Make LuaHook as Fn instead of FnMut to remove Mutex and improve performance

src/lua.rs

@@ -868,7 +868,7 @@ impl Lua {
     #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
     pub fn set_hook<F>(&self, triggers: HookTriggers, callback: F) -> Result<()>
     where
-        F: 'static + MaybeSend + FnMut(&Lua, Debug) -> Result<()>,
+        F: 'static + MaybeSend + Fn(&Lua, Debug) -> Result<()>,
     {
         unsafe extern "C" fn hook_proc(state: *mut ffi::lua_State, ar: *mut ffi::lua_Debug) {
             let lua = match Lua::make_from_ptr(state) {
@@ -880,29 +880,24 @@ impl Lua {
                 let debug = Debug::new(&lua, ar);
                 let hook_cb = (*lua.extra.get()).hook_callback.clone();
                 let hook_cb = mlua_expect!(hook_cb, "no hook callback set in hook_proc");
-
-                #[allow(clippy::match_wild_err_arm)]
-                match hook_cb.try_lock() {
-                    Ok(mut cb) => cb(&lua, debug),
-                    Err(_) => {
-                        mlua_panic!("Lua should not allow hooks to be called within another hook")
-                    }
-                }?;
-
-                Ok(())
+                if Arc::strong_count(&hook_cb) > 2 {
+                    return Ok(()); // Don't allow recursion
+                }
+                hook_cb(&lua, debug)
             })
         }
 
         let state = self.main_state.ok_or(Error::MainThreadNotAvailable)?;
         unsafe {
-            (*self.extra.get()).hook_callback = Some(Arc::new(Mutex::new(callback)));
+            (*self.extra.get()).hook_callback = Some(Arc::new(callback));
             ffi::lua_sethook(state, Some(hook_proc), triggers.mask(), triggers.count());
         }
         Ok(())
     }
 
-    /// Remove any hook previously set by `set_hook`. This function has no effect if a hook was not
-    /// previously set.
+    /// Removes any hook previously set by `set_hook`.
+    ///
+    /// This function has no effect if a hook was not previously set.
     #[cfg(not(feature = "luau"))]
     #[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
     pub fn remove_hook(&self) {

src/prelude.rs

@@ -15,6 +15,10 @@ pub use crate::{
     Value as LuaValue,
 };
 
+#[cfg(not(feature = "luau"))]
+#[doc(no_inline)]
+pub use crate::HookTriggers as LuaHookTriggers;
+
 #[cfg(feature = "luau")]
 #[doc(no_inline)]
 pub use crate::VmState as LuaVmState;

src/types.rs

@@ -49,13 +49,8 @@ pub(crate) struct AsyncPollUpvalue<'lua> {
     pub(crate) lua: Lua,
     pub(crate) fut: LocalBoxFuture<'lua, Result<MultiValue<'lua>>>,
 }
-#[cfg(all(feature = "send", not(feature = "luau")))]
-pub(crate) type HookCallback = Arc<Mutex<dyn FnMut(&Lua, Debug) -> Result<()> + Send>>;
 
-#[cfg(all(not(feature = "send"), not(feature = "luau")))]
-pub(crate) type HookCallback = Arc<Mutex<dyn FnMut(&Lua, Debug) -> Result<()>>>;
-
-/// Type to set next Lua VM action after executing interrupt function.
+/// Type to set next Luau VM action after executing interrupt function.
 #[cfg(any(feature = "luau", doc))]
 #[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
 pub enum VmState {
@@ -63,6 +58,12 @@ pub enum VmState {
     Yield,
 }
 
+#[cfg(all(feature = "send", not(feature = "luau")))]
+pub(crate) type HookCallback = Arc<dyn Fn(&Lua, Debug) -> Result<()> + Send>;
+
+#[cfg(all(not(feature = "send"), not(feature = "luau")))]
+pub(crate) type HookCallback = Arc<dyn Fn(&Lua, Debug) -> Result<()>>;
+
 #[cfg(all(feature = "luau", feature = "send"))]
 pub(crate) type InterruptCallback = Arc<dyn Fn(&Lua) -> Result<VmState> + Send>;
 

tests/hooks.rs

@@ -3,6 +3,7 @@
 use std::cell::RefCell;
 use std::ops::Deref;
 use std::str;
+use std::sync::atomic::{AtomicI64, Ordering};
 use std::sync::{Arc, Mutex};
 
 use mlua::{DebugEvent, Error, HookTriggers, Lua, Result, Value};
@@ -128,18 +129,17 @@ fn test_error_within_hook() -> Result<()> {
 #[test]
 fn test_limit_execution_instructions() -> Result<()> {
     let lua = Lua::new();
-    let mut max_instructions = 10000;
 
-    #[cfg(feature = "luajit")]
     // For LuaJIT disable JIT, as compiled code does not trigger hooks
+    #[cfg(feature = "luajit")]
     lua.load("jit.off()").exec()?;
 
+    let max_instructions = AtomicI64::new(10000);
     lua.set_hook(
         HookTriggers::every_nth_instruction(30),
         move |_lua, debug| {
             assert_eq!(debug.event(), DebugEvent::Count);
-            max_instructions -= 30;
-            if max_instructions < 0 {
+            if max_instructions.fetch_sub(30, Ordering::Relaxed) <= 30 {
                 Err(Error::RuntimeError("time's up".to_string()))
             } else {
                 Ok(())