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Discover NIFs at startup
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This is a proof-of-concept for a mechanism that does away with the need
to list all NIF functions in the `rustler::init!` invocation. A similar
mechanism will be required and implemented for resource type
registrations.

- Convert `Nif` to a `struct`
- Use `inventory` to register the `Nif` instances
- In `rustler::init!`, ignore the passed functions and instead use the
  registered `Nif` instances

Next steps:

- See whether `linkme` is not a better option (creates the array
  directly at build-time, no need to leak)
- Implement resource registration using this mechanism
- See if we can move the macros to `rustler`
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@filmor
filmor committed May 28, 2024
1 parent b882d51 commit 87ecea9
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Showing 9 changed files with 93 additions and 95 deletions.
1 change: 1 addition & 0 deletions rustler/Cargo.toml
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Expand Up @@ -22,6 +22,7 @@ nif_version_2_17 = ["nif_version_2_16", "rustler_sys/nif_version_2_17"]
serde = ["dep:serde"]

[dependencies]
inventory = "0.3"
rustler_codegen = { path = "../rustler_codegen", version = "0.32.1", optional = true}
rustler_sys = { path = "../rustler_sys", version = "~2.4.0" }
num-bigint = { version = "0.4", optional = true }
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3 changes: 3 additions & 0 deletions rustler/src/codegen_runtime.rs
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Expand Up @@ -5,6 +5,9 @@ use std::fmt;

use crate::{Encoder, Env, OwnedBinary, Term};

// Re-export of inventory
pub use inventory;

// Names used by the `rustler::init!` macro or other generated code.
pub use crate::wrapper::exception::raise_exception;
pub use crate::wrapper::{
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32 changes: 22 additions & 10 deletions rustler/src/nif.rs
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@@ -1,13 +1,25 @@
use crate::codegen_runtime::{c_char, c_int, c_uint, DEF_NIF_FUNC, NIF_ENV, NIF_TERM};

pub trait Nif {
const NAME: *const c_char;
const ARITY: c_uint;
const FLAGS: c_uint;
const FUNC: DEF_NIF_FUNC;
const RAW_FUNC: unsafe extern "C" fn(
nif_env: NIF_ENV,
argc: c_int,
argv: *const NIF_TERM,
) -> NIF_TERM;
pub struct Nif {
pub name: *const c_char,
pub arity: c_uint,
pub flags: c_uint,
// pub func: DEF_NIF_FUNC,
pub raw_func:
unsafe extern "C" fn(nif_env: NIF_ENV, argc: c_int, argv: *const NIF_TERM) -> NIF_TERM,
}

impl Nif {
pub fn get_def(&self) -> DEF_NIF_FUNC {
DEF_NIF_FUNC {
arity: self.arity,
flags: self.flags,
function: self.raw_func,
name: self.name,
}
}
}

unsafe impl Sync for Nif {}

inventory::collect!(Nif);
1 change: 1 addition & 0 deletions rustler_codegen/Cargo.toml
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Expand Up @@ -17,6 +17,7 @@ syn = { version = "2.0", features = ["full", "extra-traits"] }
quote = "1.0"
heck = "0.5"
proc-macro2 = "1.0"
inventory = "0.3"

[dev-dependencies]
trybuild = "1.0"
37 changes: 12 additions & 25 deletions rustler_codegen/src/init.rs
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@@ -1,26 +1,23 @@
use proc_macro2::{Span, TokenStream};
use quote::quote;
use syn::parse::{Parse, ParseStream};
use syn::punctuated::Punctuated;
use syn::token::Comma;
use syn::{Expr, Ident, Result, Token};
use syn::{Ident, Result, Token};

#[derive(Debug)]
pub struct InitMacroInput {
name: syn::Lit,
funcs: syn::ExprArray,
load: TokenStream,
}

impl Parse for InitMacroInput {
fn parse(input: ParseStream) -> Result<Self> {
let name = syn::Lit::parse(input)?;
let _comma = <syn::Token![,]>::parse(input)?;
let funcs = syn::ExprArray::parse(input)?;
let _funcs = syn::ExprArray::parse(input)?;
let options = parse_expr_assigns(input);
let load = extract_option(options, "load");

Ok(InitMacroInput { name, funcs, load })
Ok(InitMacroInput { name, load })
}
}

Expand Down Expand Up @@ -55,20 +52,21 @@ fn extract_option(args: Vec<syn::ExprAssign>, name: &str) -> TokenStream {
impl From<InitMacroInput> for proc_macro2::TokenStream {
fn from(input: InitMacroInput) -> Self {
let name = input.name;
let num_of_funcs = input.funcs.elems.len();
let funcs = nif_funcs(input.funcs.elems);
let load = input.load;

let inner = quote! {
static mut NIF_ENTRY: Option<rustler::codegen_runtime::DEF_NIF_ENTRY> = None;
use rustler::Nif;
let nif_funcs: Box<[_]> =
rustler::codegen_runtime::inventory::iter::<rustler::Nif>()
.map(rustler::Nif::get_def)
.collect();

let entry = rustler::codegen_runtime::DEF_NIF_ENTRY {
major: rustler::codegen_runtime::NIF_MAJOR_VERSION,
minor: rustler::codegen_runtime::NIF_MINOR_VERSION,
name: concat!(#name, "\0").as_ptr() as *const rustler::codegen_runtime::c_char,
num_of_funcs: #num_of_funcs as rustler::codegen_runtime::c_int,
funcs: [#funcs].as_ptr(),
num_of_funcs: nif_funcs.len() as rustler::codegen_runtime::c_int,
funcs: nif_funcs.as_ptr(),
load: {
extern "C" fn nif_load(
env: rustler::codegen_runtime::NIF_ENV,
Expand All @@ -91,6 +89,9 @@ impl From<InitMacroInput> for proc_macro2::TokenStream {
};

unsafe {
// Leak nif_funcs
std::mem::forget(nif_funcs);

NIF_ENTRY = Some(entry);
NIF_ENTRY.as_ref().unwrap()
}
Expand All @@ -115,17 +116,3 @@ impl From<InitMacroInput> for proc_macro2::TokenStream {
}
}
}

fn nif_funcs(funcs: Punctuated<Expr, Comma>) -> TokenStream {
let mut tokens = TokenStream::new();

for func in funcs.iter() {
if let Expr::Path(_) = *func {
tokens.extend(quote!(#func::FUNC,));
} else {
panic!("Expected an expression, found: {}", stringify!(func));
}
}

tokens
}
85 changes: 39 additions & 46 deletions rustler_codegen/src/nif.rs
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Expand Up @@ -55,54 +55,47 @@ pub fn transcoder_decorator(nif_attributes: NifAttributes, fun: syn::ItemFn) ->
}

quote! {
#[allow(non_camel_case_types)]
pub struct #name;

impl rustler::Nif for #name {
const NAME: *const rustler::codegen_runtime::c_char = concat!(#erl_func_name, "\0").as_ptr() as *const rustler::codegen_runtime::c_char;
const ARITY: rustler::codegen_runtime::c_uint = #arity;
const FLAGS: rustler::codegen_runtime::c_uint = #flags as rustler::codegen_runtime::c_uint;
const RAW_FUNC: unsafe extern "C" fn(
nif_env: rustler::codegen_runtime::NIF_ENV,
argc: rustler::codegen_runtime::c_int,
argv: *const rustler::codegen_runtime::NIF_TERM
) -> rustler::codegen_runtime::NIF_TERM = {
unsafe extern "C" fn nif_func(
nif_env: rustler::codegen_runtime::NIF_ENV,
argc: rustler::codegen_runtime::c_int,
argv: *const rustler::codegen_runtime::NIF_TERM
) -> rustler::codegen_runtime::NIF_TERM {
let lifetime = ();
let env = rustler::Env::new(&lifetime, nif_env);

let terms = std::slice::from_raw_parts(argv, argc as usize)
.iter()
.map(|term| rustler::Term::new(env, *term))
.collect::<Vec<rustler::Term>>();

fn wrapper<'a>(
env: rustler::Env<'a>,
args: &[rustler::Term<'a>]
) -> rustler::codegen_runtime::NifReturned {
let result: std::thread::Result<_> = std::panic::catch_unwind(move || {
#decoded_terms
#function
Ok(#name(#argument_names))
});

rustler::codegen_runtime::handle_nif_result(result, env)
rustler::codegen_runtime::inventory::submit!(
rustler::Nif {
name: concat!(#erl_func_name, "\0").as_ptr()
as *const rustler::codegen_runtime::c_char,
arity: #arity,
flags: #flags as rustler::codegen_runtime::c_uint,
raw_func: {
unsafe extern "C" fn nif_func(
nif_env: rustler::codegen_runtime::NIF_ENV,
argc: rustler::codegen_runtime::c_int,
argv: *const rustler::codegen_runtime::NIF_TERM
) -> rustler::codegen_runtime::NIF_TERM {
let lifetime = ();
let env = rustler::Env::new(&lifetime, nif_env);

let terms = std::slice::from_raw_parts(argv, argc as usize)
.iter()
.map(|term| rustler::Term::new(env, *term))
.collect::<Vec<rustler::Term>>();

fn wrapper<'a>(
env: rustler::Env<'a>,
args: &[rustler::Term<'a>]
) -> rustler::codegen_runtime::NifReturned {
let result: std::thread::Result<_> =
std::panic::catch_unwind(move || {
#decoded_terms
#function
Ok(#name(#argument_names))
});

rustler::codegen_runtime::handle_nif_result(
result, env
)
}
wrapper(env, &terms).apply(env)
}
wrapper(env, &terms).apply(env)
nif_func
}
nif_func
};
const FUNC: rustler::codegen_runtime::DEF_NIF_FUNC = rustler::codegen_runtime::DEF_NIF_FUNC {
arity: Self::ARITY,
flags: Self::FLAGS,
function: Self::RAW_FUNC,
name: Self::NAME
};
}
}
);
}
}

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1 change: 1 addition & 0 deletions rustler_sys/src/rustler_sys_api.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,7 @@ unsafe impl Send for ErlNifEnv {}

/// See [ErlNifFunc](http://www.erlang.org/doc/man/erl_nif.html#ErlNifFunc) in the Erlang docs.
// #[allow(missing_copy_implementations)]
#[derive(Debug)]
#[repr(C)]
pub struct ErlNifFunc {
pub name: *const c_char,
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26 changes: 13 additions & 13 deletions rustler_tests/native/rustler_serde_test/src/lib.rs
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Expand Up @@ -16,19 +16,19 @@ use rustler::{types::tuple, Encoder, Env, NifResult, SerdeTerm, Term};
init! {
"Elixir.SerdeRustlerTests",
[
// json
json::decode_json,
json::decode_json_dirty,
json::encode_json_compact,
json::encode_json_compact_dirty,
json::encode_json_pretty,
json::encode_json_pretty_dirty,

// tests
readme,
test::test,
transcode,
transcode_dirty,
// // json
// json::decode_json,
// json::decode_json_dirty,
// json::encode_json_compact,
// json::encode_json_compact_dirty,
// json::encode_json_pretty,
// json::encode_json_pretty_dirty,
//
// // tests
// readme,
// test::test,
// transcode,
// transcode_dirty,
]
}

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2 changes: 1 addition & 1 deletion rustler_tests/native/rustler_test/src/test_resource.rs
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Expand Up @@ -109,7 +109,7 @@ pub fn resource_make_binaries(
)
}

#[rustler::nif]
// #[rustler::nif]
pub fn resource_make_binary_from_vec(env: Env, resource: ResourceArc<WithBinaries>) -> Binary {
resource.make_binary(env, |w| &w.b)
}

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