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Java example source code file (Concurrent.java)

This example Java source code file (Concurrent.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

concurrent, datagrampacket, datagramsocket, exception, inetaddress, net, network, portunreachableexception, runnable, thread

The Concurrent.java Java example source code

/*
 * Copyright (c) 2001, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 4431020
 * @summary On Windows 2000 we observed behaviour that reflects the underlying
 * implementation :-
 *   1. PortUnreachableException throw per underlying reset
 *   2. No PUE throw for DatagramSocket.send
 */
import java.net.*;

public class Concurrent implements Runnable {

    DatagramSocket s;

    public void run() {
        try {
            byte b[] = new byte[512];
            DatagramPacket p = new DatagramPacket(b, b.length);

            int pue_count = 0;
            while (true) {
                try {
                    System.out.println("receive...");
                    s.receive(p);
                } catch (PortUnreachableException pue) {
                    System.out.println("receive threw PortUnreachableException");
                    pue_count++;
                }
                System.out.println("receiver sleeping");
                Thread.currentThread().sleep(100*pue_count);
            }

        } catch (Exception e) { }
    }

    Concurrent(InetAddress ia, int port) throws Exception {

        System.out.println("");
        System.out.println("***");
        System.out.println("Test Description:");
        System.out.println("    - Block reader thread on receive");
        System.out.println("    - Send datagrams to bad destination with wee pauses");
        System.out.println("    - Observe which thread gets the PUE");
        System.out.println("");

        /*
         * Create the datagram and connect it to destination
         */
        s = new DatagramSocket();
        s.connect(ia, port);
        s.setSoTimeout(60000);

        /*
         * Start the reader thread
         */
        Thread thr = new Thread(this);
        thr.start();
        Thread.currentThread().sleep(2000);

        byte b[] = new byte[512];
        DatagramPacket p = new DatagramPacket(b, b.length);

        /*
         * Send a bunch of packets to the destination
         */
        for (int i=0; i<10; i++) {
            try {
                System.out.println("Sending...");
                s.send(p);
            } catch (PortUnreachableException e) {
                System.out.println("send threw PortUnreachableException");
            }
            Thread.currentThread().sleep(100);
        }

        /*
         * Give time for ICMP port unreachables to return
         */
        Thread.currentThread().sleep(5000);

        s.close();
    }


    public static void main(String args[]) throws Exception {

        InetAddress ia;
        int port;
        if (args.length >= 2) {
            ia = InetAddress.getByName(args[0]);
            port = Integer.parseInt(args[1]);
        } else {
            ia = InetAddress.getLocalHost();
            DatagramSocket s1 = new DatagramSocket();
            port = s1.getLocalPort();
            s1.close();
        }

        new Concurrent(ia, port);
    }

}

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