| /******************************************************************************* |
| * Copyright (c) 2009, 2011 Oracle. All rights reserved. |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Public License v1.0, which accompanies this distribution |
| * and is available at http://www.eclipse.org/legal/epl-v10.html. |
| * |
| * Contributors: |
| * Oracle - initial API and implementation |
| ******************************************************************************/ |
| package org.eclipse.jpt.common.utility.synchronizers; |
| |
| import java.io.Serializable; |
| import java.util.EventListener; |
| import org.eclipse.jpt.common.utility.internal.StringTools; |
| |
| /** |
| * Extend {@link Synchronizer} to notify listeners |
| * when a synchronization "cycle" is complete; i.e. the synchronization has, |
| * for the moment, quiesced. |
| */ |
| public interface CallbackSynchronizer |
| extends Synchronizer |
| { |
| /** |
| * Add the specified listener to be notified whenever the synchronizer has |
| * quiesced. |
| * @see #removeListener(Listener) |
| */ |
| void addListener(Listener listener); |
| |
| /** |
| * Remove the specified listener. |
| * @see #addListener(Listener) |
| */ |
| void removeListener(Listener listener); |
| |
| |
| // ********** listener ********** |
| |
| /** |
| * Interface implemented by listeners to be notified whenever the |
| * synchronizer has quiesced. |
| */ |
| public interface Listener |
| extends EventListener |
| { |
| /** |
| * The specified synchronizer has quiesced. |
| */ |
| void synchronizationQuiesced(CallbackSynchronizer synchronizer); |
| } |
| |
| |
| /** |
| * Singleton implementation of the {@link CallbackSynchronizer} interface that will do |
| * nothing. |
| */ |
| final class Null |
| implements CallbackSynchronizer, Serializable |
| { |
| public static final CallbackSynchronizer INSTANCE = new Null(); |
| public static CallbackSynchronizer instance() { |
| return INSTANCE; |
| } |
| // ensure single instance |
| private Null() { |
| super(); |
| } |
| public void start() { |
| // do nothing |
| } |
| public void synchronize() { |
| // do nothing |
| } |
| public void stop() { |
| // do nothing |
| } |
| public void addListener(Listener listener) { |
| // do nothing |
| } |
| public void removeListener(Listener listener) { |
| // do nothing |
| } |
| @Override |
| public String toString() { |
| return StringTools.buildSingletonToString(this); |
| } |
| private static final long serialVersionUID = 1L; |
| private Object readResolve() { |
| // replace this object with the singleton |
| return INSTANCE; |
| } |
| } |
| } |