UDPReceiver.java

/*
 * Copyright Ericsson AB 2011-2014. All Rights Reserved.
 *
 * The contents of this file are subject to the Lesser GNU Public License,
 *  (the "License"), either version 2.1 of the License, or
 * (at your option) any later version.; you may not use this file except in
 * compliance with the License. You should have received a copy of the
 * License along with this software. If not, it can be
 * retrieved online at https://www.gnu.org/licenses/lgpl.html. Moreover
 * it could also be requested from Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * BECAUSE THE LIBRARY IS LICENSED FREE OF CHARGE, THERE IS NO
 * WARRANTY FOR THE LIBRARY, TO THE EXTENT PERMITTED BY APPLICABLE LAW.
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 * EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
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package com.ericsson.deviceaccess.coap.basedriver.communication;

import com.ericsson.deviceaccess.coap.basedriver.osgi.IncomingMessageListener;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class represents the UDP thread for listening to incoming UDP
 */
public class UDPReceiver implements Runnable, TransportLayerReceiver {

    private static final Logger LOGGER = LoggerFactory.getLogger(UDPReceiver.class);
    private final DatagramSocket socket;
    private final List<IncomingMessageListener> coapListeners = Collections.synchronizedList(new ArrayList<>());
    Thread thread;

    private volatile AtomicBoolean running = new AtomicBoolean(false);

    /**
     * Constructor using DatagramSocket
     *
     * @param socket
     */
    public UDPReceiver(DatagramSocket socket) {
        LOGGER.debug("UDP receiver with datagram socket");
        this.socket = socket;
    }

    public void cleanup() {
        coapListeners.clear();
        socket.close();
    }

    @Override
    public void run() {
        while (running.get()) {
            // TODO allocate buffer properly
            byte[] buffer = new byte[UDPConstants.MAX_DATAGRAM_SIZE + 1];
            DatagramPacket datagram = new DatagramPacket(buffer, buffer.length);
            try {
                socket.receive(datagram);
            } catch (IOException ex) {
                ex.printStackTrace();
            }
            // socket.close() will interrupt socket.receive()
            if (socket.isClosed()) {
                running.set(false);
            } else {
                this.datagramReceived(datagram);
            }
        }
    }

    @Override
    public void start() {
        running.set(true);
        thread = new Thread(this);
        thread.start();
    }

    /**
     * This method is used for notifying the CoAP listeners when a UDP datagram
     * is received
     *
     * @param datagram received datagram
     */
    private void datagramReceived(DatagramPacket datagram) {
        coapListeners.forEach(listener -> listener.messageReceived(datagram));
    }

    /**
     * Add an incoming message listener
     *
     * @param listener listener to add
     */
    @Override
    public void addListener(IncomingMessageListener listener) {
        coapListeners.add(listener);
    }

    /**
     * Removes an incomingmessagelistener
     *
     * @param listener
     * @return Returns true if the list contained the specified element
     */
    @Override
    public boolean removeListener(IncomingMessageListener listener) {
        return coapListeners.remove(listener);
    }

    @Override
    public void stopService() {
        cleanup();
    }
}