/*

 * 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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 */

/*

 * 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 8008378

 * @summary Basic checks for parallelism 0, and null returning factory

 * @run main/othervm -Djava.util.concurrent.ForkJoinPool.common.parallelism=0 ThreadLessCommon

 * @run main/othervm -Djava.util.concurrent.ForkJoinPool.common.threadFactory=ThreadLessCommon$NullForkJoinWorkerThreadFactory ThreadLessCommon

 * @author Chris Hegarty

 */

import java.util.concurrent.ForkJoinPool;

import java.util.concurrent.ForkJoinPool.ForkJoinWorkerThreadFactory;

import java.util.concurrent.ForkJoinWorkerThread;

import java.util.concurrent.RecursiveTask;

public class ThreadLessCommon {

    static final int THRESHOLD = 1000;

    static final boolean debug = true;

    private static void realMain(String[] args) throws Throwable {

        if (debug) {

            String pp = System.getProperty(

                    "java.util.concurrent.ForkJoinPool.common.parallelism");

            System.out.println(

                    "java.util.concurrent.ForkJoinPool.common.parallelism:" + pp);

            String tf = System.getProperty(

                    "java.util.concurrent.ForkJoinPool.common.threadFactory");

            System.out.println(

                    "java.util.concurrent.ForkJoinPool.common.threadFactory:" + tf);

        }

        long from = 0, to = 50000;

        RecursiveTask<Long> task = new SumTask(from, to, Thread.currentThread());

        long sum = task.invoke();

        System.out.printf("%nSum: from [%d] to [%d] = [%d]%n", from, to, sum);

        task.fork();

        sum = task.join();

        System.out.printf("%nSum: from [%d] to [%d] = [%d]%n", from, to, sum);

        sum = ForkJoinPool.commonPool().invoke(task.fork());

        System.out.printf("%nSum: from [%d] to [%d] = [%d]%n", from, to, sum);

    }

    static class SumTask extends RecursiveTask<Long> {

        final Thread expectedThread;

        final long from;

        final long to;

        SumTask(long from, long to, Thread thread) {

            this.from = from; this.to = to; expectedThread = thread;

        }

        @Override

        public Long compute() {

            check(Thread.currentThread() == expectedThread,

                  "Expected " + expectedThread + ", got " + Thread.currentThread());

            long range = to - from;

            if (range < THRESHOLD) {

                long acc = 0;

                for (long i = from; i <= to; i++)

                    acc = acc + i;

                return acc;

            } else {

                long half = from + range / 2;

                SumTask t1 = new SumTask(from, half ,expectedThread);

                SumTask t2 = new SumTask(half+1, to ,expectedThread);

                if (half % 2 == 0) {

                    t1.fork();

                    return t2.compute() + t1.join();

                } else {

                    invokeAll(t1, t2);

                    try { return t1.get() + t2.get(); }

                    catch (Exception x) { unexpected(x); return 0L;}

                }

            }

        }

    }

    public static class NullForkJoinWorkerThreadFactory

        implements ForkJoinWorkerThreadFactory

    {

        @Override

        public ForkJoinWorkerThread newThread(ForkJoinPool pool) {

            return null;

        }

    }

    //--------------------- Infrastructure ---------------------------

    static volatile int passed = 0, failed = 0;

    static void pass() {passed++;}

    static void fail() {failed++; /*Thread.dumpStack();*/}

    static void fail(String msg) {System.out.println(msg); fail();}

    static void unexpected(Throwable t) {failed++; t.printStackTrace();}

    static void check(boolean cond, String msg) {if (cond) pass(); else fail(msg);}

    static void equal(Object x, Object y) {

        if (x == null ? y == null : x.equals(y)) pass();

        else fail(x + " not equal to " + y);}

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

        try {realMain(args);} catch (Throwable t) {unexpected(t);}

        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);

        if (failed > 0) throw new AssertionError("Some tests failed");}

}