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David Jencks updated FELIX-3456: -------------------------------- Attachment: FELIX-3456-8a.diff same result as previous patch but applies to current trunk. I'm not sure how to functionally improve this, I'm tempted to suggest applying it. > Component ignores required static service addition when in Activating state > --------------------------------------------------------------------------- > > Key: FELIX-3456 > URL: https://issues.apache.org/jira/browse/FELIX-3456 > Project: Felix > Issue Type: Bug > Components: Declarative Services (SCR) > Affects Versions: scr-1.6.0 > Environment: Using org.apache.felix.scr svn rev 1298268 on Mac > Reporter: Richard Ellis > Priority: Critical > Fix For: scr-1.6.2 > > Attachments: FELIX-3456-1.1.diff, FELIX-3456-1.diff, > FELIX-3456-3.diff, FELIX-3456-4.diff, FELIX-3456-5.diff, FELIX-3456-5a.diff, > FELIX-3456-5b.diff, FELIX-3456-7.diff, FELIX-3456-7a.diff, FELIX-3456-8.diff, > FELIX-3456-8a.diff, FELIX-3456-fmeschbe-6.patch, FELIX-3456-fmeschbe.patch > > > I have a component with two required static service references (A and B). In > my scenario A and B are registered nearly simultaneously on different threads > and this causes the DependencyManager to ignore the addition of one of these > two services (B). This causes the component to remain unsatisfied and never > activate, since the service that was ignored is not re-registered at any time > and nothing subsequently causes the component to re-activate. > This happens as follows: > 12:30:59:317 Thread 1 - Registers Service B/257 > 12:30:59:320 Thread 2 - Registers Service A/258 > 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 > 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, > activate component > 12:30:59:321 Thread 2 - State transition : Unsatisfied -> Activating > 12:30:59:321 Thread 2 - Activating component > 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 > 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB > 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored > for static reference <--- I believe we end up here because Thread 2 has moved > the component from Unsatisfied to Activating and the reference is a static > reference > 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate > 12:30:59:321 Thread 2 - State transition : Activating -> Unsatisfied > Because the addition of Service B has been ignored and serviceB is a required > dependency my component then never activates even though my reqiured service > is present. > There is a comment in DependencyManager#serviceAdded method: > // FELIX-1413: if the dependency is static and the component is > // satisfied (active) added services are not considered until > // the component is reactivated for other reasons. > This suggests that the static service should only be ignored if the component > is satisfied(active), which would be correct, but in this case the component > is only activating (and will fail to activate because one of the two > dependencies is not yet satisfied) and there is no check of state at this > time. > A simple fix would be to check the state of the component as well as if the > service is static e.g. > replace if ( m_dependencyMetadata.isStatic() ) > with if ( m_dependencyMetadata.isStatic() && m_componentManager.getState() == > AbstractComponentManager.STATE_ACTIVE ) > This is an easy fix, but I guess may leave a small window where a static > reference could get replaced while a component was still activating if > another instance of the same service was registered on a different thread. > There are other fixes that could be done by synchronizing more around service > additions. > Is anyone willing to make this fix or does anyone have any thoughts about > this issue? > Thanks -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira