Re: [Libguestfs] [libnbd PATCH v4 04/11] rust: Use more specific closure traits

For closures with `cb,count = CBOnce`, `FnOnce` will be used instead of

`FnMut`. Moreover, closures in synchronous commands with `cblifetime = CBCommand` will not need to live for the static lifetime. See [here](https://doc.rust-lang.org/std/ops/trait.FnOnce.html) for more information about the advantages of using `FnOnce` when possible. --- generator/Rust.ml | 44 ++++++++++++++++++++++++++++---------------- rust/src/handle.rs | 2 ++ rust/src/types.rs | 2 ++ 3 files changed, 32 insertions(+), 16 deletions(-) diff --git a/generator/Rust.ml b/generator/Rust.ml index 3117980..d3225eb 100644 --- a/generator/Rust.ml +++ b/generator/Rust.ml @@ -111,7 +111,7 @@ let rust_cbarg_name : cbarg -> string = function | CBArrayAndLen (arg, _) | CBMutable arg -> rust_arg_name arg (* Get the Rust type for an argument. *) -let rec rust_arg_type : arg -> string = function +let rec rust_arg_type ?(async_kind = None) : arg -> string = function | Bool _ -> "bool" | Int _ -> "c_int" | UInt _ -> "c_uint" @@ -131,15 +131,18 @@ let rec rust_arg_type : arg -> string = function | BytesOut _ -> "&mut [u8]" | BytesPersistIn _ -> "&'static [u8]" | BytesPersistOut _ -> "&'static mut [u8]" - | Closure { cbargs } -> "impl " ^ rust_closure_trait cbargs + | Closure { cbargs; cbcount } -> ( + match async_kind with + | Some _ -> "impl " ^ rust_closure_trait cbargs cbcount + | None -> "impl " ^ rust_closure_trait cbargs cbcount ~lifetime:None) (* Get the Rust closure trait for a callback, That is `Fn*(...) -> ...)`. *) -and rust_closure_trait ?(lifetime = Some "'static") cbargs : string = +and rust_closure_trait ?(lifetime = Some "'static") cbargs cbcount : string = let rust_cbargs = String.concat ", " (List.map rust_cbarg_type cbargs) - and lifetime_constraint = - match lifetime with None -> "" | Some x -> " + " ^ x - in - "FnMut(" ^ rust_cbargs ^ ") -> c_int + Send + Sync" ^ lifetime_constraint + and closure_type = + match cbcount with CBOnce -> "FnOnce" | CBMany -> "FnMut" + and lifetime = match lifetime with None -> "" | Some x -> " + " ^ x in + sprintf "%s(%s) -> c_int + Send + Sync%s" closure_type rust_cbargs lifetime (* Get the Rust type for a callback argument. *) and rust_cbarg_type : cbarg -> string = function @@ -153,8 +156,8 @@ and rust_cbarg_type : cbarg -> string = function | CBMutable arg -> "&mut " ^ rust_arg_type arg (* Get the type of a rust optional argument. *) -let rust_optarg_type : optarg -> string = function - | OClosure x -> sprintf "Option<%s>" (rust_arg_type (Closure x)) +let rust_optarg_type ?(async_kind = None) : optarg -> string = function + | OClosure x -> sprintf "Option<%s>" (rust_arg_type (Closure x) ~async_kind) | OFlags (name, flags, _) -> sprintf "Option<%s>" (rust_arg_type (Flags (name, flags))) @@ -419,8 +422,8 @@ let ffi_ret_to_rust (call : call) = closure data, and a free function for the closure data. This struct is what will be sent to a C function taking the closure as an argument. In fact, the struct itself is generated by rust-bindgen. *) -let print_rust_closure_to_raw_fn ({ cbname; cbargs } : closure) = - let closure_trait = rust_closure_trait cbargs ~lifetime:None in +let print_rust_closure_to_raw_fn ({ cbname; cbargs; cbcount } : closure) = + let closure_trait = rust_closure_trait cbargs cbcount ~lifetime:None in let ffi_cbargs_names = List.flatten (List.map ffi_cbarg_names cbargs) in let ffi_cbargs_types = List.flatten (List.map ffi_cbarg_types cbargs) in let rust_cbargs_names = List.map rust_cbarg_name cbargs in @@ -435,16 +438,24 @@ let print_rust_closure_to_raw_fn ({ cbname; cbargs } : closure) = (List.map2 (sprintf "%s: %s") ffi_cbargs_names ffi_cbargs_types)); pr " where F: %s\n" closure_trait; pr " {\n"; - pr " let callback_ptr = data as *mut F;\n"; - pr " let callback = &mut *callback_ptr;\n"; + (match cbcount with + | CBMany -> + pr " let callback_ptr = data as *mut F;\n"; + pr " let callback = &mut *callback_ptr;\n" + | CBOnce -> + pr " let callback_ptr = data as *mut Option<F>;\n"; + pr " let callback_option: &mut Option<F> = &mut *callback_ptr;\n"; + pr " let callback: F = callback_option.take().unwrap();\n"); List.iter ffi_cbargs_to_rust cbargs; pr " callback(%s)\n" (String.concat ", " rust_cbargs_names); pr " }\n"; - pr " let callback_data = Box::into_raw(Box::new(f));\n"; + pr " let callback_data = Box::into_raw(Box::new(%s));\n" + (match cbcount with CBMany -> "f" | CBOnce -> "Some(f)"); pr " sys::nbd_%s_callback {\n" cbname; pr " callback: Some(call_closure::<F>),\n"; pr " user_data: callback_data as *mut _,\n"; - pr " free: Some(utils::drop_data::<F>),\n"; + pr " free: Some(utils::drop_data::<%s>),\n" + (match cbcount with CBMany -> "F" | CBOnce -> "Option<F>"); pr " }\n"; pr "}\n"; pr "\n" @@ -501,7 +512,8 @@ let print_rust_handle_method ((name, call) : string * call) = let rust_args_names = List.map rust_arg_name call.args @ List.map rust_optarg_name call.optargs and rust_args_types = - List.map rust_arg_type call.args @ List.map rust_optarg_type call.optargs + List.map (rust_arg_type ~async_kind:call.async_kind) call.args + @ List.map (rust_optarg_type ~async_kind:call.async_kind) call.optargs in let rust_args = String.concat ", " diff --git a/rust/src/handle.rs b/rust/src/handle.rs index e26755c..269d1ac 100644 --- a/rust/src/handle.rs +++ b/rust/src/handle.rs @@ -31,6 +31,8 @@ impl Handle { if handle.is_null() { Err(unsafe { Error::Fatal(ErrorKind::get_error().into()) }) } else { + // Set a debug callback communicating with any logging + // implementation as defined by the log crate. #[allow(unused_mut)] let mut nbd = Handle { handle }; #[cfg(feature = "log")] diff --git a/rust/src/types.rs b/rust/src/types.rs index eb2df06..af62140 100644 --- a/rust/src/types.rs +++ b/rust/src/types.rs @@ -15,4 +15,6 @@ // License along with this library; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA +/// A cookie is a 64 bit integer returned by some aio_* methods on +/// [crate::Handle] used to identify a running command. pub struct Cookie(pub(crate) u64);