'Return ovsdb UUIDs for our controllers
update: update cached value'

def controllerUUIDs(self, update=False):

    if ((not self._uuids) or update):
        controllers = self.cmd('ovs-vsctl    --    get    Bridge', self, 'Controller').strip()
        if (controllers.startswith('[') and controllers.endswith(']')):
            controllers = controllers[1:(-1)]
            if controllers:
                self._uuids = [c.strip() for c in controllers.split(',')]
    return self._uuids
