[cdi-dev] Producer#dispose(T instance) and similar

Mark Struberg struberg at yahoo.de
Wed Dec 5 17:34:43 EST 2012 

The CreationalContext is the only thing which contains the @Dependent scoped Interceptor.
Of course there is not yet an API to get anything out from it.

Still wondering how a portable InjectionTarget could ever invoke an interceptor on those PreDestroy and PostConstruct methods...

LieGrue,
strub




----- Original Message -----
> From: Pete Muir <pmuir at redhat.com>
> To: Mark Struberg <struberg at yahoo.de>
> Cc: Arne Limburg <arne.limburg at openknowledge.de>; cdi-dev <cdi-dev at lists.jboss.org>
> Sent: Wednesday, December 5, 2012 10:32 PM
> Subject: Re: [cdi-dev] Producer#dispose(T instance) and similar
> 
> Why do they need to take creationalContext, that is what I am missing.
> 
> On 5 Dec 2012, at 20:33, Mark Struberg wrote:
> 
>>  Oki, sounds ok so far. 
>> 
>>  What about InjectionTarget<T> ?
>> 
>>  InjectionTarget#postConstruct(T instance)
>>  InjectionTarget#preDestroy(T instance)
>> 
>> 
>>  They don't have a CreationalContext parameter. Where do they take the 
> interceptors? And of course there _are_ interceptors allowed for 
> InjectionTargets imo.
>>  That could only work if 'instance' is a proxy already, isn't?
>> 
>> 
>>  LieGrue,
>>  strub
>> 
>> 
>> 
>>  ----- Original Message -----
>>>  From: Pete Muir <pmuir at redhat.com>
>>>  To: Arne Limburg <arne.limburg at openknowledge.de>
>>>  Cc: Mark Struberg <struberg at yahoo.de>; cdi-dev 
> <cdi-dev at lists.jboss.org>
>>>  Sent: Wednesday, December 5, 2012 4:55 PM
>>>  Subject: Re: [cdi-dev] Producer#dispose(T instance) and similar
>>> 
>>>  Hey Arne,
>>> 
>>>  No, they can't :-) It's specifically called out in Chapter 8 
> and Chapter 
>>>  9 that decorators and interceptors aren't applied to the result of 
> producer 
>>>  methods.
>>> 
>>>  Pete
>>> 
>>>  On 5 Dec 2012, at 14:47, Arne Limburg wrote:
>>> 
>>>>  Hi Pete,
>>>> 
>>>> 
>>>>  A little of topic and I don't want to disturb your discussion, 
> but:
>>>> 
>>>>  Beans produced by producer methods CAN have interceptors as 
> stereotypes
>>>>  are supported on producer methods.
>>>> 
>>>>  Cheers,
>>>>  Arne
>>>> 
>>>>  Am 04.12.12 17:46 schrieb "Pete Muir" unter 
>>>  <pmuir at redhat.com>:
>>>> 
>>>>>  Hi Mark, I'll try to answer inline, but I'm missing a 
> bit of 
>>>  background
>>>>>  about what you are doing...
>>>>> 
>>>>>  On 4 Dec 2012, at 14:20, Mark Struberg wrote:
>>>>> 
>>>>>>  Another problem probably being an interceptor on the 
> @Disposes 
>>>  method
>>>>>>  itself.
>>>>>>  Where does the Proucer#dispose(T instance) get the 
> interceptor 
>>>  from?
>>>>>> 
>>>>>>  LieGrue,
>>>>>>  strub
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>  ----- Original Message -----
>>>>>>>  From: Mark Struberg <struberg at yahoo.de>
>>>>>>>  To: cdi-dev <cdi-dev at lists.jboss.org>
>>>>>>>  Cc: 
>>>>>>>  Sent: Tuesday, December 4, 2012 3:16 PM
>>>>>>>  Subject: [cdi-dev] Producer#dispose(T instance) and 
> similar
>>>>>>> 
>>>>>>>  Hi!
>>>>>>> 
>>>>>>>  I'm currently stumbling over implementing
>>>>>>> 
>>>>>>>  Producer#dispose(T instance) properly
>>>>>>> 
>>>>>>>  The Producer#produce(CreationalContext)
>>>>>>> 
>>>>>>>  has the CreationalContext parameter but the dispose
>>>>> 
>>>>>  Right, it would have been good to have included it here. 
> I'm not 
>>>  sure why
>>>>>  it wasn't, however I don't believe that it causes a 
> problem 
>>>  with the CDI
>>>>>  1.0 spec, but just limits us going forward.
>>>>> 
>>>>>>>  and others do not have it.
>>>>> 
>>>>>  Yes.
>>>>> 
>>>>>>> 
>>>>>>>  Problem here is that a Producer could probably get 
> exchanged 
>>>  via a
>>>>>>>  portable 
>>>>>>>  extension via ProcessProducer#setProducer(Producer)
>>>>> 
>>>>>  Yes, this is definitely supported
>>>>> 
>>>>>>>  so it could be from a
>>>>>>>  foreign source which must not know anything about 
> container
>>>>>>>  implementation 
>>>>>>>  details.
>>>>> 
>>>>>  Yes.
>>>>> 
>>>>>  I think the critical part of the spec to understand this is 
> 11.2. 
>>>  I'm
>>>>>  quoting here from the CDI 1.1 spec, into which we have add the
>>>>>  clarification that "The instance returned by produce() may 
> be a 
>>>  proxy.".
>>>>>  The part about building interceptors and decorators is there in 
> CDI 
>>>  1.0.
>>>>> 
>>>>>>  For a Producer that represents a class:
>>>>>> 
>>>>>>      € produce() calls the constructor annotated @Inject if 
> it 
>>>  exists, or
>>>>>>  the constructor with no parameters otherwise, as defined in
>>>>>>  [instantiation], and returns the resulting instance. If the 
> class 
>>>  has
>>>>>>  interceptors,produce() is responsible for building the 
> interceptors 
>>>  and
>>>>>>  decorators of the instance. The instance returned by 
> produce() may 
>>>  be a
>>>>>>  proxy.
>>>>>> 
>>>>>>      € dispose() does nothing.
>>>>> 
>>>>>  and
>>>>> 
>>>>>>  For a Producer that represents a producer method or field:
>>>>>> 
>>>>>>      € produce() calls the producer method on, or accesses 
> the 
>>>  producer
>>>>>>  field of, a contextual instance of the bean that declares 
> the 
>>>  producer
>>>>>>  method, as defined in [methods].
>>>>>> 
>>>>>>      € dispose() calls the disposer method, if any, on a 
> contextual
>>>>>>  instance of the bean that declares the disposer method, as 
> defined 
>>>  in
>>>>>>  [methods], or performs any additional required cleanup, if 
> any, to
>>>>>>  destroy state associated with a resource.
>>>>> 
>>>>>  Now, let me start to break down your sentence :-)
>>>>> 
>>>>>>> 
>>>>>>>  What now about having an interceptor on @PreDestroy?
>>>>> 
>>>>>  For a start, it's worth remembering interceptors can only 
> be 
>>>  associated
>>>>>  with beans defined by a class. If the bean is a producer, then 
> you 
>>>  can't
>>>>>  intercept the instance produced (only the invocation of the 
> producer).
>>>>> 
>>>>>>>  This is what you get if
>>>>>>>  your interceptor has a at PreDestroy method himself as per 
> the
>>>>>>>  interceptors and EJB
>>>>>>>  specs. That would mean that the instance passed to 
> dispose() 
>>>  whould be
>>>>>>>  the 
>>>>>>>  proxy? That purely sounds wrong to me.
>>>>> 
>>>>>  Based on my comment from above, I think it's clear that 
> dispose() 
>>>  should
>>>>>  never try to invoke predestroy methods. That is the job of
>>>>>  InjectionTarget.preDestroy(). I would expect a proxy to be 
> passed to
>>>>>  preDestroy().
>>>>> 
>>>>>> 
>>>>>> 
>>>>>>> 
>>>>>>>  Another issue being InjectionTarget#postConstruct() 
> only having 
>>>  the
>>>>>>>  instance T 
>>>>>>>  as well. Now what about @PostConstruct interceptors as 
> defined 
>>>  in the
>>>>>>>  interceptors spec?
>>>>> 
>>>>>  Again, I would expect a proxy to be passed to postConstruct(). 
> Anyway,
>>>>>  I'm not sure why you need access to the creational context 
> in the
>>>>>  postConstruct()? Here you should just invoke the postConstruct 
>>>  callback,
>>>>>  which should create any new dependent objects.
>>>>> 
>>>>>>>  Currently we have a dirty hack in OWB to pass over the
>>>>>>>  CreationalContext which
>>>>>>>  contains the dependent scoped interceptors for our own 
>>>  Producers and
>>>>>>>  InjectionTargets. But I have no clue yet how that 
> should get
>>>>>>>  implemented if one
>>>>>>>  plugs in a portable Producer via an Extension ^^
>>>>>>> 
>>>>>>>  Who is responsible of performing the interception? The 
>>>  Producer? Or
>>>>>>>  must the 
>>>>>>>  instance being handed into already be a Proxy?
>>>>> 
>>>>>  The instance returned from produce() should have interceptors 
> and
>>>>>  decorators applied.
>>>>> 
>>>>>  Please let me know if above makes sense, it took me a while to 
> work out
>>>>>  whether what was defined was sane. After quite a lot of 
> thinking +
>>>>>  talking to Jozef and Stuart I came to the conclusion it was, 
> but  if 
>>>  you
>>>>>  can poke holes then please do!
>>>>>  _______________________________________________
>>>>>  cdi-dev mailing list
>>>>>  cdi-dev at lists.jboss.org
>>>>>  https://lists.jboss.org/mailman/listinfo/cdi-dev
>>>> 
>>> 
>

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