edu.cuny.cat.comm.QueueBasedCatpConnection.java Source code

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Here is the source code for edu.cuny.cat.comm.QueueBasedCatpConnection.java

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/*
 * JCAT - TAC Market Design Competition Platform
 * Copyright (C) 2006-2010 Jinzhong Niu, Kai Cai
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 */

package edu.cuny.cat.comm;

import org.apache.commons.collections15.Buffer;
import org.apache.commons.collections15.BufferUtils;
import org.apache.commons.collections15.buffer.UnboundedFifoBuffer;
import org.apache.log4j.Logger;

/**
 * <p>
 * The implementation of {@link Connection} when
 * {@link QueueBasedInfrastructureImpl} is used.
 * </p>
 * 
 * @author Jinzhong Niu
 * @version $Revision: 1.12 $
 */

public class QueueBasedCatpConnection implements ProactiveConnection<CatpMessage> {

    static Logger logger = Logger.getLogger(QueueBasedCatpConnection.class);

    /**
     * the {@link Connector} that requested to create this connection
     */
    protected Object connector;

    /**
     * the other side of the connection that may call
     * {@link #relayMessage(CatpMessage)} to transmit messages.
     */
    protected QueueBasedCatpConnection peer;

    /**
     * the queue buffering incoming messages
     */
    protected Buffer<CatpMessage> messages;

    /**
     * an identifier for this connection
     */
    protected String id;

    public QueueBasedCatpConnection(final Object connector, final String id) {
        this.connector = connector;
        this.id = id;
    }

    public Object getConnector() {
        return connector;
    }

    public void setConnector(final Object connector) {
        this.connector = connector;
    }

    public QueueBasedCatpConnection getPeer() {
        return peer;
    }

    public void setPeer(final QueueBasedCatpConnection peer) {
        this.peer = peer;
    }

    public void sendMessage(final CatpMessage msg) throws CatException {
        if (isClosed()) {
            throw new ConnectionException(getClass().getSimpleName() + " is closed or not open yet for writing !");
        }

        peer.relayMessage(msg);
    }

    public synchronized void relayMessage(final CatpMessage msg) throws CatException {
        if (messages == null) {
            try {
                wait();
            } catch (final InterruptedException e) {
                e.printStackTrace();
                throw new ConnectionException(
                        getClass().getSimpleName() + " is closed or not open yet for relaying !");
            }
        }

        synchronized (messages) {
            messages.add(msg);
            messages.notify();
        }
    }

    public CatpMessage getMessage() throws CatException {
        if (isClosed()) {
            throw new ConnectionException(getClass().getSimpleName() + " is closed or not open yet for reading !");
        }

        synchronized (messages) {
            if (messages.isEmpty()) {
                try {
                    messages.wait();
                } catch (final InterruptedException e) {
                    // thread waiting for messages interrupted, which is normal.
                    return null;
                }
            }
            return messages.remove();
        }
    }

    public synchronized void open() throws ConnectionException {
        messages = BufferUtils.synchronizedBuffer(new UnboundedFifoBuffer<CatpMessage>());
        notifyAll();
    }

    public void close() throws ConnectionException {
        messages = null;
    }

    public synchronized boolean isClosed() {
        return messages == null;
    }

    public String getLocalAddressInfo() {
        return id + "_local";
    }

    public String getRemoteAddressInfo() {
        return id + "_remote";
    }
}