/*

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * @test

 * @bug 6450200

 * @summary Test proper handling of pool state changes

 * @run main/othervm ConfigChanges

 * @key randomness

 * @author Martin Buchholz

 */

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

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

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

import java.security.Permission;

import java.util.Random;

import java.util.concurrent.ArrayBlockingQueue;

import java.util.concurrent.CyclicBarrier;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.RejectedExecutionException;

import java.util.concurrent.ThreadFactory;

import java.util.concurrent.ThreadPoolExecutor;

import java.util.function.Supplier;

public class ConfigChanges {

    static final ThreadGroup tg = new ThreadGroup("pool");

    static final Random rnd = RandomFactory.getRandom();

    static void report(ThreadPoolExecutor tpe) {

        try {

            System.out.printf(

                "active=%d submitted=%d completed=%d queued=%d sizes=%d/%d/%d%n",

                tg.activeCount(),

                tpe.getTaskCount(),

                tpe.getCompletedTaskCount(),

                tpe.getQueue().size(),

                tpe.getPoolSize(),

                tpe.getCorePoolSize(),

                tpe.getMaximumPoolSize());

        } catch (Throwable t) { unexpected(t); }

    }

    static void report(String label, ThreadPoolExecutor tpe) {

        System.out.printf("%10s ", label);

        report(tpe);

    }

    static class PermissiveSecurityManger extends SecurityManager {

        public void checkPermission(Permission p) { /* bien sur, Monsieur */ }

    }

    static void checkShutdown(final ExecutorService es) {

        final Runnable nop = new Runnable() {public void run() {}};

        try {

            if (new Random().nextBoolean()) {

                check(es.isShutdown());

                if (es instanceof ThreadPoolExecutor)

                    check(((ThreadPoolExecutor) es).isTerminating()

                          || es.isTerminated());

                THROWS(RejectedExecutionException.class,

                       () -> es.execute(nop));

            }

        } catch (Throwable t) { unexpected(t); }

    }

    static void checkTerminated(final ThreadPoolExecutor tpe) {

        try {

            checkShutdown(tpe);

            check(tpe.getQueue().isEmpty());

            check(tpe.isTerminated());

            check(! tpe.isTerminating());

            equal(0, tpe.getActiveCount());

            equal(0, tpe.getPoolSize());

            equal(tpe.getTaskCount(), tpe.getCompletedTaskCount());

            check(tpe.awaitTermination(0L, MINUTES));

        } catch (Throwable t) { unexpected(t); }

    }

    static Runnable waiter(final CyclicBarrier barrier) {

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

            try { barrier.await(); barrier.await(); }

            catch (Throwable t) { unexpected(t); }}};

    }

    static volatile Runnable runnableDuJour;

    static void awaitIdleness(ThreadPoolExecutor tpe, long taskCount) {

        restart: for (;;) {

            // check twice to make chance of race vanishingly small

            for (int i = 0; i < 2; i++) {

                if (tpe.getQueue().size() != 0 ||

                    tpe.getActiveCount() != 0 ||

                    tpe.getCompletedTaskCount() != taskCount) {

                    Thread.yield();

                    continue restart;

                }

            }

            return;

        }

    }

    /**

     * Waits for condition to become true, first spin-polling, then sleep-polling.

     */

    static void spinAwait(Supplier<Boolean> waitingForGodot) {

        for (int spins = 0; !waitingForGodot.get(); ) {

            if ((spins = (spins + 1) & 3) > 0) {

                Thread.yield();

            } else {

                try { Thread.sleep(4); }

                catch (InterruptedException unexpected) {

                    throw new AssertionError(unexpected);

                }

            }

        }

    }

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

        if (rnd.nextBoolean())

            System.setSecurityManager(new PermissiveSecurityManger());

        final boolean prestart = rnd.nextBoolean();

        final Thread.UncaughtExceptionHandler handler

            = new Thread.UncaughtExceptionHandler() {

                    public void uncaughtException(Thread t, Throwable e) {

                        check(! Thread.currentThread().isInterrupted());

                        unexpected(e);

                    }};

        final int n = 3;

        final ThreadPoolExecutor tpe

            = new ThreadPoolExecutor(n, 3*n,

                                     3L, MINUTES,

                                     new ArrayBlockingQueue<Runnable>(3*n));

        tpe.setThreadFactory(new ThreadFactory() {

                public Thread newThread(Runnable r) {

                    Thread t = new Thread(tg, r);

                    t.setUncaughtExceptionHandler(handler);

                    return t;

                }});

        if (prestart) {

            tpe.prestartAllCoreThreads();

            equal(n, tg.activeCount());

            equal(n, tpe.getCorePoolSize());

            equal(n, tpe.getLargestPoolSize());

        }

        final Runnable runRunnableDuJour =

            new Runnable() { public void run() {

                // Delay choice of action till last possible moment.

                runnableDuJour.run(); }};

        final CyclicBarrier pumpedUp = new CyclicBarrier(3*n + 1);

        runnableDuJour = waiter(pumpedUp);

        if (prestart) {

            for (int i = 0; i < 1*n; i++)

                tpe.execute(runRunnableDuJour);

            // Wait for prestarted threads to dequeue their initial tasks.

            while (! tpe.getQueue().isEmpty())

                Thread.sleep(1);

            for (int i = 0; i < 5*n; i++)

                tpe.execute(runRunnableDuJour);

        } else {

            for (int i = 0; i < 6*n; i++)

                tpe.execute(runRunnableDuJour);

        }

        //report("submitted", tpe);

        pumpedUp.await();

        equal(3*n, tg.activeCount());

        equal(3*n, tpe.getMaximumPoolSize());

        equal(3*n, tpe.getLargestPoolSize());

        equal(n, tpe.getCorePoolSize());

        equal(3*n, tpe.getActiveCount());

        equal(6L*n, tpe.getTaskCount());

        equal(0L, tpe.getCompletedTaskCount());

        //report("pumped up", tpe);

        tpe.setMaximumPoolSize(4*n);

        equal(4*n, tpe.getMaximumPoolSize());

        //report("pumped up2", tpe);

        final CyclicBarrier pumpedUp2 = new CyclicBarrier(n + 1);

        runnableDuJour = waiter(pumpedUp2);

        for (int i = 0; i < 1*n; i++)

            tpe.execute(runRunnableDuJour);

        pumpedUp2.await();

        equal(4*n, tg.activeCount());

        equal(4*n, tpe.getMaximumPoolSize());

        equal(4*n, tpe.getLargestPoolSize());

        equal(4*n, tpe.getActiveCount());

        equal(7L*n, tpe.getTaskCount());

        equal(0L, tpe.getCompletedTaskCount());

        //report("pumped up2", tpe);

        runnableDuJour = new Runnable() { public void run() {}};

        tpe.setMaximumPoolSize(2*n);

        //report("after setMaximumPoolSize", tpe);

        pumpedUp2.await();

        pumpedUp.await();

        spinAwait(() -> tg.activeCount() == 2*n);

        equal(2*n, tpe.getMaximumPoolSize());

        equal(4*n, tpe.getLargestPoolSize());

        //report("draining", tpe);

        awaitIdleness(tpe, 7L*n);

        equal(2*n, tg.activeCount());

        equal(2*n, tpe.getMaximumPoolSize());

        equal(4*n, tpe.getLargestPoolSize());

        equal(7L*n, tpe.getTaskCount());

        equal(7L*n, tpe.getCompletedTaskCount());

        equal(0, tpe.getActiveCount());

        equal(3L, tpe.getKeepAliveTime(MINUTES));

        long t0 = System.nanoTime();

        tpe.setKeepAliveTime(7L, MILLISECONDS);

        equal(7L, tpe.getKeepAliveTime(MILLISECONDS));

        spinAwait(() -> tg.activeCount() == n);

        check(System.nanoTime() - t0 >= tpe.getKeepAliveTime(NANOSECONDS));

        //report("idle", tpe);

        check(! tpe.allowsCoreThreadTimeOut());

        t0 = System.nanoTime();

        tpe.allowCoreThreadTimeOut(true);

        check(tpe.allowsCoreThreadTimeOut());

        spinAwait(() -> tg.activeCount() == 0);

        // The following assertion is almost always true, but may

        // exceptionally not be during a transition from core count

        // too high to allowCoreThreadTimeOut.  Users will never

        // notice, and we accept the small loss of testability.

        //

        // check(System.nanoTime() - t0 >= tpe.getKeepAliveTime(NANOSECONDS));

        //report("idle", tpe);

        tpe.shutdown();

        checkShutdown(tpe);

        check(tpe.awaitTermination(3L, MINUTES));

        checkTerminated(tpe);

    }

    //--------------------- 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) {if (cond) pass(); else fail();}

    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");}

    interface Fun {void f() throws Throwable;}

    static void THROWS(Class<? extends Throwable> k, Fun... fs) {

        for (Fun f : fs)

            try { f.f(); fail("Expected " + k.getName() + " not thrown"); }

            catch (Throwable t) {

                if (k.isAssignableFrom(t.getClass())) pass();

                else unexpected(t);}}

}