org.hypergraphdb.util

Class CallbackFuture<T>

java.lang.Object

org.hypergraphdb.util.CallbackFuture<T>

All Implemented Interfaces:

Future<T>

public class CallbackFuture<T>
extends Object
implements Future<T>

An CallbackFuture offers the possibility to call back a registered listener when it is completed. To avoid taking up a thread and waiting for completion, this is accomplished by required the creator of the future to invoke the completed method when the result this Future represents has been computed.

Only one listener can be registered for call back and it is of type Mapping, T>. That is, a mapping that will receive the CallbackFuture itself as an argument and must return the result of the Future. Typically the mapping will just return the CallbackFuture's own result by calling the getResult, but it may choose to assign a different result. Note that blocking calls to get will not return until the registered listener (if any) returns, so the listener must rely on the provided getResult to obtain the Future's result value.

This class may be extended to provide semantics for cancellation. In this case the cancel method must be overridden and the canceled flag must be set to true if cancellation was successful.

Author:

Borislav Iordanov

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	canceled

Constructor Summary

Constructors

Constructor and Description
CallbackFuture()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	cancel(boolean mayInterruptIfRunning)
void	complete(T result)
T	get()
T	get(long timeout, TimeUnit unit)
T	getResult()
boolean	isCancelled()
boolean	isDone()
void	setCompletionListener(Mapping<CallbackFuture<T>,T> listener)

Methods inherited from class java.lang.Object

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

Field Detail

canceled

protected volatile boolean canceled

Constructor Detail

CallbackFuture

public CallbackFuture()

Method Detail

setCompletionListener

public void setCompletionListener(Mapping<CallbackFuture<T>,T> listener)

complete

public void complete(T result)

getResult

public T getResult()

cancel

public boolean cancel(boolean mayInterruptIfRunning)

Specified by:

cancel in interface Future<T>

get

public T get()
      throws InterruptedException,
             ExecutionException

Specified by:

get in interface Future<T>

Throws:

InterruptedException

ExecutionException

get

public T get(long timeout,
    TimeUnit unit)
      throws InterruptedException,
             ExecutionException,
             TimeoutException

Specified by:

get in interface Future<T>

Throws:

InterruptedException

ExecutionException

TimeoutException

isCancelled

public boolean isCancelled()

Specified by:

isCancelled in interface Future<T>

isDone

public boolean isDone()

Specified by:

isDone in interface Future<T>