Cohttp_lwt_unix.Connection_cache.call hangs if the server is unreachable

[lthms]

Assuming no service is bound to 127.0.0.1:55000, the following minimal snippet will hang indefinitely.

  let cache = Cohttp_lwt_unix.Connection_cache.create ~parallel:1 () in
  Cohttp_lwt_unix.Connection_cache.call cache `GET
    (Uri.of_string "http://127.0.0.1:55000")

I quick look at the functor in Cohttp_lwt.Connection_cache and I guess the get_connection recursive function is to blame? I’ll try to dig deeper, but no matter the result of my search, I wanted to share my discovery.

[lthms]

Good news, I have found the culprit. In Cohttp_lwt.Connection_cache.Make, replacing Connection.create by Connection.connect will fix the issue.

I’ve done it in my project by importing the code, and fixing manually.

I’ll open a draft MR.