}
  }

  private abstract static class AtomicHelper {
    /** Non-volatile write of the thread to the {@link Waiter#thread} field. */
    abstract void putThread(Waiter waiter, Thread newValue);

    /** Non-volatile write of the waiter to the {@link Waiter#next} field. */
    abstract void putNext(Waiter waiter, @CheckForNull Waiter newValue);

    /** Performs a CAS operation on the {@link #waiters} field. */

   * concurrently readable hash table. The map supports non-blocking reads and concurrent writes
   * across different segments.
   *
   * The page replacement algorithm's data structures are kept casually consistent with the map. The
   * ordering of writes to a segment is sequentially consistent. An update to the map and recording