Re: [Libguestfs] [libnbd PATCH 04/10] generator: Add information about the lifetime of closures

Add a new field `cbkind` to the `closure` type in generator/API.ml*. It tells how many times the closure may be invoked and for how long time it might be used. More specifically, it can take any of these values: - `CBOnceCommand`: The closure may only be called once and shall not be called after the command is retired. - `CBManyCommand`: The closure may be called any number of times but not after the command is retired. - `CBManyHandle`: The closure may be called any number of times before the handle is destructed. 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 for the `'static` lifetime. But static closures are inconveniant for 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 | 11 +++++++++++ generator/API.mli | 13 +++++++++++++ 2 files changed, 24 insertions(+) diff --git a/generator/API.ml b/generator/API.ml index f90a6fa..086b2f9 100644 --- a/generator/API.ml +++ b/generator/API.ml @@ -77,6 +77,7 @@ and ret = and closure = { cbname : string; cbargs : cbarg list; + cbkind : cbkind;

} and cbarg = | CBArrayAndLen of arg * string @@ -87,6 +88,10 @@ and cbarg = | CBString of string | CBUInt of string | CBUInt64 of string +and cbkind = +| CBOnceCommand +| CBManyCommand +| CBManyHandle and enum = { enum_prefix : string; enums : (string * int) list @@ -141,20 +146,24 @@ the handle from the NBD protocol handshake." (* Closures. *) let chunk_closure = { cbname = "chunk"; + cbkind = CBManyCommand; cbargs = [ CBBytesIn ("subbuf", "count"); CBUInt64 "offset"; CBUInt "status"; CBMutable (Int "error") ] } let completion_closure = { cbname = "completion"; + cbkind = CBOnceCommand; cbargs = [ CBMutable (Int "error") ] } let debug_closure = { cbname = "debug"; + cbkind = CBManyHandle; cbargs = [ CBString "context"; CBString "msg" ] } let extent_closure = { cbname = "extent"; + cbkind = CBManyCommand; cbargs = [ CBString "metacontext"; CBUInt64 "offset"; CBArrayAndLen (UInt32 "entries", @@ -163,10 +172,12 @@ let extent_closure = { } let list_closure = { cbname = "list"; + cbkind = CBManyCommand; cbargs = [ CBString "name"; CBString "description" ] } let context_closure = { cbname = "context"; + cbkind = CBManyCommand; cbargs = [ CBString "name" ] } let all_closures = [ chunk_closure; completion_closure; diff --git a/generator/API.mli b/generator/API.mli index 361132d..73dc40a 100644 --- a/generator/API.mli +++ b/generator/API.mli @@ -94,6 +94,10 @@ and ret = and closure = { cbname : string; (** name of callback function *) cbargs : cbarg list; (** all closures return int for now *) + (** Wether the closure should be used once or many times and wether it might

+ be used only until the command is completed or until the handle is + destructed. *) + cbkind : cbkind; } and cbarg = | CBArrayAndLen of arg * string (** array + number of entries *) @@ -104,6 +108,15 @@ and cbarg = | CBString of string (** like String *) | CBUInt of string (** like UInt *) | CBUInt64 of string (** like UInt64 *) +and cbkind = +| CBOnceCommand (** The closure will be used 0 or 1 time if the aio_* call + returned a error and exactly once if the call succeeded. + The closure may only be called before the command + is retired. (E.g., completion callback.) *) +| CBManyCommand (** The closure may be used any number of times but only + before the command is retired. (E.g., list callback.) *) +| CBManyHandle (** The closure may be used any number of times for as long + as the handle exists. (E.g., debug 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 _______________________________________________ Libguestfs mailing list Libguestfs(a)redhat.com https://listman.redhat.com/mailman/listinfo/libguestfs