Use static lua for now, to make lifetimes work

src/lune/mod.rs

@@ -6,9 +6,11 @@ mod scheduler;
 use self::scheduler::Scheduler;
 
 pub use error::LuneError;
+use mlua::Lua;
 
-#[derive(Clone, Debug, Default)]
+#[derive(Debug, Clone)]
 pub struct Lune {
+    lua: &'static Lua,
     args: Vec<String>,
 }
 
@@ -16,8 +18,12 @@ impl Lune {
     /**
         Creates a new Lune script runner.
     */
+    #[allow(clippy::new_without_default)]
     pub fn new() -> Self {
-        Self::default()
+        Self {
+            lua: Lua::new().into_static(),
+            args: Vec::new(),
+        }
     }
 
     /**
@@ -39,15 +45,25 @@ impl Lune {
         script_name: impl AsRef<str>,
         script_contents: impl AsRef<[u8]>,
     ) -> Result<ExitCode, LuneError> {
-        let scheduler = Scheduler::new();
+        let scheduler = Scheduler::new(self.lua);
+        self.lua.set_app_data(scheduler.clone());
 
-        let main = scheduler
+        let main = self
             .lua
             .load(script_contents.as_ref())
             .set_name(script_name.as_ref());
 
         scheduler.push_back(main, ())?;
-
         Ok(scheduler.run_to_completion().await)
     }
 }
+
+impl Drop for Lune {
+    fn drop(&mut self) {
+        // SAFETY: The scheduler needs the static lifetime reference to lua,
+        // when dropped nothing outside of here has access to the scheduler
+        unsafe {
+            Lua::from_static(self.lua);
+        }
+    }
+}

src/lune/scheduler/impl_async.rs

@@ -33,11 +33,11 @@ where
         FR: IntoLuaMulti<'fut>,
         F: Future<Output = LuaResult<FR>> + 'fut,
     {
-        let thread = thread.into_owned_lua_thread(&self.lua)?;
+        let thread = thread.into_owned_lua_thread(self.lua)?;
         self.schedule_future(async move {
             let rets = fut.await.expect("Failed to receive result");
             let rets = rets
-                .into_lua_multi(&self.lua)
+                .into_lua_multi(self.lua)
                 .expect("Failed to create return multi value");
             self.push_back(thread, rets)
                 .expect("Failed to schedule future thread");

src/lune/scheduler/impl_threads.rs

@@ -39,7 +39,7 @@ where
         {
             Some(thread) => {
                 let thread_id = &thread.id();
-                let (thread, args) = thread.into_inner(&self.lua);
+                let (thread, args) = thread.into_inner(self.lua);
                 let sender = self
                     .thread_senders
                     .borrow_mut()
@@ -60,10 +60,10 @@ where
         thread: impl IntoLuaOwnedThread,
         args: impl IntoLuaMulti<'a>,
     ) -> LuaResult<SchedulerThreadId> {
-        let thread = thread.into_owned_lua_thread(&self.lua)?;
-        let args = args.into_lua_multi(&self.lua)?;
+        let thread = thread.into_owned_lua_thread(self.lua)?;
+        let args = args.into_lua_multi(self.lua)?;
 
-        let thread = SchedulerThread::new(&self.lua, thread, args)?;
+        let thread = SchedulerThread::new(self.lua, thread, args)?;
         let thread_id = thread.id();
 
         self.threads
@@ -87,10 +87,10 @@ where
         thread: impl IntoLuaOwnedThread,
         args: impl IntoLuaMulti<'a>,
     ) -> LuaResult<SchedulerThreadId> {
-        let thread = thread.into_owned_lua_thread(&self.lua)?;
-        let args = args.into_lua_multi(&self.lua)?;
+        let thread = thread.into_owned_lua_thread(self.lua)?;
+        let args = args.into_lua_multi(self.lua)?;
 
-        let thread = SchedulerThread::new(&self.lua, thread, args)?;
+        let thread = SchedulerThread::new(self.lua, thread, args)?;
         let thread_id = thread.id();
 
         self.threads

src/lune/scheduler/mod.rs

@@ -2,6 +2,7 @@ use std::{
     cell::RefCell,
     collections::{HashMap, VecDeque},
     pin::Pin,
+    sync::Arc,
 };
 
 use futures_util::{stream::FuturesUnordered, Future};
@@ -23,30 +24,31 @@ use self::{
     thread::{SchedulerThread, SchedulerThreadId, SchedulerThreadSender},
 };
 
-/**
-    Scheduler for Lua threads.
+type SchedulerFuture<'fut> = Pin<Box<dyn Future<Output = ()> + 'fut>>;
 
-    This wraps a [`Lua`] struct and exposes it as the `lua` property.
+/**
+    Scheduler for Lua threads and futures.
+
+    This scheduler can be cheaply cloned and the underlying state
+    and data will remain unchanged and accessible from all clones.
 */
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub(crate) struct Scheduler<'fut> {
-    pub(crate) lua: Lua,
-    state: SchedulerState,
-    threads: RefCell<VecDeque<SchedulerThread>>,
-    thread_senders: RefCell<HashMap<SchedulerThreadId, SchedulerThreadSender>>,
-    futures: AsyncMutex<FuturesUnordered<Pin<Box<dyn Future<Output = ()> + 'fut>>>>,
+    lua: &'static Lua,
+    state: Arc<SchedulerState>,
+    threads: Arc<RefCell<VecDeque<SchedulerThread>>>,
+    thread_senders: Arc<RefCell<HashMap<SchedulerThreadId, SchedulerThreadSender>>>,
+    futures: Arc<AsyncMutex<FuturesUnordered<SchedulerFuture<'fut>>>>,
 }
 
 impl<'fut> Scheduler<'fut> {
-    pub fn new() -> Self {
-        let lua = Lua::new();
-
+    pub fn new(lua: &'static Lua) -> Self {
         Self {
             lua,
-            state: SchedulerState::new(),
-            threads: RefCell::new(VecDeque::new()),
-            thread_senders: RefCell::new(HashMap::new()),
-            futures: AsyncMutex::new(FuturesUnordered::new()),
+            state: Arc::new(SchedulerState::new()),
+            threads: Arc::new(RefCell::new(VecDeque::new())),
+            thread_senders: Arc::new(RefCell::new(HashMap::new())),
+            futures: Arc::new(AsyncMutex::new(FuturesUnordered::new())),
         }
     }
 }

src/lune/scheduler/traits.rs

@@ -13,32 +13,29 @@ return yield()
     for access to the scheduler without having to import
     it or handle registry / app data references manually.
 */
-pub trait LuaSchedulerExt<'lua, 'fut>
-where
-    'lua: 'fut,
-{
+pub trait LuaSchedulerExt {
     /**
         Creates a function callable from Lua that runs an async
         closure and returns the results of it to the call site.
     */
-    fn create_async_function<A, R, F, FR>(&'lua self, func: F) -> LuaResult<LuaFunction<'lua>>
+    fn create_async_function<A, R, F, FR>(
+        &'static self,
+        func: F,
+    ) -> LuaResult<LuaFunction<'static>>
     where
-        A: FromLuaMulti<'lua>,
-        R: IntoLuaMulti<'lua>,
-        F: Fn(&'lua Lua, A) -> FR + 'static,
-        FR: Future<Output = LuaResult<R>> + 'fut;
+        A: FromLuaMulti<'static>,
+        R: IntoLuaMulti<'static>,
+        F: Fn(&'static Lua, A) -> FR + 'static,
+        FR: Future<Output = LuaResult<R>> + 'static;
 }
 
-impl<'lua, 'fut> LuaSchedulerExt<'lua, 'fut> for Lua
-where
-    'lua: 'fut,
-{
-    fn create_async_function<A, R, F, FR>(&'lua self, func: F) -> LuaResult<LuaFunction<'lua>>
+impl LuaSchedulerExt for Lua {
+    fn create_async_function<A, R, F, FR>(&'static self, func: F) -> LuaResult<LuaFunction<'static>>
     where
-        A: FromLuaMulti<'lua>,
-        R: IntoLuaMulti<'lua>,
-        F: Fn(&'lua Lua, A) -> FR + 'static,
-        FR: Future<Output = LuaResult<R>> + 'fut,
+        A: FromLuaMulti<'static>,
+        R: IntoLuaMulti<'static>,
+        F: Fn(&'static Lua, A) -> FR + 'static,
+        FR: Future<Output = LuaResult<R>> + 'static,
     {
         let async_env = self.create_table_with_capacity(0, 2)?;
 
@@ -58,7 +55,8 @@ where
                     .app_data_ref::<&Scheduler>()
                     .expect("Lua struct is missing scheduler");
                 // FIXME: `self` escapes outside of method because we are borrowing `func`?
-                // sched.schedule_future_thread(thread, future)?;
+                // For now we solve this by just using a &'static Lua reference everywhere
+                sched.schedule_future_thread(thread, future)?;
                 Ok(())
             }),
         )?;