use std::cmp;
use std::os::raw::c_int;
use crate::error::{Error, Result};
use crate::ffi;
use crate::types::LuaRef;
use crate::util::{assert_stack, check_stack, pop_error, StackGuard};
use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti};
#[cfg(feature = "async")]
use {
crate::{
lua::{ASYNC_POLL_PENDING, WAKER_REGISTRY_KEY},
util::get_gc_userdata,
value::Value,
},
futures_core::{future::Future, stream::Stream},
std::{
cell::RefCell,
marker::PhantomData,
mem,
os::raw::c_void,
pin::Pin,
task::{Context, Poll, Waker},
},
};
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum ThreadStatus {
Resumable,
Unresumable,
Error,
}
#[derive(Clone, Debug)]
pub struct Thread<'lua>(pub(crate) LuaRef<'lua>);
#[cfg(feature = "async")]
#[cfg_attr(docsrs, doc(cfg(feature = "async")))]
#[derive(Debug)]
pub struct AsyncThread<'lua, R> {
thread: Thread<'lua>,
args0: RefCell<Option<Result<MultiValue<'lua>>>>,
ret: PhantomData<R>,
}
impl<'lua> Thread<'lua> {
pub fn resume<A, R>(&self, args: A) -> Result<R>
where
A: ToLuaMulti<'lua>,
R: FromLuaMulti<'lua>,
{
let lua = self.0.lua;
let args = args.to_lua_multi(lua)?;
let nargs = args.len() as c_int;
let results = unsafe {
let _sg = StackGuard::new(lua.state);
check_stack(lua.state, cmp::min(nargs + 1, 3))?;
lua.push_ref(&self.0);
let thread_state = ffi::lua_tothread(lua.state, -1);
ffi::lua_pop(lua.state, 1);
let status = ffi::lua_status(thread_state);
if status != ffi::LUA_YIELD && ffi::lua_gettop(thread_state) == 0 {
return Err(Error::CoroutineInactive);
}
check_stack(thread_state, nargs)?;
for arg in args {
lua.push_value(arg)?;
}
ffi::lua_xmove(lua.state, thread_state, nargs);
let mut nresults = 0;
let ret = ffi::lua_resume(thread_state, lua.state, nargs, &mut nresults as *mut c_int);
if ret != ffi::LUA_OK && ret != ffi::LUA_YIELD {
ffi::safe::error_traceback2(lua.state, thread_state)?;
return Err(pop_error(thread_state, ret));
}
let mut results = MultiValue::new();
check_stack(lua.state, nresults + 2)?;
ffi::lua_xmove(thread_state, lua.state, nresults);
for _ in 0..nresults {
results.push_front(lua.pop_value());
}
results
};
R::from_lua_multi(results, lua)
}
pub fn status(&self) -> ThreadStatus {
let lua = self.0.lua;
unsafe {
let _sg = StackGuard::new(lua.state);
assert_stack(lua.state, 1);
lua.push_ref(&self.0);
let thread_state = ffi::lua_tothread(lua.state, -1);
ffi::lua_pop(lua.state, 1);
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
}
}
}
#[cfg(feature = "async")]
#[cfg_attr(docsrs, doc(cfg(feature = "async")))]
pub fn into_async<A, R>(self, args: A) -> AsyncThread<'lua, R>
where
A: ToLuaMulti<'lua>,
R: FromLuaMulti<'lua>,
{
let args = args.to_lua_multi(&self.0.lua);
AsyncThread {
thread: self,
args0: RefCell::new(Some(args)),
ret: PhantomData,
}
}
}
impl<'lua> PartialEq for Thread<'lua> {
fn eq(&self, other: &Self) -> bool {
self.0 == other.0
}
}
#[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>> {
let lua = self.thread.0.lua;
match self.thread.status() {
ThreadStatus::Resumable => {}
_ => return Poll::Ready(None),
};
let _wg = WakerGuard::new(lua.state, cx.waker().clone());
let ret: MultiValue = if let Some(args) = self.args0.borrow_mut().take() {
self.thread.resume(args?)?
} else {
self.thread.resume(())?
};
if is_poll_pending(&ret) {
return Poll::Pending;
}
cx.waker().wake_by_ref();
Poll::Ready(Some(R::from_lua_multi(ret, 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> {
let lua = self.thread.0.lua;
match self.thread.status() {
ThreadStatus::Resumable => {}
_ => return Poll::Ready(Err(Error::CoroutineInactive)),
};
let _wg = WakerGuard::new(lua.state, cx.waker().clone());
let ret: MultiValue = if let Some(args) = self.args0.borrow_mut().take() {
self.thread.resume(args?)?
} else {
self.thread.resume(())?
};
if is_poll_pending(&ret) {
return Poll::Pending;
}
if let ThreadStatus::Resumable = self.thread.status() {
cx.waker().wake_by_ref();
return Poll::Pending;
}
Poll::Ready(R::from_lua_multi(ret, lua))
}
}
#[cfg(feature = "async")]
fn is_poll_pending(val: &MultiValue) -> bool {
match val.iter().enumerate().last() {
Some((1, Value::LightUserData(ud))) => {
ud.0 == &ASYNC_POLL_PENDING as *const u8 as *mut c_void
}
_ => false,
}
}
#[cfg(feature = "async")]
struct WakerGuard(*mut ffi::lua_State, Option<Waker>);
#[cfg(feature = "async")]
impl WakerGuard {
pub fn new(state: *mut ffi::lua_State, waker: Waker) -> Result<WakerGuard> {
unsafe {
let _sg = StackGuard::new(state);
check_stack(state, 3)?;
let waker_key = &WAKER_REGISTRY_KEY as *const u8 as *const c_void;
ffi::lua_rawgetp(state, ffi::LUA_REGISTRYINDEX, waker_key);
let waker_slot = get_gc_userdata::<Option<Waker>>(state, -1).as_mut();
let old = mlua_expect!(waker_slot, "Waker is destroyed").replace(waker);
Ok(WakerGuard(state, old))
}
}
}
#[cfg(feature = "async")]
impl Drop for WakerGuard {
fn drop(&mut self) {
let state = self.0;
unsafe {
let _sg = StackGuard::new(state);
assert_stack(state, 3);
let waker_key = &WAKER_REGISTRY_KEY as *const u8 as *const c_void;
ffi::lua_rawgetp(state, ffi::LUA_REGISTRYINDEX, waker_key);
let waker_slot = get_gc_userdata::<Option<Waker>>(state, -1).as_mut();
mem::swap(mlua_expect!(waker_slot, "Waker is destroyed"), &mut self.1);
}
}
}