[FELIX-5139] SCR logs errors for reference but works as expected

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Invalid
• Affects Version/s: scr-2.0.2, maven-bundle-plugin-3.0.1
• Component/s: Declarative Services (SCR), Maven Bundle Plugin
• Assignee: Unassigned
• Reporter: Oliver Lietz
• Created: 14/Dec/15 13:39
• Updated: 20/Dec/15 09:50
• Resolved: 14/Dec/15 15:41

Description

When annotating a field like below with bind and unbind I don't expect SCR to act on the field directly but using named bind and unbind methods instead (which is the case indeed).

    @Reference(
        service = FooService.class,
        cardinality = ReferenceCardinality.AT_LEAST_ONE,
        policy = ReferencePolicy.DYNAMIC,
        bind = "addFooService",
        unbind = "removeFooService"
    )
    private final Set<FooService> fooServices = new LinkedHashSet<FooService>();

    protected synchronized void addFooService(final FooService fooService) {
        fooServices.add(fooService);
        // operate on fooServices
    }

    protected synchronized void removeFooService(final FooService fooService) {
        fooServices.remove(fooService);
        // operate on fooServices
    }

Nevertheless SCR logs errors at runtime when binding services:

[...] | ERROR | xFrameworkWiring | [...] | [[...]] Field fooServices in component class [...] must be declared volatile to handle a dynamic reference
[...] | ERROR | xFrameworkWiring | [...] | [[...]] Field fooServices in component class [...] has unsupported type java.util.Set. It must be one of java.util.Collection or java.util.List.
[...] | ERROR | xFrameworkWiring | [...] | [[...]] Field fooServices in component class [...] must not be declared as final

The reference in SCR Component descriptor contains the attribute field (which is likely the cause for the errors):

<reference name="fooServices" cardinality="1..n" policy="dynamic" interface="FooService" bind="addFooService" unbind="removeFooService" field="fooServices"/>

If the combination of reference attributes as above is illegal, Maven Bundle Plugin should log the errors at compile time instead and break the build.

Issue Links

• is related to: FELIX-4586 A field must be volatile if methods are generated for a dynamic reference
• is related to: FELIX-4957 [DS][RFC-212] Various issues with field references