public void start()

in qpid-jms-discovery/src/main/java/org/apache/qpid/jms/provider/discovery/multicast/MulticastDiscoveryAgent.java [112:188]
64 lines of code
16 McCabe index (conditional complexity)

    public void start() throws ProviderException, IllegalStateException {
        if (listener == null) {
            throw new IllegalStateException("No DiscoveryListener configured.");
        }

        if (started.compareAndSet(false, true)) {

            if (group == null || group.length() == 0) {
                throw new ProviderException("You must specify a group to discover");
            }

            if (discoveryURI == null) {
                try {
                    discoveryURI = new URI(DEFAULT_DISCOVERY_URI_STRING);
                } catch (URISyntaxException e) {
                    // Default is always valid.
                }

                if (discoveryURI == null) {
                    throw new RuntimeException("Discovery URI unexpectedly null");
                }
            }

            LOG.trace("mcast - discoveryURI = {}", discoveryURI);

            String myHost = discoveryURI.getHost();
            int myPort = discoveryURI.getPort();

            if (myHost == null || DEFAULT_HOST_STR.equals(myHost)) {
                myHost = DEFAULT_HOST_IP;
            }

            if (myPort < 0) {
                myPort = DEFAULT_PORT;
            }

            LOG.trace("mcast - myHost = {}", myHost);
            LOG.trace("mcast - myPort = {}", myPort);
            LOG.trace("mcast - group = {}", group);
            LOG.trace("mcast - interface = {}", mcInterface);
            LOG.trace("mcast - network interface = {}", mcNetworkInterface);
            LOG.trace("mcast - join network interface = {}", mcJoinNetworkInterface);

            try {
                this.inetAddress = InetAddress.getByName(myHost);
                this.sockAddress = new InetSocketAddress(this.inetAddress, myPort);
                mcast = new MulticastSocket(myPort);
                mcast.setLoopbackMode(loopBackMode);
                mcast.setTimeToLive(getTimeToLive());
                if (mcJoinNetworkInterface != null) {
                    mcast.joinGroup(sockAddress, NetworkInterface.getByName(mcJoinNetworkInterface));
                } else {
                    if (mcNetworkInterface != null) {
                        mcast.setNetworkInterface(NetworkInterface.getByName(mcNetworkInterface));
                    } else {
                        trySetNetworkInterface(mcast);
                    }
                    mcast.joinGroup(inetAddress);
                }
                mcast.setSoTimeout((int) keepAliveInterval);
                if (mcInterface != null) {
                    mcast.setInterface(InetAddress.getByName(mcInterface));
                }

                if (mcNetworkInterface != null) {
                    mcast.setNetworkInterface(NetworkInterface.getByName(mcNetworkInterface));
                }
            } catch (IOException e) {
                throw ProviderExceptionSupport.createOrPassthroughFatal(e);
            }

            runner = new Thread(this);
            runner.setName(this.toString() + ":" + runner.getName());
            runner.setDaemon(true);
            runner.start();
        }
    }