Support multi threads under send feature flag

Author: khvzak

src/function.rs

@@ -594,9 +594,12 @@ impl IntoLua for WrappedAsyncFunction {
     }
 }
 
-// #[cfg(test)]
-// mod assertions {
-//     use super::*;
-
-//     static_assertions::assert_not_impl_any!(Function: Send);
-// }
+#[cfg(test)]
+mod assertions {
+    use super::*;
+
+    #[cfg(not(feature = "send"))]
+    static_assertions::assert_not_impl_any!(Function: Send);
+    #[cfg(feature = "send")]
+    static_assertions::assert_impl_all!(Function: Send, Sync);
+}

src/hook.rs

@@ -6,9 +6,9 @@ use std::ops::{BitOr, BitOrAssign};
 use std::os::raw::c_int;
 
 use ffi::lua_Debug;
-use parking_lot::ReentrantMutexGuard;
 
 use crate::state::RawLua;
+use crate::types::ReentrantMutexGuard;
 use crate::util::{linenumber_to_usize, ptr_to_lossy_str, ptr_to_str};
 
 /// Contains information about currently executing Lua code.

src/state.rs

@@ -6,12 +6,10 @@ use std::marker::PhantomData;
 use std::ops::Deref;
 use std::os::raw::{c_int, c_void};
 use std::panic::Location;
+use std::rc::Rc;
 use std::result::Result as StdResult;
-use std::sync::{Arc, Weak};
 use std::{mem, ptr};
 
-use parking_lot::{ReentrantMutex, ReentrantMutexGuard};
-
 use crate::chunk::{AsChunk, Chunk};
 use crate::error::{Error, Result};
 use crate::function::Function;
@@ -24,7 +22,7 @@ use crate::table::Table;
 use crate::thread::Thread;
 use crate::types::{
     AppDataRef, AppDataRefMut, ArcReentrantMutexGuard, Integer, LightUserData, MaybeSend, Number,
-    RegistryKey,
+    ReentrantMutex, ReentrantMutexGuard, RegistryKey, XRc, XWeak,
 };
 use crate::userdata::{AnyUserData, UserData, UserDataProxy, UserDataRegistry, UserDataVariant};
 use crate::util::{assert_stack, check_stack, push_string, push_table, rawset_field, StackGuard};
@@ -49,11 +47,11 @@ use util::{callback_error_ext, StateGuard};
 /// Top level Lua struct which represents an instance of Lua VM.
 #[derive(Clone)]
 #[repr(transparent)]
-pub struct Lua(Arc<ReentrantMutex<RawLua>>);
+pub struct Lua(XRc<ReentrantMutex<RawLua>>);
 
 #[derive(Clone)]
 #[repr(transparent)]
-pub(crate) struct WeakLua(Weak<ReentrantMutex<RawLua>>);
+pub(crate) struct WeakLua(XWeak<ReentrantMutex<RawLua>>);
 
 pub(crate) struct LuaGuard(ArcReentrantMutexGuard<RawLua>);
 
@@ -142,11 +140,6 @@ impl LuaOptions {
     }
 }
 
-/// Requires `feature = "send"`
-#[cfg(feature = "send")]
-#[cfg_attr(docsrs, doc(cfg(feature = "send")))]
-unsafe impl Send for Lua {}
-
 #[cfg(not(feature = "module"))]
 impl Drop for Lua {
     fn drop(&mut self) {
@@ -421,7 +414,8 @@ impl Lua {
     #[doc(hidden)]
     #[cfg(feature = "module")]
     pub fn skip_memory_check(&self, skip: bool) {
-        unsafe { (*self.extra.get()).skip_memory_check = skip };
+        let lua = self.lock();
+        unsafe { (*lua.extra.get()).skip_memory_check = skip };
     }
 
     /// Enables (or disables) sandbox mode on this Lua instance.
@@ -605,7 +599,7 @@ impl Lua {
                 let interrupt_cb = (*extra).interrupt_callback.clone();
                 let interrupt_cb =
                     mlua_expect!(interrupt_cb, "no interrupt callback set in interrupt_proc");
-                if Arc::strong_count(&interrupt_cb) > 2 {
+                if Rc::strong_count(&interrupt_cb) > 2 {
                     return Ok(VmState::Continue); // Don't allow recursion
                 }
                 let _guard = StateGuard::new((*extra).raw_lua(), state);
@@ -622,7 +616,7 @@ impl Lua {
         // Set interrupt callback
         let lua = self.lock();
         unsafe {
-            (*lua.extra.get()).interrupt_callback = Some(Arc::new(callback));
+            (*lua.extra.get()).interrupt_callback = Some(Rc::new(callback));
             (*ffi::lua_callbacks(lua.main_state)).interrupt = Some(interrupt_proc);
         }
     }
@@ -947,7 +941,8 @@ impl Lua {
     #[cfg(any(feature = "luau-jit", doc))]
     #[cfg_attr(docsrs, doc(cfg(feature = "luau-jit")))]
     pub fn enable_jit(&self, enable: bool) {
-        unsafe { (*self.extra.get()).enable_jit = enable };
+        let lua = self.lock();
+        unsafe { (*lua.extra.get()).enable_jit = enable };
     }
 
     /// Sets Luau feature flag (global setting).
@@ -1879,15 +1874,15 @@ impl Lua {
 
     #[inline(always)]
     pub(crate) fn weak(&self) -> WeakLua {
-        WeakLua(Arc::downgrade(&self.0))
+        WeakLua(XRc::downgrade(&self.0))
     }
 }
 
 impl WeakLua {
     #[track_caller]
     #[inline(always)]
     pub(crate) fn lock(&self) -> LuaGuard {
-        LuaGuard::new(self.0.upgrade().unwrap())
+        LuaGuard::new(self.0.upgrade().expect("Lua instance is destroyed"))
     }
 
     #[inline(always)]
@@ -1898,15 +1893,21 @@ impl WeakLua {
 
 impl PartialEq for WeakLua {
     fn eq(&self, other: &Self) -> bool {
-        Weak::ptr_eq(&self.0, &other.0)
+        XWeak::ptr_eq(&self.0, &other.0)
     }
 }
 
 impl Eq for WeakLua {}
 
 impl LuaGuard {
-    pub(crate) fn new(handle: Arc<ReentrantMutex<RawLua>>) -> Self {
-        Self(handle.lock_arc())
+    #[cfg(feature = "send")]
+    pub(crate) fn new(handle: XRc<ReentrantMutex<RawLua>>) -> Self {
+        LuaGuard(handle.lock_arc())
+    }
+
+    #[cfg(not(feature = "send"))]
+    pub(crate) fn new(handle: XRc<ReentrantMutex<RawLua>>) -> Self {
+        LuaGuard(handle.into_lock_arc())
     }
 }
 
@@ -1922,15 +1923,15 @@ pub(crate) mod extra;
 mod raw;
 pub(crate) mod util;
 
-// #[cfg(test)]
-// mod assertions {
-//     use super::*;
+#[cfg(test)]
+mod assertions {
+    use super::*;
 
-//     // Lua has lots of interior mutability, should not be RefUnwindSafe
-//     static_assertions::assert_not_impl_any!(Lua: std::panic::RefUnwindSafe);
+    // Lua has lots of interior mutability, should not be RefUnwindSafe
+    static_assertions::assert_not_impl_any!(Lua: std::panic::RefUnwindSafe);
 
-//     #[cfg(not(feature = "send"))]
-//     static_assertions::assert_not_impl_any!(Lua: Send);
-//     #[cfg(feature = "send")]
-//     static_assertions::assert_impl_all!(Lua: Send);
-// }
+    #[cfg(not(feature = "send"))]
+    static_assertions::assert_not_impl_any!(Lua: Send);
+    #[cfg(feature = "send")]
+    static_assertions::assert_impl_all!(Lua: Send, Sync);
+}

src/state/extra.rs

@@ -5,15 +5,15 @@ use std::rc::Rc;
 use std::mem::{self, MaybeUninit};
 use std::os::raw::{c_int, c_void};
 use std::ptr;
-use std::sync::{Arc, Weak};
+use std::sync::Arc;
 
-use parking_lot::{Mutex, ReentrantMutex};
+use parking_lot::Mutex;
 use rustc_hash::FxHashMap;
 
 use crate::error::Result;
 use crate::state::RawLua;
 use crate::stdlib::StdLib;
-use crate::types::AppData;
+use crate::types::{AppData, ReentrantMutex, XRc, XWeak};
 use crate::util::{get_gc_metatable, push_gc_userdata, WrappedFailure};
 
 #[cfg(any(feature = "luau", doc))]
@@ -34,9 +34,9 @@ const REF_STACK_RESERVE: c_int = 1;
 /// Data associated with the Lua state.
 pub(crate) struct ExtraData {
     // Same layout as `Lua`
-    pub(super) lua: MaybeUninit<Arc<ReentrantMutex<RawLua>>>,
+    pub(super) lua: MaybeUninit<XRc<ReentrantMutex<RawLua>>>,
     // Same layout as `WeakLua`
-    pub(super) weak: MaybeUninit<Weak<ReentrantMutex<RawLua>>>,
+    pub(super) weak: MaybeUninit<XWeak<ReentrantMutex<RawLua>>>,
 
     pub(super) registered_userdata: FxHashMap<TypeId, c_int>,
     pub(super) registered_userdata_mt: FxHashMap<*const c_void, Option<TypeId>>,
@@ -107,7 +107,7 @@ impl ExtraData {
     #[cfg(any(feature = "lua51", feature = "luajit", feature = "luau"))]
     pub(super) const ERROR_TRACEBACK_IDX: c_int = 1;
 
-    pub(super) unsafe fn init(state: *mut ffi::lua_State) -> Rc<UnsafeCell<Self>> {
+    pub(super) unsafe fn init(state: *mut ffi::lua_State) -> XRc<UnsafeCell<Self>> {
         // Create ref stack thread and place it in the registry to prevent it
         // from being garbage collected.
         let ref_thread = mlua_expect!(
@@ -133,7 +133,7 @@ impl ExtraData {
             assert_eq!(ffi::lua_gettop(ref_thread), Self::ERROR_TRACEBACK_IDX);
         }
 
-        let extra = Rc::new(UnsafeCell::new(ExtraData {
+        let extra = XRc::new(UnsafeCell::new(ExtraData {
             lua: MaybeUninit::uninit(),
             weak: MaybeUninit::uninit(),
             registered_userdata: FxHashMap::default(),
@@ -179,12 +179,12 @@ impl ExtraData {
         extra
     }
 
-    pub(super) unsafe fn set_lua(&mut self, lua: &Arc<ReentrantMutex<RawLua>>) {
-        self.lua.write(Arc::clone(lua));
+    pub(super) unsafe fn set_lua(&mut self, lua: &XRc<ReentrantMutex<RawLua>>) {
+        self.lua.write(XRc::clone(lua));
         if cfg!(not(feature = "module")) {
-            Arc::decrement_strong_count(Arc::as_ptr(lua));
+            XRc::decrement_strong_count(XRc::as_ptr(lua));
         }
-        self.weak.write(Arc::downgrade(lua));
+        self.weak.write(XRc::downgrade(lua));
     }
 
     pub(super) unsafe fn get(state: *mut ffi::lua_State) -> *mut Self {
@@ -206,14 +206,14 @@ impl ExtraData {
         (*extra_ptr).get()
     }
 
-    unsafe fn store(extra: &Rc<UnsafeCell<Self>>, state: *mut ffi::lua_State) -> Result<()> {
+    unsafe fn store(extra: &XRc<UnsafeCell<Self>>, state: *mut ffi::lua_State) -> Result<()> {
         #[cfg(feature = "luau")]
         if cfg!(not(feature = "module")) {
             (*ffi::lua_callbacks(state)).userdata = extra.get() as *mut _;
             return Ok(());
         }
 
-        push_gc_userdata(state, Rc::clone(extra), true)?;
+        push_gc_userdata(state, XRc::clone(extra), true)?;
         protect_lua!(state, 1, 0, fn(state) {
             let extra_key = &EXTRA_REGISTRY_KEY as *const u8 as *const c_void;
             ffi::lua_rawsetp(state, ffi::LUA_REGISTRYINDEX, extra_key);

src/state/raw.rs

@@ -8,8 +8,6 @@ use std::result::Result as StdResult;
 use std::sync::Arc;
 use std::{mem, ptr};
 
-use parking_lot::ReentrantMutex;
-
 use crate::chunk::ChunkMode;
 use crate::error::{Error, Result};
 use crate::function::Function;
@@ -21,7 +19,7 @@ use crate::table::Table;
 use crate::thread::Thread;
 use crate::types::{
     AppDataRef, AppDataRefMut, Callback, CallbackUpvalue, DestructedUserdata, Integer,
-    LightUserData, MaybeSend, RegistryKey, SubtypeId, ValueRef,
+    LightUserData, MaybeSend, ReentrantMutex, RegistryKey, SubtypeId, ValueRef, XRc,
 };
 use crate::userdata::{AnyUserData, MetaMethod, UserData, UserDataRegistry, UserDataVariant};
 use crate::util::{
@@ -50,7 +48,7 @@ pub struct RawLua {
     // The state is dynamic and depends on context
     pub(super) state: Cell<*mut ffi::lua_State>,
     pub(super) main_state: *mut ffi::lua_State,
-    pub(super) extra: Rc<UnsafeCell<ExtraData>>,
+    pub(super) extra: XRc<UnsafeCell<ExtraData>>,
 }
 
 #[cfg(not(feature = "module"))]
@@ -69,6 +67,9 @@ impl Drop for RawLua {
     }
 }
 
+#[cfg(feature = "send")]
+unsafe impl Send for RawLua {}
+
 impl RawLua {
     #[inline(always)]
     pub(crate) fn lua(&self) -> &Lua {
@@ -96,7 +97,7 @@ impl RawLua {
         unsafe { (*self.extra.get()).ref_thread }
     }
 
-    pub(super) unsafe fn new(libs: StdLib, options: LuaOptions) -> Arc<ReentrantMutex<Self>> {
+    pub(super) unsafe fn new(libs: StdLib, options: LuaOptions) -> XRc<ReentrantMutex<Self>> {
         let mem_state: *mut MemoryState = Box::into_raw(Box::default());
         let mut state = ffi::lua_newstate(ALLOCATOR, mem_state as *mut c_void);
         // If state is null then switch to Lua internal allocator
@@ -154,7 +155,7 @@ impl RawLua {
         rawlua
     }
 
-    pub(super) unsafe fn init_from_ptr(state: *mut ffi::lua_State) -> Arc<ReentrantMutex<Self>> {
+    pub(super) unsafe fn init_from_ptr(state: *mut ffi::lua_State) -> XRc<ReentrantMutex<Self>> {
         assert!(!state.is_null(), "Lua state is NULL");
         if let Some(lua) = Self::try_from_ptr(state) {
             return lua;
@@ -209,10 +210,10 @@ impl RawLua {
         assert_stack(main_state, ffi::LUA_MINSTACK);
 
         #[allow(clippy::arc_with_non_send_sync)]
-        let rawlua = Arc::new(ReentrantMutex::new(RawLua {
+        let rawlua = XRc::new(ReentrantMutex::new(RawLua {
             state: Cell::new(state),
             main_state,
-            extra: Rc::clone(&extra),
+            extra: XRc::clone(&extra),
         }));
         (*extra.get()).set_lua(&rawlua);
 
@@ -221,10 +222,10 @@ impl RawLua {
 
     pub(super) unsafe fn try_from_ptr(
         state: *mut ffi::lua_State,
-    ) -> Option<Arc<ReentrantMutex<Self>>> {
+    ) -> Option<XRc<ReentrantMutex<Self>>> {
         match ExtraData::get(state) {
             extra if extra.is_null() => None,
-            extra => Some(Arc::clone(&(*extra).lua().0)),
+            extra => Some(XRc::clone(&(*extra).lua().0)),
         }
     }
 
@@ -369,7 +370,7 @@ impl RawLua {
             callback_error_ext(state, extra, move |_| {
                 let hook_cb = (*extra).hook_callback.clone();
                 let hook_cb = mlua_expect!(hook_cb, "no hook callback set in hook_proc");
-                if Arc::strong_count(&hook_cb) > 2 {
+                if Rc::strong_count(&hook_cb) > 2 {
                     return Ok(()); // Don't allow recursion
                 }
                 let rawlua = (*extra).raw_lua();
@@ -379,7 +380,7 @@ impl RawLua {
             })
         }
 
-        (*self.extra.get()).hook_callback = Some(Arc::new(callback));
+        (*self.extra.get()).hook_callback = Some(Rc::new(callback));
         (*self.extra.get()).hook_thread = state; // Mark for what thread the hook is set
         ffi::lua_sethook(state, Some(hook_proc), triggers.mask(), triggers.count());
     }
@@ -1105,7 +1106,7 @@ impl RawLua {
             check_stack(state, 4)?;
 
             let func = mem::transmute::<Callback, Callback<'static>>(func);
-            let extra = Rc::clone(&self.extra);
+            let extra = XRc::clone(&self.extra);
             let protect = !self.unlikely_memory_error();
             push_gc_userdata(state, CallbackUpvalue { data: func, extra }, protect)?;
             if protect {
@@ -1149,7 +1150,7 @@ impl RawLua {
                 let args = MultiValue::from_stack_multi(nargs, rawlua)?;
                 let func = &*(*upvalue).data;
                 let fut = func(rawlua, args);
-                let extra = Rc::clone(&(*upvalue).extra);
+                let extra = XRc::clone(&(*upvalue).extra);
                 let protect = !rawlua.unlikely_memory_error();
                 push_gc_userdata(state, AsyncPollUpvalue { data: fut, extra }, protect)?;
                 if protect {
@@ -1209,7 +1210,7 @@ impl RawLua {
             check_stack(state, 4)?;
 
             let func = mem::transmute::<AsyncCallback, AsyncCallback<'static>>(func);
-            let extra = Rc::clone(&self.extra);
+            let extra = XRc::clone(&self.extra);
             let protect = !self.unlikely_memory_error();
             let upvalue = AsyncCallbackUpvalue { data: func, extra };
             push_gc_userdata(state, upvalue, protect)?;