def _populate_networks_cache(self):
        """Populate the networks cache when the DHCP-agent starts."""
        try:
            existing_networks = self.dhcp_driver_cls.existing_dhcp_networks(
                self.conf
            )
            for net_id in existing_networks:
                net = dhcp.NetModel({"id": net_id, "subnets": [], "ports": []})
                self.cache.put(net)
        except __HOLE__:
            # just go ahead with an empty networks cache
            LOG.debug("The '%s' DHCP-driver does not support retrieving of a "
                      "list of existing networks",
                      self.conf.dhcp_driver)
dataset/ETHPy150Open openstack/neutron/neutron/agent/dhcp/agent.py/DhcpAgent._populate_networks_cache