/*
 * 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
 */

import junit.framework.*;
import java.util.concurrent.*;
import java.util.*;

public class RecursiveTaskTest extends JSR166TestCase {

    public static void main(String[] args) {
        junit.textui.TestRunner.run(suite());
    }
    public static Test suite() {
        return new TestSuite(RecursiveTaskTest.class);
    }

    private static ForkJoinPool mainPool() {
        return new ForkJoinPool();
    }

    private static ForkJoinPool singletonPool() {
        return new ForkJoinPool(1);
    }

    private static ForkJoinPool asyncSingletonPool() {
        return new ForkJoinPool(1,
                                ForkJoinPool.defaultForkJoinWorkerThreadFactory,
                                null, true);
    }

    private <T> T testInvokeOnPool(ForkJoinPool pool, RecursiveTask<T> a) {
        try {
            return pool.invoke(a);
        } finally {
            joinPool(pool);
        }
    }

    static final class FJException extends RuntimeException {
        FJException() { super(); }
    }

    // An invalid return value for Fib
    static final Integer NoResult = Integer.valueOf(-17);

    // A simple recursive task for testing
    static final class FibTask extends RecursiveTask<Integer> {
        final int number;
        FibTask(int n) { number = n; }
        public 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 recursive action failing in base case
    static final class FailingFibTask extends RecursiveTask<Integer> {
        final int number;
        int result;
        FailingFibTask(int n) { number = n; }
        public Integer compute() {
            int n = number;
            if (n <= 1)
                throw new FJException();
            FailingFibTask f1 = new FailingFibTask(n - 1);
            f1.fork();
            return (new FibTask(n - 2)).compute() + f1.join();
        }
    }

    /**
     * invoke returns value when task completes normally.
     * isCompletedAbnormally and isCancelled return false for normally
     * completed tasks. getRawResult of a completed non-null task
     * returns value;
     */
    public void testInvoke() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                Integer r = f.invoke();
                threadAssertTrue(r == 21);
                threadAssertTrue(f.isDone());
                threadAssertFalse(f.isCancelled());
                threadAssertFalse(f.isCompletedAbnormally());
                threadAssertTrue(f.getRawResult() == 21);
                return r;
            }
        };
        assertEquals(21, (int) testInvokeOnPool(mainPool(), a));
    }

    /**
     * quietlyInvoke task returns when task completes normally.
     * isCompletedAbnormally and isCancelled return false for normally
     * completed tasks
     */
    public void testQuietlyInvoke() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                f.quietlyInvoke();
                Integer r = f.getRawResult();
                threadAssertTrue(r == 21);
                threadAssertTrue(f.isDone());
                threadAssertFalse(f.isCancelled());
                threadAssertFalse(f.isCompletedAbnormally());
                return r;
            }
        };
        assertEquals(21, (int) testInvokeOnPool(mainPool(), a));
    }

    /**
     * join of a forked task returns when task completes
     */
    public void testForkJoin() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                f.fork();
                Integer r = f.join();
                threadAssertTrue(r == 21);
                threadAssertTrue(f.isDone());
                return r;
            }
        };
        assertEquals(21, (int) testInvokeOnPool(mainPool(), a));
    }

    /**
     * get of a forked task returns when task completes
     */
    public void testForkGet() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FibTask f = new FibTask(8);
                    f.fork();
                    Integer r = f.get();
                    threadAssertTrue(r == 21);
                    threadAssertTrue(f.isDone());
                    return r;
                } catch (Exception ex) {
                    unexpectedException(ex);
                }
                return NoResult;
            }
        };
        assertEquals(21, (int) testInvokeOnPool(mainPool(), a));
    }

    /**
     * timed get of a forked task returns when task completes
     */
    public void testForkTimedGet() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FibTask f = new FibTask(8);
                    f.fork();
                    Integer r = f.get(5L, TimeUnit.SECONDS);
                    threadAssertTrue(r == 21);
                    threadAssertTrue(f.isDone());
                    return r;
                } catch (Exception ex) {
                    unexpectedException(ex);
                }
                return NoResult;
            }
        };
        assertEquals(21, (int) testInvokeOnPool(mainPool(), a));
    }

    /**
     * quietlyJoin of a forked task returns when task completes
     */
    public void testForkQuietlyJoin() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                f.fork();
                f.quietlyJoin();
                Integer r = f.getRawResult();
                threadAssertTrue(r == 21);
                threadAssertTrue(f.isDone());
                return r;
            }
        };
        assertEquals(21, (int) testInvokeOnPool(mainPool(), a));
    }


    /**
     * helpQuiesce returns when tasks are complete.
     * getQueuedTaskCount returns 0 when quiescent
     */
    public void testForkHelpQuiesce() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                f.fork();
                f.helpQuiesce();
                Integer r = f.getRawResult();
                threadAssertTrue(r == 21);
                threadAssertTrue(f.isDone());
                threadAssertTrue(getQueuedTaskCount() == 0);
                return r;
            }
        };
        assertEquals(21, (int) testInvokeOnPool(mainPool(), a));
    }


    /**
     * invoke task throws exception when task completes abnormally
     */
    public void testAbnormalInvoke() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FailingFibTask f = new FailingFibTask(8);
                    f.invoke();
                    shouldThrow();
                    return NoResult;
                } catch (FJException success) {
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * quietlyInvoke task returns when task completes abnormally
     */
    public void testAbnormalQuietlyInvoke() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FailingFibTask f = new FailingFibTask(8);
                f.quietlyInvoke();
                threadAssertTrue(f.isDone());
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * join of a forked task throws exception when task completes abnormally
     */
    public void testAbnormalForkJoin() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FailingFibTask f = new FailingFibTask(8);
                    f.fork();
                    Integer r = f.join();
                    shouldThrow();
                    return r;
                } catch (FJException success) {
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * get of a forked task throws exception when task completes abnormally
     */
    public void testAbnormalForkGet() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FailingFibTask f = new FailingFibTask(8);
                    f.fork();
                    Integer r = f.get();
                    shouldThrow();
                    return r;
                } catch (ExecutionException success) {
                } catch (Exception ex) {
                    unexpectedException(ex);
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * timed get of a forked task throws exception when task completes abnormally
     */
    public void testAbnormalForkTimedGet() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FailingFibTask f = new FailingFibTask(8);
                    f.fork();
                    Integer r = f.get(5L, TimeUnit.SECONDS);
                    shouldThrow();
                    return r;
                } catch (ExecutionException success) {
                } catch (Exception ex) {
                    unexpectedException(ex);
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * quietlyJoin of a forked task returns when task completes abnormally
     */
    public void testAbnormalForkQuietlyJoin() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FailingFibTask f = new FailingFibTask(8);
                f.fork();
                f.quietlyJoin();
                threadAssertTrue(f.isDone());
                threadAssertTrue(f.isCompletedAbnormally());
                threadAssertTrue(f.getException() instanceof FJException);
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invoke task throws exception when task cancelled
     */
    public void testCancelledInvoke() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FibTask f = new FibTask(8);
                    f.cancel(true);
                    Integer r = f.invoke();
                    shouldThrow();
                    return r;
                } catch (CancellationException success) {
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * join of a forked task throws exception when task cancelled
     */
    public void testCancelledForkJoin() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FibTask f = new FibTask(8);
                    f.cancel(true);
                    f.fork();
                    Integer r = f.join();
                    shouldThrow();
                    return r;
                } catch (CancellationException success) {
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * get of a forked task throws exception when task cancelled
     */
    public void testCancelledForkGet() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FibTask f = new FibTask(8);
                    f.cancel(true);
                    f.fork();
                    Integer r = f.get();
                    shouldThrow();
                    return r;
                } catch (CancellationException success) {
                } catch (Exception ex) {
                    unexpectedException(ex);
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * timed get of a forked task throws exception when task cancelled
     */
    public void testCancelledForkTimedGet() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FibTask f = new FibTask(8);
                    f.cancel(true);
                    f.fork();
                    Integer r = f.get(5L, TimeUnit.SECONDS);
                    shouldThrow();
                    return r;
                } catch (CancellationException success) {
                } catch (Exception ex) {
                    unexpectedException(ex);
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * quietlyJoin of a forked task returns when task cancelled
     */
    public void testCancelledForkQuietlyJoin() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                f.cancel(true);
                f.fork();
                f.quietlyJoin();
                threadAssertTrue(f.isDone());
                threadAssertTrue(f.isCompletedAbnormally());
                threadAssertTrue(f.getException() instanceof CancellationException);
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * getPool of executing task returns its pool
     */
    public void testGetPool() {
        final ForkJoinPool mainPool = mainPool();
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                threadAssertTrue(getPool() == mainPool);
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool, a));
    }

    /**
     * getPool of non-FJ task returns null
     */
    public void testGetPool2() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                threadAssertTrue(getPool() == null);
                return NoResult;
            }
        };
        a.invoke();
    }

    /**
     * inForkJoinPool of executing task returns true
     */
    public void testInForkJoinPool() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                threadAssertTrue(inForkJoinPool());
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * inForkJoinPool of non-FJ task returns false
     */
    public void testInForkJoinPool2() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                threadAssertTrue(!inForkJoinPool());
                return NoResult;
            }
        };
        a.invoke();
    }

    /**
     * setRawResult(null) succeeds
     */
    public void testSetRawResult() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                setRawResult(NoResult);
                return NoResult;
            }
        };
        assertSame(NoResult, a.invoke());
    }

    /**
     * A reinitialized task may be re-invoked
     */
    public void testReinitialize() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                Integer r = f.invoke();
                threadAssertTrue(r == 21);
                threadAssertTrue(f.isDone());
                threadAssertFalse(f.isCancelled());
                threadAssertFalse(f.isCompletedAbnormally());
                f.reinitialize();
                r = f.invoke();
                threadAssertTrue(r == 21);
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invoke task throws exception after invoking completeExceptionally
     */
    public void testCompleteExceptionally() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FibTask f = new FibTask(8);
                    f.completeExceptionally(new FJException());
                    Integer r = f.invoke();
                    shouldThrow();
                    return r;
                } catch (FJException success) {
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invoke task suppresses execution invoking complete
     */
    public void testComplete() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                f.complete(NoResult);
                Integer r = f.invoke();
                threadAssertTrue(f.isDone());
                threadAssertTrue(r == NoResult);
                return r;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invokeAll(t1, t2) invokes all task arguments
     */
    public void testInvokeAll2() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                FibTask g = new FibTask(9);
                invokeAll(f, g);
                threadAssertTrue(f.isDone());
                threadAssertTrue(f.join() == 21);
                threadAssertTrue(g.isDone());
                threadAssertTrue(g.join() == 34);
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invokeAll(tasks) with 1 argument invokes task
     */
    public void testInvokeAll1() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                invokeAll(f);
                threadAssertTrue(f.isDone());
                threadAssertTrue(f.join() == 21);
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invokeAll(tasks) with > 2 argument invokes tasks
     */
    public void testInvokeAll3() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                FibTask g = new FibTask(9);
                FibTask h = new FibTask(7);
                invokeAll(f, g, h);
                threadAssertTrue(f.isDone());
                threadAssertTrue(f.join() == 21);
                threadAssertTrue(g.isDone());
                threadAssertTrue(g.join() == 34);
                threadAssertTrue(h.isDone());
                threadAssertTrue(h.join() == 13);
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invokeAll(collection) invokes all tasks in the collection
     */
    public void testInvokeAllCollection() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask f = new FibTask(8);
                FibTask g = new FibTask(9);
                FibTask h = new FibTask(7);
                HashSet set = new HashSet();
                set.add(f);
                set.add(g);
                set.add(h);
                invokeAll(set);
                threadAssertTrue(f.isDone());
                threadAssertTrue(f.join() == 21);
                threadAssertTrue(g.isDone());
                threadAssertTrue(g.join() == 34);
                threadAssertTrue(h.isDone());
                threadAssertTrue(h.join() == 13);
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }


    /**
     * invokeAll(t1, t2) throw exception if any task does
     */
    public void testAbnormalInvokeAll2() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FibTask f = new FibTask(8);
                    FailingFibTask g = new FailingFibTask(9);
                    invokeAll(f, g);
                    shouldThrow();
                    return NoResult;
                } catch (FJException success) {
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invokeAll(tasks) with 1 argument throws exception if task does
     */
    public void testAbnormalInvokeAll1() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FailingFibTask g = new FailingFibTask(9);
                    invokeAll(g);
                    shouldThrow();
                    return NoResult;
                } catch (FJException success) {
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invokeAll(tasks) with > 2 argument throws exception if any task does
     */
    public void testAbnormalInvokeAll3() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FibTask f = new FibTask(8);
                    FailingFibTask g = new FailingFibTask(9);
                    FibTask h = new FibTask(7);
                    invokeAll(f, g, h);
                    shouldThrow();
                    return NoResult;
                } catch (FJException success) {
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * invokeAll(collection) throws exception if any task does
     */
    public void testAbnormalInvokeAllCollection() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                try {
                    FailingFibTask f = new FailingFibTask(8);
                    FibTask g = new FibTask(9);
                    FibTask h = new FibTask(7);
                    HashSet set = new HashSet();
                    set.add(f);
                    set.add(g);
                    set.add(h);
                    invokeAll(set);
                    shouldThrow();
                    return NoResult;
                } catch (FJException success) {
                }
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(mainPool(), a));
    }

    /**
     * tryUnfork returns true for most recent unexecuted task,
     * and suppresses execution
     */
    public void testTryUnfork() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask g = new FibTask(9);
                g.fork();
                FibTask f = new FibTask(8);
                f.fork();
                threadAssertTrue(f.tryUnfork());
                helpQuiesce();
                threadAssertFalse(f.isDone());
                threadAssertTrue(g.isDone());
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(singletonPool(), a));
    }

    /**
     * getSurplusQueuedTaskCount returns > 0 when
     * there are more tasks than threads
     */
    public void testGetSurplusQueuedTaskCount() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask h = new FibTask(7);
                h.fork();
                FibTask g = new FibTask(9);
                g.fork();
                FibTask f = new FibTask(8);
                f.fork();
                threadAssertTrue(getSurplusQueuedTaskCount() > 0);
                helpQuiesce();
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(singletonPool(), a));
    }

    /**
     * peekNextLocalTask returns most recent unexecuted task.
     */
    public void testPeekNextLocalTask() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask g = new FibTask(9);
                g.fork();
                FibTask f = new FibTask(8);
                f.fork();
                threadAssertTrue(peekNextLocalTask() == f);
                f.join();
                threadAssertTrue(f.isDone());
                helpQuiesce();
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(singletonPool(), a));
    }

    /**
     * pollNextLocalTask returns most recent unexecuted task
     * without executing it
     */
    public void testPollNextLocalTask() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask g = new FibTask(9);
                g.fork();
                FibTask f = new FibTask(8);
                f.fork();
                threadAssertTrue(pollNextLocalTask() == f);
                helpQuiesce();
                threadAssertFalse(f.isDone());
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(singletonPool(), a));
    }

    /**
     * pollTask returns an unexecuted task without executing it
     */
    public void testPollTask() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask g = new FibTask(9);
                g.fork();
                FibTask f = new FibTask(8);
                f.fork();
                threadAssertTrue(pollTask() == f);
                helpQuiesce();
                threadAssertFalse(f.isDone());
                threadAssertTrue(g.isDone());
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(singletonPool(), a));
    }

    /**
     * peekNextLocalTask returns least recent unexecuted task in async mode
     */
    public void testPeekNextLocalTaskAsync() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask g = new FibTask(9);
                g.fork();
                FibTask f = new FibTask(8);
                f.fork();
                threadAssertTrue(peekNextLocalTask() == g);
                f.join();
                helpQuiesce();
                threadAssertTrue(f.isDone());
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(asyncSingletonPool(), a));
    }

    /**
     * pollNextLocalTask returns least recent unexecuted task
     * without executing it, in async mode
     */
    public void testPollNextLocalTaskAsync() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask g = new FibTask(9);
                g.fork();
                FibTask f = new FibTask(8);
                f.fork();
                threadAssertTrue(pollNextLocalTask() == g);
                helpQuiesce();
                threadAssertTrue(f.isDone());
                threadAssertFalse(g.isDone());
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(asyncSingletonPool(), a));
    }

    /**
     * pollTask returns an unexecuted task
     * without executing it, in async mode
     */
    public void testPollTaskAsync() {
        RecursiveTask<Integer> a = new RecursiveTask<Integer>() {
            public Integer compute() {
                FibTask g = new FibTask(9);
                g.fork();
                FibTask f = new FibTask(8);
                f.fork();
                threadAssertTrue(pollTask() == g);
                helpQuiesce();
                threadAssertTrue(f.isDone());
                threadAssertFalse(g.isDone());
                return NoResult;
            }
        };
        assertSame(NoResult, testInvokeOnPool(asyncSingletonPool(), a));
    }

}