improvement related to performance

rate.go

@@ -15,10 +15,10 @@ import (
 )
 
 const (
-	maxQPSPerNameserver  = 100
-	numIntervalSeconds   = 10
+	maxQPSPerNameserver  = 250
+	numIntervalSeconds   = 2
 	rateUpdateInterval   = numIntervalSeconds * time.Second
-	maxTimeoutPercentage = 0.2
+	maxTimeoutPercentage = 0.5
 )
 
 type rateTrack struct {
@@ -129,13 +129,12 @@ func (rt *rateTrack) update() {
 	}
 	// timeouts in excess of maxTimeoutPercentage indicate a need to slow down
 	if float64(rt.timeout)/float64(rt.success+rt.timeout) > maxTimeoutPercentage {
-		p := float64(rt.success) / float64(rt.success+rt.timeout)
-		rt.qps = int(float64(rt.qps) * p)
+		rt.qps -= 1
 		if rt.qps <= 0 {
 			rt.qps = 1
 		}
 	} else {
-		rt.qps = rt.qps + 10
+		rt.qps += 1
 	}
 	// update the QPS rate limiter and reset counters
 	rt.rate = ratelimit.New(rt.qps)

selector.go

@@ -41,53 +41,25 @@ func newRandomSelector() *randomSelector {
 
 // GetResolver performs random selection on the pool of resolvers.
 func (r *randomSelector) GetResolver() *resolver {
-	max := r.maxQPS()
-	if max == -1 {
-		return nil
-	}
-	sel := rand.Intn(max)
-
 	r.Lock()
 	defer r.Unlock()
 
-	var cur int
 	var chosen *resolver
+	sel := rand.Intn(len(r.list) + 1)
 loop:
-	for _, res := range r.list {
+	for _, res := range r.list[sel:] {
 		select {
 		case <-res.done:
 			continue loop
 		default:
 		}
 
-		cur += res.qps
-		if sel < cur {
-			chosen = res
-			break
-		}
+		chosen = res
+		break
 	}
 	return chosen
 }
 
-func (r *randomSelector) maxQPS() int {
-	r.Lock()
-	defer r.Unlock()
-
-	if len(r.list) == 0 {
-		return -1
-	}
-
-	var max int
-	for _, res := range r.list {
-		select {
-		case <-res.done:
-		default:
-			max += res.qps
-		}
-	}
-	return max
-}
-
 func (r *randomSelector) LookupResolver(addr string) *resolver {
 	r.Lock()
 	defer r.Unlock()

walk.go

@@ -31,7 +31,7 @@ func (r *Resolvers) NsecTraversal(ctx context.Context, domain string) ([]*dns.NS
 		found = false
 		var nsec *dns.NSEC
 
-		nsec, err = r.searchGap(ctx, next, domain)
+		nsec, err = r.searchGap(ctx, next)
 		if err == nil {
 			if _, yes := names[nsec.NextDomain]; yes {
 				break
@@ -49,7 +49,7 @@ func (r *Resolvers) NsecTraversal(ctx context.Context, domain string) ([]*dns.NS
 	return results, err
 }
 
-func (r *Resolvers) searchGap(ctx context.Context, name, domain string) (*dns.NSEC, error) {
+func (r *Resolvers) searchGap(ctx context.Context, name string) (*dns.NSEC, error) {
 	for i := 0; i < maxQueryAttempts; i++ {
 		resp, err := r.QueryBlocking(ctx, WalkMsg(name, dns.TypeNSEC))
 		if err != nil || resp.Rcode == dns.RcodeNameError {