in interface java.util.concurrent.Future<V>

get

public V get()
      throws java.lang.InterruptedException,
             java.util.concurrent.ExecutionException

Specified by:

get in interface java.util.concurrent.Future<V>

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

get

public V get(long timeout,
             java.util.concurrent.TimeUnit unit)
      throws java.lang.InterruptedException,
             java.util.concurrent.ExecutionException,
             java.util.concurrent.TimeoutException

Specified by:

get in interface java.util.concurrent.Future<V>

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

java.util.concurrent.TimeoutException

addCompletionListener

public boolean addCompletionListener(FutureCompletionListener<? super V> listener)

Description copied from interface: ListenableFuture

Registers a completion listener with this future. This listener is notified when the future completes (Future.isDone() returns true). If the future completes before the listener is registered, the listener is notified immediately while being added.

If the specified listener is already registered with this future, no action is taken and this method returns false.

Important note: Typically, the listener is executed by the thread that sets the future's value. For this reason, it is important that the listener does not block or perform any long-running operations. Instead, the listener should delegate any such operation to a different thread (e.g. using an Executor). Any violation of this rule might result in unexpected or unpredictable behavior. In particular, a blocking listener might cause a dead-lock, which results in the whole application being stalled indefinitely.

Specified by:

addCompletionListener in interface ListenableFuture<V>

Parameters:

listener - listener to be registered with this future.

Returns:

true if the listener has been added, false if it has already been added earlier.

removeCompletionListener

public boolean removeCompletionListener(FutureCompletionListener<? super V> listener)

Description copied from interface: ListenableFuture

Removes the registration of a completion listener with this future. After removing, the listener is not going to be notified when the future completes.

If the specified listener is not currently registered with this future, no action is taken and this method returns false.

Specified by:

removeCompletionListener in interface ListenableFuture<V>

Parameters:

listener - listener to be unregistered from this future.

Returns:

true if the listener has been removed, false if it has already been removed earlier of if has never been added.