p2p/discover: optimize findnodeByID

p2p/discover/table.go

@@ -245,28 +245,33 @@ func (tab *Table) refresh() <-chan struct{} {
 // preferLive is true and the table contains any verified nodes, the result will not
 // contain unverified nodes. However, if there are no verified nodes at all, the result
 // will contain unverified nodes.
-func (tab *Table) findnodeByID(target enode.ID, nresults int, preferLive bool) *nodesByDistance {
+func (tab *Table) findnodeByID(target enode.ID, nresults int, preferLive bool) (nodes nodesByDistance) {
+	nodes.target = target
 	tab.mutex.Lock()
 	defer tab.mutex.Unlock()
 
 	// Scan all buckets. There might be a better way to do this, but there aren't that many
 	// buckets, so this solution should be fine. The worst-case complexity of this loop
 	// is O(tab.len() * nresults).
-	nodes := &nodesByDistance{target: target}
-	liveNodes := &nodesByDistance{target: target}
-	for _, b := range &tab.buckets {
-		for _, n := range b.entries {
-			nodes.push(n.Node, nresults)
-			if preferLive && n.isValidatedLive {
-				liveNodes.push(n.Node, nresults)
+	if preferLive {
+		for _, b := range &tab.buckets {
+			for _, n := range b.entries {
+				if n.isValidatedLive {
+					nodes.push(n.Node, nresults)
+				}
 			}
 		}
+		if len(nodes.entries) > 0 {
+			return
+		}
 	}
 
-	if preferLive && len(liveNodes.entries) > 0 {
-		return liveNodes
+	for _, b := range &tab.buckets {
+		for _, n := range b.entries {
+			nodes.push(n.Node, nresults)
+		}
 	}
-	return nodes
+	return
 }
 
 // appendBucketNodes adds nodes at the given distance to the result slice.