fix(ext/ffi): allow opting out of fast ffi calls (denoland#15131)

cli/dts/lib.deno.unstable.d.ts

@@ -430,6 +430,8 @@ declare namespace Deno {
  result: Result;
  /** When true, function calls will run on a dedicated blocking thread and will return a Promise resolving to the `result`. */
  nonblocking?: NonBlocking;
+ /** When true, function calls can safely callback into JS or trigger a GC event. Default is `false`. */
+ callback?: boolean;
  }
 
  export interface ForeignStatic<Type extends NativeType = NativeType> {

ext/ffi/lib.rs

@@ -72,6 +72,7 @@ struct Symbol {
  ptr: libffi::middle::CodePtr,
  parameter_types: Vec<NativeType>,
  result_type: NativeType,
+ can_callback: bool,
 }
 
 #[allow(clippy::non_send_fields_in_send_ty)]
@@ -433,6 +434,13 @@ struct ForeignFunction {
  result: NativeType,
  #[serde(rename = "nonblocking")]
  non_blocking: Option<bool>,
+ #[serde(rename = "callback")]
+ #[serde(default = "default_callback")]
+ callback: bool,
+}
+
+fn default_callback() -> bool {
+ false
 }
 
 // ForeignStatic's name and type fields are read and used by
@@ -599,6 +607,7 @@ where
  ptr,
  parameter_types: foreign_fn.parameters,
  result_type: foreign_fn.result,
+ can_callback: foreign_fn.callback,
  });
 
  resource.symbols.insert(symbol_key, sym.clone());
@@ -689,7 +698,8 @@ fn make_sync_fn<'s>(
 ) -> v8::Local<'s, v8::Function> {
  let mut fast_ffi_templ = None;
 
- if !sym.parameter_types.iter().any(|t| !is_fast_api(*t))
+ if !sym.can_callback
+ && !sym.parameter_types.iter().any(|t| !is_fast_api(*t))
  && is_fast_api(sym.result_type)
  {
  let mut args = sym
@@ -941,6 +951,7 @@ where
  result_type,
  cif,
  ptr: fun_ptr,
+ ..
  } = symbol;
  let mut ffi_args: Vec<NativeValue> =
  Vec::with_capacity(parameter_types.len());
@@ -1814,6 +1825,7 @@ fn op_ffi_call_nonblocking<'scope>(
  ptr,
  parameter_types,
  result_type,
+ ..
  } = symbol.clone();
  ffi_call(call_args, &cif, ptr, &parameter_types, result_type)
  });

test_ffi/tests/ffi_types.ts

@@ -5,7 +5,7 @@
 const remote = Deno.dlopen(
  "dummy_lib.so",
  {
- method1: { parameters: ["usize", "usize"], result: "void" },
+ method1: { parameters: ["usize", "usize"], result: "void", callback: true },
  method2: { parameters: [], result: "void" },
  method3: { parameters: ["usize"], result: "void" },
  method4: { parameters: ["isize"], result: "void" },

test_ffi/tests/test.js

@@ -164,10 +164,12 @@ const dylib = Deno.dlopen(libPath, {
  call_stored_function: {
  parameters: [],
  result: "void",
+ callback: true,
  },
  call_stored_function_2: {
  parameters: ["u8"],
  result: "void",
+ callback: true,
  },
  // Statics
  "static_u32": {
@@ -372,12 +374,14 @@ assertThrows(
  "hi",
 );
 
+const { call_stored_function } = dylib.symbols;
+
 dylib.symbols.call_fn_ptr(ptr(logCallback));
 dylib.symbols.call_fn_ptr_many_parameters(ptr(logManyParametersCallback));
 dylib.symbols.call_fn_ptr_return_u8(ptr(returnU8Callback));
 dylib.symbols.call_fn_ptr_return_buffer(ptr(returnBufferCallback));
 dylib.symbols.store_function(ptr(logCallback));
-dylib.symbols.call_stored_function();
+call_stored_function();
 dylib.symbols.store_function_2(ptr(add10Callback));
 dylib.symbols.call_stored_function_2(20);