Moving CompletionHandler to java.util.concurrent

[Alan Bateman]

Gili wrote:
> You know what Alan? The more I take a look at
> http://guava-libraries.googlecode.com/svn/trunk/javadoc/com/google/common/util/concurrent/ListenableFuture.html
> the more it doesn't make sense to introduce CompletionHandler in Java7.
> Instead of introducing duplicate methods (one that uses Futures, another
> that uses CompletionHandler) we should just have a single method that
> handles both use-cases using a ListenableFuture.
>
> Have you guys reviewed this possibility already...?
>   
Yes, this ground has been well covered. If you go back a few years to 
AIO4J, you'll see that it had an API that is close to what you are 
suggesting now. The API we have now is relatively simple - you wait/poll 
for a result using the Future, or you specify a callback (completion 
handler) to be invoked when the I/O operation completes. There is no 
support for "mixing" of styles where you might be waiting for the result 
and also consuming the result in a callback, or where you decide to 
register a callback after the fact. If you really need this then you can 
wrap the channels and use the completion handlers to drive the framework.

-Alan.