Add in Backoff Filter When Grafting New Peers

gossipsub.go

@@ -1036,21 +1036,25 @@ func (gs *GossipSubRouter) Join(topic string) {
 
 	gmap, ok = gs.fanout[topic]
 	if ok {
+		backoff := gs.backoff[topic]
 		// these peers have a score above the publish threshold, which may be negative
 		// so drop the ones with a negative score
 		for p := range gmap {
-			if gs.score.Score(p) < 0 {
+			_, doBackOff := backoff[p]
+			if gs.score.Score(p) < 0 || doBackOff {
 				delete(gmap, p)
 			}
 		}
 
 		if len(gmap) < gs.params.D {
 			// we need more peers; eager, as this would get fixed in the next heartbeat
 			more := gs.getPeers(topic, gs.params.D-len(gmap), func(p peer.ID) bool {
-				// filter our current peers, direct peers, and peers with negative scores
+				// filter our current peers, direct peers, peers we are backing off, and
+				// peers with negative scores
 				_, inMesh := gmap[p]
 				_, direct := gs.direct[p]
-				return !inMesh && !direct && gs.score.Score(p) >= 0
+				_, doBackOff := backoff[p]
+				return !inMesh && !direct && !doBackOff && gs.score.Score(p) >= 0
 			})
 			for _, p := range more {
 				gmap[p] = struct{}{}
@@ -1060,10 +1064,12 @@ func (gs *GossipSubRouter) Join(topic string) {
 		delete(gs.fanout, topic)
 		delete(gs.lastpub, topic)
 	} else {
+		backoff := gs.backoff[topic]
 		peers := gs.getPeers(topic, gs.params.D, func(p peer.ID) bool {
-			// filter direct peers and peers with negative score
+			// filter direct peers, peers we are backing off and peers with negative score
 			_, direct := gs.direct[p]
-			return !direct && gs.score.Score(p) >= 0
+			_, doBackOff := backoff[p]
+			return !direct && !doBackOff && gs.score.Score(p) >= 0
 		})
 		gmap = peerListToMap(peers)
 		gs.mesh[topic] = gmap

gossipsub_test.go

@@ -1862,6 +1862,51 @@ func TestGossipSubLeaveTopic(t *testing.T) {
 	}
 }
 
+func TestGossipSubJoinTopic(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	h := getNetHosts(t, ctx, 3)
+	psubs := []*PubSub{
+		getGossipsub(ctx, h[0]),
+		getGossipsub(ctx, h[1]),
+		getGossipsub(ctx, h[2]),
+	}
+
+	connect(t, h[0], h[1])
+	connect(t, h[0], h[2])
+
+	router0 := psubs[0].rt.(*GossipSubRouter)
+
+	// Add in backoff for peer.
+	peerMap := make(map[peer.ID]time.Time)
+	peerMap[h[1].ID()] = time.Now().Add(router0.params.PruneBackoff)
+
+	router0.backoff["test"] = peerMap
+
+	// Join all peers
+	var subs []*Subscription
+	for _, ps := range psubs {
+		sub, err := ps.Subscribe("test")
+		if err != nil {
+			t.Fatal(err)
+		}
+		subs = append(subs, sub)
+	}
+
+	time.Sleep(time.Second)
+
+	meshMap := router0.mesh["test"]
+	if len(meshMap) != 1 {
+		t.Fatalf("Unexpect peer included in the mesh")
+	}
+
+	_, ok := meshMap[h[1].ID()]
+	if ok {
+		t.Fatalf("Peer that was to be backed off is included in the mesh")
+	}
+}
+
 type sybilSquatter struct {
 	h host.Host
 }