Re: [ovirt-devel] hibernate's internal PersistentBag sent to FE

----- Original Message ----- > From: "Alexander Wels" <awels(a)redhat.com&gt; > To: "Tomas Jelinek" <tjelinek(a)redhat.com&gt; > Cc: "Liran Zelkha" <lzelkha(a)redhat.com&gt;, devel(a)ovirt.org > Sent: Monday, June 1, 2015 4:19:47 PM > Subject: Re: [ovirt-devel] hibernate's internal PersistentBag sent to FE > > On Monday, June 01, 2015 09:33:07 AM Tomas Jelinek wrote: > > ----- Original Message ----- > > > > > From: "Alexander Wels" <awels(a)redhat.com&gt; > > > To: devel(a)ovirt.org > > > Cc: "Tomas Jelinek" <tjelinek(a)redhat.com&gt;, "Liran Zelkha" > > > <lzelkha(a)redhat.com&gt; Sent: Monday, June 1, 2015 3:16:34 PM > > > Subject: Re: [ovirt-devel] hibernate's internal PersistentBag sent to > > > FE > > > > > > On Monday, June 01, 2015 09:08:50 AM Tomas Jelinek wrote: > > > > Hey all, > > > > > > > > since the org.ovirt.engine.core.common.job.Job/Step... has been > > > > moved > > > > to > > > > use > > > > the JPA we have a problem on frontend. The problem is that the > > > > @OneToMany > > > > annotations results in a List which is of type PersistentBag. When > > > > we > > > > send > > > > this to Frontend it fails during deserialization. It actually fails > > > > quite > > > > bad because the FE already has an ui-override of it which is not > > > > correct > > > > resulting in a ton of NPEs in development mode. > > > > > > > > So, there are 2 nasty fixes I have made where none of them should be > > > > merged > > > > but demonstrate the possibilities: 1: extend the FE to be able to > > > > work > > > > with > > > > the PersistentBag (https://gerrit.ovirt.org/#/c/41682/) not really > > > > good > > > > solution since the PersistenBag is an internal Hibernate class which > > > > is > > > > really not meant to be passed around > > > > > > > > 2: fix on the backend to not send the PersistentBag but an > > > > ArrayList. > > > > This > > > > is only a PoC fixed on a command we face the problem > > > > (https://gerrit.ovirt.org/#/c/41797/) Obviously this is not going to > > > > work > > > > for other commands accessing the same Job nor for other entities. > > > > > > > > So, the first option is generic but very very bad. The second option > > > > should > > > > be used but not sure how to do this in a cheep way (e.g. without > > > > using > > > > reflection to deep traverse everything sent back to frontend > > > > checking > > > > if > > > > it > > > > does not have a PersistentBag in it. > > > > > > Tomas, > > > > > > Thanks, I was investigating the same issue, I noticed it last Friday > > > just > > > before leaving, so I was investigating the problem to see what was > > > going > > > on. You are right we should not be sending PersistentBag to the > > > frontend > > > at all. So how about we do a combination of [1] and [2], but instead > > > of > > > delegating in [1] we actually simple throw an exception stating don't > > > sent PersistentBag to the front end. that way anyone inadvertently > > > using > > > it will be notified immediately (since their code won't work). > > > > Throwing the exception would help us in debugging but the main question > > is > > how will we make it work? Since we are planning to move more and more to > > JPA so we will face this issue more and more often. Solving it one by > > one > > on backend in each command is not going to work. > > How about something like this [1]? It appears to use some aspects to > translate > the hibernate internal classes into normal java util classes. > > [1] https://code.google.com/p/dehibernator/ Well, not sure about that from performance point of view. If we really move away from GWT completely in 4.0, then implementing all hibernate inner collections in "uioverride" in a similar way as Tomas did seems to me as the best solution from performance and "easiest to remove when not needed" point of view.

> > > Alexander > > > > > > > Any better ideas? > > > > Thanx, > > > > Tomas > > > > _______________________________________________ > > > > Devel mailing list > > > > Devel(a)ovirt.org > > > > http://lists.ovirt.org/mailman/listinfo/devel > > _______________________________________________ > Devel mailing list > Devel(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/devel