'Retrieve server mapping from database.'

def LoadServerMapping(self):

    token = access_control.ACLToken(username='GRRSystem').SetUID()
    (mapping_str, _) = self.db.Resolve(MAP_SUBJECT, MAP_VALUE_PREDICATE, token=token)
    if (not mapping_str):
        return None
    mapping = rdf_data_server.DataServerMapping.FromSerializedString(mapping_str)
    if self._DifferentPathing(list(mapping.pathing)):
        self.pathing = list(mapping.pathing)
        self.db.RecreatePathing(self.pathing)
    return mapping
