ClassLoader and augmentation issues

[FroMage]

For example, Hibernate and Panache enhance entity Foo, and Panache then generates a Foo$generated class, which uses reflection on Foo to get some info that's hard to get using jandex. It doesn't care if it sees a non-enhanced version of the class, using its class' class loader. But if it uses theTCCL (RuntimeClassLoader) that will trigger a load of the entity class before the transformers have been set and all hell breaks loose later on with really weird failures.

And if I don't use the TCCL shamrock:dev does not work, for some other reason.

We're going ot have to clarify what reflection is allowed during bytecode generation (Hibernate uses it, ASM uses it), and how to avoid these issues of difference between shamrock:dev and the normal runner.

[dmlloyd]

We shouldn't rely on TCCL IMO.

Once the new class loading model is in place, we probably should use build items: one for the extension deployment CL, one for the extension runtime CL, one for the bootstrap CL, and one for the CL used for reflective instrumentation of the original user classes.

[FroMage]

Are we really going towards a model with 4 CL?

[dmlloyd]

Yes. To be fair though, one of them is the original one that we'd have anyway.

[dmlloyd]

And one would only be created if an extension were present which needed to do reflection on the app classes.

[dmlloyd]

Here's a helpful diagram:

  ┌───────────────────────────────┐
  │   Build system class loader   │         ┌───────────────────────────────┐
  │  ┌─────────────────────────┐  │         │     Runtime class loader      │
  │  │     Application JAR     │  │         │  ┌─────────────────────────┐  │
  │  │     (orig. version)     │  │         │  │      quarkus-core       │  │
  │  ├─────────────────────────┤  │         │  │        (curated)        │  │
  │  │ Quarkus Build Bootstrap │─ ┼ ─ ─ ┐   │  ├─────────────────────────┤  │
  │  │                         │◀─┼──┬──────│  │   quarkus-* (runtime)   │  │◀───────────────┐
  │  ├─────────────────────────┤  │  │  │   │  │        (curated)        │  │                │
  │  │      JBoss Logging      │◀─┼──┤      │  ├─────────────────────────┤  │ ┌─────────────────────────────┐
  │  ├─────────────────────────┤  │  │  │   │  │ Framework dependencies  │  │ │  Augmentation class loader  │
  │  │    JBoss LogManager     │◀─┼──┤      │  └─────────────────────────┘  │ │     (created on demand)     │
  │  ├─────────────────────────┤  │  │  │   └───────────────────────────────┘ │ ┌─────────────────────────┐ │
  │  │     WildFly Common      │◀─┼──┘                      ▲                 │ │     Application JAR     │ │
  │  ├─────────────────────────┤  │     │                   │                 │ │       (original)        │ │
  │  │      quarkus-core       │  │  ┌──────────────────────┴────────┐        │ ├─────────────────────────┤ │
  │  │     (orig. version)     │  │  │  │                            │        │ │Application dependencies │ │
  │  ├─────────────────────────┤  │  │                               │        │ └─────────────────────────┘ │
  │  │   quarkus-* (runtime)   │  │  │  │                            │        └─────────────────────────────┘
  │  │    (orig. versions)     │  │  │               ┌───────────────────────────────┐       ▲
  │  ├─────────────────────────┤  │  │  └ ─ ─ ─ ─ ─ ▶│    Deployment class loader    │
  │  │Application and framework│  │  │               │  ┌─────────────────────────┐  │       │
  │  │   dependencies (orig.   │  │  │               │  │ quarkus-core-deployment │  │
  │  │        versions)        │  │  │               │  │        (curated)        │─ ┼ ─ ─ ─ ┘
  │  └─────────────────────────┘  │  │               │  ├─────────────────────────┤  │
  └───────────────────────────────┘  │               │  │  quarkus-*-deployment   │  │
                                     │         ┌ ─ ─ ┼ ─│        (curated)        │  │
                    ┌────────────────┘               │  └─────────────────────────┘  │
                    │                          │     └───────────────────────────────┘
  ┌───────────────────────────────────┐
  │       Test/Dev class loader       │        │
  │  ┌─────────────────────────────┐  │
  │  │     Application Classes     │  │        │
  │  │      (augmented, RAM)       │  │
  │  ├─────────────────────────────┤  │◀ ─ ─ ─ ┘
  │  │  Application and framework  │  │
  │  │dependencies (augmented, RAM)│  │
  │  └─────────────────────────────┘  │
  └───────────────────────────────────┘

[FroMage]

I love how the world has moved on to super cool looking diagrams with animations, 3D and gradients, and we've been left to play with ascii diagrams :)

[FroMage]

Shit I'm old enough to have started working on Borland C under DOS which looked exactly like this diagram!

[FroMage]

Note that I'm not criticising, I would have used Dia and it would have looked much worse.

[dmlloyd]

Haha. I saw this program "Monodraw" and wanted to give it a try.

[dmlloyd]

Depends on #425

[rsvoboda]

@FroMage is this fixed by the big CL change commit ?

[FroMage]

Yeah, at the very least it clarified how things work.