httpservletmessenger.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

/*
 * Copyright (c) 2001-2007 Sun Microsystems, Inc.  All rights reserved.
 *  
 *  The Sun Project JXTA(TM) Software License
 *  
 *  Redistribution and use in source and binary forms, with or without 
 *  modification, are permitted provided that the following conditions are met:
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 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
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 *     and/or other materials provided with the distribution.
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 *  3. The end-user documentation included with the redistribution, if any, must 
 *     include the following acknowledgment: "This product includes software 
 *     developed by Sun Microsystems, Inc. for JXTA(TM) technology." 
 *     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.
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 *  States and other countries.
 *  
 *  Please see the license information page at :
 *  <http://www.jxta.org/project/www/license.html> for instructions on use of 
 *  the license in source files.
 *  
 *  ====================================================================
 *  
 *  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.endpoint.servlethttp;

import java.util.Timer;
import java.util.TimerTask;

import java.io.IOException;

import java.util.logging.Level;
import net.jxta.logging.Logging;
import java.util.logging.Logger;

import net.jxta.endpoint.EndpointAddress;
import net.jxta.endpoint.Message;
import net.jxta.endpoint.MessageElement;
import net.jxta.endpoint.StringMessageElement;
import net.jxta.peergroup.PeerGroupID;

import net.jxta.impl.endpoint.BlockingMessenger;
import net.jxta.impl.endpoint.EndpointServiceImpl;
import net.jxta.impl.util.TimeUtils;

/**
 * Simple messenger that waits for a message to give back to the requesting client
 *
 * <p/>This messenger is not entirely thread-safe. You should not use any
 * of the <code>sendMessage</code> methods from more than one thread.
 *
 */
final class HttpServletMessenger extends BlockingMessenger {
    
    /**
     *  Logger
     */
    private final static transient Logger LOG = Logger.getLogger(HttpServletMessenger.class.getName());
    
    // We need an explicit idle state. outgoingMessage being null is not enough
    // because there is an intermediate state where the http servlet must know
    // that there is nothing new to be sent but the relay side must also know
    // that status has not been collected yet (the messenger is not ready to be
    // reused). We use outgoingMessage == null to know that the message
    // has already been picked-up by the servlet thread, and
    // sendResult != IDLE to know that the result has not yet been collected
    // by the relay sender thread.
    
    private final static int SEND_IDLE = 0;
    private final static int SEND_INPROGRESS = 1;
    private final static int SEND_SUCCESS = 2;
    private final static int SEND_FAIL = 3;
    private final static int SEND_TOOLONG = 4;
    
    private final static long MAX_SENDING_BLOCK = 2 * TimeUtils.AMINUTE;
    private final static long MAX_SENDING_WAIT = 3 * TimeUtils.ASECOND;
    
    private final static EndpointAddress nullEndpointAddr = new EndpointAddress("http", "0.0.0.0:0", null, null);
    
    private final static Timer closeMessengerTimer = new Timer("HttpServletMessenger Expiration timer", true);
    
    private final EndpointAddress logicalAddress;
    private final MessageElement srcAddressElement;
    private ScheduledExipry expirationTask;
    
    /**
     *  The message "queue"
     */
    private Message outgoingMessage = null;
    
    private int sendResult = SEND_IDLE;
    private long sendingSince = 0;
    
    /**
     *  Allows us to schedule the closing of a messenger.
     */
    private static class ScheduledExipry extends TimerTask {

        /**
         *  The messenger we will be expiring.
         */
        HttpServletMessenger messenger;
        
        ScheduledExipry(HttpServletMessenger toExpire) {
            messenger = toExpire;
        }
        
        /**
         *  {@inheritDoc}
         */
        @Override
        public boolean cancel() {
            // It is important we clear the messenger because Timer doesn't
            // remove cancelled TimerTasks from it's queue until they fire. This
            // means that the Messenger would not be GCed until the TimerTask
            // fired.
            messenger = null;
            boolean result = super.cancel();

            // take the opportunity to also purge canceled tasks
            closeMessengerTimer.purge();
            return result;
        }
        
        /**
         *  {@inheritDoc}
         */
        @Override
        public void run() {
            try {
                HttpServletMessenger temp = messenger;

                messenger = null;
                
                if (null != temp) {
                    temp.close();
                }
            } catch (Throwable all) {
                if (Logging.SHOW_SEVERE && LOG.isLoggable(Level.SEVERE)) {
                    LOG.log(Level.SEVERE, "Uncaught Throwable in timer task :" + Thread.currentThread().getName(), all);
                }
            }
        }
    }
    
    /**
     *  Standard constructor.
     *
     * @param peerGroupID the peer group id
     * @param srcAddress  source address
     * @param logicalAddress logical address
     * @param validFor validity in milliseconds
     */
    HttpServletMessenger(PeerGroupID peerGroupID, EndpointAddress srcAddress, EndpointAddress logicalAddress, long validFor) {
        
        // We do not use self destruction.
        super(peerGroupID, nullEndpointAddr, false);
        
        this.logicalAddress = logicalAddress;
        
        this.srcAddressElement = new StringMessageElement(EndpointServiceImpl.MESSAGE_SOURCE_NAME, srcAddress.toString(), null);
        
        if ((0 != validFor) && (validFor < Long.MAX_VALUE)) {
            expirationTask = new ScheduledExipry(this);
            
            closeMessengerTimer.schedule(expirationTask, validFor);
        }
        
        if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
            LOG.fine("HttpServletMessenger\n\t" + toString());
        }
    }
    
    /**
     * {@inheritDoc}
     */
    @Override
    public synchronized void closeImpl() {
        if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
            LOG.fine("close\n\t" + toString());
        }
        
        ScheduledExipry cancelExpire = expirationTask;

        expirationTask = null;
        if (null != cancelExpire) {
            cancelExpire.cancel();
        }
        
        super.close();
        
        notifyAll();
    }
    
    /**
     * {@inheritDoc}
     */
    @Override
    public EndpointAddress getLogicalDestinationImpl() {
        return logicalAddress;
    }
    
    /**
     * {@inheritDoc}
     */