org.jboss.netty.util

Class VirtualExecutorService

java.lang.Object

java.util.concurrent.AbstractExecutorService

org.jboss.netty.util.VirtualExecutorService

All Implemented Interfaces:

Executor, ExecutorService

public class VirtualExecutorService
extends AbstractExecutorService

A delegating ExecutorService with its own termination management.

VirtualExecutorService is used when you want to inject an ExecutorService but you do not want to allow the explicit termination of threads on shutdown request. It is particularly useful when the ExecutorService to inject is shared by different components and the life cycle of the components depend on the termination of the injected ExecutorService.

 ExecutorService globalExecutor = ...;
 ExecutorService virtualExecutor = new VirtualExecutorService(globalExecutor);

 ChannelFactory factory =
         new NioServerSocketChannelFactory(virtualExecutor, virtualExecutor);
 ...

 // ChannelFactory.releaseExternalResources() shuts down the executor and
 // interrupts the I/O threads to terminate all I/O tasks and to release all
 // resources acquired by ChannelFactory.
 factory.releaseExternalResources();

 // Note that globalExecutor is not shut down because VirtualExecutorService
 // implements its own termination management. All threads which were acquired
 // by ChannelFactory via VirtualExecutorService are returned to the pool.
 assert !globalExecutor.isShutdown();
 

The differences from an ordinary ExecutorService

A shutdown request (shutdown() or shutdownNow()) does not shut down its parent Executor but simply sets its internal flag to reject further execution request.

shutdownNow() interrupts only the thread which is executing the task executed via VirtualExecutorService.

awaitTermination(long, TimeUnit) does not wait for real thread termination but wait until VirtualExecutorService is shut down and its active tasks are finished and the threads are returned to the parent Executor.

Constructor Summary

Constructors

Constructor and Description
VirtualExecutorService(Executor parent) Creates a new instance with the specified parent Executor.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	awaitTermination(long timeout, TimeUnit unit)
void	execute(Runnable command)
boolean	isShutdown()
boolean	isTerminated()
void	shutdown()
List<Runnable>	shutdownNow()

Methods inherited from class java.util.concurrent.AbstractExecutorService

invokeAll, invokeAll, invokeAny, invokeAny, newTaskFor, newTaskFor, submit, submit, submit

Methods inherited from class java.lang.Object

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

Constructor Detail

VirtualExecutorService

public VirtualExecutorService(Executor parent)

Creates a new instance with the specified parent Executor.

Method Detail

isShutdown

public boolean isShutdown()

isTerminated

public boolean isTerminated()

shutdown

public void shutdown()

shutdownNow

public List<Runnable> shutdownNow()

awaitTermination

public boolean awaitTermination(long timeout,
                       TimeUnit unit)
                         throws InterruptedException

Throws:

InterruptedException

execute

public void execute(Runnable command)