// try to swap null into head.
      } while (!UNSAFE.compareAndSwapObject(this, HEAD_OFFSET, stack, null));

      RunnableExecutorPair reversedStack = null;
      while (stack != NULL_PAIR) {
        RunnableExecutorPair head = stack;
        stack = stack.next;
        head.next = reversedStack;
        reversedStack = head;
      }
      stack = reversedStack;
      while (stack != null) {
        stack.execute();

 * common bugs: The {@code wait()} must be inside a {@code while} instead of an {@code if}, and
 * {@code notifyAll()} must be used instead of {@code notify()} because there are two different
 * logical conditions being awaited.
 *
 * <pre>{@code
 * public class SafeBox<V> {
 *   private V value;
 *
 *   public synchronized V get() throws InterruptedException {
 *     while (value == null) {
 *       wait();
 *     }

    // Replace existing values, if any.
    while (keyValues.hasNext() && newValues.hasNext()) {
      keyValues.next();
      keyValues.set(newValues.next());
    }

    // Remove remaining old values, if any.
    while (keyValues.hasNext()) {
      keyValues.next();
      keyValues.remove();
    }

    // Add remaining new values, if any.
    while (newValues.hasNext()) {

   */
  public static String commonPrefix(CharSequence a, CharSequence b) {
    checkNotNull(a);
    checkNotNull(b);

    int maxPrefixLength = Math.min(a.length(), b.length());
    int p = 0;
    while (p < maxPrefixLength && a.charAt(p) == b.charAt(p)) {
      p++;
    }
    if (validSurrogatePairAt(a, p - 1) || validSurrogatePairAt(b, p - 1)) {
      p--;
    }
    return a.subSequence(0, p).toString();
  }

          } catch (Exception e) { // sneaky checked exception
            log.get().log(Level.SEVERE, "Exception while executing runnable " + task, e);
          } finally {
            task = null;
          }
        }
      } finally {
        // Ensure that if the thread was interrupted at all while processing the task queue, it
        // is returned to the delegate Executor interrupted so that it may handle the

        checkNotNull(appendable, "appendable");
        checkNotNull(parts, "parts");
        while (parts.hasNext()) {
          Object part = parts.next();
          if (part != null) {
            appendable.append(Joiner.this.toString(part));
            break;
          }
        }
        while (parts.hasNext()) {
          Object part = parts.next();
          if (part != null) {

              E element = entry1.getElement();
              int count = Math.max(entry1.getCount(), multiset2.count(element));
              return immutableEntry(element, count);
            }
            while (iterator2.hasNext()) {
              Entry<? extends E> entry2 = iterator2.next();
              E element = entry2.getElement();
              if (!multiset1.contains(element)) {

    final AtomicDoubleArray a = new AtomicDoubleArray(1);
    a.set(0, 1.0);
    Thread t =
        newStartedThread(
            new CheckedRunnable() {
              public void realRun() {
                while (!a.compareAndSet(0, 2.0, 3.0)) {
                  Thread.yield();
                }
              }
            });

    assertTrue(a.compareAndSet(0, 1.0, 2.0));
    awaitTermination(t);

      }
    },
    NO_SPLIT_TRY_ADVANCE {
      @Override
      <E extends @Nullable Object> void forEach(
          GeneralSpliterator<E> spliterator, Consumer<? super E> consumer) {
        while (spliterator.tryAdvance(consumer)) {
          // do nothing
        }
      }
    },
    MAXIMUM_SPLIT {
      @Override
      <E extends @Nullable Object> void forEach(

        return method;
      }
    }
    throw new NoSuchMethodError(methodName);
  }

  @Override
  public void run() {
    assertSame(this, Thread.currentThread());
    try {
      while (true) {
        Request request = requestQueue.take();
        Object result;
        try {
          result = invokeMethod(request.methodName, request.arguments);
        } catch (ThreadDeath death) {