mlua 0.11.6

High level bindings to Lua 5.5/5.4/5.3/5.2/5.1 (including LuaJIT) and Luau with async/await features and support of writing native Lua modules in Rust.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294

use std::any::TypeId;
use std::cell::UnsafeCell;
use std::mem::MaybeUninit;
use std::os::raw::{c_int, c_void};
use std::ptr;
use std::rc::Rc;
use std::sync::Arc;

use parking_lot::Mutex;
use rustc_hash::FxHashMap;

use crate::error::Result;
use crate::state::RawLua;
use crate::stdlib::StdLib;
use crate::types::{AppData, ReentrantMutex, XRc};
use crate::userdata::RawUserDataRegistry;
use crate::util::{get_internal_metatable, push_internal_userdata, TypeKey, WrappedFailure};

#[cfg(any(feature = "luau", doc))]
use crate::chunk::Compiler;

#[cfg(feature = "async")]
use {futures_util::task::noop_waker_ref, std::ptr::NonNull, std::task::Waker};

use super::{Lua, WeakLua};

// Unique key to store `ExtraData` in the registry
static EXTRA_REGISTRY_KEY: u8 = 0;

const WRAPPED_FAILURE_POOL_DEFAULT_CAPACITY: usize = 64;
const REF_STACK_RESERVE: c_int = 3;

/// Data associated with the Lua state.
pub(crate) struct ExtraData {
    pub(super) lua: MaybeUninit<Lua>,
    pub(super) weak: MaybeUninit<WeakLua>,
    pub(super) owned: bool,

    pub(super) pending_userdata_reg: FxHashMap<TypeId, RawUserDataRegistry>,
    pub(super) registered_userdata_t: FxHashMap<TypeId, c_int>,
    pub(super) registered_userdata_mt: FxHashMap<*const c_void, Option<TypeId>>,
    pub(super) last_checked_userdata_mt: (*const c_void, Option<TypeId>),

    // When Lua instance dropped, setting `None` would prevent collecting `RegistryKey`s
    pub(super) registry_unref_list: Arc<Mutex<Option<Vec<c_int>>>>,

    // Containers to store arbitrary data (extensions)
    pub(super) app_data: AppData,
    pub(super) app_data_priv: AppData,

    pub(super) safe: bool,
    pub(super) libs: StdLib,
    // Used in module mode
    pub(super) skip_memory_check: bool,

    // Auxiliary thread to store references
    pub(super) ref_thread: *mut ffi::lua_State,
    pub(super) ref_stack_size: c_int,
    pub(super) ref_stack_top: c_int,
    pub(super) ref_free: Vec<c_int>,

    // Pool of `WrappedFailure` enums in the ref thread (as userdata)
    pub(super) wrapped_failure_pool: Vec<c_int>,
    pub(super) wrapped_failure_top: usize,
    // Pool of `Thread`s (coroutines) for async execution
    #[cfg(feature = "async")]
    pub(super) thread_pool: Vec<crate::types::ValueRefIndex>,

    // Address of `WrappedFailure` metatable
    pub(super) wrapped_failure_mt_ptr: *const c_void,

    // Waker for polling futures
    #[cfg(feature = "async")]
    pub(super) waker: NonNull<Waker>,

    #[cfg(not(feature = "luau"))]
    pub(super) hook_callback: Option<crate::types::HookCallback>,
    #[cfg(not(feature = "luau"))]
    pub(super) hook_triggers: crate::debug::HookTriggers,
    #[cfg(any(feature = "lua55", feature = "lua54"))]
    pub(super) warn_callback: Option<crate::types::WarnCallback>,
    #[cfg(feature = "luau")]
    pub(super) interrupt_callback: Option<crate::types::InterruptCallback>,
    #[cfg(feature = "luau")]
    pub(super) thread_creation_callback: Option<crate::types::ThreadCreationCallback>,
    #[cfg(feature = "luau")]
    pub(super) thread_collection_callback: Option<crate::types::ThreadCollectionCallback>,

    #[cfg(feature = "luau")]
    pub(crate) running_gc: bool,
    #[cfg(feature = "luau")]
    pub(crate) sandboxed: bool,
    #[cfg(feature = "luau")]
    pub(super) compiler: Option<Compiler>,
    #[cfg(feature = "luau-jit")]
    pub(super) enable_jit: bool,
    #[cfg(feature = "luau")]
    pub(crate) mem_categories: Vec<std::ffi::CString>,
}

impl Drop for ExtraData {
    fn drop(&mut self) {
        unsafe {
            if !self.owned {
                self.lua.assume_init_drop();
            }

            self.weak.assume_init_drop();
        }
        *self.registry_unref_list.lock() = None;
    }
}

static EXTRA_TYPE_KEY: u8 = 0;

impl TypeKey for XRc<UnsafeCell<ExtraData>> {
    #[inline(always)]
    fn type_key() -> *const c_void {
        &EXTRA_TYPE_KEY as *const u8 as *const c_void
    }
}

impl ExtraData {
    // Index of `error_traceback` function in auxiliary thread stack
    #[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, owned: bool) -> 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!(
            protect_lua!(state, 0, 0, |state| {
                let thread = ffi::lua_newthread(state);
                ffi::luaL_ref(state, ffi::LUA_REGISTRYINDEX);
                thread
            }),
            "Error while creating ref thread",
        );

        let wrapped_failure_mt_ptr = {
            get_internal_metatable::<WrappedFailure>(state);
            let ptr = ffi::lua_topointer(state, -1);
            ffi::lua_pop(state, 1);
            ptr
        };

        // Store `error_traceback` function on the ref stack
        #[cfg(any(feature = "lua51", feature = "luajit", feature = "luau"))]
        {
            ffi::lua_pushcfunction(ref_thread, crate::util::error_traceback);
            assert_eq!(ffi::lua_gettop(ref_thread), Self::ERROR_TRACEBACK_IDX);
        }

        #[allow(clippy::arc_with_non_send_sync)]
        let extra = XRc::new(UnsafeCell::new(ExtraData {
            lua: MaybeUninit::uninit(),
            weak: MaybeUninit::uninit(),
            owned,
            pending_userdata_reg: FxHashMap::default(),
            registered_userdata_t: FxHashMap::default(),
            registered_userdata_mt: FxHashMap::default(),
            last_checked_userdata_mt: (ptr::null(), None),
            registry_unref_list: Arc::new(Mutex::new(Some(Vec::new()))),
            app_data: AppData::default(),
            app_data_priv: AppData::default(),
            safe: false,
            libs: StdLib::NONE,
            skip_memory_check: false,
            ref_thread,
            // We need some reserved stack space to move values in and out of the ref stack.
            ref_stack_size: ffi::LUA_MINSTACK - REF_STACK_RESERVE,
            ref_stack_top: ffi::lua_gettop(ref_thread),
            ref_free: Vec::new(),
            wrapped_failure_pool: Vec::with_capacity(WRAPPED_FAILURE_POOL_DEFAULT_CAPACITY),
            wrapped_failure_top: 0,
            #[cfg(feature = "async")]
            thread_pool: Vec::new(),
            wrapped_failure_mt_ptr,
            #[cfg(feature = "async")]
            waker: NonNull::from(noop_waker_ref()),
            #[cfg(not(feature = "luau"))]
            hook_callback: None,
            #[cfg(not(feature = "luau"))]
            hook_triggers: Default::default(),
            #[cfg(any(feature = "lua55", feature = "lua54"))]
            warn_callback: None,
            #[cfg(feature = "luau")]
            interrupt_callback: None,
            #[cfg(feature = "luau")]
            thread_creation_callback: None,
            #[cfg(feature = "luau")]
            thread_collection_callback: None,
            #[cfg(feature = "luau")]
            sandboxed: false,
            #[cfg(feature = "luau")]
            compiler: None,
            #[cfg(feature = "luau-jit")]
            enable_jit: true,
            #[cfg(feature = "luau")]
            running_gc: false,
            #[cfg(feature = "luau")]
            mem_categories: vec![std::ffi::CString::new("main").unwrap()],
        }));

        // Store it in the registry
        mlua_expect!(Self::store(&extra, state), "Error while storing extra data");

        extra
    }

    pub(super) unsafe fn set_lua(&mut self, raw: &XRc<ReentrantMutex<RawLua>>) {
        self.lua.write(Lua {
            raw: XRc::clone(raw),
            collect_garbage: false,
        });
        self.weak.write(WeakLua(XRc::downgrade(raw)));
    }

    pub(crate) unsafe fn get(state: *mut ffi::lua_State) -> *mut Self {
        #[cfg(feature = "luau")]
        if cfg!(not(feature = "module")) {
            // In the main app we can use `lua_callbacks` to access ExtraData
            return (*ffi::lua_callbacks(state)).userdata as *mut _;
        }

        let extra_key = &EXTRA_REGISTRY_KEY as *const u8 as *const c_void;
        if ffi::lua_rawgetp(state, ffi::LUA_REGISTRYINDEX, extra_key) != ffi::LUA_TUSERDATA {
            // `ExtraData` can be null only when Lua state is foreign.
            // This case in used in `Lua::try_from_ptr()`.
            ffi::lua_pop(state, 1);
            return ptr::null_mut();
        }
        let extra_ptr = ffi::lua_touserdata(state, -1) as *mut Rc<UnsafeCell<ExtraData>>;
        ffi::lua_pop(state, 1);
        (*extra_ptr).get()
    }

    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_internal_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);
        })
    }

    #[inline(always)]
    pub(super) unsafe fn lua(&self) -> &Lua {
        self.lua.assume_init_ref()
    }

    #[inline(always)]
    pub(crate) unsafe fn raw_lua(&self) -> &RawLua {
        &*self.lua.assume_init_ref().raw.data_ptr()
    }

    #[inline(always)]
    pub(super) unsafe fn weak(&self) -> &WeakLua {
        self.weak.assume_init_ref()
    }

    /// Pops a reference from top of the auxiliary stack and move it to a first free slot.
    pub(super) unsafe fn ref_stack_pop(&mut self) -> c_int {
        if let Some(free) = self.ref_free.pop() {
            ffi::lua_replace(self.ref_thread, free);
            return free;
        }

        // Try to grow max stack size
        if self.ref_stack_top >= self.ref_stack_size {
            let mut inc = self.ref_stack_size; // Try to double stack size
            while inc > 0 && ffi::lua_checkstack(self.ref_thread, inc + REF_STACK_RESERVE) == 0 {
                inc /= 2;
            }
            if inc == 0 {
                // Pop item on top of the stack to avoid stack leaking and successfully run destructors
                // during unwinding.
                ffi::lua_pop(self.ref_thread, 1);
                let top = self.ref_stack_top;
                // It is a user error to create too many references to exhaust the Lua max stack size
                // for the ref thread.
                panic!("cannot create a Lua reference, out of auxiliary stack space (used {top} slots)");
            }
            self.ref_stack_size += inc;
        }
        self.ref_stack_top += 1;
        self.ref_stack_top
    }
}