Sum lookup + query time to select the fastest server

client/client.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"net"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/miekg/dns"
@@ -18,7 +19,7 @@ type Client struct {
 
 // Response stores a DNS response.
 type Response struct {
-	Server string
+	Server Server
 	Addr   string
 	Msg    *dns.Msg
 	RTT    time.Duration
@@ -29,12 +30,16 @@ type Responses []Response
 
 // Fastest returns the fastest success response or nil.
 func (rs Responses) Fastest() *Response {
+	var fr Response
 	for _, r := range rs {
-		if r.Err == nil {
-			return &r
+		if r.Err != nil {
+			continue
+		}
+		if fr.Msg == nil || ((r.RTT + r.Server.LookupRTT) < (fr.RTT + fr.Server.LookupRTT)) {
+			fr = r
 		}
 	}
-	return nil
+	return &fr
 }
 
 type Tracer struct {
@@ -58,14 +63,14 @@ func (c *Client) ParallelQuery(m *dns.Msg, servers []Server) Responses {
 	for _, s := range servers {
 		for _, addr := range s.Addrs {
 			cnt++
-			go func(name, addr string) {
+			go func(s Server, addr string) {
 				r := Response{
-					Server: name,
+					Server: s,
 					Addr:   addr,
 				}
 				r.Msg, r.RTT, r.Err = c.Exchange(m, net.JoinHostPort(addr, "53"))
 				rc <- r
-			}(s.Name, addr)
+			}(s, addr)
 		}
 	}
 	rs := make([]Response, 0, cnt)
@@ -103,7 +108,7 @@ func (c *Client) RecursiveQuery(m *dns.Msg, tracer Tracer) (r *dns.Msg, rtt time
 			}
 			return nil, rtt, errors.New("no response")
 		}
-		rtt += fr.RTT
+		rtt += fr.Server.LookupRTT + fr.RTT
 
 		var done bool
 		var deleg bool
@@ -129,8 +134,7 @@ func (c *Client) RecursiveQuery(m *dns.Msg, tracer Tracer) (r *dns.Msg, rtt time
 		}
 
 		if deleg {
-			lrttc := make(chan time.Duration)
-			lc := 0
+			wg := &sync.WaitGroup{}
 			for _, ns := range r.Ns {
 				ns, ok := ns.(*dns.NS)
 				if !ok {
@@ -155,7 +159,7 @@ func (c *Client) RecursiveQuery(m *dns.Msg, tracer Tracer) (r *dns.Msg, rtt time
 					Addrs:   addrs,
 				}
 				if !s.HasGlue {
-					lc++
+					wg.Add(1)
 					go func() {
 						var err error
 						lm := m.Copy()
@@ -165,7 +169,7 @@ func (c *Client) RecursiveQuery(m *dns.Msg, tracer Tracer) (r *dns.Msg, rtt time
 							s.LookupErr = err
 						}
 						c.DCache.Add(name, s)
-						lrttc <- s.LookupRTT
+						wg.Done()
 					}()
 					continue
 				}
@@ -176,14 +180,7 @@ func (c *Client) RecursiveQuery(m *dns.Msg, tracer Tracer) (r *dns.Msg, rtt time
 					break
 				}
 			}
-			var lrtt time.Duration
-			for ; lc > 0; lc-- {
-				d := <-lrttc
-				if lrtt == 0 || lrtt > d {
-					lrtt = d
-				}
-			}
-			rtt += lrtt
+			wg.Wait()
 		}
 
 		if tracer.GotDelegateResponses != nil {

main.go

@@ -103,7 +103,8 @@ func main() {
 					ln = pr.Msg.Len()
 				}
 				rtt := float64(pr.RTT) / float64(time.Millisecond)
-				fmt.Printf(col("  - %d bytes in %6.2fms on %s(%s)", cDarkGray), ln, rtt, pr.Addr, pr.Server)
+				lrtt := float64(pr.Server.LookupRTT) / float64(time.Millisecond)
+				fmt.Printf(col("  - %3d bytes in %6.2fms + %6.2fms on %s(%s)", cDarkGray), ln, rtt, lrtt, pr.Addr, pr.Server.Name)
 				if pr.Err != nil {
 					err := pr.Err
 					if oerr, ok := err.(*net.OpError); ok {
@@ -146,13 +147,13 @@ func main() {
 		},
 	}
 	r, rtt, err := c.RecursiveQuery(m, t)
-
 	if err != nil {
 		fmt.Printf(col("*** error: %v\n", cRed), err)
 		os.Exit(1)
 	}
+
 	fmt.Println()
-	fmt.Printf(col(";; Cold best path RTT: %s\n\n", cGray), rtt)
+	fmt.Printf(col(";; Cold best path time: %s\n\n", cGray), rtt)
 	for _, rr := range r.Answer {
 		fmt.Println(rr)
 	}