1 files changed, 72 insertions, 4 deletions

diff --git a/src/api/stats/prometheus.rs b/src/api/stats/prometheus.rs
index 11645a3..9a4f162 100644
--- a/src/api/stats/prometheus.rs
+++ b/src/api/stats/prometheus.rs
@@ -103,6 +103,11 @@ fn escape(value: &str) -> String {
         .replace('\n', "\\n")
 }
 
+/// The transport of an address.
+fn scheme(address: &str) -> &str {
+    address.split_once(':').map_or("", |(scheme, _)| scheme)
+}
+
 fn flag(value: bool) -> f64 {
     if value { 1.0 } else { 0.0 }
 }
@@ -177,6 +182,7 @@ fn traffic_series(traffic: &PeerTraffic) -> Vec<(&'static str, &'static str, Cou
             (direction, "status_reply", by.status_reply),
             (direction, "blob", by.blob),
             (direction, "identity", by.identity),
+            (direction, "paths", by.paths),
         ]
     };
     let mut series = Vec::new();
@@ -238,6 +244,40 @@ fn transports(out: &mut Out, stats: &TransportStats) {
             out.single(name, "counter", help, value as f64);
         }
     }
+    if let Some(paths) = &stats.paths {
+        let counts = &paths.counts;
+        out.family(
+            "paths_probes_total",
+            "counter",
+            "PINGs to paths of peers with several, by result.",
+        );
+        for (result, count) in [
+            ("sent", counts.probes_sent),
+            ("answered", counts.probes_answered),
+            ("unanswered", counts.probes_unanswered),
+        ] {
+            out.sample("paths_probes_total", &[("result", result)], count as f64);
+        }
+        for (name, help, value) in [
+            (
+                "paths_send_failures_total",
+                "Sends that failed on a path, each tried at the next.",
+                counts.send_failures,
+            ),
+            (
+                "paths_failovers_total",
+                "Sends that went over another path after one failed.",
+                counts.failovers,
+            ),
+            (
+                "paths_switches_total",
+                "Changes of the path in use for a faster one.",
+                counts.switches,
+            ),
+        ] {
+            out.single(name, "counter", help, value as f64);
+        }
+    }
     if let Some(libp2p) = &stats.libp2p {
         out.family(
             "libp2p_reachability",
@@ -675,10 +715,7 @@ pub(super) async fn render(state: &AppState, stats: &StatsResponse) -> String {
     );
     for peer in &peers {
         if let Some(destination) = &peer.destination {
-            let transport = destination
-                .address
-                .split_once(':')
-                .map_or("", |(scheme, _)| scheme);
+            let transport = scheme(&destination.address);
             out.sample(
                 "peer_destination_info",
                 &[
@@ -695,6 +732,37 @@ pub(super) async fn render(state: &AppState, stats: &StatsResponse) -> String {
         }
     }
 
+    out.family(
+        "peer_path_rtt_seconds",
+        "gauge",
+        "Smoothed round-trip time of the PINGs on each path to a peer with several.",
+    );
+    for peer in &peers {
+        for path in peer.destination.iter().flat_map(|d| &d.paths) {
+            if let Some(ms) = path.rtt_ms {
+                out.sample(
+                    "peer_path_rtt_seconds",
+                    &[("peer", &peer.key), ("transport", scheme(&path.address))],
+                    ms / 1000.0,
+                );
+            }
+        }
+    }
+    out.family(
+        "peer_path_down",
+        "gauge",
+        "1 while a path to the peer is down (PINGs unanswered, or a send failed).",
+    );
+    for peer in &peers {
+        for path in peer.destination.iter().flat_map(|d| &d.paths) {
+            out.sample(
+                "peer_path_down",
+                &[("peer", &peer.key), ("transport", scheme(&path.address))],
+                flag(path.down),
+            );
+        }
+    }
+
     out.family("peer_neighbour", "gauge", "1 if the peer is a neighbour.");
     for peer in &peers {
         out.sample(