Add an Eio backend

[clecat]

This PR aims to provide a backend for Eio in the same way it is currently done for Lwt: The same interface was used, with only minor changes in the code and was written by @patricoferris.

An optional dependency to Iomux was added as well for the Eio backend, as Eio itself does not (yet ?) provide a function to check if a file descriptor is readable: It was done here using Iomux.Poll.

Thank you for your time, Gwen

[whitequark]

LGTM

[whitequark]

Looks like the CI fails.

[clecat]

My apologies, I tried to fix it however I ran into a more general problem with how dependencies are handled:

• eio is a library made for ocaml-multicore, and therefore is only available on ocaml.5.x. Because the package inotify.eio is marked in dune as optional, this is not an issue in platforms running lower versions of ocaml: The package will simply not be built.
• eio_main is a library only used in the tests, however they do not seem to allow for an optional tag and will always ask to be run. Which is why, as the testing platforms are set to 4.03.x, 4.08.x and 4.12.x, the CI fails.
• I have tried marking eio_main as both a depopt & related to the tests, but it does not seem to have any impact. I have also tried other things to no avail.

The first and less friendly way to do things could be to only run the CI on with ocaml versions of 5.x, making sure that eio_main would be available, but I do not really like the idea of forcing such a decision for an optional package.

One of the more reasonable options that come to my mind, would be to dissociate from the way lwt was integrated in inotify, and instead of declaring inotify.eio as an optional library, another package inotify-eio with it's own opam file could be added. It would directly declare a strict dependency to ocaml.5.x and resolve much of the issues. A new CI running on 5.1.x could then be added to test the second package.

What sounds better to you ? Do you have any oppositions to such an idea ?
Cordially, Gwen

[whitequark]

No idea. I haven't used OCaml (somewhat regretfully) in years and I don't want to spend any more effort on this PR than is absolutely necessary.

[clecat]

I see, thank you for your time, I'll go for what seems best and commit when it is ready

[clecat]

This PR should be done, sorry for the noise, I fought for a bit with the github actions in order to make the CI run properly:

• The work on eio now has a proper separate package
• A new CI running on 5.1.x will run all the tests on both packages
• Older CI's will only test the inotify package

Thank you for your time

[whitequark]

This broke pages build: https://github.com/whitequark/ocaml-inotify/actions/runs/8820386410/job/24213880961

[clecat]

#26 should fix it, sorry

[samoht]

Any chance to make a release with the eio support?

[whitequark]

Yep, let me remember how to do it...

@samoht Would you like to become a collaborator in this repo? It's been a while since I actually used OCaml, and I trust you to do a good job.

[clecat]

I can do it if we are ok with it

[whitequark]

If I'm handing somebody write access for a reasonably popular package I'd like it to be someone I know; I do know @samoht (I think we've been in the same OCaml circles for like a decade, at least?) but I don't know you. Nothing personal.

[clecat]

Sorry, by that I meant if we are okay with the current state of the repository, I believe that I already have write access to the repository as a maintainer.

[whitequark]

Wow, my memory really is awful sometimes. I'm sorry, and you're right.

[clecat]

No worries at all, would you prefer me to do it or @Samoth ? Both are obviously okay with me

[whitequark]

I'm fine either way. I don't remember most of the last 10 months because of a few unfortunate events that happened to me. I have now reconstructed what happened with this repository. Go ahead and make a release, please!

[clecat]

Noted, I will do the release then. I hope everything will be okay for you, take care !