[hibernate-dev] JPA 2.1 progress

[Steve Ebersole]

CompositeIndex *does exist*.  But its part of the AS codebase, not 
Jandex.

On Tue 17 Jul 2012 05:13:18 AM CDT, Strong Liu wrote:
>
> On Jul 17, 2012, at 5:58 PM, Hardy Ferentschik <hardy at hibernate.org
> <mailto:hardy at hibernate.org>> wrote:
>
>>
>> On Jul 16, 2012, at 9:06 PM, Steve Ebersole wrote:
>>
>>> Strong, I forgot to mention that Jason completely agrees that
>>> changes to
>>> Jandex are needed.  I agreed to prototype some of the things he and I
>>> discussed specifically in this code base and hand them back to him for
>>> integration back into the next rev of Jandex.
>>
>> Nice. Maybe I can lend a hand there as well. As you know I am
>> strongly attached
>> to this issue :-)
>>
>>> One such point of discussion was a common interface for "Index".
>>> Unfortunately the name Index is already taken as in the main Jandex
>>> class.  So we came up with some other names.  For this work I went
>>> ahead
>>> with the name 'IndexResult' for that common contract (interface).
>>> Anyway, no matter the name, eventually both Index and that new
>>> CompositeIndex would both implement this new common contract.
>>
>> Why do you need this contract? What benefit do you gain?
>>
>>> The other thing we discussed was integrating XML overrides into the
>>> indexing process since quite a few places where Jandex gets used would
>>> need this.  And since you worked on that in the metamodel codebase, was
>>> hoping to get your feedback as to whether you thought it would be
>>> possible to integrate XML overrides into this process up front.
>>
>> IMO it does not matter so much whether you do the overrides before or
>> after
>> annotation processing. It kind of makes sense to do it afterwards,
>> because the
>> xml configuration normally overrides existing annotations, so
>> replacing an AnnotationInstance
>> in the annotation based index with a pseudo AnnotationInstance
>> reflecting xml
>> configuration seems "natural".
>
>
>
>>
>> The problem of course is that a Jandex index is immutable and I
>> cannot just replace/modify
>> an AnnotationInstance. For that reason you have to a lot of
>> collection iterations/copies.
>>
>> If one wanted to improve on this I could imagine building some sort
>> of OverrideIndex up front
>> containing the pseudo AnnotationInstances from the XML configuration.
>> This OverrideIndex
>> would be generic and could be part of Jandex to be used by other
>> projects. This index could be
>> passed prior to Jandex prior to the annotation discovery phase. For
>> every annotation the discovery
>> index could query the OverrideIndex whether an override exists for a
>> given annotation. If so this
>> override would be added. The benefit of this approach is of course
>> that I don't have to build
>> multiple indexes.
>
> this can be done with CompositeIndex (though it doesn't exist yet), so
> we have two index, one is from annotation scan
>
> the other we manually build from xml parsing, and in the
> CompositeIndex we handle the override strategy.
>
>
>>
>> One thing I am not sure about is how to handle changes in xml
>> configuration files. How do we know
>> that we have to discard an index stored on the file system. Not even
>> quite sure how AS handles changed
>> classes (there might be some checksumming going on, not sure).
>>
>> On the ORM side we are currently not saving the index to disk. Right
>> now we create a new index and add
>> explicitly the classes/packages the user specifies via the
>> configuration. Once this processing is complete
>> we do the xml overrides and get what Steve calls the CompositeIndex.
>> After the configuration phase is
>> over the index is discarded.
>>
>> In the long run it would be good if we could store the index and load
>> it on startup.
>>
>> My 0.02$,
>> Hardy
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>
> -------------------------
> Best Regards,
>
> Strong Liu <stliu at hibernate.org <http://hibernate.org/>>
> http://about.me/stliu/bio
>

--
steve at hibernate.org
http://hibernate.org