/*

 * Copyright 2009 D.E. Shaw.  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 6912517

 * @summary JIT bug compiles out (and stops running) code that needs to be run.  Causes NPE.

 *

 * @run main/othervm -Xbatch -XX:CompileThreshold=100 -XX:+IgnoreUnrecognizedVMOptions -XX:-UseCompressedOops Test

 */

/**

 * Highlights a bug with the JIT compiler.

 * @author Matt Bruce m b r u c e __\at/__ g m a i l DOT c o m

 */

public class Test implements Runnable

{

    private final Thread myThread;

    private Thread       myInitialThread;

    private boolean      myShouldCheckThreads;

    /**

     * Sets up the running thread, and starts it.

     */

    public Test(int id)

    {

        myThread = new Thread(this);

        myThread.setName("Runner: " + id);

        myThread.start();

        myShouldCheckThreads = false;

    }

    /**

     * @param shouldCheckThreads the shouldCheckThreads to set

     */

    public void setShouldCheckThreads(boolean shouldCheckThreads)

    {

        myShouldCheckThreads = shouldCheckThreads;

    }

    /**

     * Starts up the two threads with enough delay between them for JIT to

     * kick in.

     * @param args

     * @throws InterruptedException

     */

    public static void main(String[] args) throws InterruptedException

    {

        // let this run for a bit, so the "run" below is JITTed.

        for (int id = 0; id < 20; id++) {

            System.out.println("Starting thread: " + id);

            Test bug = new Test(id);

            bug.setShouldCheckThreads(true);

            Thread.sleep(2500);

        }

    }

    /**

     * @see java.lang.Runnable#run()

     */

    public void run()

    {

        long runNumber = 0;

        while (true) {

            // run hot for a little while, give JIT time to kick in to this loop.

            // then run less hot.

            if (runNumber > 15000) {

                try {

                    Thread.sleep(5);

                }

                catch (InterruptedException e) {

                    e.printStackTrace();

                }

            }

            runNumber++;

            ensureProperCallingThread();

        }

    }

    private void ensureProperCallingThread()

    {

        // this should never be null.  but with the JIT bug, it will be.

        // JIT BUG IS HERE ==>>>>>

        if (myShouldCheckThreads) {

            if (myInitialThread == null) {

                myInitialThread = Thread.currentThread();

            }

            else if (myInitialThread != Thread.currentThread()) {

                System.out.println("Not working: " + myInitialThread.getName());

            }

        }

    }

}