io.neba.core.resourcemodels.registration

Class MappableTypeHierarchyChangeListener

java.lang.Object

io.neba.core.resourcemodels.registration.MappableTypeHierarchyChangeListener

All Implemented Interfaces:

org.osgi.service.event.EventHandler

public class MappableTypeHierarchyChangeListener
extends Object
implements org.osgi.service.event.EventHandler

Listens for resource property changes potentially altering the resource type -> model relationships. Invalidates the ModelRegistry accordingly.

In Sling, the sling type hierarchy of a resource is defined by multiple attributes and can be either explicit or implicit. For instance, a resource may explicitly specify a sling:resourceSuperType or the super type could be derived implicitly from the sling:resourceSuperType of the type the resource's sling:resourceType property is referring to, the former taking precedence. In addition, resources may specify mixin types, which can be added and removed dynamically.

Consequently, cached type hierarchy state must be cleared when these attributes change. This is what this event handler is responsible for.

Only valid cases are handled here. For instance, if a resource points to a sling:resourceType or sling:resourceSuperType, and that type or super type resource is removed at runtime, this handler does not invalidate the cache as this represents an invalid content state and is thus considered a programming error.

Author:

Olaf Otto

Constructor Summary

Constructors

Constructor and Description
MappableTypeHierarchyChangeListener()

Method Summary

Modifier and Type	Method and Description
protected void	activate()
protected void	deactivate()
void	handleEvent(org.osgi.service.event.Event event) A substantial number of events may reach this handler.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MappableTypeHierarchyChangeListener

public MappableTypeHierarchyChangeListener()

Method Detail

activate

protected void activate()

deactivate

protected void deactivate()

handleEvent

public void handleEvent(org.osgi.service.event.Event event)

A substantial number of events may reach this handler. However, we only need to clear the cache once. Thus, if there already is a pending invalidation, further invalidating events are simply discarded.

Specified by:

handleEvent in interface org.osgi.service.event.EventHandler