simplelockmanager.java

来自「java pos,你可以直接编译运行,」· Java 代码 · 共 153 行

/*
 * Copyright (c) 2000 jPOS.org.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *    "This product includes software developed by the jPOS project 
 *    (http://www.jpos.org/)". Alternately, this acknowledgment may 
 *    appear in the software itself, if and wherever such third-party 
 *    acknowledgments normally appear.
 *
 * 4. The names "jPOS" and "jPOS.org" must not be used to endorse 
 *    or promote products derived from this software without prior 
 *    written permission. For written permission, please contact 
 *    [e-mail].
 *
 * 5. Products derived from this software may not be called "jPOS",
 *    nor may "jPOS" appear in their name, without prior written
 *    permission of the jPOS project.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  
 * IN NO EVENT SHALL THE JPOS PROJECT OR ITS CONTRIBUTORS BE LIABLE FOR 
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the jPOS Project.  For more
 * information please see <http://www.jpos.org/>.
 */

package org.jpos.util;

/*
 * $Log: SimpleLockManager.java,v $
 * Revision 1.6  2003/10/13 10:46:16  apr
 * tabs expanded to spaces
 *
 * Revision 1.5  2003/05/16 04:11:04  alwyns
 * Import cleanups.
 *
 * Revision 1.4  2000/11/02 12:09:18  apr
 * Added license to every source file
 *
 * Revision 1.3  2000/03/01 14:44:45  apr
 * Changed package name to org.jpos
 *
 * Revision 1.2  2000/02/03 00:41:55  apr
 * .
 *
 * Revision 1.1  2000/01/30 23:32:53  apr
 * pre-Alpha - CVS sync
 *
 */

/**
 * @author [e-mail]
 * @since jPOS 1.1
 * @version $Id: SimpleLockManager.java,v 1.6 2003/10/13 10:46:16 apr Exp $
 */

import java.util.Hashtable;
import java.util.Map;

public class SimpleLockManager implements LockManager {
    Map locks;

    public SimpleLockManager () {
        locks = new Hashtable();
    }

    public class SimpleTicket implements Ticket {
        String resourceName;
        long expiration;
        public SimpleTicket (String resourceName, long duration) {
            this.resourceName = resourceName;
            this.expiration = System.currentTimeMillis() + duration;
        }
        public boolean renew (long duration) {
            if (!isExpired()) {
                this.expiration = System.currentTimeMillis() + duration;
                return true;
            }
            return false;
        }
        public long getExpiration() {
            return expiration;
        }
        public boolean isExpired() {
            return System.currentTimeMillis() > expiration;
        }
        public String getResourceName () {
            return resourceName;
        }
        public void cancel() {
            expiration = 0;
            locks.remove (resourceName);
            synchronized (this) {
                notify();
            }
        }
        public String toString() {
            return super.toString() 
                + "[" + resourceName + "/" +isExpired() + "/"
                + (expiration - System.currentTimeMillis()) + "ms left]";
        }
    }
    public Ticket lock (String resourceName, long duration, long wait)
    {
        long maxWait = System.currentTimeMillis() + wait;

        while (System.currentTimeMillis() < maxWait) {
            Ticket t = null;
            synchronized (this) {
                t = (Ticket) locks.get (resourceName);
                if (t == null) {
                    t = new SimpleTicket (resourceName, duration);
                    locks.put (resourceName, t);
                    return t;
                } 
                else if (t.isExpired()) {
                    t.cancel();
                    continue;
                }
            }
            synchronized (t) {
                try {
                    t.wait (Math.min (1000, wait));
                } catch (InterruptedException e) { }
            }
        }
        return null;
    }
}