How to notify mainthread when completing WorkEvent with exception?

Question

I'm working with the IBM WorkManager (v8.0.0) to do some work asynchronous to the main thread.

For this I use the following code:

// wm = via resource injected WorkManager

WorkItem item = wm.startWork(work, WorkManager.INDEFINITE, new WorkListener() {

  @Override
  public void workStarted(WorkEvent arg0) {
  }

  @Override
  public void workRejected(WorkEvent arg0) {
  }

  @Override
  public void workCompleted(WorkEvent arg0) {
    WorkException exception = arg0.getException();
    if (null != exception) {
      throw new RuntimeException("WorkCompleted with Exception");
    }
  }

  @Override
  public void workAccepted(WorkEvent arg0) {
  }
});

This works quite fine as long the WorkEvent was completed without an exception. But when it was completed with an exception, I want to notify the mainthread to stop it submitting more WorkItems to the WorkManager.

I thought I could raise an RunetimeException to notify the mainthread, but analysing the logs I found out that the exception is thrown in that moment the mainthreads finished submitting all WorkItems to the WorkManager and calling the join-method of the WorkManager - which is far too late (in most cases 50.000 items have to be done by the WorkManager).

So how can I interrupt my mainthread to stop it submitting more items to the WorkManager in this moment when an exception is recognized in workCompleted?

Answer 1

You need a "more direct" interface then.

Meaning; you are showing code that calls:

WorkItem item = wm.startWork(work, WorkManager.INDEFINITE, new WorkListener()

The class that contains that instructions need some "input" channel; for example there could be a "simple" field in that class List<Exception> that your work items add their exceptions to.

And your "main" class that creates those work items should check that list regularly; and simply stop adding new work items when an exception is found.

Of course, you have to make that thread safe, and provide a reasonable architecture.