On Thu, Aug 10, 2023 at 11:24:30AM +0000, Tage Johansson wrote:
> Add two new fields, cblifetime and cbcount, to the `closure` type
> in generator/API.ml*. cblifetime tells if the closure may only be used
> for as long as the command is in flight or if the closure may be used
> until the handle is destructed. cbcount tells whether the closure may
> be called many times or just once.
>
> This information is needed in the Rust bindings for:
> a) Knowing if the closure trait should be FnMut or FnOnce
> (see <https://doc.rust-lang.org/std/ops/trait.FnOnce.html>).
> b) Knowing for what lifetime the closure should be valid. A closure that
> may be called after the function invokation has returned must live
invocation
> for the `'static` lietime. But static closures are inconveniant for
lifetime
> the user since they can't effectively borrow any local data. So it is
> good if this restriction is relaxed when it is not needed.
> ---
> generator/API.ml | 20 ++++++++++++++++++++
> generator/API.mli | 17 +++++++++++++++++
> 2 files changed, 37 insertions(+)
>
> +++ b/generator/API.mli
> @@ -94,6 +94,12 @@ and ret =
> and closure = {
> cbname : string; (** name of callback function *)
> cbargs : cbarg list; (** all closures return int for now *)
> + (** An upper bound of the lifetime of the closure. Either it will be used
> for
> + as long as the command is in flight or it may be used until the handle
> + is destructed. *)
> + cblifetime : cblifetime;
> + (** Whether the callback may only be called once or many times. *)
> + cbcount : cbcount;
> }
> and cbarg =
> | CBArrayAndLen of arg * string (** array + number of entries *)
> @@ -104,6 +110,17 @@ and cbarg =
> | CBString of string (** like String *)
> | CBUInt of string (** like UInt *)
> | CBUInt64 of string (** like UInt64 *)
> +and cblifetime =
> +| CBCommand (** The closure may only be used until the command is retired.
> + (E.G., completion callback or list callback.) *)
> +| CBHandle (** The closure might be used until the handle is descructed.
> + (E.G., debug callback.) *)
> +and cbcount =
> +| CBOnce (** The closure will be used 0 or 1 time if the aio_* call returned
> an
> + error and exactly once if the call succeeded.
> + (E.g., completion callback.) *)
Rather, the closure will not be used if the aio_* returned error, and
used exactly once if the aio_* call succeeded.
> +| CBMany (** The closure may be used any number of times.
> + (E.g., list callback.) *)
> and enum = {
> enum_prefix : string; (** prefix of each enum variant *)
> enums : (string * int) list (** enum names and their values in C *)
> --
> 2.41.0
>
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>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc.
Virtualization: qemu.org | libguestfs.org
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