struct netflow *netflow_create(void);
struct netflow *netflow_ref(const struct netflow *);
void netflow_unref(struct netflow *);
+bool netflow_exists(void);
int netflow_set_options(struct netflow *, const struct netflow_options *);
void netflow_expire(struct netflow *, struct flow *);
void netflow_flow_clear(struct netflow *netflow, struct flow *flow);
-void netflow_flow_update(struct netflow *nf, struct flow *flow,
+void netflow_flow_update(struct netflow *nf, const struct flow *flow,
ofp_port_t output_iface,
const struct dpif_flow_stats *);