com.google.common.util.concurrent

Class ImmediateFuture<V>

java.lang.Object

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

All Implemented Interfaces:

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

Direct Known Subclasses:

ImmediateFuture.ImmediateFailedCheckedFuture, ImmediateFuture.ImmediateSuccessfulCheckedFuture, ImmediateFuture.ImmediateSuccessfulFuture

@GwtCompatible(emulated=true)
abstract class ImmediateFuture<V>
extends java.lang.Object
implements ListenableFuture<V>

Implementations of Futures.immediate*.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) static class	ImmediateFuture.ImmediateCancelledFuture<V>
(package private) static class	ImmediateFuture.ImmediateFailedCheckedFuture<V,X extends java.lang.Exception>
(package private) static class	ImmediateFuture.ImmediateFailedFuture<V>
(package private) static class	ImmediateFuture.ImmediateSuccessfulCheckedFuture<V,X extends java.lang.Exception>
(package private) static class	ImmediateFuture.ImmediateSuccessfulFuture<V>

Field Summary

Fields

Modifier and Type	Field and Description
private static java.util.logging.Logger	log

Constructor Summary

Constructors

Constructor and Description
ImmediateFuture()

Method Summary

Modifier and Type	Method and Description
void	addListener(java.lang.Runnable listener, java.util.concurrent.Executor executor) Registers a listener to be run on the given executor.
boolean	cancel(boolean mayInterruptIfRunning)
abstract V	get()
V	get(long timeout, java.util.concurrent.TimeUnit unit)
boolean	isCancelled()
boolean	isDone()

Methods inherited from class java.lang.Object

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

Field Detail

log

private static final java.util.logging.Logger log

Constructor Detail

ImmediateFuture

ImmediateFuture()

Method Detail

addListener

public void addListener(java.lang.Runnable listener,
                        java.util.concurrent.Executor executor)

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(). Otherwise, avoid it. Heavyweight directExecutor listeners can cause problems, and these problems can be difficult to reproduce because they depend on timing. For example:

• The listener may be executed by the caller of addListener. That caller may be a UI thread or other latency-sensitive thread. This can harm UI responsiveness.
• The listener may be executed by the thread that completes this Future. That thread may be an internal system thread such as an RPC network thread. Blocking that thread may stall progress of the whole system. It may even cause a deadlock.
• The listener may delay other listeners, even listeners that are not themselves directExecutor listeners.

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

Memory consistency effects: Actions in a thread prior to adding a listener happen-before its execution begins, perhaps in another thread.

Specified by:

addListener in interface ListenableFuture<V>

Parameters:

listener - the listener to run when the computation is complete

executor - the executor to run the listener in

cancel

public boolean cancel(boolean mayInterruptIfRunning)

Specified by:

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

get

public abstract V get()
               throws java.util.concurrent.ExecutionException

Specified by:

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

Throws:

java.util.concurrent.ExecutionException

get

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

Specified by:

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

Throws:

java.util.concurrent.ExecutionException

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>