Set the recursion available flag

go mod tidy

internal/dns/dns.go

@@ -172,8 +172,6 @@ func (m measurement) String() string {
 }
 
 func (s *Server) probeUpstreamLatency() {
-	if !s.once {
-		s.once = true
 	upstreams := s.upstreams()
 	results := make([]measurement, len(upstreams))
 	var wg sync.WaitGroup
@@ -201,7 +199,7 @@ func (s *Server) probeUpstreamLatency() {
 	sort.Slice(results, func(i, j int) bool {
 		return results[i].rtt < results[j].rtt
 	})
-		log.Printf("probe results: %v %v", s.once, results)
+	log.Printf("probe results: %v", results)
 	for idx, result := range results {
 		upstreams[idx] = result.upstream
 	}
@@ -209,7 +207,6 @@ func (s *Server) probeUpstreamLatency() {
 	defer s.upstreamMu.Unlock()
 	s.upstream = upstreams
 }
-}
 
 func (s *Server) hostByName(n lcHostname) (string, bool) {
 	s.mu.Lock()