java.util.concurrent.atomic.AtomicLongArray#weakCompareAndSetVolatile()源码实例Demo

/**
 * get and set for out of bound indices throw IndexOutOfBoundsException
 */
public void testIndexing() {
    AtomicLongArray aa = new AtomicLongArray(SIZE);
    for (int index : new int[] { -1, SIZE }) {
        final int j = index;
        final Runnable[] tasks = {
            () -> aa.getPlain(j),
            () -> aa.getOpaque(j),
            () -> aa.getAcquire(j),
            () -> aa.setPlain(j, 1),
            () -> aa.setOpaque(j, 1),
            () -> aa.setRelease(j, 1),
            () -> aa.compareAndExchange(j, 1, 2),
            () -> aa.compareAndExchangeAcquire(j, 1, 2),
            () -> aa.compareAndExchangeRelease(j, 1, 2),
            () -> aa.weakCompareAndSetPlain(j, 1, 2),
            () -> aa.weakCompareAndSetVolatile(j, 1, 2),
            () -> aa.weakCompareAndSetAcquire(j, 1, 2),
            () -> aa.weakCompareAndSetRelease(j, 1, 2),
        };

        assertThrows(IndexOutOfBoundsException.class, tasks);
    }
}
 

/**
 * repeated weakCompareAndSetVolatile succeeds in changing value when equal
 * to expected
 */
public void testWeakCompareAndSetVolatile() {
    AtomicLongArray aa = new AtomicLongArray(SIZE);
    for (int i = 0; i < SIZE; i++) {
        aa.set(i, 1);
        do {} while (!aa.weakCompareAndSetVolatile(i, 1, 2));
        do {} while (!aa.weakCompareAndSetVolatile(i, 2, -4));
        assertEquals(-4, aa.get(i));
        do {} while (!aa.weakCompareAndSetVolatile(i, -4, 7));
        assertEquals(7, aa.get(i));
    }
}