How to get result from conditional update

[wittyameta]

I tried using a custom ResultListener, but it doesn't always work correctly.

public class ResultListener implements LWTResultListener {

  private boolean applied;

  @Override
  public void onSuccess() {
     applied = true;
  }

  @Override
  public void onError(LWTResult lwtResult) {
    applied = false;
  }

  public boolean isApplied() {
    return applied;
  }
}

From my caller class, I call isApplied() but it seems that the onSuccess method is called asynchronously. The caller class doesn't see the updated value of applied field

[doanduyhai]

I understand your problem but it's the nature of asynchronous execution. To solve this, in my integration test, I have the following pattern:

  final CountDownLatch latch = new CountDownLatch(1);
  final AtomicBoolean success = new AtomicBoolean(false);

 //When
        manager
                .dsl()
                .update()
                .fromBaseTable()
                 ...
                .withLwtResultListener(new LWTResultListener() {
                    @Override
                    public void onSuccess() {
                        success.getAndSet(true);
                    }

                    @Override
                    public void onError(LWTResult lwtResult) {
                    }
                })
                .withResultSetAsyncListener(rs -> {
                    latch.countDown();
                    return rs;
                })
                .executeAsync();

        //Then
        latch.await();
       assertThat(success.get()).isTrue();

First I declare 2 variables:

• a countdown latch, to be triggered when the ResultSet is available asynchronously
• an atomic boolean (or any AtomicXXXX class) that is by nature thread-safe to update the result of the asynchronous operation

With withLwtResultListener() I passed in an instance of LWTResultListener to set the atomic boolean value to true

However, if you only do that, the main thread will call immediately assertThat(success.get()).isTrue() before the LWTResultListener has a chance to be called ...

Therefore I need to add an withResultSetAsyncListener() to trigger the latch count down when the result set is available asynchronously.

In the main execution thread, I block on latch.await() until the latch.countDown() is called.

You can adapt this pattern to your use-case

[wittyameta]

Thanks!