Add metric for updates denied by filters

Signed-off-by: Lee Smet <lee.smet@hotmail.com>

mycelium-metrics/src/prometheus.rs

@@ -28,6 +28,7 @@ pub struct PrometheusExporter {
     router_tlv_source_died: IntCounter,
     router_propage_selected_peers_time_spent: IntCounter,
     router_update_skipped_route_selection: IntCounter,
+    router_update_denied_by_filter: IntCounter,
     peer_manager_peer_added: IntCounterVec,
     peer_manager_known_peers: IntGauge,
     peer_manager_connection_attemps: IntCounterVec,
@@ -131,6 +132,11 @@ impl PrometheusExporter {
                 "Updates which were processed but did not run the route selection step, because the updated route could not be selected anyway",
             )
             .expect("Can register an int counter in default registry"),
+            router_update_denied_by_filter: register_int_counter!(
+                "mycelium_router_update_denied",
+                "Updates which were received and immediately denied by a configured filter",
+            )
+            .expect("Can register an int counter in default registry"),
             peer_manager_peer_added: register_int_counter_vec!(
                 opts!(
                     "mycelium_peer_manager_peers_added",
@@ -374,6 +380,11 @@ impl Metrics for PrometheusExporter {
         self.router_update_skipped_route_selection.inc()
     }
 
+    #[inline]
+    fn router_update_denied_by_filter(&self) {
+        self.router_update_denied_by_filter.inc()
+    }
+
     #[inline]
     fn peer_manager_peer_added(&self, pt: mycelium::peer_manager::PeerType) {
         let label = match pt {

mycelium/src/metrics.rs

@@ -159,6 +159,10 @@ pub trait Metrics {
     #[inline]
     fn router_update_skipped_route_selection(&self) {}
 
+    /// An update was denied by a configured filter.
+    #[inline]
+    fn router_update_denied_by_filter(&self) {}
+
     /// A new [`Peer`](crate::peer::Peer) was added to the
     /// [`PeerManager`](crate::peer_manager::PeerManager) while it is running.
     #[inline]

mycelium/src/router.rs

@@ -948,6 +948,7 @@ where
         for filter in &*self.update_filters {
             if !filter.allow(&update) {
                 debug!("Update denied by filter");
+                self.metrics.router_update_denied_by_filter();
                 return;
             }
         }