/*

 * 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

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 */

/* @test

 * @bug 4669040

 * @summary Test DatagramChannel receive with empty buffer

 * @author Mike McCloskey

 */

import java.io.*;

import java.net.*;

import java.nio.*;

import java.nio.channels.*;

import java.nio.charset.*;

public class EmptyBuffer {

    static PrintStream log = System.err;

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

        test();

    }

    static void test() throws Exception {

        Server server = new Server();

        Thread serverThread = new Thread(server);

        serverThread.start();

        DatagramChannel dc = DatagramChannel.open();

        try {

            ByteBuffer bb = ByteBuffer.allocateDirect(12);

            bb.order(ByteOrder.BIG_ENDIAN);

            bb.putInt(1).putLong(1);

            bb.flip();

            InetAddress address = InetAddress.getLocalHost();

            InetSocketAddress isa = new InetSocketAddress(address, server.port());

            dc.connect(isa);

            dc.write(bb);

            bb.rewind();

            dc.write(bb);

            bb.rewind();

            dc.write(bb);

            Thread.sleep(2000);

            serverThread.interrupt();

            server.throwException();

        } finally {

            dc.close();

        }

    }

    public static class Server implements Runnable {

        final DatagramChannel dc;

        Exception e = null;

        Server() throws IOException {

            this.dc = DatagramChannel.open().bind(new InetSocketAddress(0));

        }

        int port() {

            return dc.socket().getLocalPort();

        }

        void throwException() throws Exception {

            if (e != null)

                throw e;

        }

        void showBuffer(String s, ByteBuffer bb) {

            log.println(s);

            bb.rewind();

            for (int i=0; i<bb.limit(); i++) {

                byte element = bb.get();

                log.print(element);

            }

            log.println();

        }

        public void run() {

            SocketAddress sa = null;

            int numberReceived = 0;

            try {

                ByteBuffer bb = ByteBuffer.allocateDirect(12);

                bb.clear();

                // Only one clear. The buffer will be full after

                // the first receive, but it should still block

                // and receive and discard the next two

                while (!Thread.interrupted()) {

                    try {

                        sa = dc.receive(bb);

                    } catch (ClosedByInterruptException cbie) {

                        // Expected

                        log.println("Took expected exit");

                        break;

                    }

                    if (sa != null) {

                        log.println("Client: " + sa);

                        showBuffer("RECV", bb);

                        sa = null;

                        numberReceived++;

                        if (numberReceived > 3)

                            throw new RuntimeException("Test failed");

                    }

                }

            } catch (Exception ex) {

                e = ex;

            } finally {

                try { dc.close(); } catch (IOException ignore) { }

            }

        }

    }

}