Wrap hooks in refcounter instead of box, same as previously.

This allows to obtain independent clone of closure.
Ensure that stack is always clean when running thread hook.

Author: khvzak

src/state.rs

@@ -516,7 +516,7 @@ impl Lua {
         let lua = self.lock();
         unsafe {
             (*lua.extra.get()).hook_triggers = triggers;
-            (*lua.extra.get()).hook_callback = Some(Box::new(callback));
+            (*lua.extra.get()).hook_callback = Some(XRc::new(callback));
             lua.set_thread_hook(lua.state(), HookKind::Global)
         }
     }
@@ -564,7 +564,7 @@ impl Lua {
         F: Fn(&Lua, Debug) -> Result<VmState> + MaybeSend + 'static,
     {
         let lua = self.lock();
-        unsafe { lua.set_thread_hook(lua.state(), HookKind::Thread(triggers, Box::new(callback))) }
+        unsafe { lua.set_thread_hook(lua.state(), HookKind::Thread(triggers, XRc::new(callback))) }
     }
 
     /// Removes a global hook previously set by [`Lua::set_global_hook`].
@@ -644,8 +644,6 @@ impl Lua {
     where
         F: Fn(&Lua) -> Result<VmState> + MaybeSend + 'static,
     {
-        use std::rc::Rc;
-
         unsafe extern "C-unwind" fn interrupt_proc(state: *mut ffi::lua_State, gc: c_int) {
             if gc >= 0 {
                 // We don't support GC interrupts since they cannot survive Lua exceptions
@@ -654,7 +652,7 @@ impl Lua {
             let result = callback_error_ext(state, ptr::null_mut(), move |extra, _| {
                 let interrupt_cb = (*extra).interrupt_callback.clone();
                 let interrupt_cb = mlua_expect!(interrupt_cb, "no interrupt callback set in interrupt_proc");
-                if Rc::strong_count(&interrupt_cb) > 2 {
+                if XRc::strong_count(&interrupt_cb) > 2 {
                     return Ok(VmState::Continue); // Don't allow recursion
                 }
                 let _guard = StateGuard::new((*extra).raw_lua(), state);
@@ -671,7 +669,7 @@ impl Lua {
         // Set interrupt callback
         let lua = self.lock();
         unsafe {
-            (*lua.extra.get()).interrupt_callback = Some(Rc::new(callback));
+            (*lua.extra.get()).interrupt_callback = Some(XRc::new(callback));
             (*ffi::lua_callbacks(lua.main_state())).interrupt = Some(interrupt_proc);
         }
     }

src/state/raw.rs

@@ -410,15 +410,12 @@ impl RawLua {
 
         unsafe extern "C-unwind" fn global_hook_proc(state: *mut ffi::lua_State, ar: *mut ffi::lua_Debug) {
             let status = callback_error_ext(state, ptr::null_mut(), move |extra, _| {
-                let rawlua = (*extra).raw_lua();
-                let _guard = StateGuard::new(rawlua, state);
-                let debug = Debug::new(rawlua, ar);
-                match (*extra).hook_callback.take() {
-                    Some(hook_cb) => {
-                        // Temporary obtain ownership of the hook callback
-                        let result = hook_cb((*extra).lua(), debug);
-                        (*extra).hook_callback = Some(hook_cb);
-                        result
+                match (*extra).hook_callback.clone() {
+                    Some(hook_callback) => {
+                        let rawlua = (*extra).raw_lua();
+                        let _guard = StateGuard::new(rawlua, state);
+                        let debug = Debug::new(rawlua, ar);
+                        hook_callback((*extra).lua(), debug)
                     }
                     None => {
                         ffi::lua_sethook(state, None, 0, 0);
@@ -430,11 +427,17 @@ impl RawLua {
         }
 
         unsafe extern "C-unwind" fn hook_proc(state: *mut ffi::lua_State, ar: *mut ffi::lua_Debug) {
+            let top = ffi::lua_gettop(state);
+            let mut hook_callback_ptr = ptr::null();
             ffi::luaL_checkstack(state, 3, ptr::null());
-            ffi::lua_getfield(state, ffi::LUA_REGISTRYINDEX, HOOKS_KEY);
-            ffi::lua_pushthread(state);
-            if ffi::lua_rawget(state, -2) != ffi::LUA_TUSERDATA {
-                ffi::lua_pop(state, 2);
+            if ffi::lua_getfield(state, ffi::LUA_REGISTRYINDEX, HOOKS_KEY) == ffi::LUA_TTABLE {
+                ffi::lua_pushthread(state);
+                if ffi::lua_rawget(state, -2) == ffi::LUA_TUSERDATA {
+                    hook_callback_ptr = get_internal_userdata::<HookCallback>(state, -1, ptr::null());
+                }
+            }
+            ffi::lua_settop(state, top);
+            if hook_callback_ptr.is_null() {
                 ffi::lua_sethook(state, None, 0, 0);
                 return;
             }
@@ -443,13 +446,8 @@ impl RawLua {
                 let rawlua = (*extra).raw_lua();
                 let _guard = StateGuard::new(rawlua, state);
                 let debug = Debug::new(rawlua, ar);
-                match get_internal_userdata::<HookCallback>(state, -1, ptr::null()).as_ref() {
-                    Some(hook_cb) => hook_cb((*extra).lua(), debug),
-                    None => {
-                        ffi::lua_sethook(state, None, 0, 0);
-                        Ok(VmState::Continue)
-                    }
-                }
+                let hook_callback = (*hook_callback_ptr).clone();
+                hook_callback((*extra).lua(), debug)
             });
             process_status(state, (*ar).event, status)
         }
@@ -482,7 +480,6 @@ impl RawLua {
 
             ffi::lua_pushthread(thread_state);
             ffi::lua_xmove(thread_state, state, 1); // key (thread)
-            let callback: HookCallback = Box::new(callback);
             let _ = push_internal_userdata(state, callback, false); // value (hook callback)
             ffi::lua_rawset(state, -3); // hooktable[thread] = hook callback
         })?;

src/thread.rs

@@ -272,7 +272,12 @@ impl Thread {
         F: Fn(&crate::Lua, Debug) -> Result<crate::VmState> + crate::MaybeSend + 'static,
     {
         let lua = self.0.lua.lock();
-        unsafe { lua.set_thread_hook(self.state(), HookKind::Thread(triggers, Box::new(callback))) }
+        unsafe {
+            lua.set_thread_hook(
+                self.state(),
+                HookKind::Thread(triggers, crate::types::XRc::new(callback)),
+            )
+        }
     }
 
     /// Removes any hook function from this thread.

src/types.rs

@@ -79,16 +79,16 @@ pub(crate) enum HookKind {
 }
 
 #[cfg(all(feature = "send", not(feature = "luau")))]
-pub(crate) type HookCallback = Box<dyn Fn(&Lua, Debug) -> Result<VmState> + Send>;
+pub(crate) type HookCallback = XRc<dyn Fn(&Lua, Debug) -> Result<VmState> + Send>;
 
 #[cfg(all(not(feature = "send"), not(feature = "luau")))]
-pub(crate) type HookCallback = Box<dyn Fn(&Lua, Debug) -> Result<VmState>>;
+pub(crate) type HookCallback = XRc<dyn Fn(&Lua, Debug) -> Result<VmState>>;
 
 #[cfg(all(feature = "send", feature = "luau"))]
-pub(crate) type InterruptCallback = std::rc::Rc<dyn Fn(&Lua) -> Result<VmState> + Send>;
+pub(crate) type InterruptCallback = XRc<dyn Fn(&Lua) -> Result<VmState> + Send>;
 
 #[cfg(all(not(feature = "send"), feature = "luau"))]
-pub(crate) type InterruptCallback = std::rc::Rc<dyn Fn(&Lua) -> Result<VmState>>;
+pub(crate) type InterruptCallback = XRc<dyn Fn(&Lua) -> Result<VmState>>;
 
 #[cfg(all(feature = "send", feature = "lua54"))]
 pub(crate) type WarnCallback = Box<dyn Fn(&Lua, &str, bool) -> Result<()> + Send>;