fix(transport/grpc): default base ctx (#1465)

* fix grpc base ctx

transport/grpc/server.go

@@ -92,7 +92,7 @@ func Options(opts ...grpc.ServerOption) ServerOption {
 // Server is a gRPC server wrapper.
 type Server struct {
 	*grpc.Server
-	ctx        context.Context
+	baseCtx    context.Context
 	tlsConf    *tls.Config
 	lis        net.Listener
 	once       sync.Once
@@ -112,6 +112,7 @@ type Server struct {
 // NewServer creates a gRPC server by options.
 func NewServer(opts ...ServerOption) *Server {
 	srv := &Server{
+		baseCtx: context.Background(),
 		network: "tcp",
 		address: ":0",
 		timeout: 1 * time.Second,
@@ -175,7 +176,7 @@ func (s *Server) Start(ctx context.Context) error {
 	if _, err := s.Endpoint(); err != nil {
 		return err
 	}
-	s.ctx = ctx
+	s.baseCtx = ctx
 	s.log.Infof("[gRPC] server listening on: %s", s.lis.Addr().String())
 	s.health.Resume()
 	return s.Serve(s.lis)
@@ -191,7 +192,7 @@ func (s *Server) Stop(ctx context.Context) error {
 
 func (s *Server) unaryServerInterceptor() grpc.UnaryServerInterceptor {
 	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
-		ctx, cancel := ic.Merge(ctx, s.ctx)
+		ctx, cancel := ic.Merge(ctx, s.baseCtx)
 		defer cancel()
 		md, _ := grpcmd.FromIncomingContext(ctx)
 		replyHeader := grpcmd.MD{}

transport/grpc/server_test.go

@@ -143,7 +143,7 @@ func TestServer_unaryServerInterceptor(t *testing.T) {
 	u, err := url.Parse("grpc://hello/world")
 	assert.NoError(t, err)
 	srv := &Server{
-		ctx:        context.Background(),
+		baseCtx:    context.Background(),
 		endpoint:   u,
 		middleware: []middleware.Middleware{EmptyMiddleware()},
 		timeout:    time.Duration(10),