Streams.java

/*
 * Copyright (c) 2012, 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 8003833
 * @summary Spurious NPE from Socket.getIn/OutputStream
 */

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.Phaser;

// Racey test, will not always fail, but if it does then there is a problem.

public class Streams {
    static final int NUM_THREADS = 100;
    static volatile boolean failed;
    static final Phaser startingGate = new Phaser(NUM_THREADS + 1);

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

        try (ServerSocket ss = new ServerSocket(0)) {
            runTest(OutputStreamGetter.class, ss);
            runTest(InputStreamGetter.class, ss);
        }

        if (failed)
            throw new RuntimeException("Failed, check output");
    }

    static void runTest(Class<? extends StreamGetter> klass, ServerSocket ss)
        throws Exception
    {
        final int port = ss.getLocalPort();
        Socket[] sockets = new Socket[NUM_THREADS];
        for (int i=0; i<NUM_THREADS; i++) {
            sockets[i] = new Socket("localhost", port);
            try (Socket socket = ss.accept()) {}
        }

        Constructor<? extends StreamGetter> ctr = klass.getConstructor(Socket.class);

        Thread[] threads = new Thread[NUM_THREADS];
        for (int i=0; i<NUM_THREADS; i++)
            threads[i] = ctr.newInstance(sockets[i]);
        for (int i=0; i<NUM_THREADS; i++)
            threads[i].start();

        startingGate.arriveAndAwaitAdvance();
        for (int i=0; i<NUM_THREADS; i++)
            sockets[i].close();

        for (int i=0; i<NUM_THREADS; i++)
            threads[i].join();
    }

    static abstract class StreamGetter extends Thread {
        final Socket socket;
        StreamGetter(Socket s) { socket = s; }

        @Override
        public void run() {
            try {
                startingGate.arriveAndAwaitAdvance();
                getStream();
            } catch (IOException x) {
                // OK, socket may be closed
            } catch (NullPointerException x) {
                x.printStackTrace();
                failed = true;
            }
        }

        abstract void getStream() throws IOException;
    }

    static class InputStreamGetter extends StreamGetter {
        public InputStreamGetter(Socket s) { super(s); }
        void getStream() throws IOException {
            socket.getInputStream();
        }
    }

    static class OutputStreamGetter extends StreamGetter {
        public OutputStreamGetter(Socket s) { super(s); }
        void getStream() throws IOException {
            socket.getOutputStream();
        }
    }
}