edu.rice.cs.plt.concurrent
Class PollingTaskController<R>

java.lang.Object
  edu.rice.cs.plt.concurrent.TaskController<R>
      edu.rice.cs.plt.concurrent.PollingTaskController<R>

All Implemented Interfaces:

ResolvingThunk<R>, Thunk<R>, Future<R>

Direct Known Subclasses:

FutureTaskController

public abstract class PollingTaskController<R>
extends TaskController<R>

A TaskController for tasks that are run without any facility for executing code when the task is complete — instead, the controller must either block, poll for the task's current status. When most of the controller's methods are invoked, the current status is polled before proceeding; operations depending on completion block (finishListeners() are handled by blocking in a new daemon thread).

To implement a concrete instance, a subclass must provide TaskController.doStart(), TaskController.doStop(), update(), finish(), and, optionally, TaskController.discard().

Nested Class Summary

protected class	PollingTaskController.PollingCancelingState CancelingState variant based on a PollingRunner.
protected class	PollingTaskController.PollingRunningState RunningState variant based on a PollingRunner.

Nested classes/interfaces inherited from class edu.rice.cs.plt.concurrent.TaskController

TaskController.CanceledStartingState, TaskController.CanceledState, TaskController.CancelingState, TaskController.CleanlyFinishedState, TaskController.ComputingState, TaskController.ExecutionExceptionState, TaskController.FinishedState, TaskController.FreshStartingState, TaskController.FreshState, TaskController.InternalExceptionState, TaskController.RunningState, TaskController.StartingState, TaskController.State, TaskController.Status, TaskController.WaitingState

Field Summary

Fields inherited from class edu.rice.cs.plt.concurrent.TaskController

state

Constructor Summary

protected

PollingTaskController()

Method Summary

protected abstract void	finish() Block until the task is complete or this thread is interrupted.
protected abstract void	finish(long timeout, TimeUnit unit) Block until the task is complete, this thread is interrupted, or the given timeout is reached.
ListenerSet.Sink	finishListeners() Access the ListenerSet responding to the completion of computation.
protected TaskController.RunningState	runningState() Produce a running state.
protected abstract void	update() Check the current status and call the appropriate method if the task is complete.

Methods inherited from class edu.rice.cs.plt.concurrent.TaskController

attemptGet, attemptGet, cancel, cancel, discard, doStart, doStop, finishedCleanly, finishedWithImplementationException, finishedWithTaskException, get, get, get, hasValue, isCanceled, isCancelled, isDone, isResolved, start, started, status, stopped, value

Methods inherited from class java.lang.Object

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

Constructor Detail

PollingTaskController

protected PollingTaskController()

Method Detail

finishListeners

public ListenerSet.Sink finishListeners()

Access the ListenerSet responding to the completion of computation. The first time this method is invoked, a daemon thread is started that will wait for computation to complete (otherwise, any registered listeners will not run until the task is manually polled).

Overrides:

finishListeners in class TaskController<R>

update

protected abstract void update()

Check the current status and call the appropriate method if the task is complete. This method is invoked frequently and should not block.

finish

protected abstract void finish()
                        throws InterruptedException

Block until the task is complete or this thread is interrupted. Must not return until after one of the completion methods are called.

Throws:

InterruptedException

finish

protected abstract void finish(long timeout,
                               TimeUnit unit)
                        throws InterruptedException,
                               TimeoutException

Block until the task is complete, this thread is interrupted, or the given timeout is reached. Must not return until after one of the completion methods are called.

Throws:

InterruptedException

TimeoutException

runningState

protected TaskController.RunningState runningState()

Description copied from class: TaskController

Produce a running state. May be overridden to change the way RunningStates are implemented.

Overrides:

runningState in class TaskController<R>