public static void dispose() {
   try {
     w.lock();
     DbConnection.force();
     DbConnection.closeFiles();
   } catch (Throwable e) {
     throw DbConnection.handleError(e);
   } finally {
     ourIsDisposed = true;
     w.unlock();
   }
 }
 @Override
 public void force() {
   DbConnection.force();
 }