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/***************************************************************************
* Copyright (c) 2004, 2005, 2006 Eike Stepper, Germany.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Eike Stepper - initial API and implementation
**************************************************************************/
package org.eclipse.net4j.util.registry;
import org.eclipse.net4j.util.om.trace.ContextTracer;
import org.eclipse.net4j.util.registry.IRegistryElement.Descriptor;
import org.eclipse.net4j.util.registry.IRegistryListener.EventType;
import org.eclipse.internal.net4j.bundle.Net4j;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedQueue;
/**
* @author Eike Stepper
*/
public abstract class AbstractRegistry<ID, E extends IRegistryElement<ID>> implements
IRegistry<ID, E>
{
public static final boolean DEFAULT_RESOLVING = true;
private static final ContextTracer TRACER = new ContextTracer(Net4j.DEBUG_REGISTRY,
AbstractRegistry.class);
private boolean resolving;
/**
* Don't initialize lazily to circumvent synchronization!
*/
private Queue<IRegistryListener> listeners = new ConcurrentLinkedQueue();
protected AbstractRegistry()
{
this(DEFAULT_RESOLVING);
}
public AbstractRegistry(boolean resolving)
{
setResolving(resolving);
}
public void setResolving(boolean resolving)
{
this.resolving = resolving;
}
public final boolean isResolving()
{
return resolving;
}
public final boolean isResolved(ID id)
{
E element = lookup(id, false);
return element != null && !(element instanceof Descriptor);
}
public final boolean isRegistered(ID id)
{
return lookup(id, false) != null;
}
public int size()
{
return getElementIDs().size();
}
public final E lookup(ID id)
{
return lookup(id, isResolving());
}
public final Collection<E> getElements()
{
return getElements(isResolving());
}
/**
* Synchronized to support {@link #resolveElement(IRegistryElement)}
*/
public final synchronized Collection<E> getElements(boolean resolve)
{
Set<ID> elementKeys = getElementIDs();
List<E> elements = new ArrayList(elementKeys.size());
for (ID id : elementKeys)
{
elements.add(lookup(id, resolve));
}
return elements;
}
public void addRegistryListener(IRegistryListener<ID, E> listener)
{
listeners.add(listener);
}
public void removeRegistryListener(IRegistryListener<ID, E> listener)
{
listeners.remove(listener);
}
public void dispose()
{
listeners.clear();
}
protected void fireRegistryEvent(EventType eventType, E element)
{
for (IRegistryListener listener : listeners)
{
try
{
listener.notifyRegistryEvent(this, eventType, element);
}
catch (Exception ex)
{
if (TRACER.isEnabled())
{
TRACER.trace(ex);
}
}
}
}
protected void fireElementRegistered(E element)
{
fireRegistryEvent(EventType.REGISTERED, element);
}
protected void fireElementDeregistering(E element)
{
fireRegistryEvent(EventType.DEREGISTERING, element);
}
protected void fireElementResolved(E element)
{
fireRegistryEvent(EventType.RESOLVED, element);
}
/**
* Calling thread must already synchronize on this {@link IRegistry}!
*/
protected E resolveElement(E element)
{
if (element instanceof Descriptor)
{
element = (E)((Descriptor)element).resolve();
replaceElement(element.getID(), element);
fireElementResolved(element);
}
return element;
}
/**
* Calling thread must already synchronize on this {@link IRegistry}!
*/
protected abstract void replaceElement(ID id, E element);
}
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