offerer asked first

2 files changed, 5 insertions, 2 deletions

diff --git a/src/swarm/blob.rs b/src/swarm/blob.rs
index f3494af..588868f 100644
--- a/src/swarm/blob.rs
+++ b/src/swarm/blob.rs
@@ -474,7 +474,9 @@ pub(crate) async fn fetch(
     }
     let _registration = Registration { state, id };
 
-    // Closest first; peers without a round-trip time last.
+    // Closest first; peers without a round-trip time last. For a delta, the first is
+    // the one that offered it, which holds it: asked first however far.
+    let offerer = delta.and_then(|_| peers.first().cloned());
     let now = Instant::now();
     let mut peers: Vec<(String, Option<Duration>)> = {
         let rtt = state.lock_rtt();
@@ -486,7 +488,7 @@ pub(crate) async fn fetch(
             })
             .collect()
     };
-    peers.sort_by_key(|(_, rtt)| rtt.unwrap_or(Duration::MAX));
+    peers.sort_by_key(|(peer, rtt)| (offerer.as_ref() != Some(peer), rtt.unwrap_or(Duration::MAX)));
     let rtts: HashMap<String, Option<Duration>> = peers.iter().cloned().collect();
     let mut candidates: VecDeque<String> = peers.into_iter().map(|(peer, _)| peer).collect();
     if candidates.is_empty() {
diff --git a/src/swarm/sync.rs b/src/swarm/sync.rs
index 5100b98..62bb27e 100644
--- a/src/swarm/sync.rs
+++ b/src/swarm/sync.rs
@@ -752,6 +752,7 @@ async fn download_and_apply_delta(
     epoch: transport::Epoch,
     spec: transport::DeltaSpec,
 ) -> Result<bool> {
+    // The offerer first: it holds what it offers (`blob::fetch` asks it first).
     let mut peers = vec![peer.to_owned()];
     peers.extend(
         state