code: protected Session getReadSession() throws CpoException {
      Session session;
  
      try {
        if (!(invalidReadSession)) {
          session = getReadDataSource().getSession();
        } else {
          session = getWriteDataSource().getSession();
        }
      } catch (Exception e) {
        invalidReadSession = true;
  
        String msg = "getReadConnection(): failed";
        logger.error(msg, e);
  
        session = getWriteSession();
      }
  
      return session;
    }
docs: getReadSession returns the read session for Cassandra
  
  @return A Session object for reading
  @throws CpoException