[infinispan-dev] Async Notification API

[Manik Surtani]

On 16 May 2009, at 00:47, Adrian Cole wrote:

> Well, this could be useful in many contexts, even outside of  
> infinispan.
>
> One thing to consider is the three ways things finish in Futures:  
> completion, cancellation, and exception.  I suspect the listener  
> interface may want to handle all three, or some object that  
> encapsulates those states.

Well, the listener just notifies that a future is done, passing back a  
reference to the same future.  Any sane implementation of the listener  
would then call future.get() to test for exceptions, or test  
future.isCancelled() if it cares.

> I kindof like this flow in that case:
>
>        Future f = cache.putAsync(k, v).andInform(listener);

+1 to a builder-like API.

> where NotifyingFuture has a method:
>
> NotifyingFuture andInform(NotifyingFutureListener listener)
>
> interesting stuff...
> what do you think?
>
> -Adrian
> jclouds
>
> On Sat, May 16, 2009 at 1:27 AM, Manik Surtani <manik at jboss.org>  
> wrote:
> While the new async API has been getting rave reviews, someone did  
> bring up async notifications.  E.g.,
>
>        Future f = cache.putAsync(k, v);
>        f.get();
>
> But what if I don't want to wait on f.get(), I'd rather be told when  
> the future is done so I can do an f.get()?
>
> Sounds pretty useful to me.  But just wanted to sound you guys on  
> the API choices for notifications.
>
> My immediate thought was to use the existing notification API.  You  
> register a cache listener, annotate a method with @RpcCallMade,  
> receive an RpcCallMadeEvent.  But this is probably pretty useless,  
> since you couldn't associate the notification with the specific put  
> you've just done.  Even if you have the key in the event (which is  
> unlikely - since we need to use the same event for all cache  
> operations, some which take > 1 key such as putAll()), multiple  
> threads could be working on the same key.
>
> Another approach is to design a sub-interface to Future.   
> NotifyingFuture.
>
> public interface NotifyingFuture extends Future {
>  void addListener(NotifyingFutureListener l);
> }
>
> public interface NotifyingFutureListener {
>  void futureDone(Future f);
> }
>
> WDYT?
> --
> Manik Surtani
> manik at jboss.org
> Lead, Infinispan
> Lead, JBoss Cache
> http://www.infinispan.org
> http://www.jbosscache.org
>
>
>
>
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>

--
Manik Surtani
manik at jboss.org
Lead, Infinispan
Lead, JBoss Cache
http://www.infinispan.org
http://www.jbosscache.org




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