centralize call to topology_change

2 files changed, 14 insertions, 1 deletions

diff --git a/src/state/mod.rs b/src/state/mod.rs
index 8f3a841..a2d5d74 100644
--- a/src/state/mod.rs
+++ b/src/state/mod.rs
@@ -143,7 +143,7 @@ pub(crate) struct AppState {
     /// Our neighbours, once known (`swarm::topology`).
     pub(crate) neighbours: Arc<std::sync::RwLock<Option<crate::swarm::topology::NeighbourView>>>,
     /// Something the neighbours are computed from may have changed: the member list or a
-    /// peer's reachability (`swarm::topology::run_worker`).
+    /// peer's state (`swarm::topology::run_worker`, `swarm::topology::change_peer`).
     pub(crate) topology_changed: Arc<tokio::sync::Notify>,
 
     /// While rejoining a newer epoch, the previous document, served read-only (and
diff --git a/src/state/peer.rs b/src/state/peer.rs
index 95a9dc3..99f912b 100644
--- a/src/state/peer.rs
+++ b/src/state/peer.rs
@@ -288,6 +288,19 @@ impl PeerState {
         self.unreachable_since.is_some()
     }
 
+    /// What choosing neighbours reads of this peer (`swarm::topology::refresh`): whether
+    /// it is unreachable, whether it was ever heard from, whether it is a member, and
+    /// whether it syncs with us. A change to any may change the neighbours
+    /// (`swarm::topology::change_peer`).
+    pub(crate) fn neighbour_inputs(&self) -> impl PartialEq + use<> {
+        (
+            self.is_unreachable(),
+            self.last_seen.is_some(),
+            matches!(self.standing, Standing::Member { .. }),
+            self.syncs_with_us,
+        )
+    }
+
     /// The wait before the next HELLO: a probe's if unreachable.
     pub(crate) fn next_hello_wait(&mut self) -> Duration {
         if self.is_unreachable() {