Handle peer disconnect in blocking calls

[jgirtakovskis]

Problem: Cancelled blocking call to XREADGROUP results in items put on PEL and inaccessible to other subscribers

Scenario:
Connection A writes items [XADD] in one goroutine
Connection B fetches items [XREADGROUP] from second goroutine - blocking
B is in the middle of a blocking call and is cancelled. Client disconnects as expected

Expected: Cancelled blocking call by B does not change the state of the stream and does not put items on PEL
Actual: blocking call proceeds and items are put on PEL

CC: @alicebob

[alicebob]

Thanks for the PR(s)! I'm getting a race in CI: https://github.com/alicebob/miniredis/actions/runs/3348331876/jobs/5577096047

[jgirtakovskis]

yeah, I'm seeing that. for some reason the race is not happening on my setup, so I missed it. my bad! will look into

…

On Mon, Oct 31, 2022 at 1:41 PM Harmen ***@***.***> wrote: Thanks for the PR(s)! I'm getting a race in CI: https://github.com/alicebob/miniredis/actions/runs/3348331876/jobs/5577096047 — Reply to this email directly, view it on GitHub <#300 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AZVJYXTTF4VW7X6V4SR4ULDWGAHG3ANCNFSM6AAAAAARRMWQXI> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[alicebob]

Your code look good, the race looks related to a recent change, and I may or may not have fixed that. Thanks for the change! And sorry for the slow replies from my side.

[jgirtakovskis]

awesome, thank you!