/*

 * 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

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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/

 */

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

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

import java.security.PrivilegedAction;

import java.security.PrivilegedExceptionAction;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.List;

import java.util.concurrent.Callable;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.Executors;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.ForkJoinPool;

import java.util.concurrent.ForkJoinTask;

import java.util.concurrent.ForkJoinWorkerThread;

import java.util.concurrent.Future;

import java.util.concurrent.RecursiveTask;

import java.util.concurrent.RejectedExecutionException;

import java.util.concurrent.atomic.AtomicBoolean;

import java.util.concurrent.atomic.AtomicInteger;

import java.util.concurrent.locks.ReentrantLock;

import junit.framework.AssertionFailedError;

import junit.framework.Test;

import junit.framework.TestSuite;

public class ForkJoinPoolTest extends JSR166TestCase {

    public static void main(String[] args) {

        main(suite(), args);

    }

    public static Test suite() {

        return new TestSuite(ForkJoinPoolTest.class);

    }

    /*

     * Testing coverage notes:

     *

     * 1. shutdown and related methods are tested via super.joinPool.

     *

     * 2. newTaskFor and adapters are tested in submit/invoke tests

     *

     * 3. We cannot portably test monitoring methods such as

     * getStealCount() since they rely ultimately on random task

     * stealing that may cause tasks not to be stolen/propagated

     * across threads, especially on uniprocessors.

     *

     * 4. There are no independently testable ForkJoinWorkerThread

     * methods, but they are covered here and in task tests.

     */

    // Some classes to test extension and factory methods

    static class MyError extends Error {}

    // to test handlers

    static class FailingFJWSubclass extends ForkJoinWorkerThread {

        public FailingFJWSubclass(ForkJoinPool p) { super(p) ; }

        protected void onStart() { super.onStart(); throw new MyError(); }

    }

    static class FailingThreadFactory

            implements ForkJoinPool.ForkJoinWorkerThreadFactory {

        final AtomicInteger calls = new AtomicInteger(0);

        public ForkJoinWorkerThread newThread(ForkJoinPool p) {

            if (calls.incrementAndGet() > 1) return null;

            return new FailingFJWSubclass(p);

        }

    }

    static class SubFJP extends ForkJoinPool { // to expose protected

        SubFJP() { super(1); }

        public int drainTasksTo(Collection<? super ForkJoinTask<?>> c) {

            return super.drainTasksTo(c);

        }

        public ForkJoinTask<?> pollSubmission() {

            return super.pollSubmission();

        }

    }

    static class ManagedLocker implements ForkJoinPool.ManagedBlocker {

        final ReentrantLock lock;

        boolean hasLock = false;

        ManagedLocker(ReentrantLock lock) { this.lock = lock; }

        public boolean block() {

            if (!hasLock)

                lock.lock();

            return true;

        }

        public boolean isReleasable() {

            return hasLock || (hasLock = lock.tryLock());

        }

    }

    // A simple recursive task for testing

    static final class FibTask extends RecursiveTask<Integer> {

        final int number;

        FibTask(int n) { number = n; }

        protected Integer compute() {

            int n = number;

            if (n <= 1)

                return n;

            FibTask f1 = new FibTask(n - 1);

            f1.fork();

            return (new FibTask(n - 2)).compute() + f1.join();

        }

    }

    // A failing task for testing

    static final class FailingTask extends ForkJoinTask<Void> {

        public final Void getRawResult() { return null; }

        protected final void setRawResult(Void mustBeNull) { }

        protected final boolean exec() { throw new Error(); }

        FailingTask() {}

    }

    // Fib needlessly using locking to test ManagedBlockers

    static final class LockingFibTask extends RecursiveTask<Integer> {

        final int number;

        final ManagedLocker locker;

        final ReentrantLock lock;

        LockingFibTask(int n, ManagedLocker locker, ReentrantLock lock) {

            number = n;

            this.locker = locker;

            this.lock = lock;

        }

        protected Integer compute() {

            int n;

            LockingFibTask f1 = null;

            LockingFibTask f2 = null;

            locker.block();

            n = number;

            if (n > 1) {

                f1 = new LockingFibTask(n - 1, locker, lock);

                f2 = new LockingFibTask(n - 2, locker, lock);

            }

            lock.unlock();

            if (n <= 1)

                return n;

            else {

                f1.fork();

                return f2.compute() + f1.join();

            }

        }

    }

    /**

     * Successfully constructed pool reports default factory,

     * parallelism and async mode policies, no active threads or

     * tasks, and quiescent running state.

     */

    public void testDefaultInitialState() {

        ForkJoinPool p = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(p)) {

            assertSame(ForkJoinPool.defaultForkJoinWorkerThreadFactory,

                       p.getFactory());

            assertFalse(p.getAsyncMode());

            assertEquals(0, p.getActiveThreadCount());

            assertEquals(0, p.getStealCount());

            assertEquals(0, p.getQueuedTaskCount());

            assertEquals(0, p.getQueuedSubmissionCount());

            assertFalse(p.hasQueuedSubmissions());

            assertFalse(p.isShutdown());

            assertFalse(p.isTerminating());

            assertFalse(p.isTerminated());

        }

    }

    /**

     * Constructor throws if size argument is less than zero

     */

    public void testConstructor1() {

        try {

            new ForkJoinPool(-1);

            shouldThrow();

        } catch (IllegalArgumentException success) {}

    }

    /**

     * Constructor throws if factory argument is null

     */

    public void testConstructor2() {

        try {

            new ForkJoinPool(1, null, null, false);

            shouldThrow();

        } catch (NullPointerException success) {}

    }

    /**

     * getParallelism returns size set in constructor

     */

    public void testGetParallelism() {

        ForkJoinPool p = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(p)) {

            assertEquals(1, p.getParallelism());

        }

    }

    /**

     * getPoolSize returns number of started workers.

     */

    public void testGetPoolSize() {

        final CountDownLatch taskStarted = new CountDownLatch(1);

        final CountDownLatch done = new CountDownLatch(1);

        final ForkJoinPool p = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(p)) {

            assertEquals(0, p.getActiveThreadCount());

            final Runnable task = new CheckedRunnable() {

                public void realRun() throws InterruptedException {

                    taskStarted.countDown();

                    assertEquals(1, p.getPoolSize());

                    assertEquals(1, p.getActiveThreadCount());

                    await(done);

                }};

            Future<?> future = p.submit(task);

            await(taskStarted);

            assertEquals(1, p.getPoolSize());

            assertEquals(1, p.getActiveThreadCount());

            done.countDown();

        }

        assertEquals(0, p.getPoolSize());

        assertEquals(0, p.getActiveThreadCount());

    }

    /**

     * awaitTermination on a non-shutdown pool times out

     */

    public void testAwaitTermination_timesOut() throws InterruptedException {

        ForkJoinPool p = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(p)) {

            assertFalse(p.isTerminated());

            assertFalse(p.awaitTermination(Long.MIN_VALUE, NANOSECONDS));

            assertFalse(p.awaitTermination(Long.MIN_VALUE, MILLISECONDS));

            assertFalse(p.awaitTermination(-1L, NANOSECONDS));

            assertFalse(p.awaitTermination(-1L, MILLISECONDS));

            assertFalse(p.awaitTermination(randomExpiredTimeout(),

                                           randomTimeUnit()));

            long timeoutNanos = 999999L;

            long startTime = System.nanoTime();

            assertFalse(p.awaitTermination(timeoutNanos, NANOSECONDS));

            assertTrue(System.nanoTime() - startTime >= timeoutNanos);

            assertFalse(p.isTerminated());

            startTime = System.nanoTime();

            long timeoutMillis = timeoutMillis();

            assertFalse(p.awaitTermination(timeoutMillis, MILLISECONDS));

            assertTrue(millisElapsedSince(startTime) >= timeoutMillis);

            assertFalse(p.isTerminated());

            p.shutdown();

            assertTrue(p.awaitTermination(LONG_DELAY_MS, MILLISECONDS));

            assertTrue(p.isTerminated());

        }

    }

    /**

     * setUncaughtExceptionHandler changes handler for uncaught exceptions.

     *

     * Additionally tests: Overriding ForkJoinWorkerThread.onStart

     * performs its defined action

     */

    public void testSetUncaughtExceptionHandler() throws InterruptedException {

        final CountDownLatch uehInvoked = new CountDownLatch(1);

        final Thread.UncaughtExceptionHandler ueh =

            new Thread.UncaughtExceptionHandler() {

                public void uncaughtException(Thread t, Throwable e) {

                    threadAssertTrue(e instanceof MyError);

                    threadAssertTrue(t instanceof FailingFJWSubclass);

                    uehInvoked.countDown();

                }};

        ForkJoinPool p = new ForkJoinPool(1, new FailingThreadFactory(),

                                          ueh, false);

        try (PoolCleaner cleaner = cleaner(p)) {

            assertSame(ueh, p.getUncaughtExceptionHandler());

            try {

                p.execute(new FibTask(8));

                await(uehInvoked);

            } finally {

                p.shutdownNow(); // failure might have prevented processing task

            }

        }

    }

    /**

     * After invoking a single task, isQuiescent eventually becomes

     * true, at which time queues are empty, threads are not active,

     * the task has completed successfully, and construction

     * parameters continue to hold

     */

    public void testIsQuiescent() throws Exception {

        ForkJoinPool p = new ForkJoinPool(2);

        try (PoolCleaner cleaner = cleaner(p)) {

            assertTrue(p.isQuiescent());

            long startTime = System.nanoTime();

            FibTask f = new FibTask(20);

            p.invoke(f);

            assertSame(ForkJoinPool.defaultForkJoinWorkerThreadFactory,

                       p.getFactory());

            while (! p.isQuiescent()) {

                if (millisElapsedSince(startTime) > LONG_DELAY_MS)

                    throw new AssertionFailedError("timed out");

                assertFalse(p.getAsyncMode());

                assertFalse(p.isShutdown());

                assertFalse(p.isTerminating());

                assertFalse(p.isTerminated());

                Thread.yield();

            }

            assertTrue(p.isQuiescent());

            assertFalse(p.getAsyncMode());

            assertEquals(0, p.getQueuedTaskCount());

            assertEquals(0, p.getQueuedSubmissionCount());

            assertFalse(p.hasQueuedSubmissions());

            while (p.getActiveThreadCount() != 0

                   && millisElapsedSince(startTime) < LONG_DELAY_MS)

                Thread.yield();

            assertFalse(p.isShutdown());

            assertFalse(p.isTerminating());

            assertFalse(p.isTerminated());

            assertTrue(f.isDone());

            assertEquals(6765, (int) f.get());

            assertTrue(millisElapsedSince(startTime) < LONG_DELAY_MS);

        }

    }

    /**

     * Completed submit(ForkJoinTask) returns result

     */

    public void testSubmitForkJoinTask() throws Throwable {

        ForkJoinPool p = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(p)) {

            ForkJoinTask<Integer> f = p.submit(new FibTask(8));

            assertEquals(21, (int) f.get());

        }

    }

    /**

     * A task submitted after shutdown is rejected

     */

    public void testSubmitAfterShutdown() {

        ForkJoinPool p = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(p)) {

            p.shutdown();

            assertTrue(p.isShutdown());

            try {

                ForkJoinTask<Integer> f = p.submit(new FibTask(8));

                shouldThrow();

            } catch (RejectedExecutionException success) {}

        }

    }

    /**

     * Pool maintains parallelism when using ManagedBlocker

     */

    public void testBlockingForkJoinTask() throws Throwable {

        ForkJoinPool p = new ForkJoinPool(4);

        try {

            ReentrantLock lock = new ReentrantLock();

            ManagedLocker locker = new ManagedLocker(lock);

            ForkJoinTask<Integer> f = new LockingFibTask(20, locker, lock);

            p.execute(f);

            assertEquals(6765, (int) f.get());

        } finally {

            p.shutdownNow(); // don't wait out shutdown

        }

    }

    /**

     * pollSubmission returns unexecuted submitted task, if present

     */

    public void testPollSubmission() {

        final CountDownLatch done = new CountDownLatch(1);

        SubFJP p = new SubFJP();

        try (PoolCleaner cleaner = cleaner(p)) {

            ForkJoinTask a = p.submit(awaiter(done));

            ForkJoinTask b = p.submit(awaiter(done));

            ForkJoinTask c = p.submit(awaiter(done));

            ForkJoinTask r = p.pollSubmission();

            assertTrue(r == a || r == b || r == c);

            assertFalse(r.isDone());

            done.countDown();

        }

    }

    /**

     * drainTasksTo transfers unexecuted submitted tasks, if present

     */

    public void testDrainTasksTo() {

        final CountDownLatch done = new CountDownLatch(1);

        SubFJP p = new SubFJP();

        try (PoolCleaner cleaner = cleaner(p)) {

            ForkJoinTask a = p.submit(awaiter(done));

            ForkJoinTask b = p.submit(awaiter(done));

            ForkJoinTask c = p.submit(awaiter(done));

            ArrayList<ForkJoinTask> al = new ArrayList();

            p.drainTasksTo(al);

            assertTrue(al.size() > 0);

            for (ForkJoinTask r : al) {

                assertTrue(r == a || r == b || r == c);

                assertFalse(r.isDone());

            }

            done.countDown();

        }

    }

    // FJ Versions of AbstractExecutorService tests

    /**

     * execute(runnable) runs it to completion

     */

    public void testExecuteRunnable() throws Throwable {

        ExecutorService e = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(e)) {

            final AtomicBoolean done = new AtomicBoolean(false);

            Future<?> future = e.submit(new CheckedRunnable() {

                public void realRun() {

                    done.set(true);

                }});

            assertNull(future.get());

            assertNull(future.get(randomExpiredTimeout(), randomTimeUnit()));

            assertTrue(done.get());

            assertTrue(future.isDone());

            assertFalse(future.isCancelled());

        }

    }

    /**

     * Completed submit(callable) returns result

     */

    public void testSubmitCallable() throws Throwable {

        ExecutorService e = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(e)) {

            Future<String> future = e.submit(new StringTask());

            assertSame(TEST_STRING, future.get());

            assertTrue(future.isDone());

            assertFalse(future.isCancelled());

        }

    }

    /**

     * Completed submit(runnable) returns successfully

     */

    public void testSubmitRunnable() throws Throwable {

        ExecutorService e = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(e)) {

            Future<?> future = e.submit(new NoOpRunnable());

            assertNull(future.get());

            assertTrue(future.isDone());

            assertFalse(future.isCancelled());

        }

    }

    /**

     * Completed submit(runnable, result) returns result

     */

    public void testSubmitRunnable2() throws Throwable {

        ExecutorService e = new ForkJoinPool(1);

        try (PoolCleaner cleaner = cleaner(e)) {

            Future<String> future = e.submit(new NoOpRunnable(), TEST_STRING);

            assertSame(TEST_STRING, future.get());

            assertTrue(future.isDone());

            assertFalse(future.isCancelled());

        }

    }

    /**

     * A submitted privileged action runs to completion

     */

    public void testSubmitPrivilegedAction() throws Exception {

        final Callable callable = Executors.callable(new PrivilegedAction() {

                public Object run() { return TEST_STRING; }});

        Runnable r = new CheckedRunnable() {

        public void realRun() throws Exception {

            ExecutorService e = new ForkJoinPool(1);

            try (PoolCleaner cleaner = cleaner(e)) {

                Future future = e.submit(callable);

                assertSame(TEST_STRING, future.get());

            }

        }};

        runWithPermissions(r, new RuntimePermission("modifyThread"));

    }

    /**

     * A submitted privileged exception action runs to completion

     */

    public void testSubmitPrivilegedExceptionAction() throws Exception {

        final Callable callable =

            Executors.callable(new PrivilegedExceptionAction() {

                public Object run() { return TEST_STRING; }});

        Runnable r = new CheckedRunnable() {

        public void realRun() throws Exception {

            ExecutorService e = new ForkJoinPool(1);

            try (PoolCleaner cleaner = cleaner(e)) {