refactor: rewrite getHandler

api/router/router.go

@@ -62,26 +62,35 @@ func (hs *APIRouter) getHandlerByDomain(domain string) http.Handler {
 
 func (hs *APIRouter) getHandler(protocol string) http.Handler {
 	hs.mutex.RLock()
-	defer hs.mutex.RUnlock()
-	if handler := hs.apiHandlers[protocol]; handler == nil {
-		if proto := hs.apis[protocol]; proto == nil {
+	handler, ok := hs.apiHandlers[protocol]
+	hs.mutex.RUnlock()
+
+	if ok {
+		return handler
+	}
+
+	hs.mutex.Lock()
+	defer hs.mutex.Unlock()
+
+	// Double-check if the handler was created while acquiring the write lock
+	if handler, ok := hs.apiHandlers[protocol]; ok {
+		return handler
+	}
+
+	proto, ok := hs.apis[protocol]
+	if !ok {
 		hs.logger.Fatal("Protocol not found", zap.String("protocol", protocol))
 		return nil
 	}
 
-		routes, err := hs.apis[protocol].Routes()
-
+	routes, err := proto.Routes()
 	if err != nil {
 		hs.logger.Fatal("Error getting routes", zap.Error(err))
 		return nil
 	}
 
-		hs.mutex.Lock()
-		defer hs.mutex.Unlock()
 	hs.apiHandlers[protocol] = routes
-	}
-
-	return hs.apiHandlers[protocol]
+	return routes
 }
 
 func NewAPIRouter() *APIRouter {