Re: [hibernate-dev] HHH-9701 - Develop "immutable EntityEntry" impl

On Thu, Apr 2, 2015 at 4:45 AM, John O'Hara <johara(a)redhat.com <mailto:johara@redhat.com>> wrote: Steve, I have pushed a proposal for HHH-9701 to: https://github.com/johnaoahra80/hibernate-orm/tree/HHH-9701 There are a couple of areas that I would appreciate feedback; 1) Serialization/Deserialization - EntityEntries implementations can be serialized and each implementation provide their own serialization method. I have modified the serialization of EntityEntry in EntityEntryContext to write the Implementation class to the OutputStream so the correct class can be used to deserialize the object stream. Is the exception handling sufficient here, or do we need more robust handling of deserialization exceptions? : see https://github.com/johnaoahra80/hibernate-orm/commit/ec9b1fa3b97131ff1e65... I added some comments to that section. Also, overall I would extract the deserialization bit into a separate method (deserializeEntityEntry). 2) In our (perf team) use case, we want to be able to share the ImmutableEntityEntry between sessions when they are referenced cached in the 2lc. I have modified EntityEntryContext to not null managedEntity.$$_hibernate_setEntityEntry if the EntityEntry is an instance of ImmutableEntityEntry. Do we need to add an extra checks here, to ensure that the entity is Reference Cached? I am not sure how we would test that case? : see https://github.com/johnaoahra80/hibernate-orm/commit/ec9b1fa3b97131ff1e65... It really depends on what y'all consider the trigger for using ImmutableEntityEntry. When would the EntityPersister use the EntityEntryFactory producing ImmutableEntityEntry instances? a) when the entity is marked immutable? b) when the entity is marked immutable *and* we need to cache it by reference? c) some other condition? I agree that we should only not clear that reference when the entity is enabled for cache-by-reference. How that plays into this depends on the answer to the above question. If (a), then I think that yes it makes sense to add a check to only clear the ManagedEntity's EntityEntry reference if using cache-by-reference. If (b), then the EntiytPersister is only using the EntityEntryFactory producing ImmutableEntityEntry instances when both are true. So the fact that an entry is an instance of ImmutableEntityEntry indicates that we need to not clear it from the ManagedEntity. 3) Lock Mode: Steve you mentioned about not doing locking for Immutable entities. Where is the locking implemented? Would it be sufficient to simply set the LockMode on the ImmutableEntityEntry to NONE/READ_ONLY when setLockMode is called? Locking is implemented in many places. What I had in mind, in terms of implementation for EntityEntry, is somewhat influenced by the choice between ignore versus exception in cases where something is not supported. Basically I had thought to throw an exception in ImmutableEntityEntry#setLockMode or to simply ignore the call altogether. This is not a great solution. It is hard for me to justify ignoring the lock request in all cases. What does everyone else think?