| /* |
| * 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.openaz.xacml.admin; |
| |
| import java.io.Serializable; |
| import java.util.LinkedList; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Executors; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| /** |
| * Handle Notifications from the PAP that the PDP Groups have been changed. |
| * We need a Server Push Broadcaster because there may be multiple Vaadin instances (i.e. Users) that need to be told when a change occurs. |
| * |
| * Initially we only update the entire set of PDPGroups in one shot. |
| * |
| * (Code copied from Book of Vaadin chapter on Server Push |
| * @author glenngriffin |
| * |
| */ |
| public class PAPNotificationBroadcaster implements Serializable { |
| /** |
| * |
| */ |
| private static final long serialVersionUID = -2539940306348821754L; |
| |
| |
| private static Log logger = LogFactory.getLog(PAPNotificationBroadcaster.class); |
| |
| |
| static ExecutorService executorService = Executors.newSingleThreadExecutor(); |
| |
| /** |
| * Interface used by all classes that need to be notified when PAP sends an update message. |
| * |
| * @author glenngriffin |
| * |
| */ |
| public interface PAPNotificationBroadcastListener { |
| void updateAllGroups(); |
| } |
| |
| |
| |
| /* |
| * list of registered listeners |
| */ |
| private static LinkedList<PAPNotificationBroadcastListener> listeners = |
| new LinkedList<PAPNotificationBroadcastListener>(); |
| |
| /** |
| * Listener registers to hear about updates. |
| * @param listener |
| */ |
| public static synchronized void register( |
| PAPNotificationBroadcastListener listener) { |
| listeners.add(listener); |
| } |
| |
| |
| /** |
| * Listener is going away. |
| * |
| * @param listener |
| */ |
| public static synchronized void unregister( |
| PAPNotificationBroadcastListener listener) { |
| listeners.remove(listener); |
| } |
| |
| |
| |
| /** |
| * Tell all listeners about an update. |
| * |
| * @param message |
| */ |
| public static synchronized void updateAllGroups() { |
| for (final PAPNotificationBroadcastListener listener: listeners) { |
| // Original code copied from example: |
| // executorService.execute(new Runnable() { |
| // @Override |
| // public void run() { |
| // The problem with this is that the execute starts a new Thread, but the thing we are calling (the listener.updateAllGroups) |
| // happens in this case to ALSO create a new thread, and it locks up because the shared threadpool queue is already locked by this method. |
| // On application shutdown that left us with a blocked thread, so the process never goes away. |
| // Since the listener.updateAllGroups does ALL of its work inside a new Runnable thread, there should be no need for this method to also create a thread. |
| |
| /* |
| * IMPORTANT: |
| * All listeners MUST either execute with no possibility of blocking |
| * OR must start their own threads to handle blocking and concurrent operations. |
| */ |
| if (logger.isDebugEnabled()) { |
| logger.debug("updateAllGroups"); |
| } |
| listener.updateAllGroups(); |
| } |
| } |
| } |