Ensure H2 state is only accessed by the connection, not per-stream.

[tomchristie]

This refactor moves all the H2 state management onto the Connection class, rather than being per-stream.

I think we'll want to eventually move our stream-locks out of the stream implementation and onto HTTP2Connection instead, so eg...

async with self.write_lock:  # Ensure that outgoing data cannot get sent out-of-sequence.
    data_to_send = self.state.data_to_send()
    await self.socket.write(data_to_send, timeout)

[florimondmanca]

I think we'll want to eventually move our stream-locks out of the stream implementation and onto HTTP2Connection instead

It's probably a good idea, provided those locks were indeed added to solve issues for HTTP/2. (It was the case for the read_lock - see #527. For write_lock, I think we only have it on trio for now - it was added as part of #276, and I think that was also to fix an HTTP/2 concurrency issue, see #276 (comment).)

[tomchristie]

Thanks, those are great pointers.

[florimondmanca]

Sounds good! 🎉

[florimondmanca]

Formatting nit (I've already had these, not sure why Black doesn't reformat them):

Suggested change

	def __init__(self, stream_id: int, connection: HTTP2Connection,) -> None:
	def __init__(self, stream_id: int, connection: HTTP2Connection) -> None:

[tomchristie]

Thanks!

[StephenBrown2]

https://github.com/psf/black#trailing-commas was changed recently, I believe psf/black#826 was the culprit responsible PR. There appears to be a follow-up PR psf/black#1164 to remedy it.