code: @SuppressWarnings("unchecked")
      @Override
      public E get(int index) {
  
          _tailLock.lock();
          try {
  
              _headLock.lock();
              try {
                  if (index < 0 || index >= _size.get())
                      throw new IndexOutOfBoundsException("!(" + 0 + "<" + index + "<=" + _size + ")");
                  int i = _indexes[HEAD_OFFSET] + index;
                  int capacity = _elements.length;
                  if (i >= capacity)
                      i -= capacity;
                  return (E) _elements[i];
              } finally {
                  _headLock.unlock();
              }
          } finally {
              _tailLock.unlock();
          }
      }
docs: /*----------------------------------------------------------------------------