org.jboss.xnio
Interface IoFuture<T>

Type Parameters:

T - the type of result that this operation produces

All Superinterfaces:

Cancellable

All Known Implementing Classes:

AbstractConvertingIoFuture, AbstractIoFuture, FailedIoFuture, FinishedIoFuture

public interface IoFuture<T>
extends Cancellable

The future result of an asynchronous request. Use instances of this interface to retrieve the final status of an asynchronous operation.

It is recommended, due to the vagaries of the way generics work, that when you use IoFuture instances, you use a wildcard to express the return type. This enables you to take advantage of covariance to retrofit more specific types later on without breaking anything.

For example, if you have a method which returns a future InputStream, you might be tempted to declare it like this:

 IoFuture<InputStream> getFutureInputStream();
 

Now if you later decide that what you really need is a DataInputStream (which extends InputStream), you're in trouble because you have written IoFuture<InputStream> everywhere, which cannot be assigned to or from an IoFuture<DataInputStream>.

On the other hand, if you declare it like this:

 IoFuture<? extends InputStream> getFutureInputStream();
 

Now you can change it at any time to IoFuture<? extends DataInputStream> without breaking the contract, since it will be assignable to variables of type IoFuture<? extends InputStream>.

Nested Class Summary

static class	IoFuture.HandlingNotifier<T,A> A base notifier class that calls the designated handler method on notification.
static interface	IoFuture.Notifier<T,A> A notifier that handles changes in the status of an IoFuture.
static class	IoFuture.Status The current status of an asynchronous operation.

Method Summary

<A> IoFuture<T>	addNotifier(IoFuture.Notifier<? super T,A> notifier, A attachment) Add a notifier to be called when this operation is complete.
IoFuture.Status	await() Wait for the operation to complete.
IoFuture.Status	await(long time, TimeUnit timeUnit) Wait for the operation to complete, with a timeout.
IoFuture.Status	awaitInterruptibly() Wait for the operation to complete.
IoFuture.Status	awaitInterruptibly(long time, TimeUnit timeUnit) Wait for the operation to complete, with a timeout.
IoFuture<T>	cancel() Cancel an operation.
T	get() Get the result of the operation.
IOException	getException() Get the failure reason.
T	getInterruptibly() Get the result of the operation.
IoFuture.Status	getStatus() Get the current status.

Method Detail

cancel

IoFuture<T> cancel()

Cancel an operation. The actual cancel may be synchronous or asynchronous.

Specified by:

cancel in interface Cancellable

Returns:

this instance

getStatus

IoFuture.Status getStatus()

Get the current status.

Returns:

the current status

await

IoFuture.Status await()

Wait for the operation to complete. This method will block until the status changes from IoFuture.Status.WAITING.

Returns:

the new status

await

IoFuture.Status await(long time,
                      TimeUnit timeUnit)

Wait for the operation to complete, with a timeout. This method will block until the status changes from IoFuture.Status.WAITING, or the given time elapses. If the time elapses before the operation is complete, IoFuture.Status.WAITING is returned.

Parameters:

time - the amount of time to wait

timeUnit - the time unit

Returns:

the new status, or IoFuture.Status.WAITING if the timeout expired

awaitInterruptibly

IoFuture.Status awaitInterruptibly()
                                   throws InterruptedException

Wait for the operation to complete. This method will block until the status changes from IoFuture.Status.WAITING, or the current thread is interrupted.

Returns:

the new status

Throws:

InterruptedException - if the operation is interrupted

awaitInterruptibly

IoFuture.Status awaitInterruptibly(long time,
                                   TimeUnit timeUnit)
                                   throws InterruptedException

Wait for the operation to complete, with a timeout. This method will block until the status changes from IoFuture.Status.WAITING, the given time elapses, or the current thread is interrupted. If the time elapses before the operation is complete, IoFuture.Status.WAITING is returned.

Parameters:

time - the amount of time to wait

timeUnit - the time unit

Returns:

the new status, or IoFuture.Status.WAITING if the timeout expired

Throws:

InterruptedException - if the operation is interrupted

get

T get()
      throws IOException,
             CancellationException

Get the result of the operation. If the operation is not complete, blocks until the operation completes. If the operation fails, or has already failed at the time this method is called, the failure reason is thrown.

Returns:

the result of the operation

Throws:

IOException - if the operation failed

CancellationException - if the operation was cancelled

getInterruptibly

T getInterruptibly()
                   throws IOException,
                          InterruptedException,
                          CancellationException

Get the result of the operation. If the operation is not complete, blocks until the operation completes. If the operation fails, or has already failed at the time this method is called, the failure reason is thrown. If the current thread is interrupted while waiting, an exception is thrown.

Returns:

the result of the operation

Throws:

IOException - if the operation failed

InterruptedException - if the operation is interrupted

CancellationException - if the operation was cancelled

getException

IOException getException()
                         throws IllegalStateException

Get the failure reason.

Returns:

the failure reason

Throws:

IllegalStateException - if the operation did not fail

addNotifier

<A> IoFuture<T> addNotifier(IoFuture.Notifier<? super T,A> notifier,
                            A attachment)

Add a notifier to be called when this operation is complete. If the operation is already complete, the notifier is called immediately, possibly in the caller's thread. The given attachment is provided to the notifier.

Type Parameters:

A - the attachment type

Parameters:

notifier - the notifier to be called

attachment - the attachment to pass in to the notifier

Returns:

this instance