com.google.common.util.concurrent

Class ListenableFutureTask<V>

java.lang.Object

java.util.concurrent.FutureTask<V>

com.google.common.util.concurrent.ListenableFutureTask<V>

All Implemented Interfaces:

ListenableFuture<V>, Runnable, Future<V>, RunnableFuture<V>

public class ListenableFutureTask<V>
extends FutureTask<V>
implements ListenableFuture<V>

A FutureTask that also implements the ListenableFuture interface. Unlike FutureTask, ListenableFutureTask does not provide an overrideable done() method. For similar functionality, call addListener(java.lang.Runnable, java.util.concurrent.Executor).

Since:

1.0

Author:

Sven Mawson

Method Summary

Methods

Modifier and Type	Method and Description
void	addListener(Runnable listener, Executor exec) Registers a listener to be run on the given executor.
static <V> ListenableFutureTask<V>	create(Callable<V> callable) Creates a ListenableFutureTask that will upon running, execute the given Callable.
static <V> ListenableFutureTask<V>	create(Runnable runnable, V result) Creates a ListenableFutureTask that will upon running, execute the given Runnable, and arrange that get will return the given result on successful completion.
protected void	done() Internal implementation detail used to invoke the listeners.

Methods inherited from class java.util.concurrent.FutureTask

cancel, get, get, isCancelled, isDone, run, runAndReset, set, setException

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.concurrent.Future

cancel, get, get, isCancelled, isDone

Method Detail

create

public static <V> ListenableFutureTask<V> create(Callable<V> callable)

Creates a ListenableFutureTask that will upon running, execute the given Callable.

Parameters:

callable - the callable task

Since:

10.0

create

public static <V> ListenableFutureTask<V> create(Runnable runnable,
                                 @Nullable
                                 V result)

Creates a ListenableFutureTask that will upon running, execute the given Runnable, and arrange that get will return the given result on successful completion.

Parameters:

runnable - the runnable task

result - the result to return on successful completion. If you don't need a particular result, consider using constructions of the form: ListenableFuture<?> f = ListenableFutureTask.create(runnable, null)

Since:

10.0

addListener

public void addListener(Runnable listener,
               Executor exec)

Description copied from interface: ListenableFuture

Registers a listener to be run on the given executor. The listener will run when the Future's computation is complete or, if the computation is already complete, immediately.

There is no guaranteed ordering of execution of listeners, but any listener added through this method is guaranteed to be called once the computation is complete.

Exceptions thrown by a listener will be propagated up to the executor. Any exception thrown during Executor.execute (e.g., a RejectedExecutionException or an exception thrown by direct execution) will be caught and logged.

Note: For fast, lightweight listeners that would be safe to execute in any thread, consider MoreExecutors.directExecutor(). For heavier listeners, directExecutor() carries some caveats. For example, the listener may run on an unpredictable or undesirable thread:

• If this Future is done at the time addListener is called, addListener will execute the listener inline.
• If this Future is not yet done, addListener will schedule the listener to be run by the thread that completes this Future, which may be an internal system thread such as an RPC network thread.

Also note that, regardless of which thread executes the directExecutor() listener, all other registered but unexecuted listeners are prevented from running during its execution, even if those listeners are to run in other executors.

This is the most general listener interface. For common operations performed using listeners, see Futures. For a simplified but general listener interface, see addCallback().

Specified by:

addListener in interface ListenableFuture<V>

Parameters:

listener - the listener to run when the computation is complete

exec - the executor to run the listener in

done

protected void done()

Internal implementation detail used to invoke the listeners.

Overrides:

done in class FutureTask<V>