[hibernate-dev] Jandex, scanning and discovery

[Hardy Ferentschik]

On 21 Jan 2014, at 16:48, Steve Ebersole <steve at hibernate.org> wrote:

> As Brett finishes up the "unified schema" work I wanted to start discussion
> about some simplifications that could/should come from that.

I really like where all these work is going. I hope the unification will work

> As I said, in the cases we are not handed a Jandex Index we need to build
> one.  Currently this is a tedious process handled by manually indexing all
> known classes (known from a few different sources).  But this need to know
> the classes to index them is problematic.

+1 In this area we had (or maybe still have some failing tests). The old code
used to take used to take the configured classes from the config, build
the hierarchy and process all classes in the hierarchy. So it would for example 
“discover” a @MappedSuperclass even so the class was not explicitly listed 
in the the persistence unit / hibernate config. 

When doing the initial work on Jandex I assumed that all annotated classes 
are in the Jandex index. This, however, requires that all annotated classes would 
need to be explicitly configured. To keep backwards compatibility  we added some
code which would also do the processing of the hierarchy.

> Which got me to thinking that it sure would be nice to tie this in to the
> scanning (org.hibernate.jpa.boot.scan.spi.Scanner) stuff we do already such
> that as we walk the "archive" we automatically add classes we encounter to
> the Index.  I'd actually add things to the Index whether or not they are
> supposed to be managed classes (exclude-unlisted-classes).

+1 Sounds like a good idea and also solves the problem described above in a nice
way.

> There are lots of benefits to this.  And not just to ORM, provided we start
> sharing the Jandex with Search (etc) as we have discussed.

+1 This would be very useful for HSEARCH-1213 where the aim is to switch to Jandex.

>  This better
> ensures that all needed classes are available in the Index.  This allows
> better discovery of "ancillary" classes via annotation.  Etc…

+1

> I think the solution is to expose all the 'persistence-unit-defaults'
> values on the org.hibernate.metamodel.source.spi.MappingDefaults and grab
> them from there.

+1

—Hardy