[hibernate-dev] Introducing a "none" BytecodeProvider

[Yoann Rodiere]

Can't say if it's a good or bad idea, but if you don't document it in the
user guide, please at least document how dangerous it is and why it can be
useful in the source code where the "none" option appears. I expect some
users will find it while debugging, try it out to solve their problems or
maybe just "to improve performance" and will have a bad experience... Not
to mention ourselves in a few weeks, of course :)

Regarding "BasicProxyFactory", Guillaume and I had to fight with this think
a few weeks ago, I think. If I remember correctly, it's used in particular
to instantiate abstract classes (!) during bootstrap. It seems to be needed
when copying data around from an object to another in particular; maybe
when the type of an @Embedded property is abstract? Someone else probably
knows more. All I can say is it made some tests fail some time ago, so you
can try making it throw exceptions and run the tests that fail in debug
mode, to see why it's useful exactly.


Yoann Rodière
Hibernate NoORM Team
yoann at hibernate.org


On Wed, 17 Oct 2018 at 19:47, Sanne Grinovero <sanne at hibernate.org> wrote:

> After some experimentation I figured out that the BytecodeProvider is
> not really necessary, if you are happy to use the tools we have to
> enhance the entities upfront.
>
> In some environments such as on GraalVM I need to pre-enhance the
> entities (need as in "not optional"), but some further things would be
> really much simpler if I then could exclude Byte Buddy from runtime
> dependencies.
>
> As the code stands today, the Byte Buddy engine is loaded very early
> during bootstrap (even if the entities are already enhanced, as we
> didn't test for that yet at this point) and can't be disabled.
>
> I have a successful experiment which introduces a "none" configuration
> value for the "hibernate.bytecode.provider" property which allows me
> to fully disable the need to have ByteBuddy on classpath at runtime.
>
> I would not generally recommend this as there is no safety net: if you
> set this property AND did not enhance your entities, I expect trouble.
>
> Also there's a strong limitation: I could not implement the
> `BasicProxyFactory`, which is probably making this unfit for general
> purpose; I could use some help to nail down why exactly we need this
> and see if we can actually implement an alternative - possibly having
> the build time entity enhancement tools generate the necessary
> bytecode upfront?
>
> Still, I'd propose to merge this feature as an advanced feature that
> some power users will need when making progress on support for new
> platforms. Because of this experimental aspect, I'm not bothering to
> mention it on the user guide :)
>
> Ok?
>
> Thanks,
> Sanne
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