内容是nodejs 官方的，对于需要开发自己的stream 是很值得学习参考的

参考资料

​​https://nodejs.org/en/docs/guides/backpressuring-in-streams/​​​​https://nodejs.org/docs/latest/api/stream.html#stream_readable_pipe_destination_options​​​​https://nodejs.org/api/stream.html#stream_buffering​​​​https://nodejs.org/docs/latest/api/stream.html#stream_implementing_a_readable_stream​​​​https://nodejs.org/docs/latest/api/stream.html#stream_implementing_a_writable_stream​​