docs: private long[] lockAll() {
      OptimisticLock[] _locks = locks;
      int sn = _locks.length;
      long[] _stamps = new long[locks.length];
      for (int i = 0; i < sn; i++) {
        OptimisticLock l = _locks[i];
        _stamps[i] = l.writeLock();
      }
      return _stamps;
    }