javax.enterprise.concurrent.ManagedTaskListener Maven / Gradle / Ivy
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package javax.enterprise.concurrent;
import java.util.concurrent.Future;
/**
* A ManagedTaskListener is used to monitor the state of a task's Future.
* It can be registered with a {@link ManagedExecutorService} using the
* submit methods and will be invoked when the state of the
* {@link Future} changes.
* Each listener method will run with unspecified context.
* All listeners run without an explicit transaction
* (they do not enlist in the application component's transaction). If a transaction is required, use a
* {@link javax.transaction.UserTransaction} instance.
*
*
* Each listener instance will be invoked within the same process in which the listener was registered.
* If a single listener is submitted to multiple ManagedExecutorService instances, the
* listener object may be invoked concurrently by multiple threads.
*
* Each listener method supports a minimum quality of service of at-most-once. A listener is not
* guaranteed to be invoked due to a process failure or termination.
*
* State Transition Diagram
*
* The following state transition figure and tables describe
* the possible task lifecycle events that can occur when a
* ManagedTaskListener is associated with a task. Each method is invoked
* when the state of the {@link Future} moves from one state to another.
*
* 
*
* A. The task runs normally:
*
* Sequence State Action Listener Next state 1. None submit() taskSubmitted Submitted 2. Submitted About to call run() taskStarting Started 3. Started Exit run() taskDone Done
*
* B. The task is cancelled during taskSubmitted():
*
* Sequence State Action Listener Next state 1. None submit() taskSubmitted
Future is cancelled. Cancelling 2. Cancelling taskAborted Cancelled 3. Cancelled taskDone Done
*
* C. The task is cancelled or aborted after submitted, but before started:
*
*
* Sequence State Action Listener Next state 1. None submit() taskSubmitted Submitted 2. Submitted cancel() or abort taskAborted Cancelled 3. Cancelled taskDone Done
*
* D. The task is cancelled when it is starting:
*
* Sequence State Action Listener Next state 1. None submit() taskSubmitted Submitted 2. Submitted About to call run() taskStarting
Future is cancelled. Cancelling 3. Cancelling taskAborted Cancelled 4. Cancelled taskDone Done
*
*
* @since 1.0
*/
public interface ManagedTaskListener {
/**
* Called after the task has been submitted to the Executor. The task will not enter the
* starting state until the taskSubmitted listener has completed.
* This method may be called from the same thread that the task was submitted with.
*
* This event does not indicate that the task has been scheduled for execution.
*
* @param future the Future instance that was created when the task was submitted.
* @param executor the executor used to run the associated Future.
* @param task the task that was submitted.
*/
public void taskSubmitted(java.util.concurrent.Future future,
ManagedExecutorService executor,
Object task);
/**
* Called when a task's Future has been cancelled anytime during the life of a task.
* This method may be called after taskDone(). The {@link Future#isCancelled()}
* method returns false if the task was aborted through another means other than
* {@link Future#cancel(boolean) }.
* The exception argument will represent the cause of the cancellation:
*
* - {@link java.util.concurrent.CancellationException} if the task was cancelled,
*
- {@link SkippedException} if the task was skipped or
*
- {@link AbortedException} if the task failed to start for another reason.
*
* The AbortedException.getCause() method will return the exception that
* caused the task to fail to start.
*
* @param future the {@link Future} instance that was created when the task was submitted.
* @param executor the executor used to run the associated Future.
* @param task the task that was submitted.
* @param exception the cause of the task abort.
*/
public void taskAborted(java.util.concurrent.Future future,
ManagedExecutorService executor,
Object task,
java.lang.Throwable exception);
/**
* Called when a submitted task has completed running, either successfully or
* failed due to any exception thrown from the task, task being cancelled,
* rejected, or aborted.
*
* @param future the {@link Future} instance that was created when the task was submitted.
* @param executor the executor used to run the associated Future.
* @param task the task that was submitted.
* @param exception if not null, the exception that caused the task to fail.
*/
public void taskDone(java.util.concurrent.Future future,
ManagedExecutorService executor,
Object task,
java.lang.Throwable exception);
/**
* This method is called before the task is about to start. The task will
* not enter the starting state until the taskSubmitted listener has completed. This method
* may be called from the same thread that the task was submitted with.
*
* @param future the {@link Future} instance that was created when the task was submitted.
* @param executor the executor used to run the associated Future.
* @param task the task that was submitted.
*/
public void taskStarting(java.util.concurrent.Future future,
ManagedExecutorService executor,
Object task);
}