Brent Daniel created FELIX-6036:
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Summary: Race condition prevents optional/greedy ref setter method
from being called
Key: FELIX-6036
URL: https://issues.apache.org/jira/browse/FELIX-6036
Project: Felix
Issue Type: Bug
Components: Declarative Services (SCR)
Affects Versions: scr-2.1.14
Reporter: Brent Daniel
I have a component with an optional/dynamic/greedy reference. The target is
registered directly with OSGi using BundleContext.registerService(). Normally,
either SingleDynamicCustomizer.addedService() or
SingleComponentManager.createImplementationObject() will succeed in binding the
reference, but there is a race condition that can prevent the setter method
from ever being called.
The failure path is as follows:
1) SingleComponentManager.createImplementationObject calls open() on each of
its DependencyManagers. This generates an OpenStatus where the RefPair list is
empty because our target has not been registered yet.
2) Before createImplementationObject() can set the component context, the
customizer's addedService() method is called in response to the target service
registration. It attempts to bind the target service, but that will not happen
because the component context has not been set yet.
3) createImplementationObject then creates the implementation, sets the
component context, and goes through the list of OpenStatus objects to bind
target services. The RefPair list for the OpenStatus object will still be
empty, so we will not call the setter method for the reference we're concerned
about.
I'm not sure of a good way to fix this. I couldn't come up with a good approach
using synchronization or earlier creation of the implementation object. At the
moment I am working around this by refreshing the list of RefPairs in the
OpenStatus object at the top of DependencyManager.bindDependency():
{code:java}
// Refresh ref list before binding
synchronized(m_tracker.tracked()) {
status.refs=m_customizer.getRefs(status.trackingCount);
}
{code}
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