refactor(engine): use hasProcessingReachedTheEnd to detect state

[pihme]

Description

Use hasProcessingReachedTheEnd to detect state

Related issues

closes #133

Definition of Done

Not all items need to be done depending on the issue and the pull request.

Code changes:

• The changes are backwards compatibility with previous versions
• If it fixes a bug then PRs are created to backport the fix

Testing:

• There are unit/integration tests that verify all acceptance criterias of the issue
• New tests are written to ensure backwards compatibility with further versions
• The behavior is tested manually

Documentation:

• Javadoc has been written
• The documentation is updated

[github-actions]

Unit Test Results

  32 files    32 suites   1m 9s ⏱️
  98 tests   98 ✔️ 0 💤 0 ❌
307 runs  307 ✔️ 0 💤 0 ❌

Results for commit 824c909.

♻️ This comment has been updated with latest results.

[CLAassistant]

All committers have signed the CLA.

[remcowesterhoud]

@pihme I finally found the cause of the testcontainer getting killed. I still don't know why it happens, but could you have a look at the latest commit and see what you think?

[pihme]

@remcowesterhoud Seems ok.

I wonder whether we can improve it to something like this:

    try {
      return streamProcessor.hasProcessingReachedTheEnd().join();
    } catch (final Exception e) {
      LOG.debug("Exception occurred while checking idle state", e);
      // A ExecutionException may be thrown here if the actor is already closed. For some mysterious
      // reason this causes the testcontainer to terminate, which is why we need to catch it.
      // We cannot catch the ExecutionException itself, as Zeebe turns this into an unchecked
      // exception. Because of this we need to catch Exception instead.
      return actor.isClosed();
    }

I would assume that a closed actor is equivalent to an idle state. This way we wouldn't stall callers when the actor is closed

[remcowesterhoud]

@korthout This one might be slightly complex to review, but as Peter and I both worked on it I think it'd be good if someone else reviews it.
If you need any help or extra explanation please let me know. I'll be happy to walk you through it.

[remcowesterhoud]

@saig0 Since @korthout mentioned he was a bit swarmed at the moment, maybe you have time for this review instead 🙂

[saig0]

@pihme / @remcowesterhoud LGTM 🚀