/*

 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

/*

 * @test

 * @bug 4992438 6633113

 * @summary Checks that fairness setting is respected.

 */

import java.util.concurrent.*;

import java.util.concurrent.locks.*;

public class Fairness {

    private static void testFairness(boolean fair,

                                     final BlockingQueue<Integer> q)

        throws Throwable

    {

        final ReentrantLock lock = new ReentrantLock();

        final Condition ready = lock.newCondition();

        final int threadCount = 10;

        final Throwable[] badness = new Throwable[1];

        lock.lock();

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

            final Integer I = i;

            Thread t = new Thread() { public void run() {

                try {

                    lock.lock();

                    ready.signal();

                    lock.unlock();

                    q.put(I);

                } catch (Throwable t) { badness[0] = t; }}};

            t.start();

            ready.await();

            // Probably unnecessary, but should be bullet-proof

            while (t.getState() == Thread.State.RUNNABLE)

                Thread.yield();

        }

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

            int j = q.take();

            // Non-fair queues are lifo in our implementation

            if (fair ? j != i : j != threadCount - 1 - i)

                throw new Error(String.format("fair=%b i=%d j=%d%n",

                                              fair, i, j));

        }

        if (badness[0] != null) throw new Error(badness[0]);

    }

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

        testFairness(false, new SynchronousQueue<Integer>());

        testFairness(false, new SynchronousQueue<Integer>(false));

        testFairness(true,  new SynchronousQueue<Integer>(true));

    }

}