org.restlet.service

Class TaskService

java.lang.Object

org.restlet.service.Service

org.restlet.service.TaskService

All Implemented Interfaces:

java.util.concurrent.Executor, java.util.concurrent.ExecutorService

public class TaskService
extends Service
implements java.util.concurrent.ExecutorService

Application service capable of running tasks asynchronously. The service instance returned will not invoke the runnable task in the current thread.

In addition to allowing pooling, this method will ensure that the threads executing the tasks will have the thread local variables copied from the calling thread. This will ensure that call to static methods like Application.getCurrent() still work.

Also, note that this executor service will be shared among all Restlets and Resources that are part of your context. In general this context corresponds to a parent Application's context. If you want to have your own service instance, you can use the wrap(ExecutorService) method to ensure that thread local variables are correctly set.

Author:

Jerome Louvel, Doug Lea (docs of ExecutorService in public domain), Tim Peierls

Constructor Summary

Constructors

Constructor and Description
TaskService() Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	awaitTermination(long timeout, java.util.concurrent.TimeUnit unit) Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first.
protected java.util.concurrent.ExecutorService	createExecutorService() Creates a new JDK executor service that will be wrapped.
protected java.util.concurrent.ThreadFactory	createThreadFactory() Creates a new thread factory that will properly name the Restlet created threads with a "restlet-" prefix.
void	execute(java.lang.Runnable command) Executes the given command asynchronously.
java.util.List	invokeAll(java.util.Collection tasks) Executes the given tasks, returning a list of Futures holding their status and results when all complete. Due to a breaking change between Java SE versions 5 and 6, and in order to maintain compatibility both at the source and binary level, we have removed the generic information from this method.
java.util.List	invokeAll(java.util.Collection tasks, long timeout, java.util.concurrent.TimeUnit unit) Executes the given tasks, returning a list of Futures holding their status and results when all complete or the timeout expires, whichever happens first.
java.lang.Object	invokeAny(java.util.Collection tasks) Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do.
java.lang.Object	invokeAny(java.util.Collection tasks, long timeout, java.util.concurrent.TimeUnit unit) Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do before the given timeout elapses.
boolean	isShutdown() Returns true if this executor has been shut down.
boolean	isShutdownAllowed() Indicates if the shutdown() and shutdownNow() methods are allowed to effectively shutdown the wrapped executor service.
boolean	isTerminated() Returns true if all tasks have completed following shut down.
void	setShutdownAllowed(boolean allowShutdown) Indicates if the shutdown() and shutdownNow() methods are allowed to effectively shutdown the wrapped executor service.
void	shutdown() Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.
java.util.List<java.lang.Runnable>	shutdownNow() Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.
void	start() Starts the Restlet.
void	stop() Stops the Restlet.
<T> java.util.concurrent.Future<T>	submit(java.util.concurrent.Callable<T> task) Submits a value-returning task for execution and returns a Future representing the pending results of the task.
java.util.concurrent.Future<?>	submit(java.lang.Runnable task)
<T> java.util.concurrent.Future<T>	submit(java.lang.Runnable task, T result)
static java.util.concurrent.ExecutorService	wrap(java.util.concurrent.ExecutorService executorService) Wraps a JDK executor service to ensure that the threads executing the tasks will have the thread local variables copied from the calling thread.

Methods inherited from class org.restlet.service.Service

createInboundFilter, createOutboundFilter, getContext, isEnabled, isStarted, isStopped, setContext, setEnabled

Methods inherited from class java.lang.Object

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

Constructor Detail

TaskService

public TaskService()

Constructor.

Method Detail

wrap

public static java.util.concurrent.ExecutorService wrap(java.util.concurrent.ExecutorService executorService)

Wraps a JDK executor service to ensure that the threads executing the tasks will have the thread local variables copied from the calling thread. This will ensure that call to static methods like Application.getCurrent() still work.

Parameters:

executorService - The JDK service to wrap.

Returns:

The wrapper service to use.

awaitTermination

public boolean awaitTermination(long timeout,
                       java.util.concurrent.TimeUnit unit)
                         throws java.lang.InterruptedException

Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first.

Specified by:

awaitTermination in interface java.util.concurrent.ExecutorService

Parameters:

timeout - The maximum time to wait.

unit - The time unit.

Returns:

True if this executor terminated and false if the timeout elapsed before termination.

Throws:

java.lang.InterruptedException

createExecutorService

protected java.util.concurrent.ExecutorService createExecutorService()

Creates a new JDK executor service that will be wrapped. By default it calls Executors.newCachedThreadPool(ThreadFactory), passing the result of createThreadFactory() as a parameter.

Returns:

A new JDK executor service.

createThreadFactory

protected java.util.concurrent.ThreadFactory createThreadFactory()

Creates a new thread factory that will properly name the Restlet created threads with a "restlet-" prefix.

Returns:

A new thread factory.

execute

public void execute(java.lang.Runnable command)

Executes the given command asynchronously.

Specified by:

execute in interface java.util.concurrent.Executor

Parameters:

command - The command to execute.

invokeAll

public java.util.List invokeAll(java.util.Collection tasks)
                         throws java.lang.InterruptedException

Executes the given tasks, returning a list of Futures holding their status and results when all complete.

Due to a breaking change between Java SE versions 5 and 6, and in order to maintain compatibility both at the source and binary level, we have removed the generic information from this method. You can check the ExecutorService interface for typing details.

Specified by:

invokeAll in interface java.util.concurrent.ExecutorService

Parameters:

tasks - The task to execute.

Returns:

The list of futures.

Throws:

java.lang.InterruptedException

invokeAll

public java.util.List invokeAll(java.util.Collection tasks,
                       long timeout,
                       java.util.concurrent.TimeUnit unit)
                         throws java.lang.InterruptedException

Executes the given tasks, returning a list of Futures holding their status and results when all complete or the timeout expires, whichever happens first. Future.isDone() is true for each element of the returned list. Upon return, tasks that have not completed are canceled. Note that a completed task could have terminated either normally or by throwing an exception. The results of this method are undefined if the given collection is modified while this operation is in progress.

Due to a breaking change between Java SE versions 5 and 6, and in order to maintain compatibility both at the source and binary level, we have removed the generic information from this method. You can check the ExecutorService interface for typing details.

Specified by:

invokeAll in interface java.util.concurrent.ExecutorService

Parameters:

tasks - The task to execute.

timeout - The maximum time to wait.

unit - The time unit.

Returns:

The list of futures.

Throws:

java.lang.InterruptedException

invokeAny

public java.lang.Object invokeAny(java.util.Collection tasks)
                           throws java.lang.InterruptedException,
                                  java.util.concurrent.ExecutionException

Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do. Upon normal or exceptional return, tasks that have not completed are cancelled. The results of this method are undefined if the given collection is modified while this operation is in progress. Due to a breaking change between Java SE versions 5 and 6, and in order to maintain compatibility both at the source and binary level, we have removed the generic information from this method. You can check the ExecutorService interface for typing details.

Specified by:

invokeAny in interface java.util.concurrent.ExecutorService

Parameters:

tasks - The task to execute.

Returns:

The result returned by one of the tasks.

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

invokeAny

public java.lang.Object invokeAny(java.util.Collection tasks,
                         long timeout,
                         java.util.concurrent.TimeUnit unit)
                           throws java.lang.InterruptedException,
                                  java.util.concurrent.ExecutionException,
                                  java.util.concurrent.TimeoutException

Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do before the given timeout elapses. Upon normal or exceptional return, tasks that have not completed are cancelled. The results of this method are undefined if the given collection is modified while this operation is in progress. Due to a breaking change between Java SE versions 5 and 6, and in order to maintain compatibility both at the source and binary level, we have removed the generic information from this method. You can check the ExecutorService interface for typing details.

Specified by:

invokeAny in interface java.util.concurrent.ExecutorService

Parameters:

tasks - The task to execute.

timeout - The maximum time to wait.

unit - The time unit.

Returns:

The result returned by one of the tasks.

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

java.util.concurrent.TimeoutException

isShutdown

public boolean isShutdown()

Returns true if this executor has been shut down.

Specified by:

isShutdown in interface java.util.concurrent.ExecutorService

Returns:

True if this executor has been shut down.

isShutdownAllowed

public boolean isShutdownAllowed()

Indicates if the shutdown() and shutdownNow() methods are allowed to effectively shutdown the wrapped executor service. Return false by default.

Returns:

True if shutdown is allowed.

isTerminated

public boolean isTerminated()

Returns true if all tasks have completed following shut down. Note that isTerminated is never true unless either shutdown or shutdownNow was called first.

Specified by:

isTerminated in interface java.util.concurrent.ExecutorService

Returns:

True if all tasks have completed following shut down.

setShutdownAllowed

public void setShutdownAllowed(boolean allowShutdown)

Indicates if the shutdown() and shutdownNow() methods are allowed to effectively shutdown the wrapped executor service.

Parameters:

allowShutdown - True if shutdown is allowed.

shutdown

public void shutdown()

Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.

Specified by:

shutdown in interface java.util.concurrent.ExecutorService

shutdownNow

public java.util.List<java.lang.Runnable> shutdownNow()

Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.

Specified by:

shutdownNow in interface java.util.concurrent.ExecutorService

Returns:

The list of tasks that never commenced execution;

start

public void start()
           throws java.lang.Exception

Description copied from class: Service

Starts the Restlet.

Overrides:

start in class Service

Throws:

java.lang.Exception

stop

public void stop()
          throws java.lang.Exception

Description copied from class: Service

Stops the Restlet.

Overrides:

stop in class Service

Throws:

java.lang.Exception

submit

public <T> java.util.concurrent.Future<T> submit(java.util.concurrent.Callable<T> task)

Submits a value-returning task for execution and returns a Future representing the pending results of the task.

Specified by:

submit in interface java.util.concurrent.ExecutorService

Parameters:

task - The task to submit.

Returns:

A Future representing pending completion of the task, and whose get() method will return the given result upon completion.

submit

public java.util.concurrent.Future<?> submit(java.lang.Runnable task)

Specified by:

submit in interface java.util.concurrent.ExecutorService

Parameters:

task - The task to submit.

Returns:

A Future representing pending completion of the task, and whose get() method will return the given result upon completion.

submit

public <T> java.util.concurrent.Future<T> submit(java.lang.Runnable task,
                                        T result)

Specified by:

submit in interface java.util.concurrent.ExecutorService

Parameters:

task - The task to submit.

result - The result to return.

Returns:

A Future representing pending completion of the task, and whose get() method will return the given result upon completion.