cache scores throughout the heartbeat

gossipsub.go

@@ -1146,6 +1146,17 @@ func (gs *GossipSubRouter) heartbeat() {
 	// ensure direct peers are connected
 	gs.directConnect()
 
+	// cache scores throughout the heartbeat
+	scores := make(map[peer.ID]float64)
+	score := func(p peer.ID) float64 {
+		s, ok := scores[p]
+		if !ok {
+			s = gs.score.Score(p)
+			scores[p] = s
+		}
+		return s
+	}
+
 	// maintain the mesh for topics we have joined
 	for topic, peers := range gs.mesh {
 		prunePeer := func(p peer.ID) {
@@ -1166,16 +1177,10 @@ func (gs *GossipSubRouter) heartbeat() {
 			tograft[p] = append(topics, topic)
 		}
 
-		// compute mesh peer scores
-		scores := make(map[peer.ID]float64)
-		for p := range peers {
-			scores[p] = gs.score.Score(p)
-		}
-
 		// drop all peers with negative score, without PX
 		for p := range peers {
-			if scores[p] < 0 {
+			if score(p) < 0 {
-				log.Debugf("HEARTBEAT: Prune peer %s with negative score [score = %f, topic = %s]", p, scores[p], topic)
+				log.Debugf("HEARTBEAT: Prune peer %s with negative score [score = %f, topic = %s]", p, score(p), topic)
 				prunePeer(p)
 				noPX[p] = true
 			}
@@ -1190,7 +1195,7 @@ func (gs *GossipSubRouter) heartbeat() {
 				_, inMesh := peers[p]
 				_, doBackoff := backoff[p]
 				_, direct := gs.direct[p]
-				return !inMesh && !doBackoff && !direct && gs.score.Score(p) >= 0
+				return !inMesh && !doBackoff && !direct && score(p) >= 0
 			})
 
 			for _, p := range plst {
@@ -1205,7 +1210,7 @@ func (gs *GossipSubRouter) heartbeat() {
 			// sort by score (but shuffle first for the case we don't use the score)
 			shufflePeers(plst)
 			sort.Slice(plst, func(i, j int) bool {
-				return scores[plst[i]] > scores[plst[j]]
+				return score(plst[i]) > score(plst[j])
 			})
 
 			// We keep the first D_score peers by score and the remaining up to D randomly
@@ -1262,7 +1267,7 @@ func (gs *GossipSubRouter) heartbeat() {
 					_, inMesh := peers[p]
 					_, doBackoff := backoff[p]
 					_, direct := gs.direct[p]
-					return !inMesh && !doBackoff && !direct && gs.outbound[p] && gs.score.Score(p) >= 0
+					return !inMesh && !doBackoff && !direct && gs.outbound[p] && score(p) >= 0
 				})
 
 				for _, p := range plst {
@@ -1280,19 +1285,10 @@ func (gs *GossipSubRouter) heartbeat() {
 			// scoring peers that may have been gossiping at us. This allows us to get out of sticky
 			// situations where we are stuck with poor peers and also recover from churn of good peers.
 
-			// first cache scores for new peers that may have been added since the initial score computation
-			for p := range peers {
-				_, haveScore := scores[p]
-				if haveScore {
-					continue
-				}
-				scores[p] = gs.score.Score(p)
-			}
-
 			// now compute the median peer score in the mesh
 			plst := peerMapToList(peers)
 			sort.Slice(plst, func(i, j int) bool {
-				return scores[plst[i]] < scores[plst[j]]
+				return score(plst[i]) < score(plst[j])
 			})
 			medianIndex := len(peers) / 2
 			medianScore := scores[plst[medianIndex]]
@@ -1304,7 +1300,7 @@ func (gs *GossipSubRouter) heartbeat() {
 					_, inMesh := peers[p]
 					_, doBackoff := backoff[p]
 					_, direct := gs.direct[p]
-					return !inMesh && !doBackoff && !direct && gs.score.Score(p) > medianScore
+					return !inMesh && !doBackoff && !direct && score(p) > medianScore
 				})
 
 				for _, p := range plst {
@@ -1333,7 +1329,7 @@ func (gs *GossipSubRouter) heartbeat() {
 		// check whether our peers are still in the topic and have a score above the publish threshold
 		for p := range peers {
 			_, ok := gs.p.topics[topic][p]
-			if !ok || gs.score.Score(p) < gs.publishThreshold {
+			if !ok || score(p) < gs.publishThreshold {
 				delete(peers, p)
 			}
 		}
@@ -1345,7 +1341,7 @@ func (gs *GossipSubRouter) heartbeat() {
 				// filter our current and direct peers and peers with score above the publish threshold
 				_, inFanout := peers[p]
 				_, direct := gs.direct[p]
-				return !inFanout && !direct && gs.score.Score(p) >= gs.publishThreshold
+				return !inFanout && !direct && score(p) >= gs.publishThreshold
 			})
 
 			for _, p := range plst {