org.jtrim2.executor

Class AbstractTaskExecutor

java.lang.Object

org.jtrim2.executor.AbstractTaskExecutor

All Implemented Interfaces:

Executor, TaskExecutor

Direct Known Subclasses:

AbstractTaskExecutorService, ManualTaskExecutor

public abstract class AbstractTaskExecutor
extends Object
implements TaskExecutor

Defines a convenient abstract base class for TaskExecutor implementations.

AbstractTaskExecutor defines default implementations for all the execute methods which all rely on the protected submitTask method. Only this submitTask method is needed to be implemented by subclasses to actually schedule a task. Note that all the execute methods rely directly the submitTask method and overriding any of them has no effect on the others (i.e.: they don't call each other). For further details on how to implement the submitTask method: see its documentation.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AbstractTaskExecutor.SubmittedTask<V> Defines the submitted task to be executed by subclasses of AbstractTaskExecutor.

Constructor Summary

Constructors

Constructor and Description
AbstractTaskExecutor()

Method Summary

Modifier and Type	Method and Description
<V> CompletionStage<V>	executeFunction(CancellationToken cancelToken, CancelableFunction<? extends V> function) Executes the function at some time in the future.
protected abstract void	submitTask(CancellationToken cancelToken, AbstractTaskExecutor.SubmittedTask<?> submittedTask) Implementations must override this method to actually execute submitted tasks.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jtrim2.executor.TaskExecutor

execute, execute, executeStaged

Constructor Detail

AbstractTaskExecutor

public AbstractTaskExecutor()

Method Detail

submitTask

protected abstract void submitTask(CancellationToken cancelToken,
                                   AbstractTaskExecutor.SubmittedTask<?> submittedTask)

Implementations must override this method to actually execute submitted tasks.

Assuming no cancellation requests, implementations must call submittedTask.execute.

Cancellation requests can be detected using the provided CancellationToken and if an implementation chooses not to even try to execute task, it must only call submittedTask.cancel.

Implementations must always complete the passed task in some way. Either by calling its execute or its completeExceptionally (or cancel) method.

Parameters:

cancelToken - the CancellationToken which can be checked by implementations if the currently submitted task has been canceled. Also this is the CancellationToken implementations should pass to task. This argument cannot be null.

submittedTask - the task to be executed. Implementations must execute this task at most once by calling its execute method. If the execute method is not called, an exceptional return state must be set via the completeExceptionally method. This argument cannot be null.

executeFunction

public <V> CompletionStage<V> executeFunction(CancellationToken cancelToken,
                                              CancelableFunction<? extends V> function)

Executes the function at some time in the future. When and on what thread, the function is to be executed is completely implementation dependent. Implementations may choose to execute tasks later on a separate thread or synchronously in the calling thread at the discretion of the implementation.

Specified by:

executeFunction in interface TaskExecutor

Type Parameters:

V - the type of the result of the submitted function

Parameters:

cancelToken - the CancellationToken which is to be checked if the submitted task is to be canceled. If this CancellationToken signals a cancellation request, this TaskExecutor may choose to not even attempt to execute the submitted task. This argument may not be null. When the task cannot be canceled, use the static Cancellation.UNCANCELABLE_TOKEN for this argument (even in this case, the TaskExecutor may be able to cancel the task, if it was not submitted for execution).

function - the function to be executed by this TaskExecutor. This argument cannot be null.

Returns:

the CompletionStage which can be used to execute tasks after the completion of the submitted function and process the result of the submitted function. This method never returns null.

See Also:

Cancellation.createCancellationSource(), Cancellation.UNCANCELABLE_TOKEN