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use std::os::raw::{c_int, c_void};
use crate::error::{Error, Result};
#[allow(unused)]
use crate::lua::Lua;
use crate::types::LuaRef;
use crate::util::{check_stack, error_traceback_thread, pop_error, StackGuard};
use crate::value::{FromLuaMulti, IntoLuaMulti};
#[cfg(not(feature = "luau"))]
use crate::{
hook::{Debug, HookTriggers},
types::MaybeSend,
};
#[cfg(feature = "async")]
use {
crate::value::MultiValue,
futures_util::stream::Stream,
std::{
future::Future,
marker::PhantomData,
pin::Pin,
ptr::NonNull,
task::{Context, Poll, Waker},
},
};
/// Status of a Lua thread (coroutine).
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum ThreadStatus {
/// The thread was just created, or is suspended because it has called `coroutine.yield`.
///
/// If a thread is in this state, it can be resumed by calling [`Thread::resume`].
///
/// [`Thread::resume`]: crate::Thread::resume
Resumable,
/// Either the thread has finished executing, or the thread is currently running.
Unresumable,
/// The thread has raised a Lua error during execution.
Error,
}
/// Handle to an internal Lua thread (coroutine).
#[derive(Clone, Debug)]
pub struct Thread<'lua>(pub(crate) LuaRef<'lua>, pub(crate) *mut ffi::lua_State);
/// Owned handle to an internal Lua thread (coroutine).
///
/// The owned handle holds a *strong* reference to the current Lua instance.
/// Be warned, if you place it into a Lua type (eg. [`UserData`] or a Rust callback), it is *very easy*
/// to accidentally cause reference cycles that would prevent destroying Lua instance.
///
/// [`UserData`]: crate::UserData
#[cfg(feature = "unstable")]
#[cfg_attr(docsrs, doc(cfg(feature = "unstable")))]
#[derive(Clone, Debug)]
pub struct OwnedThread(
pub(crate) crate::types::LuaOwnedRef,
pub(crate) *mut ffi::lua_State,
);
#[cfg(feature = "unstable")]
impl OwnedThread {
/// Get borrowed handle to the underlying Lua table.
#[cfg_attr(feature = "send", allow(unused))]
pub const fn to_ref(&self) -> Thread {
Thread(self.0.to_ref(), self.1)
}
}
/// Thread (coroutine) representation as an async [`Future`] or [`Stream`].
///
/// Requires `feature = "async"`
///
/// [`Future`]: std::future::Future
/// [`Stream`]: futures_util::stream::Stream
#[cfg(feature = "async")]
#[cfg_attr(docsrs, doc(cfg(feature = "async")))]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct AsyncThread<'lua, R> {
thread: Thread<'lua>,
init_args: Option<Result<MultiValue<'lua>>>,
ret: PhantomData<R>,
recycle: bool,
}
impl<'lua> Thread<'lua> {
#[inline(always)]
pub(crate) fn new(r#ref: LuaRef<'lua>) -> Self {
let state = unsafe { ffi::lua_tothread(r#ref.lua.ref_thread(), r#ref.index) };
Thread(r#ref, state)
}
const fn state(&self) -> *mut ffi::lua_State {
self.1
}
/// Resumes execution of this thread.
///
/// Equivalent to `coroutine.resume`.
///
/// Passes `args` as arguments to the thread. If the coroutine has called `coroutine.yield`, it
/// will return these arguments. Otherwise, the coroutine wasn't yet started, so the arguments
/// are passed to its main function.
///
/// If the thread is no longer in `Active` state (meaning it has finished execution or
/// encountered an error), this will return `Err(CoroutineInactive)`, otherwise will return `Ok`
/// as follows:
///
/// If the thread calls `coroutine.yield`, returns the values passed to `yield`. If the thread
/// `return`s values from its main function, returns those.
///
/// # Examples
///
/// ```
/// # use mlua::{Error, Lua, Result, Thread};
/// # fn main() -> Result<()> {
/// # let lua = Lua::new();
/// let thread: Thread = lua.load(r#"
/// coroutine.create(function(arg)
/// assert(arg == 42)
/// local yieldarg = coroutine.yield(123)
/// assert(yieldarg == 43)
/// return 987
/// end)
/// "#).eval()?;
///
/// assert_eq!(thread.resume::<_, u32>(42)?, 123);
/// assert_eq!(thread.resume::<_, u32>(43)?, 987);
///
/// // The coroutine has now returned, so `resume` will fail
/// match thread.resume::<_, u32>(()) {
/// Err(Error::CoroutineInactive) => {},
/// unexpected => panic!("unexpected result {:?}", unexpected),
/// }
/// # Ok(())
/// # }
/// ```
pub fn resume<A, R>(&self, args: A) -> Result<R>
where
A: IntoLuaMulti<'lua>,
R: FromLuaMulti<'lua>,
{
let lua = self.0.lua;
let state = lua.state();
let thread_state = self.state();
unsafe {
let _sg = StackGuard::new(state);
let _thread_sg = StackGuard::with_top(thread_state, 0);
let nresults = self.resume_inner(args)?;
check_stack(state, nresults + 1)?;
ffi::lua_xmove(thread_state, state, nresults);
R::from_stack_multi(nresults, lua)
}
}
/// Resumes execution of this thread.
///
/// It's similar to `resume()` but leaves `nresults` values on the thread stack.
unsafe fn resume_inner<A: IntoLuaMulti<'lua>>(&self, args: A) -> Result<c_int> {
let lua = self.0.lua;
let state = lua.state();
let thread_state = self.state();
if self.status() != ThreadStatus::Resumable {
return Err(Error::CoroutineInactive);
}
let nargs = args.push_into_stack_multi(lua)?;
if nargs > 0 {
check_stack(thread_state, nargs)?;
ffi::lua_xmove(state, thread_state, nargs);
}
let mut nresults = 0;
let ret = ffi::lua_resume(thread_state, state, nargs, &mut nresults as *mut c_int);
if ret != ffi::LUA_OK && ret != ffi::LUA_YIELD {
if ret == ffi::LUA_ERRMEM {
// Don't call error handler for memory errors
return Err(pop_error(thread_state, ret));
}
check_stack(state, 3)?;
protect_lua!(state, 0, 1, |state| error_traceback_thread(
state,
thread_state
))?;
return Err(pop_error(state, ret));
}
Ok(nresults)
}
/// Gets the status of the thread.
pub fn status(&self) -> ThreadStatus {
let thread_state = self.state();
unsafe {
let status = ffi::lua_status(thread_state);
if status != ffi::LUA_OK && status != ffi::LUA_YIELD {
ThreadStatus::Error
} else if status == ffi::LUA_YIELD || ffi::lua_gettop(thread_state) > 0 {
ThreadStatus::Resumable
} else {
ThreadStatus::Unresumable
}
}
}
/// Sets a 'hook' function that will periodically be called as Lua code executes.
///
/// This function is similar or [`Lua::set_hook()`] except that it sets for the thread.
/// To remove a hook call [`Lua::remove_hook()`].
#[cfg(not(feature = "luau"))]
#[cfg_attr(docsrs, doc(cfg(not(feature = "luau"))))]
pub fn set_hook<F>(&self, triggers: HookTriggers, callback: F)
where
F: Fn(&Lua, Debug) -> Result<()> + MaybeSend + 'static,
{
let lua = self.0.lua;
unsafe {
lua.set_thread_hook(self.state(), triggers, callback);
}
}
/// Resets a thread
///
/// In [Lua 5.4]: cleans its call stack and closes all pending to-be-closed variables.
/// Returns a error in case of either the original error that stopped the thread or errors
/// in closing methods.
///
/// In Luau: resets to the initial state of a newly created Lua thread.
/// Lua threads in arbitrary states (like yielded or errored) can be reset properly.
///
/// Sets a Lua function for the thread afterwards.
///
/// Requires `feature = "lua54"` OR `feature = "luau"`.
///
/// [Lua 5.4]: https://www.lua.org/manual/5.4/manual.html#lua_closethread
#[cfg(any(feature = "lua54", feature = "luau"))]
#[cfg_attr(docsrs, doc(cfg(any(feature = "lua54", feature = "luau"))))]
pub fn reset(&self, func: crate::function::Function<'lua>) -> Result<()> {
let lua = self.0.lua;
let thread_state = self.state();
unsafe {
#[cfg(all(feature = "lua54", not(feature = "vendored")))]
let status = ffi::lua_resetthread(thread_state);
#[cfg(all(feature = "lua54", feature = "vendored"))]
let status = ffi::lua_closethread(thread_state, lua.state());
#[cfg(feature = "lua54")]
if status != ffi::LUA_OK {
return Err(pop_error(thread_state, status));
}
#[cfg(feature = "luau")]
ffi::lua_resetthread(thread_state);
// Push function to the top of the thread stack
ffi::lua_xpush(lua.ref_thread(), thread_state, func.0.index);
#[cfg(feature = "luau")]
{
// Inherit `LUA_GLOBALSINDEX` from the main thread
ffi::lua_xpush(lua.main_state(), thread_state, ffi::LUA_GLOBALSINDEX);
ffi::lua_replace(thread_state, ffi::LUA_GLOBALSINDEX);
}
Ok(())
}
}
/// Converts Thread to an AsyncThread which implements [`Future`] and [`Stream`] traits.
///
/// `args` are passed as arguments to the thread function for first call.
/// The object calls [`resume()`] while polling and also allows to run rust futures
/// to completion using an executor.
///
/// Using AsyncThread as a Stream allows to iterate through `coroutine.yield()`
/// values whereas Future version discards that values and poll until the final
/// one (returned from the thread function).
///
/// Requires `feature = "async"`
///
/// [`Future`]: std::future::Future
/// [`Stream`]: futures_util::stream::Stream
/// [`resume()`]: https://www.lua.org/manual/5.4/manual.html#lua_resume
///
/// # Examples
///
/// ```
/// # use mlua::{Lua, Result, Thread};
/// use futures::stream::TryStreamExt;
/// # #[tokio::main]
/// # async fn main() -> Result<()> {
/// # let lua = Lua::new();
/// let thread: Thread = lua.load(r#"
/// coroutine.create(function (sum)
/// for i = 1,10 do
/// sum = sum + i
/// coroutine.yield(sum)
/// end
/// return sum
/// end)
/// "#).eval()?;
///
/// let mut stream = thread.into_async::<_, i64>(1);
/// let mut sum = 0;
/// while let Some(n) = stream.try_next().await? {
/// sum += n;
/// }
///
/// assert_eq!(sum, 286);
///
/// # Ok(())
/// # }
/// ```
#[cfg(feature = "async")]
#[cfg_attr(docsrs, doc(cfg(feature = "async")))]
pub fn into_async<A, R>(self, args: A) -> AsyncThread<'lua, R>
where
A: IntoLuaMulti<'lua>,
R: FromLuaMulti<'lua>,
{
let args = args.into_lua_multi(self.0.lua);
AsyncThread {
thread: self,
init_args: Some(args),
ret: PhantomData,
recycle: false,
}
}
/// Enables sandbox mode on this thread.
///
/// Under the hood replaces the global environment table with a new table,
/// that performs writes locally and proxies reads to caller's global environment.
///
/// This mode ideally should be used together with the global sandbox mode [`Lua::sandbox()`].
///
/// Please note that Luau links environment table with chunk when loading it into Lua state.
/// Therefore you need to load chunks into a thread to link with the thread environment.
///
/// # Examples
///
/// ```
/// # use mlua::{Lua, Result};
/// # fn main() -> Result<()> {
/// let lua = Lua::new();
/// let thread = lua.create_thread(lua.create_function(|lua2, ()| {
/// lua2.load("var = 123").exec()?;
/// assert_eq!(lua2.globals().get::<_, u32>("var")?, 123);
/// Ok(())
/// })?)?;
/// thread.sandbox()?;
/// thread.resume(())?;
///
/// // The global environment should be unchanged
/// assert_eq!(lua.globals().get::<_, Option<u32>>("var")?, None);
/// # Ok(())
/// # }
/// ```
///
/// Requires `feature = "luau"`
#[cfg(any(feature = "luau", docsrs))]
#[cfg_attr(docsrs, doc(cfg(feature = "luau")))]
#[doc(hidden)]
pub fn sandbox(&self) -> Result<()> {
let lua = self.0.lua;
let state = lua.state();
let thread_state = self.state();
unsafe {
check_stack(thread_state, 3)?;
check_stack(state, 3)?;
protect_lua!(state, 0, 0, |_| ffi::luaL_sandboxthread(thread_state))
}
}
/// Converts this thread to a generic C pointer.
///
/// There is no way to convert the pointer back to its original value.
///
/// Typically this function is used only for hashing and debug information.
#[inline]
pub fn to_pointer(&self) -> *const c_void {
self.0.to_pointer()
}
/// Convert this handle to owned version.
#[cfg(all(feature = "unstable", any(not(feature = "send"), doc)))]
#[cfg_attr(docsrs, doc(cfg(all(feature = "unstable", not(feature = "send")))))]
#[inline]
pub fn into_owned(self) -> OwnedThread {
OwnedThread(self.0.into_owned(), self.1)
}
}
impl<'lua> PartialEq for Thread<'lua> {
fn eq(&self, other: &Self) -> bool {
self.0 == other.0
}
}
// Additional shortcuts
#[cfg(feature = "unstable")]
impl OwnedThread {
/// Resumes execution of this thread.
///
/// See [`Thread::resume()`] for more details.
pub fn resume<'lua, A, R>(&'lua self, args: A) -> Result<R>
where
A: IntoLuaMulti<'lua>,
R: FromLuaMulti<'lua>,
{
self.to_ref().resume(args)
}
/// Gets the status of the thread.
pub fn status(&self) -> ThreadStatus {
self.to_ref().status()
}
}
#[cfg(feature = "async")]
impl<'lua, R> AsyncThread<'lua, R> {
#[inline]
pub(crate) fn set_recyclable(&mut self, recyclable: bool) {
self.recycle = recyclable;
}
}
#[cfg(feature = "async")]
#[cfg(any(feature = "lua54", feature = "luau"))]
impl<'lua, R> Drop for AsyncThread<'lua, R> {
fn drop(&mut self) {
if self.recycle {
unsafe {
let lua = self.thread.0.lua;
// For Lua 5.4 this also closes all pending to-be-closed variables
if !lua.recycle_thread(&mut self.thread) {
#[cfg(feature = "lua54")]
if self.thread.status() == ThreadStatus::Error {
#[cfg(not(feature = "vendored"))]
ffi::lua_resetthread(self.thread.state());
#[cfg(feature = "vendored")]
ffi::lua_closethread(self.thread.state(), lua.state());
}
}
}
}
}
}
#[cfg(feature = "async")]
impl<'lua, R> Stream for AsyncThread<'lua, R>
where
R: FromLuaMulti<'lua>,
{
type Item = Result<R>;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
if self.thread.status() != ThreadStatus::Resumable {
return Poll::Ready(None);
}
let lua = self.thread.0.lua;
let state = lua.state();
let thread_state = self.thread.state();
unsafe {
let _sg = StackGuard::new(state);
let _thread_sg = StackGuard::with_top(thread_state, 0);
let _wg = WakerGuard::new(lua, cx.waker());
// This is safe as we are not moving the whole struct
let this = self.get_unchecked_mut();
let nresults = if let Some(args) = this.init_args.take() {
this.thread.resume_inner(args?)?
} else {
this.thread.resume_inner(())?
};
if nresults == 1 && is_poll_pending(thread_state) {
return Poll::Pending;
}
check_stack(state, nresults + 1)?;
ffi::lua_xmove(thread_state, state, nresults);
cx.waker().wake_by_ref();
Poll::Ready(Some(R::from_stack_multi(nresults, lua)))
}
}
}
#[cfg(feature = "async")]
impl<'lua, R> Future for AsyncThread<'lua, R>
where
R: FromLuaMulti<'lua>,
{
type Output = Result<R>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
if self.thread.status() != ThreadStatus::Resumable {
return Poll::Ready(Err(Error::CoroutineInactive));
}
let lua = self.thread.0.lua;
let state = lua.state();
let thread_state = self.thread.state();
unsafe {
let _sg = StackGuard::new(state);
let _thread_sg = StackGuard::with_top(thread_state, 0);
let _wg = WakerGuard::new(lua, cx.waker());
// This is safe as we are not moving the whole struct
let this = self.get_unchecked_mut();
let nresults = if let Some(args) = this.init_args.take() {
this.thread.resume_inner(args?)?
} else {
this.thread.resume_inner(())?
};
if nresults == 1 && is_poll_pending(thread_state) {
return Poll::Pending;
}
if ffi::lua_status(thread_state) == ffi::LUA_YIELD {
// Ignore value returned via yield()
cx.waker().wake_by_ref();
return Poll::Pending;
}
check_stack(state, nresults + 1)?;
ffi::lua_xmove(thread_state, state, nresults);
Poll::Ready(R::from_stack_multi(nresults, lua))
}
}
}
#[cfg(feature = "async")]
#[inline(always)]
unsafe fn is_poll_pending(state: *mut ffi::lua_State) -> bool {
ffi::lua_tolightuserdata(state, -1) == Lua::poll_pending().0
}
#[cfg(feature = "async")]
struct WakerGuard<'lua, 'a> {
lua: &'lua Lua,
prev: NonNull<Waker>,
_phantom: PhantomData<&'a ()>,
}
#[cfg(feature = "async")]
impl<'lua, 'a> WakerGuard<'lua, 'a> {
#[inline]
pub fn new(lua: &'lua Lua, waker: &'a Waker) -> Result<WakerGuard<'lua, 'a>> {
let prev = unsafe { lua.set_waker(NonNull::from(waker)) };
Ok(WakerGuard {
lua,
prev,
_phantom: PhantomData,
})
}
}
#[cfg(feature = "async")]
impl<'lua, 'a> Drop for WakerGuard<'lua, 'a> {
fn drop(&mut self) {
unsafe { self.lua.set_waker(self.prev) };
}
}
#[cfg(test)]
mod assertions {
use super::*;
static_assertions::assert_not_impl_any!(Thread: Send);
}