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Diffstat (limited to 'branches/sca-java-2.0-M4/modules/extensibility/src/main/java/org/apache/tuscany/sca/core/DefaultExtensionPointRegistry.java')
-rw-r--r-- | branches/sca-java-2.0-M4/modules/extensibility/src/main/java/org/apache/tuscany/sca/core/DefaultExtensionPointRegistry.java | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/branches/sca-java-2.0-M4/modules/extensibility/src/main/java/org/apache/tuscany/sca/core/DefaultExtensionPointRegistry.java b/branches/sca-java-2.0-M4/modules/extensibility/src/main/java/org/apache/tuscany/sca/core/DefaultExtensionPointRegistry.java new file mode 100644 index 0000000000..f6be464cbc --- /dev/null +++ b/branches/sca-java-2.0-M4/modules/extensibility/src/main/java/org/apache/tuscany/sca/core/DefaultExtensionPointRegistry.java @@ -0,0 +1,182 @@ +/* + * 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. + * + * @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"); + } + 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 = + ServiceDiscovery.getInstance().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 void start() { + // Do nothing + } + + public 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(); + } + +} |