Reduce chain allocations number

server.go

@@ -1115,22 +1115,24 @@ func chainUnaryServerInterceptors(s *Server) {
 	} else if len(interceptors) == 1 {
 		chainedInt = interceptors[0]
 	} else {
-		for i := len(interceptors) - 1; i >= 0; i-- {
-			chainedInt = chainUnaryInterceptors(chainedInt, interceptors[i])
-		}
+		chainedInt = chainUnaryInterceptors(interceptors)
 	}
 
 	s.opts.unaryInt = chainedInt
 }
 
-func chainUnaryInterceptors(curr, next UnaryServerInterceptor) UnaryServerInterceptor {
-	if curr == nil {
-		return next
-	}
+func chainUnaryInterceptors(interceptors []UnaryServerInterceptor) UnaryServerInterceptor {
 	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)
-		})
+		var i int
+		var next UnaryHandler
+		next = func(ctx context.Context, req interface{}) (interface{}, error) {
+			if i == len(interceptors)-1 {
+				return interceptors[i](ctx, req, info, handler)
+			}
+			i++
+			return interceptors[i-1](ctx, req, info, next)
+		}
+		return next(ctx, req)
 	}
 }
 
@@ -1396,22 +1398,24 @@ func chainStreamServerInterceptors(s *Server) {
 	} else if len(interceptors) == 1 {
 		chainedInt = interceptors[0]
 	} else {
-		for i := len(interceptors) - 1; i >= 0; i-- {
-			chainedInt = chainStreamInterceptors(chainedInt, interceptors[i])
-		}
+		chainedInt = chainStreamInterceptors(interceptors)
 	}
 
 	s.opts.streamInt = chainedInt
 }
 
-func chainStreamInterceptors(curr, next StreamServerInterceptor) StreamServerInterceptor {
-	if curr == nil {
-		return next
-	}
+func chainStreamInterceptors(interceptors []StreamServerInterceptor) StreamServerInterceptor {
 	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)
-		})
+		var i int
+		var next StreamHandler
+		next = func(srv interface{}, ss ServerStream) error {
+			if i == len(interceptors)-1 {
+				return interceptors[i](srv, ss, info, handler)
+			}
+			i++
+			return interceptors[i-1](srv, ss, info, handler)
+		}
+		return next(srv, ss)
 	}
 }