feat(lua): also pass errors in callbacks

.github/workflows/lua.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - stable
+      - dev
 
 permissions:
   contents: read

src/ffi/lua/buffer.rs

@@ -4,7 +4,6 @@ use crate::prelude::*;
 
 use super::ext::a_sync::a_sync;
 use super::ext::from_lua_serde;
-use super::ext::callback::CHANNEL;
 
 
 impl LuaUserData for CodempBufferController {
@@ -25,7 +24,7 @@ impl LuaUserData for CodempBufferController {
 
 		methods.add_method("clear_callback", |_, this, ()| { this.clear_callback(); Ok(()) });
 		methods.add_method("callback", |_, this, (cb,):(LuaFunction,)| {
-			this.callback(move |controller: CodempBufferController| CHANNEL.send(cb.clone(), controller));
+			this.callback(move |controller: CodempBufferController| super::ext::callback().invoke(cb.clone(), controller));
 			Ok(())
 		});
 	}

src/ffi/lua/cursor.rs

@@ -4,7 +4,6 @@ use crate::prelude::*;
 
 use super::ext::a_sync::a_sync;
 use super::ext::from_lua_serde;
-use super::ext::callback::CHANNEL;
 use super::ext::lua_tuple;
 
 impl LuaUserData for CodempCursorController {
@@ -24,7 +23,7 @@ impl LuaUserData for CodempCursorController {
 
 		methods.add_method("clear_callback", |_, this, ()| { this.clear_callback(); Ok(()) });
 		methods.add_method("callback", |_, this, (cb,):(LuaFunction,)| {
-			this.callback(move |controller: CodempCursorController| CHANNEL.send(cb.clone(), controller));
+			this.callback(move |controller: CodempCursorController| super::ext::callback().invoke(cb.clone(), controller));
 			Ok(())
 		});
 	}

src/ffi/lua/ext/a_sync.rs

@@ -1,8 +1,6 @@
 use mlua_codemp_patch as mlua;
 use mlua::prelude::*;
 
-use super::callback::CHANNEL;
-
 pub(crate) fn tokio() -> &'static tokio::runtime::Runtime {
 	use std::sync::OnceLock;
 	static RT: OnceLock<tokio::runtime::Runtime> = OnceLock::new();
@@ -60,8 +58,10 @@ impl LuaUserData for Promise {
 					.spawn(async move {
 						match x.await {
 							Err(e) => tracing::error!("could not join promise to run callback: {e}"),
-							Ok(Err(e)) => tracing::error!("promise returned error: {e}"),
-							Ok(Ok(res)) => CHANNEL.send(cb, res),
+							Ok(res) => match res {
+								Err(e) => super::callback().failure(e),
+								Ok(val) => super::callback().invoke(cb, val),
+							},
 						}
 					});
 				Ok(())

src/ffi/lua/ext/callback.rs

@@ -3,16 +3,17 @@ use mlua::prelude::*;
 use crate::prelude::*;
 use crate::ext::IgnorableError;
 
-lazy_static::lazy_static! {
-	pub(crate) static ref CHANNEL: CallbackChannel = CallbackChannel::default();
+pub(crate) fn callback() -> &'static CallbackChannel<LuaCallback> {
+	static CHANNEL: std::sync::OnceLock<CallbackChannel<LuaCallback>> = std::sync::OnceLock::new();
+	CHANNEL.get_or_init(CallbackChannel::default)
 }
 
-pub(crate) struct CallbackChannel {
-	tx: std::sync::Arc<tokio::sync::mpsc::UnboundedSender<(LuaFunction, CallbackArg)>>,
-	rx: std::sync::Mutex<tokio::sync::mpsc::UnboundedReceiver<(LuaFunction, CallbackArg)>>
+pub(crate) struct CallbackChannel<T> {
+	tx: std::sync::Arc<tokio::sync::mpsc::UnboundedSender<T>>,
+	rx: std::sync::Mutex<tokio::sync::mpsc::UnboundedReceiver<T>>
 }
 
-impl Default for CallbackChannel {
+impl Default for CallbackChannel<LuaCallback> {
 	fn default() -> Self {
 		let (tx, rx) = tokio::sync::mpsc::unbounded_channel();
 		let rx = std::sync::Mutex::new(rx);
@@ -23,30 +24,40 @@ impl Default for CallbackChannel {
 	}
 }
 
-impl CallbackChannel {
-	pub(crate) fn send(&self, cb: LuaFunction, arg: impl Into<CallbackArg>) {
-		self.tx.send((cb, arg.into()))
+impl CallbackChannel<LuaCallback> {
+	pub(crate) fn invoke(&self, cb: LuaFunction, arg: impl Into<CallbackArg>) {
+		self.tx.send(LuaCallback::Invoke(cb, arg.into()))
 			.unwrap_or_warn("error scheduling callback")
 	}
 
-	pub(crate) fn recv(&self) -> Option<(LuaFunction, CallbackArg)> {
+	pub(crate) fn failure(&self, err: impl std::error::Error) {
+		self.tx.send(LuaCallback::Fail(format!("promise failed with error: {err:?}")))
+			.unwrap_or_warn("error scheduling callback failure")
+	}
+
+	pub(crate) fn recv(&self) -> Option<LuaCallback> {
 		match self.rx.try_lock() {
 			Err(e) => {
-				tracing::warn!("could not acquire callback channel mutex: {e}");
+				tracing::debug!("backing off from callback mutex: {e}");
 				None
 			},
 			Ok(mut lock) => match lock.try_recv() {
-				Err(tokio::sync::mpsc::error::TryRecvError::Empty) => None,
 				Err(tokio::sync::mpsc::error::TryRecvError::Disconnected) => {
 					tracing::error!("callback channel closed");
 					None
 				},
-				Ok((cb, arg)) => Some((cb, arg)),
+				Err(tokio::sync::mpsc::error::TryRecvError::Empty) => None,
+				Ok(cb) => Some(cb),
 			},
 		}
 	}
 }
 
+pub(crate) enum LuaCallback {
+	Fail(String),
+	Invoke(LuaFunction, CallbackArg),
+}
+
 pub(crate) enum CallbackArg {
 	Nil,
 	Str(String),

src/ffi/lua/ext/log.rs

@@ -66,7 +66,7 @@ pub(crate) fn logger(_: &Lua, (printer, debug): (LuaValue, Option<bool>)) -> Lua
 			if res {
 				super::a_sync::tokio().spawn(async move {
 					while let Some(msg) = rx.recv().await {
-						super::callback::CHANNEL.send(cb.clone(), msg);
+						super::callback().invoke(cb.clone(), msg);
 					}
 				});
 			}

src/ffi/lua/ext/mod.rs

@@ -6,6 +6,7 @@ use mlua_codemp_patch as mlua;
 use mlua::prelude::*;
 
 pub(crate) use a_sync::tokio;
+pub(crate) use callback::callback;
 
 pub(crate) fn lua_tuple<T: IntoLua>(lua: &Lua, (a, b): (T, T)) -> LuaResult<LuaTable> {
 	let table = lua.create_table()?;

src/ffi/lua/mod.rs

@@ -30,11 +30,16 @@ fn entrypoint(lua: &Lua) -> LuaResult<LuaTable> {
 	// runtime
 	exports.set("spawn_runtime_driver", lua.create_function(ext::a_sync::spawn_runtime_driver)?)?;
 	exports.set("poll_callback", lua.create_function(|lua, ()| {
-		// TODO pass args too
 		let mut val = LuaMultiValue::new();
-		if let Some((cb, arg)) = ext::callback::CHANNEL.recv() {
-			val.push_back(LuaValue::Function(cb));
-			val.push_back(arg.into_lua(lua)?);
+		match ext::callback().recv() {
+			None => {},
+			Some(ext::callback::LuaCallback::Invoke(cb, arg)) => {
+				val.push_back(LuaValue::Function(cb));
+				val.push_back(arg.into_lua(lua)?);
+			}
+			Some(ext::callback::LuaCallback::Fail(msg)) => {
+				return Err(LuaError::runtime(msg));
+			},
 		}
 		Ok(val)
 	})?)?;