add propagation stats

1 files changed, 31 insertions, 0 deletions

diff --git a/src/api/stats.rs b/src/api/stats.rs
index e426c7a..3822b5f 100644
--- a/src/api/stats.rs
+++ b/src/api/stats.rs
@@ -24,6 +24,27 @@ pub(crate) struct StatsResponse {
     traffic: PeerTraffic,
     /// The peers listed in /peers together (a forgotten peer's are gone).
     incidents: Incidents,
+    propagation: PropagationStats,
+}
+
+/// How long changes written elsewhere took from their commit there until applied here,
+/// once caught up. Includes the clock skew between the writer and us.
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct PropagationStats {
+    count: u64,
+    sum_ms: u64,
+    /// Changes stamped later than our clock on arrival (writer's clock ahead).
+    ahead: u64,
+    /// Not cumulative; the last bucket has no bound.
+    buckets: Vec<PropagationBucket>,
+}
+
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct PropagationBucket {
+    le_ms: Option<u64>,
+    count: u64,
 }
 
 #[derive(Debug, Serialize)]
@@ -139,5 +160,15 @@ pub(crate) async fn get_stats(State(state): State<AppState>) -> Json<StatsRespon
         stale_hello_replies: node.stale_hello_replies,
         traffic: state.traffic.total(),
         incidents,
+        propagation: PropagationStats {
+            count: node.propagation.count,
+            sum_ms: node.propagation.sum_ms,
+            ahead: node.propagation.ahead,
+            buckets: node
+                .propagation
+                .buckets()
+                .map(|(le_ms, count)| PropagationBucket { le_ms, count })
+                .collect(),
+        },
     })
 }