Re: [infinispan-dev] Cache entry not invalidated callback?

On 10/28/2009 05:50 PM, Manik Surtani wrote: > > On 28 Oct 2009, at 09:29, Galder Zamarreno wrote: > >> Hi, >> >> Re: Porting over >> http://opensource.atlassian.com/projects/hibernate/browse/HHH-3818 >> to >> Infinispan 2nd level cache. >> >> For HHH-3818, Brian used the cache as a bus to notify that the cache >> contents where invalid. To do so, he implemented cache entry >> modified >> and invalidated callbacks that react to cache modifications or >> invalidations where the FQN is an internal fqn which contains the >> local >> address. >> >> Now, the trick he uses for the invalidation is that on startup or >> whenever there's a view change, he establishes these internal FQNs >> in >> each node for each of the members in the cluster, i.e. >> fqn=/test/com/foo/test/ENTITY/NODE/127.0.0.1:39104 >> >> So, in an invalidation scenario, if you a node puts something on >> /test/com/foo/test/ENTITY/NODE/127.0.0.1:39104, the other nodes have >> at >> least /test/com/foo/test/ENTITY/NODE/127.0.0.1:39104 created on >> their >> caches which means that the invalidation callback works fine cos the >> FQN >> exists in other nodes. >> >> Now, in Infinispan's case, bearing in mind that there're no FQNs, I >> could set up such keys when there's a view change too. However, I >> was >> thinking of another alternative. >> >> Currently, cache invalidation callback fails on Infinispan because >> when >> you do a put on key=127.0.0.1:39104, the other nodes do not contain >> the >> key=127.0.0.1:39104, so no invalidation callback is received. So, my >> suggestion is the following: >> >> Why not have a callback saying: "I attempted to do an invalidation >> on >> k=x but k=x did not exist". Maybe something like >> CacheEntryNotInvalidated callback? It looks to me that it'd be >> relatively simply to implement such notification and would simplify >> the >> code on the Infinispan 2nd level cache provider. > > Hmm, where would you impl this callback? As a part of the core > Infinispan notification system? The implementation would be somewhere in between RemoveCommand and InvalidateCommand. In RemoveCommand, after logging: log.trace("Nothing to remove since the entry is null or we have a null entry"); you'd have the possibility to notify that attempt was made to remove something but it wasn't there. I'm not sure whether it'd make a lot of sense to implement it for RemoveCommand so, we either add a notify method afterwards and make InvalidateCommand only provide a impl for it, or override perform() in IC, or somewhere in between, i.e. wrap code within the if (e == null || e.isNull()) into a method that is overriden by IC. Thoughts?