packetqueuesender.java

Bluetooth chat Server and Client in j2me

/*
 The Bluetooth Library for client-server communication
 Copyright (C) 2006 Martin Vysny

 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 net.sf.btw.btlib;

import java.io.IOException;
import java.io.InterruptedIOException;

import javax.bluetooth.L2CAPConnection;

import net.sf.btw.tools.Logger;
import net.sf.btw.tools.Queue;

/**
 * Contains all inner-class threads, to squeeze the package size.
 * 
 * @author Martin Vysny
 */
final class PacketQueueSender extends Thread {
	private volatile boolean interrupted = false;

	/**
	 * Constructs new instance and executes {@link #packetSchedulerThread()}.
	 * 
	 * @param scheduler
	 *            scheduler instance.
	 * @param id
	 *            client id
	 * @param connection
	 *            the connection to use. Sink.
	 */
	PacketQueueSender(final PacketScheduler scheduler, final byte id,
			final L2CAPConnection connection) {
		super();
		this.scheduler = scheduler;
		this.connection = connection;
		this.id = id;
	}

	private final PacketScheduler scheduler;

	private final static int MAX_PACKETS = 100;

	/**
	 * Thread locks onto this object whenever something needs to be done with
	 * the buffer.
	 */
	private final Queue buffer = new Queue(MAX_PACKETS);

	/**
	 * Client id.
	 */
	private final byte id;

	/**
	 * Sink packets here.
	 */
	private L2CAPConnection connection;

	/**
	 * Executes if {@link #scheduler} is not <code>null</code>. Schedules
	 * given packet for sending.
	 * 
	 * @throws InterruptedException
	 *             if the thread has been interrupted.
	 */
	private void packetSchedulerThread() throws InterruptedException {
		boolean firstRun = true;
		while (true) {
			synchronized (buffer) {
				if (interrupted)
					return;
				if (!firstRun)
					buffer.wait();
				else
					firstRun = false;
			}
			while (true) {
				// grab packet to send.
				byte[] toSend;
				synchronized (buffer) {
					if (interrupted)
						return;
					toSend = (byte[]) buffer.poll();
				}
				if (toSend == null)
					break;
				// send it.
				try {
					connection.send(toSend);
				} catch (InterruptedIOException e) {
					Logger.debug("PacketQueueSender" + id //$NON-NLS-1$
							+ ".packetSchedulerThread():sending", e); //$NON-NLS-1$
					return;
				} catch (IOException e) {
					Logger.log(interrupted ? Logger.LEVEL_INFO
							: Logger.LEVEL_ERROR, "PacketQueueSender" + id //$NON-NLS-1$
							+ "packetSchedulerThread():sending", e); //$NON-NLS-1$
					scheduler.listener.errorOccured(id,
							IErrorListener.ERROR_HINT_COMMUNICATING, false, e);
				}
			}
		}
	}

	/**
	 * Adds packet to the buffer.
	 * 
	 * @param packet
	 *            the packet to add.
	 */
	public void addPacket(byte[] packet) {
		synchronized (buffer) {
			if (!buffer.offer(packet)) {
				Logger.error("PacketQueueSender" + id //$NON-NLS-1$
						+ ".addPacket(): Buffer full", null); //$NON-NLS-1$
				scheduler.listener.errorOccured(id,
						IErrorListener.ERROR_HINT_COMMUNICATING, false, null);
			} else {
				buffer.notify();
			}
		}
	}

	/**
	 * Terminates the queue sender thread asap.
	 */
	public void interrupt() {
		interrupted = true;
		synchronized (buffer) {
			buffer.notify();
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.lang.Thread#run()
	 */
	public void run() {
		Logger.debug("PacketQueueSender.run(): started", null); //$NON-NLS-1$
		try {
			packetSchedulerThread();
		} catch (Exception ex) {
			Logger.log(interrupted ? Logger.LEVEL_INFO : Logger.LEVEL_ERROR,
					"PacketQueueSender" + id + ".run()", ex); //$NON-NLS-1$ //$NON-NLS-2$
		}
		Logger.debug("PacketQueueSender.run(): terminated", null); //$NON-NLS-1$
	}

}