Examples with Collectors java8.util.stream.Collectors used on opensource projects

Example 1 with Collectors

use of java8.util.stream.Collectors in project streamsupport by stefan-zobel.

the class Collection8Test method testDetectRaces.

/**
 * Motley crew of threads concurrently randomly hammer the collection.
 */
@SuppressWarnings({ "rawtypes", "unchecked" })
@Test(dataProvider = "Source")
public void testDetectRaces(String description, Supplier<CollectionImplementation> sci) throws Throwable {
    CollectionImplementation impl = sci.get();
    if (!impl.isConcurrent())
        return;
    if (HAS_JAVA8_SPLITERATOR_BUG && LinkedBlockingDeque.class.equals(impl.klazz())) {
        // https://bugs.openjdk.java.net/browse/JDK-8169739
        return;
    }
    if (CopyOnWriteArraySet.class.equals(impl.klazz())) {
        return;
    }
    final ThreadLocalRandom rnd = ThreadLocalRandom.current();
    final Collection c = impl.emptyCollection();
    final long testDurationMillis = expensiveTests ? LONG_DELAY_MS : timeoutMillis();
    final AtomicBoolean done = new AtomicBoolean(false);
    final Object one = impl.makeElement(1);
    final Object two = impl.makeElement(2);
    final Consumer checkSanity = x -> assertTrue(x == one || x == two);
    final Consumer<Object[]> checkArraySanity = array -> {
        // assertTrue(array.length <= 2); // duplicates are permitted
        for (Object x : array) assertTrue(x == one || x == two);
    };
    final Object[] emptyArray = (Object[]) java.lang.reflect.Array.newInstance(one.getClass(), 0);
    final List<Future<?>> futures;
    // register this thread
    final Phaser threadsStarted = new Phaser(1);
    final Runnable[] frobbers = { () -> Iterables.forEach(c, checkSanity), () -> StreamSupport.stream(c).forEach(checkSanity), () -> StreamSupport.parallelStream(c).forEach(checkSanity), () -> Spliterators.spliterator(c).trySplit(), () -> {
        Spliterator<?> s = Spliterators.spliterator(c);
        s.tryAdvance(checkSanity);
        s.trySplit();
    }, () -> {
        Spliterator<?> s = Spliterators.spliterator(c);
        do {
        } while (s.tryAdvance(checkSanity));
    }, () -> {
        for (Object x : c) checkSanity.accept(x);
    }, () -> checkArraySanity.accept(c.toArray()), () -> checkArraySanity.accept(c.toArray(emptyArray)), () -> {
        Object[] a = new Object[5];
        Object three = impl.makeElement(3);
        Arrays.fill(a, 0, a.length, three);
        Object[] x = c.toArray(a);
        if (x == a)
            for (int i = 0; i < a.length && a[i] != null; i++) checkSanity.accept(a[i]);
        else
            // A careful reading of the spec does not support:
            // for (i++; i < a.length; i++) assertSame(three, a[i]);
            checkArraySanity.accept(x);
    }, adderRemover(c, one), adderRemover(c, two) };
    final List<Runnable> tasks = J8Arrays.stream(frobbers).filter(// random subset
    task -> rnd.nextBoolean()).map(task -> (Runnable) () -> {
        threadsStarted.arriveAndAwaitAdvance();
        while (!done.get()) task.run();
    }).collect(Collectors.<Runnable>toList());
    final ExecutorService pool = Executors.newCachedThreadPool();
    PoolCleaner cleaner = null;
    try {
        cleaner = cleaner(pool, done);
        threadsStarted.bulkRegister(tasks.size());
        futures = StreamSupport.stream(tasks).map(pool::submit).collect(Collectors.toList());
        threadsStarted.arriveAndDeregister();
        Thread.sleep(testDurationMillis);
    } finally {
        if (cleaner != null) {
            cleaner.close();
        }
    }
    for (Future<?> future : futures) assertNull(future.get(0L, MILLISECONDS));
}