def connected?(klass)
      return false if Process.pid != @process_pid.get
      conn = self.retrieve_connection_pool(klass)
      conn && conn.connected?
    end
def connected?(klass)
      return false if Process.pid != @process_pid.get
      conn = self.retrieve_connection_pool(klass)
      conn && conn.connected?
    end
Returns true if a connection that's accessible to this class has
 already been opened.