Pierre De Rop created FELIX-5045:
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Summary: DM Optional callbacks may sometimes be invoked before
start callback
Key: FELIX-5045
URL: https://issues.apache.org/jira/browse/FELIX-5045
Project: Felix
Issue Type: Bug
Components: Dependency Manager
Affects Versions: org.apache.felix.dependencymanager-r5
Reporter: Pierre De Rop
Assignee: Pierre De Rop
Fix For: org.apache.felix.dependencymanager-r6
We just found a corner case that triggers optional dependency callbacks before
the component is invoked in its 'start' lifecycel callback. This is a bug,
because in DM, optional dependency callbacks should be always invoked after the
component's 'start' lifecycle callback.
I'm describing now the use case: we have the following component players:
- B: a simple service component.
- BFactory: a service that has a 'create' method which registers in the OSGi
registry a new B service instance.
- A: a component that adds from A.init() lifecycle callback a required
dependency (with a callback) on BFactory, as well as an optional dependency
(with a callback) on B.
- when A.bind(BFactory factory) is called, it then calls "factory.create()"
method which triggers the registration of the B Service. At this point,
A.bind(B b) is then invoked, but the A.start() lifecycle callback has not yet
been called. This is because we are currently transiting from
INSTANTIATED_AND_WAITING_FOR_REQUIRED -> TRACKING_OPTIONAL; so the current
state is TRACKING_OPTIONAL, and we are calling the
invokeAddRequiredInstanceBoundDependencies()
method, which calls A.bind(BFactory) method, which synchronously registers a B
service instance; so this ends up calling the handleAdded method, which invoke
A.bind(B b) method, but at this point we have not yet called the A.start()
callback.
- then "A.start()" is called.
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