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

To post my question again... 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? Because the answer to this ^^ dictates how we need to check whether we can clear this reference On Fri, Apr 10, 2015 at 11:45 AM, Steve Ebersole <steve(a)hibernate.org <mailto:steve@hibernate.org>> wrote: Well the performance is exactly what I had in mind when I asked you about the exact "trigger for using ImmutableEntityEntry" in your use-case. But you never replied to that. On Fri, Apr 10, 2015 at 9:26 AM, John O'Hara <johara(a)redhat.com <mailto:johara@redhat.com>> wrote: I have updated my current branch: https://github.com/johnaoahra80/hibernate-orm/tree/HHH-9701 * Extracted the deserialization of EntityEntry in EntityEntryContext into a separate method: https://github.com/johnaoahra80/hibernate-orm/commit/d9f5dc76e05a111d37db... * Created a LockModeException for invalid lock modes for an ImmutableEntity: https://github.com/johnaoahra80/hibernate-orm/commit/99e308ae267f9bfc3054... Do we need a new Exception type here, or could we just use a HibernateException with a message about invalid lock type? * Added a check when EntityEntryContext.clear() or EntityEntry. removeEntityEntry() is called to see if the EntityEntry is ImmutableEntityEntry AND the Entity is referenced cached in the 2lc: https://github.com/johnaoahra80/hibernate-orm/commit/310a2eb5b8988189806a... Not sure of the performance implications on this, I am planning a run on WF9 to test and regressions in our use case. * Extracted an AbstractEntityEntry superclass that MutableEntityEntry and ImmutableEntityEntry both inherit from: https://github.com/johnaoahra80/hibernate-orm/commit/df50d344441ed4cc8f3c... John On 07/04/15 20:20, Steve Ebersole wrote: > TBH, I have no idea what happens to comments on a Pull > Request when you squash and force push. > > I'd just leave the multiple commits. We can squash them later. > > On Tue, Apr 7, 2015 at 1:59 PM, John O'Hara > <johara(a)redhat.com <mailto:johara@redhat.com>> wrote: > > Steve, > > I have made changes based on the github comments and your > comments below > (https://github.com/johnaoahra80/hibernate-orm/commits/HHH-9701). > > Do you want me to squash the commits down to one? Not > sure how this would effect the comments you have already > made on GH > > Thanks > > John > > > On 06/04/15 04:51, Steve Ebersole wrote: >> >> >> 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? >> >> >> > > > -- > John O'Hara > johara(a)redhat.com <mailto:johara@redhat.com> > > JBoss, by Red Hat > Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. > Registered in UK and Wales under Company Registration No. 3798903 Directors: Michael Cunningham (USA), Charlie Peters (USA), Matt Parsons (USA) and Michael O'Neill (Ireland). > > -- John O'Hara johara(a)redhat.com <mailto:johara@redhat.com> JBoss, by Red Hat Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in UK and Wales under Company Registration No. 3798903 Directors: Michael Cunningham (USA), Charlie Peters (USA), Matt Parsons (USA) and Michael O'Neill (Ireland).