/*

 * 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,

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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 6785442

 * @summary Checks race between poll and remove(Object), while

 * occasionally moonlighting as a microbenchmark.

 * @run main RemovePollRace 12345

 */

import java.util.concurrent.ArrayBlockingQueue;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.ConcurrentLinkedQueue;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.LinkedBlockingDeque;

import java.util.concurrent.LinkedBlockingQueue;

import java.util.concurrent.atomic.AtomicLong;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.List;

import java.util.Queue;

import java.util.Map;

public class RemovePollRace {

    // Suitable for benchmarking.  Overriden by args[0] for testing.

    int count = 1024 * 1024;

    final Map<String,String> results = new ConcurrentHashMap<String,String>();

    Collection<Queue<Boolean>> concurrentQueues() {

        List<Queue<Boolean>> queues = new ArrayList<Queue<Boolean>>();

        queues.add(new ConcurrentLinkedQueue<Boolean>());

        queues.add(new ArrayBlockingQueue<Boolean>(count, false));

        queues.add(new ArrayBlockingQueue<Boolean>(count, true));

        queues.add(new LinkedBlockingQueue<Boolean>());

        queues.add(new LinkedBlockingDeque<Boolean>());

        try {

            queues.add((Queue<Boolean>)

                       Class.forName("java.util.concurrent.LinkedTransferQueue")

                       .newInstance());

        } catch (IllegalAccessException e) {

        } catch (InstantiationException e) {

        } catch (ClassNotFoundException e) {

            // OK; not yet added to JDK

        }

        // Following additional implementations are available from:

        // http://gee.cs.oswego.edu/dl/concurrency-interest/index.html

        // queues.add(new LinkedTransferQueue<Boolean>());

        // queues.add(new SynchronizedLinkedListQueue<Boolean>());

        // Avoid "first fast, second slow" benchmark effect.

        Collections.shuffle(queues);

        return queues;

    }

    void prettyPrintResults() {

        List<String> classNames = new ArrayList<String>(results.keySet());

        Collections.sort(classNames);

        int maxClassNameLength = 0;

        int maxNanosLength = 0;

        for (String name : classNames) {

            if (maxClassNameLength < name.length())

                maxClassNameLength = name.length();

            if (maxNanosLength < results.get(name).length())

                maxNanosLength = results.get(name).length();

        }

        String format = String.format("%%%ds %%%ds nanos/item%%n",

                                      maxClassNameLength, maxNanosLength);

        for (String name : classNames)

            System.out.printf(format, name, results.get(name));

    }

    void test(String[] args) throws Throwable {

        if (args.length > 0)

            count = Integer.valueOf(args[0]);

        // Warmup

        for (Queue<Boolean> queue : concurrentQueues())

            test(queue);

        results.clear();

        for (Queue<Boolean> queue : concurrentQueues())

            test(queue);

        prettyPrintResults();

    }

    void await(CountDownLatch latch) {

        try { latch.await(); }

        catch (InterruptedException e) { unexpected(e); }

    }

    void test(final Queue<Boolean> q) throws Throwable {

        long t0 = System.nanoTime();

        final int SPINS = 5;

        final AtomicLong removes = new AtomicLong(0);

        final AtomicLong polls = new AtomicLong(0);

        final int adderCount =

            Math.max(1, Runtime.getRuntime().availableProcessors() / 4);

        final int removerCount =

            Math.max(1, Runtime.getRuntime().availableProcessors() / 4);

        final int pollerCount = removerCount;

        final int threadCount = adderCount + removerCount + pollerCount;

        final CountDownLatch startingGate = new CountDownLatch(1);

        final CountDownLatch addersDone = new CountDownLatch(adderCount);

        final Runnable remover = new Runnable() {

            public void run() {

                await(startingGate);

                int spins = 0;

                for (;;) {

                    boolean quittingTime = (addersDone.getCount() == 0);

                    if (q.remove(Boolean.TRUE))

                        removes.getAndIncrement();

                    else if (quittingTime)

                        break;

                    else if (++spins > SPINS) {

                        Thread.yield();

                        spins = 0;

                    }}}};

        final Runnable poller = new Runnable() {

            public void run() {

                await(startingGate);

                int spins = 0;

                for (;;) {

                    boolean quittingTime = (addersDone.getCount() == 0);

                    if (q.poll() == Boolean.TRUE)

                        polls.getAndIncrement();

                    else if (quittingTime)

                        break;

                    else if (++spins > SPINS) {

                        Thread.yield();

                        spins = 0;

                    }}}};

        final Runnable adder = new Runnable() {

            public void run() {

                await(startingGate);

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

                    for (;;) {

                        try { q.add(Boolean.TRUE); break; }

                        catch (IllegalStateException e) { Thread.yield(); }

                    }

                }

                addersDone.countDown();

            }};

        final List<Thread> adders   = new ArrayList<Thread>();

        final List<Thread> removers = new ArrayList<Thread>();

        final List<Thread> pollers  = new ArrayList<Thread>();

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

            adders.add(checkedThread(adder));

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

            removers.add(checkedThread(remover));

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

            pollers.add(checkedThread(poller));

        final List<Thread> allThreads = new ArrayList<Thread>();

        allThreads.addAll(removers);

        allThreads.addAll(pollers);

        allThreads.addAll(adders);

        for (Thread t : allThreads)

            t.start();

        startingGate.countDown();

        for (Thread t : allThreads)

            t.join();

        String className = q.getClass().getSimpleName();

        long elapsed = System.nanoTime() - t0;

        int nanos = (int) ((double) elapsed / (adderCount * count));

        results.put(className, String.valueOf(nanos));

        if (removes.get() + polls.get() != adderCount * count) {

            String msg = String.format

                ("class=%s removes=%s polls=%d count=%d",

                 className, removes.get(), polls.get(), count);

            fail(msg);

        }

    }

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

    volatile int passed = 0, failed = 0;

    void pass() {passed++;}

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

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

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

    void check(boolean cond) {if (cond) pass(); else fail();}

    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 {

        new RemovePollRace().instanceMain(args);}

    public void instanceMain(String[] args) throws Throwable {

        try {test(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");}

    Thread checkedThread(final Runnable r) {

        return new Thread() {public void run() {

            try {r.run();} catch (Throwable t) {unexpected(t);}}};}

}