users can set their customized selectors

client/mode.go

@@ -28,6 +28,9 @@ const (
 	ConsistentHash
 	//Closest is selecting the closest server
 	Closest
+
+	// SelectByUser is selecting by implementation of users
+	SelectByUser = 1000
 )
 
 var selectModeStrs = [...]string{

client/selector.go

@@ -29,6 +29,8 @@ func newSelector(selectMode SelectMode, servers map[string]string) Selector {
 		return newWeightedICMPSelector(servers)
 	case ConsistentHash:
 		return newConsistentHashSelector(servers)
+	case SelectByUser:
+		return nil
 	default:
 		return newRandomSelector(servers)
 	}

client/xclient.go

@@ -90,14 +90,19 @@ func NewXClient(servicePath string, failMode FailMode, selectMode SelectMode, di
 		servers[p.Key] = p.Value
 	}
 	client.servers = servers
-	if selectMode != Closest {
+	if selectMode != Closest && selectMode != SelectByUser {
 		client.selector = newSelector(selectMode, servers)
 	}
 
 	client.Plugins = &pluginContainer{}
 	return client
 }
 
+// SetSelector sets customized selector by users.
+func (c *xClient) SetSelector(s Selector) {
+	c.selector = s
+}
+
 // SetPlugins sets client's plugins.
 func (c *xClient) SetPlugins(plugins PluginContainer) {
 	c.Plugins = plugins