Update to Eio 0.12

[talex5]

Eio 0.12 no longer uses OCaml objects for OS resources. This requires a minor change to mirage-crypto-rng-eio to use the new variant types instead.

(tested using my Eio 0.12 branch of ocaml-tls)

[bikallem]

Seems straightforward. LGTM.

@haesbaert ocaml-tls depends on this package so would appreciate if we could expedite a new release of mirage-crypto-rng-eio

[haesbaert]

Seems straightforward. LGTM.

@haesbaert ocaml-tls depends on this package so would appreciate if we could expedite a new release of mirage-crypto-rng-eio

I'm sure you meant @hannesm here though :)

[bikallem]

I'm sure you meant @hannesm here though :)

Oops, sorry. Yes, I meant @hannesm.

[talex5]

There are some CI failures here (error: writing 1 byte into a region of size 0 and Cannot parse point: point is not on curve), but they are unrelated to this PR and are also failing on the main branch.

As this PR is only changing a type, and only affects the Eio package, it should be safe to merge.

[hannesm]

Thanks for your PR. Indeed the CI failures look unrelated (see #178 and a lengthy discussion in mit-plv/fiat-crypto#1606 (comment)).

In order to get a new release of mirage-crypto, I'd like to solve these outstanding issues, and merge this PR as well. I hope to find some time next week to get around cutting a release.

Just to be sure we're on the same page -- the Eio.Flow.read_exact env#secure_random buf; and Eio.Time.sleep env#clock (Duration.to_f delta); are fine with the most recent eio (I'm asking since in both cases still objects are used..).

[talex5]

Just to be sure we're on the same page -- the Eio.Flow.read_exact env#secure_random buf; and Eio.Time.sleep env#clock (Duration.to_f delta); are fine with the most recent eio (I'm asking since in both cases still objects are used..).

Yes, that's fine (clock and secure_random are no longer objects, but env is).

We could pass the resources to mirage-crypto as separate arguments instead of bundling them up in an object, e.g.

 val run
   :  ?g:'a
   -> ?sleep:int64
   -> 'a Mirage_crypto_rng.generator
-  -> _ env
+  -> clock:_ Eio.Time.clock
+  -> mono_clock:_ Eio.Time.Mono.t
+  -> secure_random:_ Eio.Flow.source
   -> (unit -> 'b) -> 'b

However, continuing to use an object here means code using mirage-crypto doesn't need to change, and it allows adding extra resources without requiring changes to user code in the common case (e.g. I see that #176 added a monotonic clock that way).

BTW, the only use of the non-monotonic clock is to sleep for 10s, which could also be done with the monotonic clock, avoiding the need for clock at all. If you'd like clock removed, I could do that here, or in a separate PR.

[hannesm]

this is part of the 0.11.2 release at ocaml/opam-repository#24461. thanks again for your PR. You can PR what you like, I have no preference when it comes to "eio" and its usage of objects and clocks (I tried again to understand the whole "env" stuff, but failed and will just merge whatever CI and authors consider as being fine).