| /* |
| * 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.cloudstack.framework.messagebus; |
| |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| |
| import org.apache.logging.log4j.Logger; |
| import org.apache.logging.log4j.LogManager; |
| |
| public class MessageDispatcher implements MessageSubscriber { |
| protected Logger logger = LogManager.getLogger(getClass()); |
| |
| private static Map<Class<?>, List<Method>> s_handlerCache = new HashMap<Class<?>, List<Method>>(); |
| |
| private static Map<Object, MessageDispatcher> s_targetMap = new HashMap<Object, MessageDispatcher>(); |
| private Object _targetObject; |
| |
| public MessageDispatcher(Object targetObject) { |
| _targetObject = targetObject; |
| buildHandlerMethodCache(targetObject.getClass()); |
| } |
| |
| @Override |
| public void onPublishMessage(String senderAddress, String subject, Object args) { |
| dispatch(_targetObject, subject, senderAddress, args); |
| } |
| |
| public static MessageDispatcher getDispatcher(Object targetObject) { |
| MessageDispatcher dispatcher; |
| synchronized (s_targetMap) { |
| dispatcher = s_targetMap.get(targetObject); |
| if (dispatcher == null) { |
| dispatcher = new MessageDispatcher(targetObject); |
| s_targetMap.put(targetObject, dispatcher); |
| } |
| } |
| return dispatcher; |
| } |
| |
| public static void removeDispatcher(Object targetObject) { |
| synchronized (s_targetMap) { |
| s_targetMap.remove(targetObject); |
| } |
| } |
| |
| public boolean dispatch(Object target, String subject, String senderAddress, Object args) { |
| assert (subject != null); |
| assert (target != null); |
| |
| Method handler = resolveHandler(target.getClass(), subject); |
| if (handler == null) |
| return false; |
| |
| try { |
| handler.invoke(target, subject, senderAddress, args); |
| } catch (IllegalArgumentException e) { |
| logger.error("Unexpected exception when calling " + target.getClass().getName() + "." + handler.getName(), e); |
| throw new RuntimeException("IllegalArgumentException when invoking event handler for subject: " + subject); |
| } catch (IllegalAccessException e) { |
| logger.error("Unexpected exception when calling " + target.getClass().getName() + "." + handler.getName(), e); |
| throw new RuntimeException("IllegalAccessException when invoking event handler for subject: " + subject); |
| } catch (InvocationTargetException e) { |
| logger.error("Unexpected exception when calling " + target.getClass().getName() + "." + handler.getName(), e); |
| throw new RuntimeException("InvocationTargetException when invoking event handler for subject: " + subject); |
| } |
| |
| return true; |
| } |
| |
| public Method resolveHandler(Class<?> handlerClz, String subject) { |
| synchronized (s_handlerCache) { |
| List<Method> handlerList = s_handlerCache.get(handlerClz); |
| if (handlerList != null) { |
| for (Method method : handlerList) { |
| MessageHandler annotation = method.getAnnotation(MessageHandler.class); |
| assert (annotation != null); |
| |
| if (match(annotation.topic(), subject)) { |
| return method; |
| } |
| } |
| } else { |
| logger.error("Handler class " + handlerClz.getName() + " is not registered"); |
| } |
| } |
| |
| return null; |
| } |
| |
| private static boolean match(String expression, String param) { |
| return param.matches(expression); |
| } |
| |
| private void buildHandlerMethodCache(Class<?> handlerClz) { |
| if (logger.isInfoEnabled()) |
| logger.info("Build message handler cache for " + handlerClz.getName()); |
| |
| synchronized (s_handlerCache) { |
| List<Method> handlerList = s_handlerCache.get(handlerClz); |
| if (handlerList == null) { |
| handlerList = new ArrayList<Method>(); |
| s_handlerCache.put(handlerClz, handlerList); |
| |
| Class<?> clz = handlerClz; |
| while (clz != null && clz != Object.class) { |
| for (Method method : clz.getDeclaredMethods()) { |
| MessageHandler annotation = method.getAnnotation(MessageHandler.class); |
| if (annotation != null) { |
| // allow private member access via reflection |
| method.setAccessible(true); |
| handlerList.add(method); |
| |
| if (logger.isInfoEnabled()) |
| logger.info("Add message handler " + handlerClz.getName() + "." + method.getName() + " to cache"); |
| } |
| } |
| |
| clz = clz.getSuperclass(); |
| } |
| } else { |
| if (logger.isInfoEnabled()) |
| logger.info("Message handler for class " + handlerClz.getName() + " is already in cache"); |
| } |
| } |
| |
| if (logger.isInfoEnabled()) |
| logger.info("Done building message handler cache for " + handlerClz.getName()); |
| } |
| } |