[weld-issues] [JBoss JIRA] (WELD-1076) Deal with non-serializable dependent instances of a passivation capable bean

[Jozef Hartinger (JIRA)]

    [ https://issues.jboss.org/browse/WELD-1076?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12684393#comment-12684393 ] 

Jozef Hartinger commented on WELD-1076:
---------------------------------------

Alternatively, we should not use creational context to store dependent instances that do not define @PreDestroy callbacks nor are they intercepted by a @PreDestroy interceptor.
                
> Deal with non-serializable dependent instances of a passivation capable bean
> ----------------------------------------------------------------------------
>
>                 Key: WELD-1076
>                 URL: https://issues.jboss.org/browse/WELD-1076
>             Project: Weld
>          Issue Type: Task
>    Affects Versions: 2.0.0.Alpha1
>            Reporter: Jozef Hartinger
>            Assignee: Jozef Hartinger
>             Fix For: 2.0.0.Alpha2
>
>
> Since https://github.com/jboss/cdi/pull/47 it is legal for a normal-scoped component to have a non-passivation capable dependency, e.g:
> {CODE:JAVA}
> @SessionScoped
> public class Foo implements Serializable {
>    @Inject
>    public Foo(Bar bar) {
>    }
> }
> public class Bar {
> }
> {CODE}
> Although the Bar instance reference is not retained by the Foo instance, the Bar instance is still technically a dependent instance of Foo and therefore the container needs to keep a reference to it in order to eventually destroy it properly.
> This is a problem because dependent instances of a bean are currently supposed to be serialized together with the normal-scoped instance but the Bar instance is not serializable.
> We may work around by making use of the following part of the spec:
> {QUOTE}
> Finally, the container is permitted to destroy any @Dependent scoped contextual instance at any time if the instance is no
> longer referenced by the application (excluding weak, soft and phantom references)."
> {QUOTE}
> and destroy every non-serializable dependent bean instance of a normal-scoped bean when the creational context for the normal-scoped bean instance is serialized.
> This is not 100% equivalent to "the instance is no longer referenced by the application" however covers all the sensible cases including:
> * Foo no longer holds a reference to Bar, therefore we can safely destroy Bar
> * Foo holds a reference to Bar - does not matter if we destroy Bar prematurely or not since serialization of Bar is going to fail anyway
> * Foo holds a reference to Bar in a transient field and is therefore either going to "forget" the reference no serialization (therefore we can destroy it) or is able to recreate the Bar instance itself on deserialization

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