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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.tuscany.sca.core;
import static org.apache.tuscany.sca.extensibility.ServiceHelper.newInstance;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.HashSet;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.Set;
import org.apache.tuscany.sca.extensibility.ServiceDeclaration;
import org.apache.tuscany.sca.extensibility.ServiceDiscovery;
import org.apache.tuscany.sca.extensibility.ServiceHelper;
/**
* Default implementation of a registry to hold all the Tuscany core extension
* points. As the point of contact for all extension artifacts this registry
* allows loaded extensions to find all other parts of the system and register
* themselves appropriately.
*
* @tuscany.spi.extension.asclient
*
* @version $Rev$ $Date$
*/
public class DefaultExtensionPointRegistry implements ExtensionPointRegistry {
protected Map<Class<?>, Object> extensionPoints = new HashMap<Class<?>, Object>();
private ServiceDiscovery discovery;
/**
* Constructs a new registry.
*/
public DefaultExtensionPointRegistry() {
this.discovery = ServiceDiscovery.getInstance();
}
public DefaultExtensionPointRegistry(ServiceDiscovery discovery) {
this.discovery = discovery;
}
/**
* Add an extension point to the registry. This default implementation
* stores extensions against the interfaces that they implement.
*
* @param extensionPoint The instance of the extension point
*
* @throws IllegalArgumentException if extensionPoint is null
*/
public synchronized void addExtensionPoint(Object extensionPoint) {
addExtensionPoint(extensionPoint, null);
}
public synchronized void addExtensionPoint(Object extensionPoint, ServiceDeclaration declaration) {
if (extensionPoint == null) {
throw new IllegalArgumentException("Cannot register null as an ExtensionPoint");
}
ServiceHelper.start(extensionPoint);
Set<Class<?>> interfaces = getAllInterfaces(extensionPoint.getClass());
for (Class<?> i : interfaces) {
registerExtensionPoint(i, extensionPoint, declaration);
}
}
protected void registerExtensionPoint(Class<?> i, Object extensionPoint, ServiceDeclaration declaration) {
extensionPoints.put(i, extensionPoint);
}
/**
* Get the extension point by the interface that it implements
*
* @param extensionPointType The lookup key (extension point interface)
* @return The instance of the extension point
*
* @throws IllegalArgumentException if extensionPointType is null
*/
public synchronized <T> T getExtensionPoint(Class<T> extensionPointType) {
if (extensionPointType == null) {
throw new IllegalArgumentException("Cannot lookup ExtensionPoint of type null");
}
Object extensionPoint = findExtensionPoint(extensionPointType);
if (extensionPoint == null) {
// Dynamically load an extension point class declared under META-INF/services
try {
ServiceDeclaration extensionPointDeclaration =
getServiceDiscovery().getServiceDeclaration(extensionPointType);
if (extensionPointDeclaration != null) {
extensionPoint = newInstance(this, extensionPointDeclaration);
// Cache the loaded extension point
addExtensionPoint(extensionPoint, extensionPointDeclaration);
}
} catch (Throwable e) {
throw new IllegalArgumentException(e);
}
}
return extensionPointType.cast(extensionPoint);
}
protected <T> Object findExtensionPoint(Class<T> extensionPointType) {
return extensionPoints.get(extensionPointType);
}
/**
* Remove an extension point based on the interface that it implements
*
* @param extensionPoint The extension point to remove
*
* @throws IllegalArgumentException if extensionPoint is null
*/
public synchronized void removeExtensionPoint(Object extensionPoint) {
if (extensionPoint == null) {
throw new IllegalArgumentException("Cannot remove null as an ExtensionPoint");
}
ServiceHelper.stop(extensionPoint);
Set<Class<?>> interfaces = getAllInterfaces(extensionPoint.getClass());
for (Class<?> i : interfaces) {
unregisterExtensionPoint(i);
}
}
protected void unregisterExtensionPoint(Class<?> i) {
extensionPoints.remove(i);
}
/**
* Returns the set of interfaces implemented by the given class and its
* ancestors or a blank set if none
*/
private static Set<Class<?>> getAllInterfaces(Class<?> clazz) {
Set<Class<?>> implemented = new HashSet<Class<?>>();
getAllInterfaces(clazz, implemented);
implemented.remove(LifeCycleListener.class);
return implemented;
}
private static void getAllInterfaces(Class<?> clazz, Set<Class<?>> implemented) {
Class<?>[] interfaces = clazz.getInterfaces();
for (Class<?> interfaze : interfaces) {
if (Modifier.isPublic(interfaze.getModifiers())) {
implemented.add(interfaze);
}
}
Class<?> superClass = clazz.getSuperclass();
// Object has no superclass so check for null
if (superClass != null && !superClass.equals(Object.class)) {
getAllInterfaces(superClass, implemented);
}
}
public synchronized void start() {
ExtensionPointRegistryLocator.addExtensionPointRegistry(this);
}
public synchronized void stop() {
// Get a unique map as an extension point may exist in the map by different keys
Map<LifeCycleListener, LifeCycleListener> map = new IdentityHashMap<LifeCycleListener, LifeCycleListener>();
for (Object extp : extensionPoints.values()) {
if (extp instanceof LifeCycleListener) {
LifeCycleListener listener = (LifeCycleListener)extp;
map.put(listener, listener);
}
}
ServiceHelper.stop(map.values());
extensionPoints.clear();
ExtensionPointRegistryLocator.removeExtensionPointRegistry(this);
}
public ServiceDiscovery getServiceDiscovery() {
return discovery;
}
}
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