3 files changed, 56 insertions, 16 deletions
diff --git a/ext/ffi/00_ffi.js b/ext/ffi/00_ffi.js
index 553ea1dd3..c7fdd0e8c 100644
--- a/ext/ffi/00_ffi.js
+++ b/ext/ffi/00_ffi.js
@@ -13,8 +13,15 @@
       this.#rid = core.opSync("op_ffi_load", { path, symbols });
 
       for (const symbol in symbols) {
-        this.symbols[symbol] = (...parameters) =>
-          core.opSync("op_ffi_call", { rid: this.#rid, symbol, parameters });
+        this.symbols[symbol] = symbols[symbol].nonblocking
+          ? (...parameters) =>
+            core.opAsync("op_ffi_call_nonblocking", {
+              rid: this.#rid,
+              symbol,
+              parameters,
+            })
+          : (...parameters) =>
+            core.opSync("op_ffi_call", { rid: this.#rid, symbol, parameters });
       }
     }
 
diff --git a/ext/ffi/Cargo.toml b/ext/ffi/Cargo.toml
index 398aa5995..6d6357562 100644
--- a/ext/ffi/Cargo.toml
+++ b/ext/ffi/Cargo.toml
@@ -18,3 +18,4 @@ deno_core = { version = "0.101.0", path = "../../core" }
 dlopen = "0.1.8"
 libffi = { version = "=0.0.7", package = "deno-libffi" }
 serde = { version = "1.0.129", features = ["derive"] }
+tokio = { version = "1.10.1", features = ["full"] }
diff --git a/ext/ffi/lib.rs b/ext/ffi/lib.rs
index e0430366c..e1acd097a 100644
--- a/ext/ffi/lib.rs
+++ b/ext/ffi/lib.rs
@@ -3,6 +3,7 @@
 use deno_core::error::bad_resource_id;
 use deno_core::error::AnyError;
 use deno_core::include_js_files;
+use deno_core::op_async;
 use deno_core::op_sync;
 use deno_core::serde_json::json;
 use deno_core::serde_json::Value;
@@ -14,6 +15,7 @@ use dlopen::raw::Library;
 use libffi::middle::Arg;
 use serde::Deserialize;
 use std::borrow::Cow;
+use std::cell::RefCell;
 use std::collections::HashMap;
 use std::convert::TryFrom;
 use std::ffi::c_void;
@@ -37,6 +39,7 @@ pub trait FfiPermissions {
   fn check(&mut self, path: &str) -> Result<(), AnyError>;
 }
 
+#[derive(Clone)]
 struct Symbol {
   cif: libffi::middle::Cif,
   ptr: libffi::middle::CodePtr,
@@ -44,6 +47,9 @@ struct Symbol {
   result_type: NativeType,
 }
 
+unsafe impl Send for Symbol {}
+unsafe impl Sync for Symbol {}
+
 struct DynamicLibraryResource {
   lib: Library,
   symbols: HashMap<String, Symbol>,
@@ -99,6 +105,7 @@ pub fn init<P: FfiPermissions + 'static>(unstable: bool) -> Extension {
     .ops(vec![
       ("op_ffi_load", op_sync(op_ffi_load::<P>)),
       ("op_ffi_call", op_sync(op_ffi_call)),
+      ("op_ffi_call_nonblocking", op_async(op_ffi_call_nonblocking)),
     ])
     .state(move |state| {
       // Stolen from deno_webgpu, is there a better option?
@@ -294,20 +301,7 @@ struct FfiCallArgs {
   parameters: Vec<Value>,
 }
 
-fn op_ffi_call(
-  state: &mut deno_core::OpState,
-  args: FfiCallArgs,
-  _: (),
-) -> Result<Value, AnyError> {
-  let resource = state
-    .resource_table
-    .get::<DynamicLibraryResource>(args.rid)?;
-
-  let symbol = resource
-    .symbols
-    .get(&args.symbol)
-    .ok_or_else(bad_resource_id)?;
-
+fn ffi_call(args: FfiCallArgs, symbol: &Symbol) -> Result<Value, AnyError> {
   let native_values = symbol
     .parameter_types
     .iter()
@@ -366,3 +360,41 @@ fn op_ffi_call(
     }
   })
 }
+
+fn op_ffi_call(
+  state: &mut deno_core::OpState,
+  args: FfiCallArgs,
+  _: (),
+) -> Result<Value, AnyError> {
+  let resource = state
+    .resource_table
+    .get::<DynamicLibraryResource>(args.rid)?;
+
+  let symbol = resource
+    .symbols
+    .get(&args.symbol)
+    .ok_or_else(bad_resource_id)?;
+
+  ffi_call(args, symbol)
+}
+
+/// A non-blocking FFI call.
+async fn op_ffi_call_nonblocking(
+  state: Rc<RefCell<deno_core::OpState>>,
+  args: FfiCallArgs,
+  _: (),
+) -> Result<Value, AnyError> {
+  let resource = state
+    .borrow()
+    .resource_table
+    .get::<DynamicLibraryResource>(args.rid)?;
+  let symbols = &resource.symbols;
+  let symbol = symbols
+    .get(&args.symbol)
+    .ok_or_else(bad_resource_id)?
+    .clone();
+
+  tokio::task::spawn_blocking(move || ffi_call(args, &symbol))
+    .await
+    .unwrap()
+}