[jira] Work started: (FELIX-993) Reference target filters not handled correctly

["Felix Meschberger (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FELIX-993?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Work on FELIX-993 started by Felix Meschberger.

> Reference target filters not handled correctly
> ----------------------------------------------
>
>                 Key: FELIX-993
>                 URL: https://issues.apache.org/jira/browse/FELIX-993
>             Project: Felix
>          Issue Type: Bug
>          Components: Declarative Services (SCR)
>    Affects Versions: scr-1.0.6
>            Reporter: Soren Petersen
>            Assignee: Felix Meschberger
>         Attachments: DependencyManager.patch
>
>
> The SCR implementation does not handle references with target filter correctly. When the properties of a bound service is modified so that the service no longer matches the reference filter it isn't unbound as it should.
> Suppose we have an event broadcaster component defined by:
> 	<component name="EventBroadcaster">
> 		<implementation class="example.EventBroadcaster" />
> 		<reference 
> 			name="eventListeners" 
> 			interface="example.EventListener"
> 			cardinality="0..n"
> 			policy="dynamic"
> 			bind="addListener"
> 			unbind="removeListener" 
> 			target="(listener.state=Active)" 
> 		/>
> 	</component>
> If an event listener is registered by the code
> 	Dictionary<String, Object> props = new Hashtable<String, Object>();
> 	props.put("listener.state", "Active");
> 	ServiceRegistration reg = context.registerService(EventListener.class.getName(), new EventListener(), props);
> the new service will be bound to our event broadcaster and the addListener method will be called. This is as it should be. Now, suppose we changed the properties of the service by executing
> 	Dictionary<String, Object> props2 = new Hashtable<String, Object>();
> 	props2.put("listener.state", "Inactive");
> 	reg.setProperties(props2);
> At this point, the event listener service should be unbound from the event broadcaster component since it does no longer match the target filter. However, due to a bug in org.apache.felix.scr.impl.DependencyManager, this the service stays bound and isn't even unbound if
> 	reg.unregister();
> is executed.
> The problem is, basically, caused by the following two segments of code:
> 	public void serviceChanged( ServiceEvent event )
> 	{
> 		switch ( event.getType() )
> 		{
> 			case ServiceEvent.REGISTERED:
> 				serviceAdded( event.getServiceReference() );
> 				break;
> 			case ServiceEvent.MODIFIED:
> 				serviceRemoved( event.getServiceReference() );
> 				serviceAdded( event.getServiceReference() );
> 				break;
> 			case ServiceEvent.UNREGISTERING:
> 				serviceRemoved( event.getServiceReference() );
> 				break;
> 		}
> 	}
> and
> 	private void serviceRemoved( ServiceReference reference )
> 	{
> 		// ignore the service, if it does not match the target filter
> 		if ( !targetFilterMatch( reference ) )
> 		{
> 			[...]
> 			return;
> 		}
> 		[...]
> 	}
> Since the properties of the service has already been modified when serviceChanged is called, the filter will no longer match the service and serviceRemoved will ignore it.

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