relaylease.java

jxme的一些相关程序,主要是手机上程序开发以及手机和计算机通信的一些程序资料,程序编译需要Ant支持

/************************************************************************
 *
 * $Id: RelayLease.java,v 1.3 2002/06/05 18:34:51 jice Exp $
 *
 * Copyright (c) 2001 Sun Microsystems, Inc.  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
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
 *    must not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * 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 SUN MICROSYSTEMS 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 Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *********************************************************************************/

package net.jxta.impl.relay;

import java.util.TimerTask;
import net.jxta.impl.util.BoundedQueue;

/**
 * Represents a lease for either a relay server or a relay client.
 * All operations must be called from synchronized context except close
 * which it is better to call out-of-sync.
 */
public class RelayLease {

    /** How long the current lease was issued for **/
    private int leaseLength = 0;

    /** the lease key; stored as Base64-encoded string **/
    private String leaseId = null;
    
    /** the peerid that the lease is with **/
    private String peerId = null;

    /** the time in millis when the lease was obtained/renewed **/
    private long issueTime = 0;

    /** the expiration task currently registered with the timer **/
    private TimerTask currTimerTask = null;

    /** the queue used to store pending messages **/
    private BoundedQueue queue = new BoundedQueue(32);

    /**
     * Constructs a new lease
     * @param peerId The peerId of the client peer in the case that
     *   this is a server-side lease, or the peerId of the router peer if this
     *   is a client-side lease.
     * @param leaseId The Lease ID. Lease IDs are made up by the router peer
     * @param leaseLength The length in milliseconds of the lease
     */
    public RelayLease(String peerId, String leaseId, int leaseLength) {
	this.peerId = peerId;
	this.leaseId = leaseId;
	this.leaseLength = leaseLength;
	issueTime = System.currentTimeMillis();       
    }

    /**
     * safe keeps the given timer task reference.
     */
    public void setTimerTask(TimerTask currTimerTask) {
	this.currTimerTask = currTimerTask;
    }
    
    /**
     * Resets the issue time to right now, same length.
     */
    public void refresh() {
	issueTime = System.currentTimeMillis();
    }

    public boolean isValid() {
	long elapsedTime = System.currentTimeMillis() - issueTime;
	return (elapsedTime < leaseLength);
    }

    /**
     * returns a copy of the lease id
     */
    public String getLeaseId() {
	return leaseId;
    }

    /** Tells the length of the lease **/
    public int getLeaseLength() {
	return leaseLength;
    }

    /** Tells the time left **/
    public long getTimeLeft() {
	return  (issueTime + leaseLength) - System.currentTimeMillis();
    }

    /** Returns the other party's peerid **/
    public String getPeerId() {
	return peerId;
    }

    /** Returns the timer task that was last set **/
    public TimerTask getTimerTask() {
	return currTimerTask;
    }

    /** Returns the timer task that was last set **/
    public BoundedQueue getQueue() {
	return queue;
    }

    /**
     * Clears criticial resources such as the queue; there could be threads
     * waiting on the queue.
     * We remove the existing Q atomically. Then clear it out of sync.
     * That's the only operation that may and should be called out-of-sync.
     */
    public void close() {
	BoundedQueue oldQueue;
	synchronized(this) {
	    oldQueue = queue;
	    queue = null;
	}

	if (oldQueue != null) oldQueue.clear();
    }
}