BeanScope PreDestroy

[SentryMan]

Now can do

  @PreDestroy(priority = 100)
  void preDestroy(BeanScope scope) {
  
   // use the beanscope to close tricky beans

  }

• Adds a new interface for pre-destroy hooks that accept the current BeanScope
• refactor internals to convert AutoCloseable Interfaces for compatibility
• refactor postConstruct internals to convert Runnable to Consumer<BeanScope> instead of having two separate lists

Solves #749

[rbygrave]

I don't like this idea of void preDestroy(BeanScope scope) as we are invoking methods on a BeanScope that is in the process of "shutting down" - I feel there will be a lot of problematic cases / race conditions etc.

My preference would be to NOT support this. Currently there is no actual known use cases for PreDestroy methods that need to take the BeanScope right?

[ascopes]

@rbygrave another option could be to allow the BeanScopeBuilder to be passed as a parameter to Bean methods. That'd allow registration via the destroy hook method.

[ascopes]

Looking at https://docs.oracle.com/javase/8/docs/api/javax/annotation/PreDestroy.html it violates these constraints too.

[rbygrave]

another option could be to allow the BeanScopeBuilder

I'm suggesting we try to stick to "First Principals" and first understand clearly the use cases that are not supported nicely/elegantly and the options for handling these cases. Currently, the ONLY use case we have at this stage is the Vertx one with a PreDestroy method that has method chaining .close().blockingAwait() [and we can actually support this by extending the existing mechanism - I have a PR ready to go for that].

We have no other use cases presented to us [yet]. That is, we currently have no use cases of a PreDestroy method that actually needs BeanScope. We currently have no use cases of a PreDestroy method that needs any parameters [and yes, as you point out if we did that would violate the standard there].