Improve interceptors chaining

server.go

@@ -1115,22 +1115,22 @@ func chainUnaryServerInterceptors(s *Server) {
 	} else if len(interceptors) == 1 {
 		chainedInt = interceptors[0]
 	} else {
-		chainedInt = func(ctx context.Context, req interface{}, info *UnaryServerInfo, handler UnaryHandler) (interface{}, error) {
-			return interceptors[0](ctx, req, info, getChainUnaryHandler(interceptors, 0, info, handler))
+		for i := len(interceptors) - 1; i >= 0; i-- {
+			chainedInt = chainUnaryInterceptors(chainedInt, interceptors[i])
 		}
 	}
 
 	s.opts.unaryInt = chainedInt
 }
 
-// getChainUnaryHandler recursively generate the chained UnaryHandler
-func getChainUnaryHandler(interceptors []UnaryServerInterceptor, curr int, info *UnaryServerInfo, finalHandler UnaryHandler) UnaryHandler {
-	if curr == len(interceptors)-1 {
-		return finalHandler
+func chainUnaryInterceptors(curr, next UnaryServerInterceptor) UnaryServerInterceptor {
+	if curr == nil {
+		return next
 	}
-
-	return func(ctx context.Context, req interface{}) (interface{}, error) {
-		return interceptors[curr+1](ctx, req, info, getChainUnaryHandler(interceptors, curr+1, info, finalHandler))
+	return func(ctx context.Context, req interface{}, info *UnaryServerInfo, handler UnaryHandler) (interface{}, error) {
+		return next(ctx, req, info, func(ctx context.Context, req interface{}) (interface{}, error) {
+			return curr(ctx, req, info, handler)
+		})
 	}
 }
 
@@ -1396,22 +1396,22 @@ func chainStreamServerInterceptors(s *Server) {
 	} else if len(interceptors) == 1 {
 		chainedInt = interceptors[0]
 	} else {
-		chainedInt = func(srv interface{}, ss ServerStream, info *StreamServerInfo, handler StreamHandler) error {
-			return interceptors[0](srv, ss, info, getChainStreamHandler(interceptors, 0, info, handler))
+		for i := len(interceptors) - 1; i >= 0; i-- {
+			chainedInt = chainStreamInterceptors(chainedInt, interceptors[i])
 		}
 	}
 
 	s.opts.streamInt = chainedInt
 }
 
-// getChainStreamHandler recursively generate the chained StreamHandler
-func getChainStreamHandler(interceptors []StreamServerInterceptor, curr int, info *StreamServerInfo, finalHandler StreamHandler) StreamHandler {
-	if curr == len(interceptors)-1 {
-		return finalHandler
+func chainStreamInterceptors(curr, next StreamServerInterceptor) StreamServerInterceptor {
+	if curr == nil {
+		return next
 	}
-
-	return func(srv interface{}, ss ServerStream) error {
-		return interceptors[curr+1](srv, ss, info, getChainStreamHandler(interceptors, curr+1, info, finalHandler))
+	return func(srv interface{}, ss ServerStream, info *StreamServerInfo, handler StreamHandler) error {
+		return next(srv, ss, info, func(srv interface{}, stream ServerStream) error {
+			return curr(srv, ss, info, handler)
+		})
 	}
 }