close() database should close the db no matter what the ref count says

        lock();

        try {

            closeClosable();

            releaseReference();

            // close this database instance - regardless of its reference count value

            onAllReferencesReleased();

            // set path to null, to cause bad stuff to happen if this object is reused without

            // being opened first

            mPath = null;

        } finally {

            unlock();

        }