/*

 * Copyright (c) 2013, 2014, 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.

 *

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 */

/* @test

 * @bug 8014890

 * @summary Verify that a race between ReferenceQueue.enqueue() and poll() does not occur.

 * @author thomas.schatzl@oracle.com

 * @run main/othervm -Xmx10M EnqueuePollRace

 */

import java.lang.ref.*;

public class EnqueuePollRace {

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

        new WeakRef().run();

        System.out.println("Test passed.");

    }

    static class WeakRef {

        ReferenceQueue<Object> queue = new ReferenceQueue<Object>();

        final int numReferences = 100;

        final Reference refs[] = new Reference[numReferences];

        final int iterations = 1000;

        void run() throws InterruptedException {

            for (int i = 0; i < iterations; i++) {

                queue = new ReferenceQueue<Object>();

                for (int j = 0; j < refs.length; j++) {

                    refs[j] = new WeakReference(new Object(), queue);

                }

                System.gc(); // enqueues references into the list of discovered references

                // now manually enqueue all of them

                for (int j = 0; j < refs.length; j++) {

                    refs[j].enqueue();

                }

                // and get them back. There should be exactly numReferences

                // entries in the queue now.

                int foundReferences = 0;

                while (queue.poll() != null) {

                    foundReferences++;

                }

                if (foundReferences != refs.length) {

                    throw new RuntimeException("Got " + foundReferences + " references in the queue, but expected " + refs.length);

                }

            }

        }

    }

}