[hibernate-dev] 5.3 cache issues [Requires Steve]

[Steve Ebersole]

On Tue, Jul 3, 2018 at 5:11 AM Yoann Rodiere <yoann at hibernate.org> wrote:

> 2) This is easily handled by the providers, if they wish.  They would
>> simply map any undefined regions/caches to a pre-defined one (probably
>> after warning the user).  Keep in mind that region != cache.  A provider
>> might map multiple region names to a single cache.  That was always the
>> case, but every provider mapped region <-> cache as 1-1 - the new API
>> makes
>> this much more clear.
>
>
> Just to clarify: this would require cache implementors to provide their
> own region factory, and in that case we all agree they can do whatever they
> want, which is nice.
>
> The problem is more with the built-in Ehcache and JCache region factories.
> Our built-in region factories call getCache(String), and if it returns
> null, they throw an exception. So the cache implementors do not have an
> easy way to auto-create a cache using some internal, default configuration:
> they would have to do that in the getCache(String) method, and it's
> arguably not something you want to do in a method with such a name,
> especially considering it's exposed to other clients than just Hibernate
> ORM. And I'm not sure the JCache specification even allows that.
>
> Ideally we'd like Ehcache/JCache to expose some getOrCreate(String)
> method, and decide for themselves whether to throw an exception or not, but
> well... they don't. Which explains the suggestion to handle the "default"
> logic on our end.
>

Not sure exactly what you expect this to return - that's the problem.  It
would need to return a `net.sf.ehcache.Cache` or a `javax.cache.Cache` or a
...

So I think you need to split this into a discussion about Ehcache and one
about JCache.

For Ehcache... whatever. As I keep saying, that provider is based on
Ehcache 2 which the Ehcache team hasn't supported for years now.  People
really should not be using that one.  If you want to revert that one,
that's fine

For JCache, as I have already said, I am fine with adding a setting here to
allow on-the-fly creations.  On-the-fly creations are a terrible idea, but
people can chose that option if they wish.

Just make sure that any logging here (especially the "we are creating an
on-the-fly Cache for you") happens through
`org.hibernate.cache.spi.SecondLevelCacheLogger`