Package org.restlet.service

Class TaskService

java.lang.Object
org.restlet.service.Service
org.restlet.service.TaskService
All Implemented Interfaces:
Executor, ExecutorService, ScheduledExecutorService
public class TaskService extends Service implements ScheduledExecutorService
Application service capable of running and scheduling 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(ScheduledExecutorService) 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
    Description
    TaskService()
    Constructor.
    TaskService(boolean enabled)
    Constructor.
    TaskService(boolean enabled, boolean daemon)
    Constructor.
    TaskService(boolean enabled, int corePoolSize)
    Constructor.
    TaskService(int corePoolSize)
    Constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    awaitTermination(long timeout, 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 ScheduledExecutorService
    createExecutorService(int corePoolSize)
    Creates a new JDK executor service that will be wrapped.
    protected ThreadFactory
    createThreadFactory()
    Creates a new thread factory that will properly name the Restlet created threads with a "restlet-" prefix.
    void
    execute(Runnable command)
    Executes the given command asynchronously.
    int
    getCorePoolSize()
    Returns the core pool size defining the maximum number of threads.
    List
    invokeAll(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.
    List
    invokeAll(Collection tasks, long timeout, 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.
    Object
    invokeAny(Collection tasks)
    Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do.
    Object
    invokeAny(Collection tasks, long timeout, 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
    isDaemon()
    Indicates whether the threads are created as daemon threads.
    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.
    ScheduledFuture<?>
    schedule(Runnable command, long delay, TimeUnit unit)
    Creates and executes a one-shot action that becomes enabled after the given delay.
    <V> ScheduledFuture<V>
    schedule(Callable<V> callable, long delay, TimeUnit unit)
    Creates and executes a ScheduledFuture that becomes enabled after the given delay.
    ScheduledFuture<?>
    scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit)
    Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given period; that is executions will commence after initialDelay then initialDelay+period, then initialDelay + 2 * period, and so on.
    ScheduledFuture<?>
    scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit)
    Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given delay between the termination of one execution and the commencement of the next.
    void
    setCorePoolSize(int corePoolSize)
    Sets the core pool size defining the maximum number of threads.
    void
    setDaemon(boolean daemon)
    Indicates whether or not the threads are daemon threads.
    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.
    List<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.
    Future<?>
    submit(Runnable task)
     
    <T> Future<T>
    submit(Runnable task, T result)
     
    <T> Future<T>
    submit(Callable<T> task)
    Submits a value-returning task for execution and returns a Future representing the pending results of the task.
    static ScheduledExecutorService
    wrap(ScheduledExecutorService 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 Details

    • TaskService

      public TaskService()
      Constructor. Enables the service and set the core pool size to 4 by default.

    • TaskService

      public TaskService(boolean enabled)
      Constructor. Set the core pool size to 4 by default.
      Parameters:
      enabled - True if the service has been enabled.

    • TaskService

      public TaskService(boolean enabled, boolean daemon)
      Constructor. Set the core pool size to 4 by default.
      Parameters:
      enabled - True if the service has been enabled.
      daemon - True if the threads are created as daemon threads.

    • TaskService

      public TaskService(boolean enabled, int corePoolSize)
      Constructor. The default minimum size
      Parameters:
      enabled - True if the service has been enabled.
      corePoolSize - The core pool size defining the maximum number of threads.

    • TaskService

      public TaskService(int corePoolSize)
      Constructor.
      Parameters:
      corePoolSize - The core pool size defining the maximum number of threads.

  • Method Details

    • wrap

      public static ScheduledExecutorService wrap(ScheduledExecutorService 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, TimeUnit unit) throws 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 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:
      InterruptedException

    • createExecutorService

      protected ScheduledExecutorService createExecutorService(int corePoolSize)
      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.
      Parameters:
      corePoolSize - The core pool size defining the maximum number of threads.
      Returns:
      A new JDK executor service.

    • createThreadFactory

      protected 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(Runnable command)
      Executes the given command asynchronously.
      Specified by:
      execute in interface Executor
      Parameters:
      command - The command to execute.

    • getCorePoolSize

      public int getCorePoolSize()
      Returns the core pool size defining the maximum number of threads.
      Returns:
      The core pool size defining the maximum number of threads.

    • invokeAll

      public List invokeAll(Collection tasks) throws 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 ExecutorService
      Parameters:
      tasks - The task to execute.
      Returns:
      The list of futures.
      Throws:
      InterruptedException

    • invokeAll

      public List invokeAll(Collection tasks, long timeout, TimeUnit unit) throws 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 ExecutorService
      Parameters:
      tasks - The task to execute.
      timeout - The maximum time to wait.
      unit - The time unit.
      Returns:
      The list of futures.
      Throws:
      InterruptedException

    • invokeAny

      public Object invokeAny(Collection tasks) throws InterruptedException, 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 ExecutorService
      Parameters:
      tasks - The task to execute.
      Returns:
      The result returned by one of the tasks.
      Throws:
      InterruptedException
      ExecutionException

    • invokeAny

      public Object invokeAny(Collection tasks, long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, 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 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:
      InterruptedException
      ExecutionException
      TimeoutException

    • isDaemon

      public boolean isDaemon()
      Indicates whether the threads are created as daemon threads.
      Returns:
      True if the threads are created as daemon threads.

    • isShutdown

      public boolean isShutdown()
      Returns true if this executor has been shut down.
      Specified by:
      isShutdown in interface 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 ExecutorService
      Returns:
      True if all tasks have completed following shut down.

    • schedule

      public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit)
      Creates and executes a ScheduledFuture that becomes enabled after the given delay.
      Specified by:
      schedule in interface ScheduledExecutorService
      Parameters:
      callable - The function to execute.
      delay - The time from now to delay execution.
      unit - The time unit of the delay parameter.
      Returns:
      a ScheduledFuture that can be used to extract result or cancel.
      Throws:
      RejectedExecutionException - if task cannot be scheduled for execution.
      NullPointerException - if callable is null

    • schedule

      public ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit)
      Creates and executes a one-shot action that becomes enabled after the given delay.
      Specified by:
      schedule in interface ScheduledExecutorService
      Parameters:
      command - The task to execute.
      delay - The time from now to delay execution.
      unit - The time unit of the delay parameter.
      Returns:
      a Future representing pending completion of the task, and whose get() method will return null upon completion.
      Throws:
      RejectedExecutionException - if task cannot be scheduled for execution.
      NullPointerException - if command is null

    • scheduleAtFixedRate

      public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit)
      Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given period; that is executions will commence after initialDelay then initialDelay+period, then initialDelay + 2 * period, and so on. If any execution of the task encounters an exception, subsequent executions are suppressed. Otherwise, the task will only terminate via cancellation or termination of the executor.
      Specified by:
      scheduleAtFixedRate in interface ScheduledExecutorService
      Parameters:
      command - The task to execute.
      initialDelay - The time to delay first execution.
      period - The period between successive executions.
      unit - The time unit of the initialDelay and period parameters
      Returns:
      a Future representing pending completion of the task, and whose get() method will throw an exception upon cancellation.
      Throws:
      RejectedExecutionException - if task cannot be scheduled for execution.
      NullPointerException - if command is null
      IllegalArgumentException - if period less than or equal to zero.

    • scheduleWithFixedDelay

      public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit)
      Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given delay between the termination of one execution and the commencement of the next. If any execution of the task encounters an exception, subsequent executions are suppressed. Otherwise, the task will only terminate via cancellation or termination of the executor.
      Specified by:
      scheduleWithFixedDelay in interface ScheduledExecutorService
      Parameters:
      command - The task to execute.
      initialDelay - The time to delay first execution.
      delay - The delay between the termination of one execution and the commencement of the next.
      unit - The time unit of the initialDelay and delay parameters
      Returns:
      a Future representing pending completion of the task, and whose get() method will throw an exception upon cancellation.
      Throws:
      RejectedExecutionException - if task cannot be scheduled for execution.
      NullPointerException - if command is null
      IllegalArgumentException - if delay less than or equal to zero.

    • setCorePoolSize

      public void setCorePoolSize(int corePoolSize)
      Sets the core pool size defining the maximum number of threads.
      Parameters:
      corePoolSize - The core pool size defining the maximum number of threads.

    • setDaemon

      public void setDaemon(boolean daemon)
      Indicates whether or not the threads are daemon threads. True by default.
      Parameters:
      daemon - True if the threads are daemon threads.

    • 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 ExecutorService

    • shutdownNow

      public List<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 ExecutorService
      Returns:
      The list of tasks that never commenced execution;

    • start

      public void start() throws Exception
      Description copied from class: Service
      Starts the Restlet.
      Overrides:
      start in class Service
      Throws:
      Exception

    • stop

      public void stop() throws Exception
      Description copied from class: Service
      Stops the Restlet.
      Overrides:
      stop in class Service
      Throws:
      Exception

    • submit

      public <T> Future<T> submit(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 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 Future<?> submit(Runnable task)
      Specified by:
      submit in interface 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> Future<T> submit(Runnable task, T result)
      Specified by:
      submit in interface 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.