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https://issues.apache.org/jira/browse/FELIX-6036?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16751587#comment-16751587
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ASF GitHub Bot commented on FELIX-6036:
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GitHub user tjwatson opened a pull request:
https://github.com/apache/felix/pull/170
FELIX-6036 - avoid stashing stale RefPair objects in OpenStatus
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/tjwatson/felix fixSCR-6036
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/felix/pull/170.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #170
----
commit 072aa9539a9ce1636304ee25e4b1fc598959a393
Author: Tom Watson <tjwatson@...>
Date: 2019-01-24T16:46:13Z
FELIX-6036 - avoid stashing stale RefPair objects in OpenStatus
----
> 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
> Priority: Major
>
> 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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