From 4c6604db27f26998b72fd815b6bd1de5a3b08780 Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Thu, 5 Nov 2026 00:56:24 +0100
Subject: own tree shape

---
 src/api/stats.rs            | 25 +++++++++++++++++++++++++
 src/api/stats/prometheus.rs | 26 ++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

(limited to 'src/api')

diff --git a/src/api/stats.rs b/src/api/stats.rs
index 5061ff7..3851ef7 100644
--- a/src/api/stats.rs
+++ b/src/api/stats.rs
@@ -187,6 +187,18 @@ struct TopologyView {
     stable: usize,
     neighbours: usize,
     stable_neighbours: usize,
+    /// Our own writer's tree (`swarm::tree::own_shape`); absent while we aren't in the
+    /// member list's graph.
+    own_tree: Option<OwnTree>,
+}
+
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct OwnTree {
+    members: usize,
+    depth: u32,
+    mean_depth: f64,
+    off_tree: usize,
 }
 
 #[derive(Debug, Serialize)]
@@ -264,6 +276,18 @@ pub(crate) async fn get_stats(State(state): State<AppState>, headers: HeaderMap)
 /// totals over the peers from their list (`peer_list`), read once for both.
 pub(crate) async fn collect(state: &AppState, list: &PeerListResponse) -> StatsResponse {
     let node = state.stats.snapshot();
+    let own_tree = crate::swarm::tree::own_shape(state)
+        .await
+        .map(|shape| OwnTree {
+            members: shape.members,
+            depth: shape.depth,
+            mean_depth: if shape.members == 0 {
+                0.0
+            } else {
+                shape.hops as f64 / shape.members as f64
+            },
+            off_tree: shape.off,
+        });
 
     let (heads, tier, remakes) = {
         let replica = state.doc.read().await;
@@ -358,6 +382,7 @@ pub(crate) async fn collect(state: &AppState, list: &PeerListResponse) -> StatsR
                 stable: s.stable,
                 neighbours: s.neighbours,
                 stable_neighbours: s.stable_neighbours,
+                own_tree,
             }),
         },
         stability: StabilityStats {
diff --git a/src/api/stats/prometheus.rs b/src/api/stats/prometheus.rs
index 595466a..db3cef3 100644
--- a/src/api/stats/prometheus.rs
+++ b/src/api/stats/prometheus.rs
@@ -713,6 +713,32 @@ pub(super) fn render(stats: &StatsResponse, list: &PeerListResponse) -> String {
             "Current neighbours with the stable tier.",
             view.stable_neighbours as f64,
         );
+        if let Some(tree) = &view.own_tree {
+            out.single(
+                "own_tree_members",
+                "gauge",
+                "Other members in this node's own writer's tree.",
+                tree.members as f64,
+            );
+            out.single(
+                "own_tree_depth",
+                "gauge",
+                "Most hops from this node to a member along its own writer's tree.",
+                f64::from(tree.depth),
+            );
+            out.single(
+                "own_tree_mean_depth",
+                "gauge",
+                "Mean hops from this node to a member along its own writer's tree.",
+                tree.mean_depth,
+            );
+            out.single(
+                "own_tree_off_members",
+                "gauge",
+                "Members this node's own writer's tree doesn't reach (they get its writes by announcement).",
+                tree.off_tree as f64,
+            );
+        }
     }
 
     let stability = &stats.stability;
-- 
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