Hey all, I¹m excited about having a new Producer API, and I really like the idea of removing the distinction between a synchronous and asynchronous producer. The one comment I have about the current API is that it¹s hard to write truly asynchronous code with the type of future returned by the send method. The issue is that send returns a RecordSend and there¹s no way to register a callback with that object. It is therefore necessary to poll the object periodically to see if the send has completed. So if you have n send calls outstanding you have to check n RecordSend objects which is slow. In general this tends to lead to people using one thread per send call and then calling RecordSend#await which removes much of the benefit of an async API.
I think it¹s much easier to write truly asynchronous code if the returned future allows you to register a callback. That way, instead of polling you can simply wait for the callback to be called. A good example of the kind of thing I¹m thinking is the ListenableFuture class in the Guava libraries: https://code.google.com/p/guava-libraries/wiki/ListenableFutureExplained HTH, Oliver
