/*
 * 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/publicdomain/zero/1.0/
 */

/*
 * Simple benchmark comparing various locking techniques.
 */

import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.locks.*;

public final class LockLoops {
    static final ExecutorService pool = Executors.newCachedThreadPool();
    static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
    static boolean print = false;
    static boolean doBuiltin = true;
    static boolean doReadWrite = true;
    static boolean doSemaphore = true;
    static boolean doStampedLock = true;
    static boolean doFair = true;

    public static void main(String[] args) throws Exception {
        int maxThreads = 100;
        int iters = 1000000;
        int replications = 1;

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

        if (args.length > 1)
            iters = Integer.parseInt(args[1]);

        if (args.length > 2)
            replications = Integer.parseInt(args[2]);

        rng.setSeed(3122688L);

        print = false;
        System.out.println("Warmup...");
        oneTest(3, 10000);
        Thread.sleep(1000);
        oneTest(2, 10000);
        Thread.sleep(100);
        oneTest(1, 100000);
        Thread.sleep(100);
        oneTest(1, 100000);
        Thread.sleep(1000);
        print = true;

        for (int i = 1; i <= maxThreads; ++i) {
            for (int j = 0; j < replications; ++j) {
                System.out.println("Threads:" + i);
                oneTest(i, iters / i);
                Thread.sleep(100);
            }
        }
        pool.shutdown();
    }

    static void oneTest(int nthreads, int iters) throws Exception {
        int v = rng.next();

        if (print)
            System.out.print("No shared vars        ");
        new NoLockLoop().test(v, nthreads, iters * 10);
        Thread.sleep(10);

        if (print)
            System.out.print("No Lock + volatile    ");
        new NoLockVolatileLoop().test(v, nthreads, iters);
        Thread.sleep(10);

        if (doBuiltin) {
            if (print)
                System.out.print("builtin lock          ");
            new BuiltinLockLoop().test(v, nthreads, iters);
            Thread.sleep(10);
        }

        if (print)
            System.out.print("ReentrantLock         ");
        new ReentrantLockLoop().test(v, nthreads, iters);
        Thread.sleep(10);

        if (doReadWrite) {
            if (print)
                System.out.print("ReentrantWriteLock    ");
            new ReentrantWriteLockLoop().test(v, nthreads, iters);
            Thread.sleep(10);

            if (print)
                System.out.print("ReentrantReadLock    ");
            new ReentrantReadLockLoop().test(v, nthreads, iters);
            Thread.sleep(10);

            if (print)
                System.out.print("ReentrantReadWriteLock");
            new ReentrantReadWriteLockLoop().test(v, nthreads, iters);
            Thread.sleep(10);
        }

        if (doSemaphore) {
            if (print)
                System.out.print("Semaphore             ");
            new SemaphoreLoop().test(v, nthreads, iters);
            Thread.sleep(10);

            if (print)
                System.out.print("FairSemaphore         ");
            new FairSemaphoreLoop().test(v, nthreads, iters);
            Thread.sleep(10);
        }

        if (doFair) {
            if (print)
                System.out.print("FairReentrantLock     ");
            new FairReentrantLockLoop().test(v, nthreads, iters);
            Thread.sleep(10);

            if (doReadWrite) {
                if (print)
                    System.out.print("FairRWriteLock         ");
                new FairReentrantWriteLockLoop().test(v, nthreads, iters);
                Thread.sleep(10);

                if (print)
                    System.out.print("FairRReadWriteLock     ");
                new FairReentrantReadWriteLockLoop().test(v, nthreads, iters);
                Thread.sleep(10);
            }
        }

        if (doStampedLock) {
            if (print)
                System.out.print("StampedLockWrite   ");
            new StampedLockWriteLoop().test(v, nthreads, iters);
            Thread.sleep(10);

            if (print)
                System.out.print("StampedLockRead    ");
            new StampedLockReadLoop().test(v, nthreads, iters);
            Thread.sleep(10);

            if (print)
                System.out.print("StampedLockOptRead");
            new StampedLockOptimisticReadLoop().test(v, nthreads, iters);
            Thread.sleep(10);

            if (print)
                System.out.print("StampedLockReadWrite");
            new StampedLockReadWriteLoop().test(v, nthreads, iters);
            Thread.sleep(10);
        }
    }

    abstract static class LockLoop implements Runnable {
        int v;
        int iters;
        volatile int result;
        final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
        CyclicBarrier barrier;

        final void test(int initialValue, int nthreads, int iters) throws Exception {
            v = initialValue;
            this.iters = iters;
            barrier = new CyclicBarrier(nthreads+1, timer);
            for (int i = 0; i < nthreads; ++i)
                pool.execute(this);
            barrier.await();
            barrier.await();
            long time = timer.getTime();
            if (print) {
                long tpi = time / (iters * nthreads);
                System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per update");
                //                double secs = (double) time / 1000000000.0;
                //                System.out.print("\t " + secs + "s run time");
                System.out.println();
            }

            if (result == 0) // avoid overoptimization
                System.out.println("useless result: " + result);
        }
        abstract int loop(int n);
        public final void run() {
            try {
                barrier.await();
                result += loop(iters);
                barrier.await();
            }
            catch (Exception ie) {
                return;
            }
        }

    }

    private static class BuiltinLockLoop extends LockLoop {
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                synchronized (this) {
                    v = LoopHelpers.compute1(v);
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class NoLockLoop extends LockLoop {
        final int loop(int n) {
            int sum = 0;
            int y = v;
            while (n-- > 0) {
                y = LoopHelpers.compute1(y);
                sum += LoopHelpers.compute2(y);
            }
            return sum;
        }
    }

    private static class NoLockVolatileLoop extends LockLoop {
        private volatile int vv;
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                int y = LoopHelpers.compute1(vv);
                vv = y;
                sum += LoopHelpers.compute2(y);
            }
            return sum;
        }
    }

    private static class ReentrantLockLoop extends LockLoop {
        private final ReentrantLock lock = new ReentrantLock();
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                lock.lock();
                try {
                    v = LoopHelpers.compute1(v);
                }
                finally {
                    lock.unlock();
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class FairReentrantLockLoop extends LockLoop {
        private final ReentrantLock lock = new ReentrantLock(true);
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                lock.lock();
                try {
                    v = LoopHelpers.compute1(v);
                }
                finally {
                    lock.unlock();
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class ReentrantWriteLockLoop extends LockLoop {
        private final Lock lock = new ReentrantReadWriteLock().writeLock();
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                lock.lock();
                try {
                    v = LoopHelpers.compute1(v);
                }
                finally {
                    lock.unlock();
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class ReentrantReadLockLoop extends LockLoop {
        private final Lock lock = new ReentrantReadWriteLock().readLock();
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                lock.lock();
                try {
                    v = LoopHelpers.compute1(v);
                }
                finally {
                    lock.unlock();
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class ReentrantReadWriteLockLoop extends LockLoop {
        private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                int x;
                lock.readLock().lock();
                try {
                    x = LoopHelpers.compute1(v);
                }
                finally {
                    lock.readLock().unlock();
                }
                lock.writeLock().lock();
                try {
                    v = x;
                }
                finally {
                    lock.writeLock().unlock();
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class FairReentrantWriteLockLoop extends LockLoop {
        final Lock lock = new ReentrantReadWriteLock(true).writeLock();
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                lock.lock();
                try {
                    v = LoopHelpers.compute1(v);
                }
                finally {
                    lock.unlock();
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class SemaphoreLoop extends LockLoop {
        private final Semaphore sem = new Semaphore(1, false);
        final int loop(int n) {
            int sum = 0;
            try {
                while (n-- > 0) {
                    sem.acquire();
                    try {
                        v = LoopHelpers.compute1(v);
                    }
                    finally {
                        sem.release();
                    }
                    sum += LoopHelpers.compute2(v);
                }
            }
            catch (InterruptedException ie) {
                return sum;
            }
            return sum;
        }
    }

    private static class FairSemaphoreLoop extends LockLoop {
        private final Semaphore sem = new Semaphore(1, true);
        final int loop(int n) {
            int sum = 0;
            try {
                while (n-- > 0) {
                    sem.acquire();
                    try {
                        v = LoopHelpers.compute1(v);
                    }
                    finally {
                        sem.release();
                    }
                    sum += LoopHelpers.compute2(v);
                }
            }
            catch (InterruptedException ie) {
                return sum;
            }
            return sum;
        }
    }

    private static class FairReentrantReadWriteLockLoop extends LockLoop {
        private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock(true);
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                int x;
                lock.readLock().lock();
                try {
                    x = LoopHelpers.compute1(v);
                }
                finally {
                    lock.readLock().unlock();
                }
                lock.writeLock().lock();
                try {
                    v = x;
                }
                finally {
                    lock.writeLock().unlock();
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class StampedLockWriteLoop extends LockLoop {
        private final StampedLock lock = new StampedLock();
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                long stamp = lock.writeLock();
                try {
                    v = LoopHelpers.compute1(v);
                }
                finally {
                    lock.unlockWrite(stamp);
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class StampedLockReadLoop extends LockLoop {
        private final StampedLock lock = new StampedLock();
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                long stamp = lock.readLock();
                try {
                    v = LoopHelpers.compute1(v);
                }
                finally {
                    lock.unlockRead(stamp);
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class StampedLockOptimisticReadLoop extends LockLoop {
        private final StampedLock lock = new StampedLock();
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                long stamp;
                do {
                    stamp = lock.tryOptimisticRead();
                    v = LoopHelpers.compute1(v);
                } while (!lock.validate(stamp));
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }

    private static class StampedLockReadWriteLoop extends LockLoop {
        private final StampedLock lock = new StampedLock();
        final int loop(int n) {
            int sum = 0;
            while (n-- > 0) {
                int x;
                long stamp = lock.readLock();
                try {
                    x = LoopHelpers.compute1(v);
                }
                finally {
                    lock.unlockRead(stamp);
                }
                stamp = lock.writeLock();
                try {
                    v = x;
                } finally {
                    lock.unlockWrite(stamp);
                }
                sum += LoopHelpers.compute2(v);
            }
            return sum;
        }
    }
}