import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.StandardSocketOptions;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.util.logging.Level;

/**
 * Created by leonid on 08.07.14.
 */
public class UDPListenerTest {
    private volatile DatagramChannel channel;
    private ListenerThread listenerThread;

    UDPListenerTest() {
        try {
            channel = DatagramChannel.open();
            // The following receive buffer value is empirical. It's known to
            // be enough to handle 1000 clients sending JUT records every 1-10s
            channel.setOption(StandardSocketOptions.SO_RCVBUF, 6553600);
            channel.bind(new InetSocketAddress(19870));
            listenerThread = new ListenerThread();
            listenerThread.start();
        } catch (Exception z) {
            z.printStackTrace();
        }
    }

    public void shutdown() {
        listenerThread.terminate();
        try {
            listenerThread.join();
        } catch (Exception z) {
            z.printStackTrace(System.err);
        }
    }

    public static void main(String[] args) {
        UDPListenerTest t = new UDPListenerTest();
        try {
            Thread.sleep(3000);
        } catch (Exception e) {
        }

        t.shutdown();
    }

    public class ListenerThread extends Thread {
        private volatile boolean shouldTerminate;

        @Override
        public void run() {
            ByteBuffer buf = ByteBuffer.allocate(6553600);
            shouldTerminate = false;
            while (!shouldTerminate) {
                try {
                    buf.rewind();
                    channel.receive(buf);
                } catch (IOException z) {
                    if (!shouldTerminate) {
                        z.printStackTrace(System.err);
                    }
                }
            }
        }

        public void terminate() {
            shouldTerminate = true;
            try {
                channel.close();
            } catch (Exception z) {
                z.printStackTrace(System.err);
                // ignore
            }
        }
    }
}