io.zeebe.util.sched

Interface AsyncContext

public interface AsyncContext

Method Summary

Modifier and Type	Method and Description
void	async(ActorFuture<?> future) Use with care

Method Detail

async

void async(ActorFuture<?> future)

Use with care

Note that the following pattern does not work

 void fetch(AsyncContext ctx)
 {
      ActorFuture future = asyncApi.fetchData();

      actor.runOnCompletion(future, (someData, err) ->
      {
          // do something
      });

      ctx.async(future);
 }

 

The problem is that now, if another component is awaiting on future, both this component and the actor.runOnCompletion are waiting on the same future, and there is no guaranteed order in which these are invoked, which could lead to unexpected behaviour (e.g. the stream processor moves to the next processing stage before the callback runs).

You can refactor it to this:

 void process(AsyncContext ctx)
 {
      ActorFuture future = asyncApi.fetchData();
      ActorFuture whenProcessingDone = new CompletableActorFuture();

      actor.runOnCompletion(future, (someData, err) ->
      {
          // do something
          whenProcessingDone.complete(null);
      });

      ctx.async(whenProcessingDone);
 }
 

Parameters:

future - the future to pass