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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 java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
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;
/**
* 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.
*
* @version $Rev$ $Date$
*/
public class DefaultExtensionPointRegistry implements ExtensionPointRegistry {
private Map<Class<?>, Object> extensionPoints = new HashMap<Class<?>, Object>();
/**
* Constructs a new registry.
*/
public DefaultExtensionPointRegistry() {
}
/**
* 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");
}
if (extensionPoint instanceof ModuleActivator) {
((ModuleActivator)extensionPoint).start(this);
}
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);
}
private Constructor<?> getConstructor(Constructor<?>[] constructors, Class<?>[] paramTypes) {
for (Constructor<?> c : constructors) {
Class<?>[] types = c.getParameterTypes();
if (c.getParameterTypes().length == paramTypes.length) {
boolean found = true;
for (int i = 0; i < types.length; i++) {
if (types[i] != paramTypes[i]) {
found = false;
break;
}
}
if (found) {
return c;
}
}
}
return null;
}
/**
* 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 =
ServiceDiscovery.getInstance().getServiceDeclaration(extensionPointType.getName());
if (extensionPointDeclaration != null) {
Class<?> extensionPointClass = extensionPointDeclaration.loadClass();
// Construct the extension point
Constructor<?>[] constructors = extensionPointClass.getConstructors();
Constructor<?> constructor =
getConstructor(constructors, new Class<?>[] {ExtensionPointRegistry.class});
if (constructor != null) {
extensionPoint = constructor.newInstance(this);
} else {
constructor = getConstructor(constructors, new Class<?>[] {});
if (constructor != null) {
extensionPoint = constructor.newInstance();
} else {
throw new IllegalArgumentException(
"No valid constructor is found for " + extensionPointClass);
}
}
// Cache the loaded extension point
addExtensionPoint(extensionPoint, extensionPointDeclaration);
}
} catch (InvocationTargetException e) {
throw new IllegalArgumentException(e);
} catch (IOException e) {
throw new IllegalArgumentException(e);
} catch (ClassNotFoundException e) {
throw new IllegalArgumentException(e);
} catch (InstantiationException e) {
throw new IllegalArgumentException(e);
} catch (IllegalAccessException 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");
}
if (extensionPoint instanceof ModuleActivator) {
((ModuleActivator)extensionPoint).stop(this);
}
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);
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 void destroy() {
// Get a unique map as an extension point may exist in the map by different keys
Map<ModuleActivator, ModuleActivator> map = new IdentityHashMap<ModuleActivator, ModuleActivator>();
for (Object extp : extensionPoints.values()) {
if (extp instanceof ModuleActivator) {
ModuleActivator activator = (ModuleActivator)extp;
map.put(activator, activator);
}
}
for (ModuleActivator activator : map.values()) {
activator.stop(this);
}
extensionPoints.clear();
}
}
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