[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13252653#comment-13252653 ] Richard Ellis commented on FELIX-3456: -- On second thoughts I'm not sure my proposed fix goes far enough because even though it allows the second service to attempt to be bound, there is no guarantee that this bind operation will complete in a timely enough fashion for the activate process triggered by the first service to complete successfully. I think some synchronization will probably be required. 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 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
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13252655#comment-13252655 ] Richard Ellis commented on FELIX-3456: -- If only my browser had refreshed faster I could have agreed with you already David instead of disagreeing with myself :) I do agree David, my hasty attempt at a fix without a full understanding of the code is not correct. 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 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
