for (double x : VALUES) {
        assertBitEquals(prev, aa.get(i));
        assertFalse(aa.compareAndSet(i, unused, x));
        assertBitEquals(prev, aa.get(i));
        assertTrue(aa.compareAndSet(i, prev, x));
        assertBitEquals(x, aa.get(i));
        prev = x;
      }
    }
  }

  /** compareAndSet in one thread enables another waiting for value to succeed */

      for (double x : VALUES) {
        assertBitEquals(prev, aa.get(i));
        assertFalse(aa.compareAndSet(i, unused, x));
        assertBitEquals(prev, aa.get(i));
        assertTrue(aa.compareAndSet(i, prev, x));
        assertBitEquals(x, aa.get(i));
        prev = x;
      }
    }
  }

  /** compareAndSet in one thread enables another waiting for value to succeed */

   * AtomicInteger's atomic operations, with some help from ConcurrentMap's atomic operations on
   * creation and removal (including automatic removal of zeroes). If the modification of an
   * AtomicInteger results in zero, we compareAndSet the value to zero; if that succeeds, we remove
   * the entry from the Map. If another operation sees a zero in the map, it knows that the entry is

     * interrupt, yet it will still run, since interruptTask will leave the runner value null,
     * allowing the CAS below to succeed.
     */
    Thread currentThread = Thread.currentThread();
    if (!compareAndSet(null, currentThread)) {
      return; // someone else has run or is running.
    }

    boolean run = !isDone();
    T result = null;
    Throwable error = null;
    try {
      if (run) {

      assertBitEquals(x, at.doubleValue());
    }
  }

  /** compareAndSet treats +0.0 and -0.0 as distinct values */
  public void testDistinctZeros() {
    AtomicDouble at = new AtomicDouble(+0.0);
    assertFalse(at.compareAndSet(-0.0, 7.0));
    assertFalse(at.weakCompareAndSet(-0.0, 7.0));
    assertBitEquals(+0.0, at.get());
    assertTrue(at.compareAndSet(+0.0, -0.0));
    assertBitEquals(-0.0, at.get());

   * AtomicInteger's atomic operations, with some help from ConcurrentMap's atomic operations on
   * creation and removal (including automatic removal of zeroes). If the modification of an
   * AtomicInteger results in zero, we compareAndSet the value to zero; if that succeeds, we remove
   * the entry from the Map. If another operation sees a zero in the map, it knows that the entry is

        if (oldValue == 0L) {
          // don't compareAndSet a zero
          if (map.replace(key, atomic, new AtomicLong(delta))) {
            return delta;
          }
          // atomic replaced
          continue outer;
        }

        long newValue = oldValue + delta;
        if (atomic.compareAndSet(oldValue, newValue)) {
          return newValue;
        }

      long newValue;
      do {
        oldValue = data.get(longIndex);
        newValue = oldValue | mask;
        if (oldValue == newValue) {
          return false;
        }
      } while (!data.compareAndSet(longIndex, oldValue, newValue));

      // We turned the bit on, so increment bitCount.
      bitCount.increment();
      return true;
    }

    boolean get(long bitIndex) {

        executingTaskQueue.thread = null;
      }
    }

    private boolean trySetStarted() {
      return compareAndSet(NOT_RUN, STARTED);
    }

    private boolean trySetCancelled() {
      return compareAndSet(NOT_RUN, CANCELLED);
    }
  }

      if (existing != null) {
        return existing;
      }
      L created = supplier.get();
      ArrayReference<L> newRef = new ArrayReference<>(created, index, queue);
      while (!locks.compareAndSet(index, existingRef, newRef)) {
        // we raced, we need to re-read and try again
        existingRef = locks.get(index);
        existing = existingRef == null ? null : existingRef.get();