360 lines
11 KiB
Rust
360 lines
11 KiB
Rust
use std::os::raw::c_int;
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use crate::error::{Error, Result};
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use crate::ffi;
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use crate::types::LuaRef;
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use crate::util::{
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assert_stack, check_stack, error_traceback, pop_error, protect_lua_closure, StackGuard,
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};
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use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti};
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#[cfg(feature = "async")]
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use {
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crate::{
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error::ExternalError,
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lua::{AsyncPollPending, Lua, WAKER_REGISTRY_KEY},
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util::{get_gc_userdata, push_gc_userdata},
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value::Value,
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},
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futures_core::{future::Future, stream::Stream},
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std::{
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cell::RefCell,
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marker::PhantomData,
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os::raw::c_void,
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pin::Pin,
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task::{Context, Poll, Waker},
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},
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};
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/// Status of a Lua thread (or coroutine).
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#[derive(Debug, Copy, Clone, Eq, PartialEq)]
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pub enum ThreadStatus {
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/// The thread was just created, or is suspended because it has called `coroutine.yield`.
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///
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/// If a thread is in this state, it can be resumed by calling [`Thread::resume`].
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///
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/// [`Thread::resume`]: struct.Thread.html#method.resume
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Resumable,
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/// Either the thread has finished executing, or the thread is currently running.
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Unresumable,
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/// The thread has raised a Lua error during execution.
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Error,
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}
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/// Handle to an internal Lua thread (or coroutine).
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#[derive(Clone, Debug)]
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pub struct Thread<'lua>(pub(crate) LuaRef<'lua>);
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/// Thread (coroutine) representation as an async Future or Stream.
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#[cfg(feature = "async")]
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#[derive(Debug)]
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pub struct AsyncThread<'lua, R> {
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thread: Thread<'lua>,
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args0: RefCell<Option<Result<MultiValue<'lua>>>>,
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ret: PhantomData<R>,
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}
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impl<'lua> Thread<'lua> {
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/// Resumes execution of this thread.
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///
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/// Equivalent to `coroutine.resume`.
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///
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/// Passes `args` as arguments to the thread. If the coroutine has called `coroutine.yield`, it
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/// will return these arguments. Otherwise, the coroutine wasn't yet started, so the arguments
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/// are passed to its main function.
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///
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/// If the thread is no longer in `Active` state (meaning it has finished execution or
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/// encountered an error), this will return `Err(CoroutineInactive)`, otherwise will return `Ok`
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/// as follows:
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///
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/// If the thread calls `coroutine.yield`, returns the values passed to `yield`. If the thread
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/// `return`s values from its main function, returns those.
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///
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/// # Examples
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///
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/// ```
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/// # use mlua::{Error, Lua, Result, Thread};
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/// # fn main() -> Result<()> {
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/// # let lua = Lua::new();
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/// let thread: Thread = lua.load(r#"
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/// coroutine.create(function(arg)
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/// assert(arg == 42)
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/// local yieldarg = coroutine.yield(123)
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/// assert(yieldarg == 43)
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/// return 987
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/// end)
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/// "#).eval()?;
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///
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/// assert_eq!(thread.resume::<_, u32>(42)?, 123);
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/// assert_eq!(thread.resume::<_, u32>(43)?, 987);
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///
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/// // The coroutine has now returned, so `resume` will fail
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/// match thread.resume::<_, u32>(()) {
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/// Err(Error::CoroutineInactive) => {},
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/// unexpected => panic!("unexpected result {:?}", unexpected),
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/// }
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/// # Ok(())
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/// # }
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/// ```
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pub fn resume<A, R>(&self, args: A) -> Result<R>
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where
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A: ToLuaMulti<'lua>,
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R: FromLuaMulti<'lua>,
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{
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let lua = self.0.lua;
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let args = args.to_lua_multi(lua)?;
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let results = unsafe {
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let _sg = StackGuard::new(lua.state);
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assert_stack(lua.state, 3);
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lua.push_ref(&self.0);
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let thread_state = ffi::lua_tothread(lua.state, -1);
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let status = ffi::lua_status(thread_state);
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if status != ffi::LUA_YIELD && ffi::lua_gettop(thread_state) == 0 {
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return Err(Error::CoroutineInactive);
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}
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ffi::lua_pop(lua.state, 1);
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let nargs = args.len() as c_int;
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check_stack(lua.state, nargs)?;
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check_stack(thread_state, nargs + 1)?;
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for arg in args {
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lua.push_value(arg)?;
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}
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ffi::lua_xmove(lua.state, thread_state, nargs);
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let ret = ffi::lua_resume(thread_state, lua.state, nargs);
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if ret != ffi::LUA_OK && ret != ffi::LUA_YIELD {
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protect_lua_closure(lua.state, 0, 0, |_| {
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error_traceback(thread_state);
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0
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})?;
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return Err(pop_error(thread_state, ret));
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}
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let nresults = ffi::lua_gettop(thread_state);
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let mut results = MultiValue::new();
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ffi::lua_xmove(thread_state, lua.state, nresults);
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assert_stack(lua.state, 2);
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for _ in 0..nresults {
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results.push_front(lua.pop_value());
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}
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results
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};
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R::from_lua_multi(results, lua)
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}
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/// Gets the status of the thread.
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pub fn status(&self) -> ThreadStatus {
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let lua = self.0.lua;
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unsafe {
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let _sg = StackGuard::new(lua.state);
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assert_stack(lua.state, 1);
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lua.push_ref(&self.0);
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let thread_state = ffi::lua_tothread(lua.state, -1);
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ffi::lua_pop(lua.state, 1);
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let status = ffi::lua_status(thread_state);
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if status != ffi::LUA_OK && status != ffi::LUA_YIELD {
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ThreadStatus::Error
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} else if status == ffi::LUA_YIELD || ffi::lua_gettop(thread_state) > 0 {
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ThreadStatus::Resumable
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} else {
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ThreadStatus::Unresumable
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}
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}
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}
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/// Converts Thread to an AsyncThread which implements Future and Stream traits.
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///
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/// `args` are passed as arguments to the thread function for first call.
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/// The object call `resume()` while polling and also allows to run rust futures
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/// to completion using an executor.
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///
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/// Using AsyncThread as a Stream allows to iterate through `coroutine.yield()`
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/// values whereas Future version discards that values and poll until the final
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/// one (returned from the thread function).
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///
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/// # Examples
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///
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/// ```
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/// # use mlua::{Error, Lua, Result, Thread};
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/// use futures_executor::block_on;
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/// use futures_util::stream::TryStreamExt;
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/// # fn main() -> Result<()> {
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/// # let lua = Lua::new();
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/// let thread: Thread = lua.load(r#"
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/// coroutine.create(function(sum)
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/// for i = 1,10 do
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/// sum = sum + i
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/// coroutine.yield(sum)
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/// end
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/// return sum
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/// end)
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/// "#).eval()?;
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///
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/// let result = block_on(async {
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/// let mut s = thread.into_async::<_, i64>(1);
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/// let mut sum = 0;
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/// while let Some(n) = s.try_next().await? {
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/// sum += n;
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/// }
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/// Ok::<_, Error>(sum)
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/// })?;
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///
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/// assert_eq!(result, 286);
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///
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/// # Ok(())
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/// # }
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/// ```
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#[cfg(feature = "async")]
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pub fn into_async<A, R>(self, args: A) -> AsyncThread<'lua, R>
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where
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A: ToLuaMulti<'lua>,
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R: FromLuaMulti<'lua>,
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{
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let args = args.to_lua_multi(&self.0.lua);
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AsyncThread {
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thread: self,
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args0: RefCell::new(Some(args)),
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ret: PhantomData,
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}
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}
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}
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impl<'lua> PartialEq for Thread<'lua> {
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fn eq(&self, other: &Self) -> bool {
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self.0 == other.0
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}
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}
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#[cfg(feature = "async")]
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impl<'lua, R> Stream for AsyncThread<'lua, R>
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where
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R: FromLuaMulti<'lua>,
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{
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type Item = Result<R>;
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fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
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let lua = self.thread.0.lua;
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match self.thread.status() {
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ThreadStatus::Resumable => {}
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_ => return Poll::Ready(None),
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};
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let _wg = WakerGuard::new(lua.state, cx.waker().clone());
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let ret: MultiValue = if let Some(args) = self.args0.borrow_mut().take() {
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self.thread.resume(args?)?
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} else {
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self.thread.resume(())?
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};
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if is_poll_pending(lua, &ret) {
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return Poll::Pending;
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}
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cx.waker().wake_by_ref();
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Poll::Ready(Some(R::from_lua_multi(ret, lua)))
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}
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}
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#[cfg(feature = "async")]
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impl<'lua, R> Future for AsyncThread<'lua, R>
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where
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R: FromLuaMulti<'lua>,
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{
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type Output = Result<R>;
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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let lua = self.thread.0.lua;
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match self.thread.status() {
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ThreadStatus::Resumable => {}
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_ => return Poll::Ready(Err("Thread already finished".to_lua_err())),
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};
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let _wg = WakerGuard::new(lua.state, cx.waker().clone());
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let ret: MultiValue = if let Some(args) = self.args0.borrow_mut().take() {
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self.thread.resume(args?)?
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} else {
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self.thread.resume(())?
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};
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if is_poll_pending(lua, &ret) {
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return Poll::Pending;
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}
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if let ThreadStatus::Resumable = self.thread.status() {
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// Ignore value returned via yield()
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cx.waker().wake_by_ref();
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return Poll::Pending;
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}
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Poll::Ready(R::from_lua_multi(ret, lua))
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}
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}
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#[cfg(feature = "async")]
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fn is_poll_pending(lua: &Lua, val: &MultiValue) -> bool {
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if val.len() != 1 {
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return false;
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}
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if let Some(Value::UserData(ud)) = val.iter().next() {
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unsafe {
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let _sg = StackGuard::new(lua.state);
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assert_stack(lua.state, 3);
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lua.push_ref(&ud.0);
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let is_pending = get_gc_userdata::<AsyncPollPending>(lua.state, -1)
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.as_ref()
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.is_some();
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ffi::lua_pop(lua.state, 1);
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return is_pending;
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}
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}
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false
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}
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#[cfg(feature = "async")]
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struct WakerGuard(*mut ffi::lua_State);
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#[cfg(feature = "async")]
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impl WakerGuard {
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pub fn new(state: *mut ffi::lua_State, waker: Waker) -> Result<WakerGuard> {
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unsafe {
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let _sg = StackGuard::new(state);
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assert_stack(state, 6);
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ffi::lua_pushlightuserdata(state, &WAKER_REGISTRY_KEY as *const u8 as *mut c_void);
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push_gc_userdata(state, waker)?;
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ffi::lua_rawset(state, ffi::LUA_REGISTRYINDEX);
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Ok(WakerGuard(state))
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}
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}
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}
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#[cfg(feature = "async")]
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impl Drop for WakerGuard {
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fn drop(&mut self) {
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unsafe {
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let state = self.0;
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let _sg = StackGuard::new(state);
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assert_stack(state, 2);
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ffi::lua_pushlightuserdata(state, &WAKER_REGISTRY_KEY as *const u8 as *mut c_void);
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ffi::lua_pushnil(state);
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ffi::lua_rawset(state, ffi::LUA_REGISTRYINDEX);
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}
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}
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}
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