multiplexedmanagedconnection.java

一个java方面的消息订阅发送的源码

/**
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 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 name "Exolab" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of Exoffice Technologies.  For written permission,
 *    please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "Exolab"
 *    nor may "Exolab" appear in their names without prior written
 *    permission of Exoffice Technologies. Exolab is a registered
 *    trademark of Exoffice Technologies.
 *
 * 5. Due credit should be given to the Exolab Project
 *    (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
 * ``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
 * EXOFFICE TECHNOLOGIES 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.
 *
 * Copyright 2004-2005 (C) Exoffice Technologies Inc. All Rights Reserved.
 *
 * $Id: MultiplexedManagedConnection.java,v 1.7 2005/06/04 14:28:53 tanderson Exp $
 */
package org.exolab.jms.net.multiplexer;

import java.io.IOException;
import java.security.Principal;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import EDU.oswego.cs.dl.util.concurrent.PooledExecutor;

import org.exolab.jms.net.connector.AbstractManagedConnection;
import org.exolab.jms.net.connector.Authenticator;
import org.exolab.jms.net.connector.Caller;
import org.exolab.jms.net.connector.CallerImpl;
import org.exolab.jms.net.connector.ConnectException;
import org.exolab.jms.net.connector.Connection;
import org.exolab.jms.net.connector.IllegalStateException;
import org.exolab.jms.net.connector.InvocationHandler;
import org.exolab.jms.net.connector.Request;
import org.exolab.jms.net.connector.ResourceException;
import org.exolab.jms.net.connector.Response;
import org.exolab.jms.net.connector.SecurityException;
import org.exolab.jms.net.uri.URI;
import org.exolab.jms.net.util.ThreadPool;


/**
 * A <code>ManagedConnection</code> that uses a {@link Multiplexer} to multiplex
 * data over an {@link Endpoint}
 *
 * @author <a href="mailto:[e-mail]">Tim Anderson</a>
 * @version $Revision: 1.7 $ $Date: 2005/06/04 14:28:53 $
 */
public abstract class MultiplexedManagedConnection
        extends AbstractManagedConnection
        implements MultiplexerListener {

    /**
     * The multiplexer.
     */
    private Multiplexer _multiplexer;

    /**
     * The thread used to run {@link #_multiplexer}.
     */
    private Thread _multiplexThread;

    /**
     * The endpoint to multiplex data over.
     */
    private Endpoint _endpoint;

    /**
     * The invocation handler.
     */
    private InvocationHandler _invoker;

    /**
     * The security principal.
     */
    private Principal _principal;

    /**
     * The connection authenticator, for server side instances.
     */
    private Authenticator _authenticator;

    /**
     * Cached caller instance. Non-null if this is a server-side instance.
     */
    private Caller _caller;

    /**
     * The thread pool for handling invocation requests.
     */
    private PooledExecutor _pool;

    /**
     * Determines if the thread pool is shared amongst multiple managed
     * connections. If so, this isn't responsible for cleaning it up.
     */
    private final boolean _sharedPool;

    /**
     * The thread group to associate any allocated threads with.
     */
    private ThreadGroup _group;

    /**
     * The maximum no. of threads to use at any one time.
     */
    private static final int THREAD_POOL_SIZE = 10;

    /**
     * The logger.
     */
    private static final Log _log =
            LogFactory.getLog(MultiplexedManagedConnection.class);


    /**
     * Construct a new client <code>MultiplexedManagedConnection</code>.
     *
     * @param principal the security principal. May be <code>null</code>
     */
    public MultiplexedManagedConnection(Principal principal) {
        _principal = principal;
        _sharedPool = false;
    }

    /**
     * Construct a new server <code>MultiplexedManagedConnection</code>.
     *
     * @param authenticator the connection authenticator
     * @param pool          the thread pool for handling invocation requests.
     *                      May be <code>null</code>
     */
    public MultiplexedManagedConnection(Authenticator authenticator,
                                        PooledExecutor pool) {
        if (authenticator == null) {
            throw new IllegalArgumentException(
                    "Argument 'authenticator' is null");
        }
        _authenticator = authenticator;
        if (pool != null) {
            _pool = pool;
            _sharedPool = true;
        } else {
            _sharedPool = false;
        }
    }

    /**
     * Registers a handler for handling invocations on objects exported via this
     * connection. Once a handler is registered, it cannot be de-registered.
     *
     * @param handler the invocation handler
     * @throws IllegalStateException if a handler is already registered
     * @throws ResourceException     for any error
     */
    public void setInvocationHandler(InvocationHandler handler)
            throws ResourceException {
        if (_invoker != null) {
            throw new IllegalStateException(
                    "An invocation handler is already registered");
        }
        _invoker = handler;
        try {
            _endpoint = createEndpoint();
            if (isClient()) {
                _multiplexer = createMultiplexer(_endpoint, _principal,
                                                 getThreadPool());
            } else {
                _multiplexer = createMultiplexer(_endpoint, _authenticator,
                                                 getThreadPool());
                _principal = _multiplexer.getPrincipal();
                _caller = new CallerImpl(getRemoteURI(), getLocalURI());
            }
            String name = getDisplayName() + "-Multiplexer";
            _multiplexThread = new Thread(getThreadGroup(), _multiplexer,
                                          name);
            _multiplexThread.start();
        } catch (IOException exception) {
            throw new ConnectException("Failed to start multiplexer",
                                       exception);
        }
    }

    /**
     * Creates a new connection handle for the underlying physical connection.
     *
     * @return a new connection handle
     * @throws IllegalStateException if an invocation handler hasn't been
     *                               registered
     */
    public synchronized Connection getConnection()
            throws IllegalStateException {
        if (_invoker == null) {
            throw new IllegalStateException("No InvocationHandler registered");
        }
        return new MultiplexedConnection(this);
    }

    /**
     * Determines if the underlying physical connection is alive.
     *
     * @return <code>true</code> if the connection is alive
     */
    public boolean isAlive() {
        boolean alive = false;
        Multiplexer multiplexer;
        synchronized (this) {
            multiplexer = _multiplexer;
        }
        if (multiplexer != null) {
            Channel channel = null;
            try {
                channel = multiplexer.getChannel();
                channel.ping();
                alive = true;
                channel.release();
            } catch (IOException exception) {
                _log.debug("Failed to ping", exception);
                if (channel != null) {
                    channel.destroy();
                }
            }
        }
        return alive;
    }