Re: [infinispan-dev] Cache Java 8 API proposal - First draft

Thanks Radim for the great feedback, comments inline: ^ `Value` class will expose metadata and versioning information somehow, but as said in the proposal, there are still some things that need to be added. Exposing version of the existing entry to the functions is crucial because one of the problems I'm trying to find a good solution for is [1] (see also slides in [2] that I prepared for Berlin). The problem there is that existing replace() is only atomic when comparing objects by equality, and the `eval` method design will allow you to customize that comparison the way you want, and in fact for Hot Rod, we'd compare using version information. E.g. here's how it could work (TBD!): CompletableFuture<Boolean> replaced = functionalCache.eval("e", v -> { if (v.version().equals(userProvidedVersion)) return true; else return false; }); [1] https://issues.jboss.org/browse/ISPN-4972 [2] https://dl.dropboxusercontent.com/u/6148072/berlin-2015-galder-versionedr... I've pinged David, JBoss Marshalling creator, to get some tips about this and I also plan to check with other Java 8 gurus such as Mario, but from what I can understand, there's three parts to a lambda: - the lambda function class instance itself - the parameters you pass in to the lambda - any objects captured/referenced by the lambda I think the lambda functions can be cached but of course, the parameters nor captured objects can't. When we create Map/ConcurrentMap/JCache decorators, we'll control the decorator contents and we'd have the chance to do whatever caching we need. I don't think we even need to replicate them at all since the classes themselves will cache the functions. So, that would leave parameters and captured/referenced objects to be serialized since that's the variable part. Not sure if these two can be serialized independently. Parameters maybe but captured objects might be tough. I've not done benchmarking yet. You'd replicate the lambda (or if you can cache it, then somehow avoid sending all its info), along with parameters, and any capture values. So, for `Map.put` implementation function you are replicating, it includes the full value. If you're trying to store a data structure and and non-tx, there's indeed a chance of having partially applied updates. We'd need some merging here possibly... Cheers, -- Galder Zamarreño galder(a)redhat.com