Java tutorial
// Copyright (c) 2007-Present Pivotal Software, Inc. All rights reserved. // // This software, the RabbitMQ Java client library, is triple-licensed under the // Mozilla Public License 1.1 ("MPL"), the GNU General Public License version 2 // ("GPL") and the Apache License version 2 ("ASL"). For the MPL, please see // LICENSE-MPL-RabbitMQ. For the GPL, please see LICENSE-GPL2. For the ASL, // please see LICENSE-APACHE2. // // This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, // either express or implied. See the LICENSE file for specific language governing // rights and limitations of this software. // // If you have any questions regarding licensing, please contact us at // info@rabbitmq.com. package com.rabbitmq.client.impl; import java.util.ArrayList; import java.util.List; import com.rabbitmq.client.ShutdownListener; import com.rabbitmq.client.ShutdownNotifier; import com.rabbitmq.client.ShutdownSignalException; /** * A class that manages {@link ShutdownListener}s and remembers the reason for a shutdown. Both * {@link com.rabbitmq.client.Channel Channel}s and {@link com.rabbitmq.client.Connection * Connection}s have shutdown listeners. */ public class ShutdownNotifierComponent implements ShutdownNotifier { /** Monitor for shutdown listeners and shutdownCause */ private final Object monitor = new Object(); /** List of all shutdown listeners associated with the component */ private final List<ShutdownListener> shutdownListeners = new ArrayList<ShutdownListener>(); /** * When this value is null, the component is in an "open" * state. When non-null, the component is in "closed" state, and * this value indicates the circumstances of the shutdown. */ private volatile ShutdownSignalException shutdownCause = null; @Override public void addShutdownListener(ShutdownListener listener) { ShutdownSignalException sse = null; synchronized (this.monitor) { sse = this.shutdownCause; this.shutdownListeners.add(listener); } if (sse != null) // closed listener.shutdownCompleted(sse); } @Override public ShutdownSignalException getCloseReason() { synchronized (this.monitor) { return this.shutdownCause; } } @Override public void notifyListeners() { ShutdownSignalException sse = null; ShutdownListener[] sdls = null; synchronized (this.monitor) { sdls = this.shutdownListeners.toArray(new ShutdownListener[this.shutdownListeners.size()]); sse = this.shutdownCause; } for (ShutdownListener l : sdls) { try { l.shutdownCompleted(sse); } catch (Exception e) { // FIXME: proper logging } } } @Override public void removeShutdownListener(ShutdownListener listener) { synchronized (this.monitor) { this.shutdownListeners.remove(listener); } } @Override public boolean isOpen() { synchronized (this.monitor) { return this.shutdownCause == null; } } /** * Internal: this is the means of registering shutdown. * @param sse the reason for the shutdown * @return <code>true</code> if the component is open; <code>false</code> otherwise. */ public boolean setShutdownCauseIfOpen(ShutdownSignalException sse) { synchronized (this.monitor) { if (isOpen()) { this.shutdownCause = sse; return true; } return false; } } }