strip strategy

roundrobin/rr.go

@@ -106,9 +106,8 @@ func (r *RoundRobin) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 // NextServer gets the next server.
 func (r *RoundRobin) NextServer(w http.ResponseWriter, req *http.Request, neq *http.Request) (*url.URL, error) {
 	// Use extension balance server, if extension return multiple servers, choose anyone.
-	if ss := Strategy().Next(w, req, neq, r.servers); len(ss) > 0 {
-		srv := ss[rand.Intn(len(ss))]
-		return utils.CopyURL(srv.URL()), nil
+	if ss := Strategy().Next(w, req, neq, r.servers); len(ss) > 0 && len(ss) < len(r.servers) {
+		return Strategy().Strip(utils.CopyURL(ss[rand.Intn(len(ss))].URL())), nil
 	}
 	srv, err := r.nextServer(w, req)
 	if err != nil {

roundrobin/strategy.go

@@ -42,6 +42,9 @@ type LBStrategy interface {
 	// Next servers
 	// Load balancer extension for custom rules filter.
 	Next(w http.ResponseWriter, req *http.Request, neq *http.Request, servers []Server) []Server
+
+	// Strip filter the server URL
+	Strip(uri *url.URL) *url.URL
 }
 
 type CompositeStrategy struct {
@@ -68,3 +71,10 @@ func (that *CompositeStrategy) Next(w http.ResponseWriter, req *http.Request, ne
 	}
 	return servers
 }
+
+func (that *CompositeStrategy) Strip(uri *url.URL) *url.URL {
+	for _, strategy := range that.strategies {
+		uri = strategy.Strip(uri)
+	}
+	return uri
+}