func (s *http2Server) afterFunc(d time.Duration, f func()) http2timer {
	if s.group != nil {
		return s.group.AfterFunc(d, f)
	}
	return http2timeTimer{time.AfterFunc(d, f)}
}

func (s *http2Server) initialConnRecvWindowSize() int32 {
	if s.MaxUploadBufferPerConnection >= http2initialWindowSize {
		return s.MaxUploadBufferPerConnection
	}
	return 1 << 20
}

func (s *http2Server) initialStreamRecvWindowSize() int32 {