/*

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 *

 * This code is free software; you can redistribute it and/or modify it

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 * 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).

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 * 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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/*

 * 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/publicdomain/zero/1.0/

 */

/*

 * @test

 * @bug 4486658

 * @summary Exercise multithreaded maps, by default ConcurrentHashMap.

 * Multithreaded hash table test.  Each thread does a random walk

 * though elements of "key" array. On each iteration, it checks if

 * table includes key.  If absent, with probability pinsert it

 * inserts it, and if present, with probability premove it removes

 * it.  (pinsert and premove are expressed as percentages to simplify

 * parsing from command line.)

 * @run main/timeout=1600 MapLoops

 */

import static java.util.concurrent.TimeUnit.MILLISECONDS;

import java.util.List;

import java.util.Map;

import java.util.SplittableRandom;

import java.util.concurrent.CopyOnWriteArrayList;

import java.util.concurrent.CyclicBarrier;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

public class MapLoops {

    static final long LONG_DELAY_MS = Utils.adjustTimeout(10_000);

    static int nkeys       = 1000; // 10_000

    static int pinsert     = 60;

    static int premove     = 2;

    static int maxThreads  = 100;

    static int nops        = 10000; // 100_000

    static int removesPerMaxRandom;

    static int insertsPerMaxRandom;

    static final ExecutorService pool = Executors.newCachedThreadPool();

    static final List<Throwable> throwables = new CopyOnWriteArrayList<>();

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

        Class mapClass = null;

        if (args.length > 0) {

            try {

                mapClass = Class.forName(args[0]);

            } catch (ClassNotFoundException e) {

                throw new RuntimeException("Class " + args[0] + " not found.");

            }

        }

        else

            mapClass = java.util.concurrent.ConcurrentHashMap.class;

        if (args.length > 1)

            maxThreads = Integer.parseInt(args[1]);

        if (args.length > 2)

            nkeys = Integer.parseInt(args[2]);

        if (args.length > 3)

            pinsert = Integer.parseInt(args[3]);

        if (args.length > 4)

            premove = Integer.parseInt(args[4]);

        if (args.length > 5)

            nops = Integer.parseInt(args[5]);

        // normalize probabilities wrt random number generator

        removesPerMaxRandom = (int)(((double)premove/100.0 * 0x7FFFFFFFL));

        insertsPerMaxRandom = (int)(((double)pinsert/100.0 * 0x7FFFFFFFL));

        System.out.print("Class: " + mapClass.getName());

        System.out.print(" threads: " + maxThreads);

        System.out.print(" size: " + nkeys);

        System.out.print(" ins: " + pinsert);

        System.out.print(" rem: " + premove);

        System.out.print(" ops: " + nops);

        System.out.println();

        int k = 1;

        int warmups = 2;

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

            test(i, nkeys, mapClass);

            if (warmups > 0)

                --warmups;

            else if (i == k) {

                k = i << 1;

                i = i + (i >>> 1);

            }

            else if (i == 1 && k == 2) {

                i = k;

                warmups = 1;

            }

            else

                i = k;

        }

        pool.shutdown();

        if (! pool.awaitTermination(LONG_DELAY_MS, MILLISECONDS))

            throw new Error();

        if (! throwables.isEmpty())

            throw new Error

                (throwables.size() + " thread(s) terminated abruptly.");

    }

    static Integer[] makeKeys(int n) {

        SplittableRandom rnd = new SplittableRandom();

        Integer[] key = new Integer[n];

        for (int i = 0; i < key.length; ++i)

            key[i] = new Integer(rnd.nextInt());

        return key;

    }

    static void shuffleKeys(Integer[] key) {

        SplittableRandom rnd = new SplittableRandom();

        for (int i = key.length; i > 1; --i) {

            int j = rnd.nextInt(i);

            Integer tmp = key[j];

            key[j] = key[i-1];

            key[i-1] = tmp;

        }

    }

    static void test(int i, int nkeys, Class mapClass) throws Exception {

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

        Map<Integer, Integer> map = (Map<Integer, Integer>)

            mapClass.getDeclaredConstructor().newInstance();

        Integer[] key = makeKeys(nkeys);

        // Uncomment to start with a non-empty table

        //        for (int j = 0; j < nkeys; j += 4) // start 1/4 occupied

        //            map.put(key[j], key[j]);

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

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

        SplittableRandom rnd = new SplittableRandom();

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

            pool.execute(new Runner(map, key, barrier, rnd.split()));

        barrier.await();

        barrier.await();

        long time = timer.getTime();

        long tpo = time / (i * (long)nops);

        System.out.print(LoopHelpers.rightJustify(tpo) + " ns per op");

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

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

        map.clear();

    }

    static class Runner implements Runnable {

        final Map<Integer,Integer> map;

        final Integer[] key;

        final CyclicBarrier barrier;

        final SplittableRandom rnd;

        int position;

        int total;

        Runner(Map<Integer,Integer> map,

               Integer[] key,

               CyclicBarrier barrier,

               SplittableRandom rnd) {

            this.map = map;

            this.key = key;

            this.barrier = barrier;

            this.rnd = rnd;

            position = key.length / 2;

        }

        int step() {

            // random-walk around key positions, bunching accesses

            int r = rnd.nextInt(Integer.MAX_VALUE);

            position += (r & 7) - 3;

            while (position >= key.length) position -= key.length;

            while (position < 0) position += key.length;

            Integer k = key[position];

            Integer x = map.get(k);

            if (x != null) {

                if (x.intValue() != k.intValue())

                    throw new Error("bad mapping: " + x + " to " + k);

                if (r < removesPerMaxRandom) {

                    if (map.remove(k) != null) {

                        position = total % key.length; // move from position

                        return 2;

                    }

                }

            }

            else if (r < insertsPerMaxRandom) {

                ++position;

                map.put(k, k);

                return 2;

            }

            // Uncomment to add a little computation between accesses

            //            total += LoopHelpers.compute1(k.intValue());

            total += r;

            return 1;

        }

        public void run() {

            try {

                barrier.await();

                int ops = nops;

                while (ops > 0)

                    ops -= step();

                barrier.await();

            }

            catch (Throwable throwable) {

                synchronized (System.err) {

                    System.err.println("--------------------------------");

                    throwable.printStackTrace();

                }

                throwables.add(throwable);

            }

        }

    }

}