1 files changed, 9 insertions, 0 deletions

diff --git a/src/swarm/stats.rs b/src/swarm/stats.rs
index 02ccad5..218d5e8 100644
--- a/src/swarm/stats.rs
+++ b/src/swarm/stats.rs
@@ -166,6 +166,10 @@ pub(crate) struct Relay {
     /// counting them so (so they weren't what we passed on built on), and later.
     pub(crate) asked_known_lately: u64,
     pub(crate) asked_known_later: u64,
+    /// Messages taken as delivered by their sender, which was behind us: answered with
+    /// what it lacks (it got changes we had along its tree late, or we got them early by
+    /// another way).
+    pub(crate) answering_behind: u64,
     /// Changes from elsewhere that came not along a writer's tree (pulled, with an
     /// answer, sent again, fetched as a delta), and their delays summed (as `Propagation`).
     pub(crate) off_tree: u64,
@@ -312,6 +316,11 @@ impl NodeStats {
         inner.relay.nothing_new_change_bytes += change_bytes as u64;
     }
 
+    /// A message taken as delivered came from a peer behind us (`Relay::answering_behind`).
+    pub(crate) fn answering_behind(&self) {
+        self.lock().relay.answering_behind += 1;
+    }
+
     /// A sync message carried changes that wait for predecessors (`Relay::waiting`).
     pub(crate) fn waiting(&self) {
         self.lock().relay.waiting += 1;