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Glassfish example source code file (UniqueIdGenerator.java)
The Glassfish UniqueIdGenerator.java source code/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can * obtain a copy of the License at * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html * or packager/legal/LICENSE.txt. See the License for the specific * language governing permissions and limitations under the License. * * When distributing the software, include this License Header Notice in each * file and include the License file at packager/legal/LICENSE.txt. * * GPL Classpath Exception: * Oracle designates this particular file as subject to the "Classpath" * exception as provided by Oracle in the GPL Version 2 section of the License * file that accompanied this code. * * Modifications: * If applicable, add the following below the License Header, with the fields * enclosed by brackets [] replaced by your own identifying information: * "Portions Copyright [year] [name of copyright owner]" * * Contributor(s): * If you wish your version of this file to be governed by only the CDDL or * only the GPL Version 2, indicate your decision by adding "[Contributor] * elects to include this software in this distribution under the [CDDL or GPL * Version 2] license." If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ package com.sun.ejb.codegen; import java.util.logging.Logger; import java.util.logging.Level; import com.sun.ejb.containers.EjbContainerUtilImpl; import com.sun.logging.LogDomains; /** * Generates unique id for an application or stand alone ejb module. * * It uses the low order 6 bytes of the system current time. The remaining * 2 bytes are reserved for the beans inside the application and stand * alone ejb module. * * The unique id generated by this generator will eventually wrap after * 2^48 milli-seconds (8,925.25 years). * * The two bytes reserved for the beans in the application or stand alone ejb * module will allow max 2^16 (65,536) beans. * * @author Nazrul Islam * @since JDK1.4 */ public class UniqueIdGenerator { /** last unique id given out by this id generator */ private long _lastUid = 0; /** the singleton instance */ private static final UniqueIdGenerator _instance = new UniqueIdGenerator(); private Logger _logger = LogDomains.getLogger(UniqueIdGenerator.class, LogDomains.EJB_LOGGER); private UniqueIdGenerator() { } /** * Returns the singleton instance of this class. * * @return the singleton instance */ public static UniqueIdGenerator getInstance() { return _instance; } /** * Returns the next unique id for an application or * stand alone ejb module. * * @return the next unique id */ public long getNextUniqueId() { synchronized (this) { while (true) { long uid = System.currentTimeMillis(); // uses the low order 6 bytes as unique id; // remaining 2 bytes are reserved for the beans inside the app uid = (uid << 16); // ensures that we have a unique id if (this._lastUid != uid) { this._lastUid = uid; break; } else { try { Thread.currentThread().sleep(1); } catch (InterruptedException ie) { // log debug msg here _logger.log(Level.WARNING,"Thread.sleep interrupted ",ie); } } } return this._lastUid; } } } Other Glassfish examples (source code examples)Here is a short list of links related to this Glassfish UniqueIdGenerator.java source code file: |
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