From 4bbadf6fdc4733b4c3c5eeb575508b2f9334ebdb Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Mon, 26 Oct 2026 19:29:59 +0100
Subject: keepalive sends head samples alongside digest

When there are more than 32 heads that can be send in a single keepalive
message, the digest is accompanied by 32 heads, a different window each
time, so after a few keepalives every head has been listed.
---
 src/swarm/relay.rs | 43 ++++++++++++++++++++++---------------------
 1 file changed, 22 insertions(+), 21 deletions(-)

(limited to 'src/swarm/relay.rs')

diff --git a/src/swarm/relay.rs b/src/swarm/relay.rs
index 7c56c90..087e028 100644
--- a/src/swarm/relay.rs
+++ b/src/swarm/relay.rs
@@ -128,20 +128,26 @@ pub(crate) async fn pull_if_behind(
     if ours == remote.heads {
         return false;
     }
-    let missing = match &remote.heads {
-        HeadsSummary::Heads(heads) => {
-            // AutoCommit's lookups take &mut self.
-            let mut replica = state.doc.write().await;
-            let missing = heads
-                .iter()
-                .any(|head| replica.doc.get_change_by_hash(head).is_none());
-            if !missing {
-                return false;
-            }
-            Some(heads.clone())
-        }
-        // Can't tell which heads are missing; the digest differs from ours, though.
-        HeadsSummary::Digest(_) => None,
+    // Those of the listed heads we lack. With a digest only a sample is listed; if we
+    // have all of it, a later keepalive lists others.
+    let missing: Vec<_> = {
+        // AutoCommit's lookups take &mut self.
+        let mut replica = state.doc.write().await;
+        remote
+            .heads
+            .listed()
+            .iter()
+            .filter(|head| replica.doc.get_change_by_hash(head).is_none())
+            .copied()
+            .collect()
+    };
+    if missing.is_empty() {
+        return false;
+    }
+    // All heads, when we know them; otherwise those we lack.
+    let theirs = match remote.heads.heads() {
+        Some(heads) => heads.to_vec(),
+        None => missing,
     };
 
     let Some(peer_state) = state.get_peer_state(peer).await else {
@@ -166,13 +172,8 @@ pub(crate) async fn pull_if_behind(
         pulling.waiting.remove(peer);
     }
 
-    match missing {
-        // Automerge asks for whatever these heads need that we don't have.
-        Some(heads) => peer_state.lock().await.sync.pull_from(heads),
-        // A fresh session's opening carries our heads and bloom filter; the answer
-        // brings what we lack.
-        None => peer_state.lock().await.reset_sync(),
-    }
+    // Automerge asks for whatever these heads need that we don't have.
+    peer_state.lock().await.sync.pull_from(theirs);
     debug!(peer = %peer, "Neighbour has changes we lack; pulling");
     let _ = state
         .sync_events
-- 
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