void setAddress(int _address, PageUnsafe sharedBuffer) throws IOException {
      if (DO_SANITY_CHECK) assert _address % pageSize == 0;

      address = _address;
      addressInBuffer = storage.toOffsetInPage(address);

      disposePage();

      if (sharedBuffer != null) {
        page = sharedBuffer;
        isSharedPage = true;
      }
      syncWithStore();
    }
void setAddress(int _address, PageUnsafe sharedBuffer)