/*

 * 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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 */

/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file:

 *

 * Written by Doug Lea with assistance from members of JCP JSR-166

 * Expert Group and released to the public domain, as explained at

 * http://creativecommons.org/licenses/publicdomain

 */

/*

 * @test

 * @bug 4486658

 * @run main/timeout=4500 SimpleReentrantLockLoops

 * @summary multiple threads using a single lock

 */

import java.util.concurrent.*;

import java.util.concurrent.locks.*;

import java.util.*;

public final class SimpleReentrantLockLoops {

    static final ExecutorService pool = Executors.newCachedThreadPool();

    static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();

    static boolean print = false;

    static int iters = 1000000;

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

        int maxThreads = 5;

        if (args.length > 0)

            maxThreads = Integer.parseInt(args[0]);

        print = true;

        int reps = 2;

        for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) {

            int n = reps;

            if (reps > 1) --reps;

            while (n-- > 0) {

                System.out.print("Threads: " + i);

                new ReentrantLockLoop(i).test();

                Thread.sleep(100);

            }

        }

        pool.shutdown();

        if (! pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS))

            throw new Error();

    }

    static final class ReentrantLockLoop implements Runnable {

        private int v = rng.next();

        private volatile int result = 17;

        private final ReentrantLock lock = new ReentrantLock();

        private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();

        private final CyclicBarrier barrier;

        private final int nthreads;

        ReentrantLockLoop(int nthreads) {

            this.nthreads = nthreads;

            barrier = new CyclicBarrier(nthreads+1, timer);

        }

        final void test() throws Exception {

            for (int i = 0; i < nthreads; ++i)

                pool.execute(this);

            barrier.await();

            barrier.await();

            if (print) {

                long time = timer.getTime();

                long tpi = time / ((long)iters * nthreads);

                System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock");

                double secs = (double)(time) / 1000000000.0;

                System.out.println("\t " + secs + "s run time");

            }

            int r = result;

            if (r == 0) // avoid overoptimization

                System.out.println("useless result: " + r);

        }

        public final void run() {

            try {

                barrier.await();

                int sum = v;

                int x = 0;

                int n = iters;

                do {

                    lock.lock();

                    try {

                        if ((n & 255) == 0)

                            v = x = LoopHelpers.compute2(LoopHelpers.compute1(v));

                        else

                            v = x += ~(v - n);

                    }

                    finally {

                        lock.unlock();

                    }

                    // Once in a while, do something more expensive

                    if ((~n & 255) == 0) {

                        sum += LoopHelpers.compute1(LoopHelpers.compute2(x));

                    }

                    else

                        sum += sum ^ x;

                } while (n-- > 0);

                barrier.await();

                result += sum;

            }

            catch (Exception ie) {

                return;

            }

        }

    }

}