Ensure h2 connection gets closed in case of exception

[florimondmanca]

May close encode/httpx#1414

Tweaks our HTTP/2 connection implementation so that the underlying h2_state is properly closed before bubbling up any exceptions.

Right now it seems possible for the underlying state to leak eg if the connection gets lost unexpectedly — see: https://github.com/encode/httpx/issues/1414#issuecomment-742127990

[frankwalter1301]

Doesn't work with the new version of httpcore. 'AsyncHTTP2Connection' object has no attribute 'h2_state' By changing h2_state to _h2_state in respect to the new naming of the new releases I get another error: Invalid input ConnectionInputs.SEND_HEADERS in state ConnectionState.CLOSED

[lovelydinosaur]

@frankwalter1301 Could you give some more background about why you're bumping into this?

[frankwalter1301]

I simple encountered the same error as the issue linked to this talks about. Same circumstances: too many failed connections in the same http client. Il mar 16 nov 2021, 12:15 Tom Christie ***@***.***> ha scritto:

…

@frankwalter1301 <https://github.com/frankwalter1301> Could you give some more background about why you're bumping into this? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#253 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AOMI7TKTVHOBUR7P2S2SQJDUMI4L7ANCNFSM4UYPAXVA> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[lovelydinosaur]

Believe that #440 is what we need to close encode/httpx#1414, but yes! this is a good and sensible bit of defensive programming, and we should have it in.