[cdi-dev] Managing Dependent Scoped Beans

[John D. Ament]

Martin,


On Mon, May 16, 2016 at 3:54 AM Martin Kouba <mkouba at redhat.com> wrote:

> Dne 15.5.2016 v 17:14 John D. Ament napsal(a):
> > Romain,
> >
> > On Sun, May 15, 2016 at 11:05 AM Romain Manni-Bucau
> > <rmannibucau at gmail.com <mailto:rmannibucau at gmail.com>> wrote:
> >
> >     Hi Jon
> >
> >     Le 15 mai 2016 16:15, "John D. Ament" <john.d.ament at gmail.com
> >     <mailto:john.d.ament at gmail.com>> a écrit :
> >      >
> >      > Hey guys
> >      >
> >      > Seems like we have some issues in JIRA all focused on managing
> >     the lifecycle of Dependent scoped beans.  It also seems like we have
> >     many differing opinions about how to manage them.
> >      >
> >      > - Martin raised a PR to add a release() method to Instance to
> >     help destroy a dependent bean
> https://github.com/cdi-spec/cdi/pull/286
> >      > - I raised a PR https://github.com/cdi-spec/cdi/pull/289 to
> >     update the spec to clarify how to manage a dependent scoped bean.
> >      >
> >      > Right now, it seems that the big disagreement is whether
> >     Instance.destroy() can destroy objects not created by it (the case
> >     being around the CDI utility class, being an impl of Instance).  I'm
> >     currently heavily against Martin's proposed changes, but want to get
> >     input from others on the group to understand their perspective.
> >      >
> >      > - Does the spec require destroy() to be called only on instances
> >     that it created?  When I read 5.6.1 the only requirement I see is
> >     that it has to be a dependent scoped bean.  Note when I ask this I'm
> >     asking from the spec perspective, its a different problem if there's
> >     some issues with implementations following suite (I would imagine
> >     there needs to be some shared global registry of dependent scoped
> >     beans for this to work).
> >      >
> >
> >     Sound the only clean impl. Any other is not symmetric and
> >     potentially lead to "oops this time it didnt work". I also not
> >     seeing any use case limitation with that so think it is the same
> >     solution
> >
> >
> > I'm not sure I follow or if this isn't an answer to "Does the spec
> > require destroy() to be called only on instances that it created?" ?
> >
> > Anyways I did look a bit closer and it seems that Martin's statement is
> > consistent with how OWB works,
> >
> https://github.com/apache/openwebbeans/blob/trunk/webbeans-impl/src/main/java/org/apache/webbeans/inject/instance/InstanceImpl.java#L293
> so
> > I wonder if there's a part of the spec I'm missing, or if there was some
> > offline agreement on how to understand it.
>
> John, I believe Instance CANNOT be used to destroy a dependent bean
> instance it didn't created, because a dependent bean instance doesn't
> know the dependent objects it depends on - that's what CreationalContext
> is for.
>
>
This is the area I'm looking for clarification around.  Where in the spec
is this mandated?


> So if you pass any dependent instance to Instance.destroy() there is no
> CreationalContext apart from the one Instance<> has. In other words you
> wouldn't be able to destroy the @Dependent dependencies of a @Dependent
> bean instane. Does it make sense?
>
> See also https://issues.jboss.org/browse/CDI-519 (cdi-spec/cdi/pull/278
> is already merged).
>
>
> >
> > John
> >
> >      > - Do we want two methods that effectively do the same thing?  I
> >     don't see a strong difference between the two.
> >      >
> >      > On the flipside, my change is more a spec clarification.  I'm
> >     thinking more now that it belongs as a reword of 5.6.1 to clarify
> >     how to use destroy() on dependent beans, rather than where I put
> >     it.  I think realistically we have all of the tools needed to manage
> >     the lifecycle of these classes, just need to clarify them for people
> >     to use.
> >      >
> >      > John
> >      >
> >
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>
> --
> Martin Kouba
> Software Engineer
> Red Hat, Czech Republic
>
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