Want to implement rfc7692, but writer side can not be implemented

[tebruno99]

From websocket created by smith-30: gorilla#339

This is a copy for Reference. See the important discussion/comments in the original issue before merging

Hi,

I'd like to use the context-takeover mechanism defined in rfc7692.
I forked and developed it and I could implement the reader side.
This [branch] (https://github.com/smith-30/websocket/tree/feature/upgrade_writer) is the newest.

However, I am in trouble because I can not implement the writer.

Implementation I'm thinking

Attempting to implement context-takeover by attaching flateWriteWrapper to Conn struct.

In flateWriteWrapper, attach flat.Writer called with flat.NewWriterDict.
https://github.com/smith-30/websocket/blob/ee46f8548a106a02264f711a1838887fd3cf58cf/conn.go#L518-L536
I do not want to make flateWriter every time I make a call.
Because performance is very poor.
Not using Pool is because GC may clean it without permission.
Avoid the window of flateWriter disappearing and inconsistency with reader side.

However, in my implementation I can not initialize the truncWriter passed to flateWriter.
In the second execution, truncWriter has state and fails in compress processing.
I'd like to reset the state of truncWriter after compression
Is there a good way to do it?

I am sorry for my poor English.
It would be extremely helpful If you review my implementation..