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

   * 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;
        }

        executingTaskQueue.thread = null;
      }
    }

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

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

   * test case failure. Only the first failure is recorded; subsequent calls to this method from
   * within the same test have no effect.
   */
  public void threadRecordFailure(Throwable t) {
    threadFailure.compareAndSet(null, t);
  }

  @Override
  public void setUp() {
    setDelays();
  }

  /**
   * Extra checks that get done for all test cases.
   *

   * test case failure. Only the first failure is recorded; subsequent calls to this method from
   * within the same test have no effect.
   */
  public void threadRecordFailure(Throwable t) {
    threadFailure.compareAndSet(null, t);
  }

  public void setUp() {
    setDelays();
  }

  /**
   * Extra checks that get done for all test cases.
   *