84 lines
2.8 KiB
Rust
84 lines
2.8 KiB
Rust
#[cfg(feature = "executor-interrupt")]
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compile_error!("`executor-interrupt` is not supported with `arch-wasm`.");
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#[cfg(feature = "executor-thread")]
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pub use thread::*;
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#[cfg(feature = "executor-thread")]
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mod thread {
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use core::marker::PhantomData;
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#[cfg(feature = "nightly")]
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pub use embassy_macros::main_wasm as main;
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use js_sys::Promise;
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use wasm_bindgen::prelude::*;
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use crate::raw::util::UninitCell;
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use crate::{raw, Spawner};
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#[export_name = "__thread_mode_pender"]
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fn __thread_mode_pender(context: *mut ()) {
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let signaler: &'static WasmContext = unsafe { std::mem::transmute(context) };
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let _ = signaler.promise.then(unsafe { signaler.closure.as_mut() });
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}
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pub(crate) struct WasmContext {
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promise: Promise,
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closure: UninitCell<Closure<dyn FnMut(JsValue)>>,
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}
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impl WasmContext {
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pub fn new() -> Self {
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Self {
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promise: Promise::resolve(&JsValue::undefined()),
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closure: UninitCell::uninit(),
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}
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}
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}
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/// WASM executor, wasm_bindgen to schedule tasks on the JS event loop.
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pub struct Executor {
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inner: raw::Executor,
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ctx: &'static WasmContext,
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not_send: PhantomData<*mut ()>,
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}
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impl Executor {
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/// Create a new Executor.
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pub fn new() -> Self {
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let ctx = Box::leak(Box::new(WasmContext::new()));
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Self {
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inner: raw::Executor::new(ctx as *mut WasmContext as *mut ()),
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ctx,
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not_send: PhantomData,
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}
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}
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/// Run the executor.
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///
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/// The `init` closure is called with a [`Spawner`] that spawns tasks on
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/// this executor. Use it to spawn the initial task(s). After `init` returns,
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/// the executor starts running the tasks.
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///
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/// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`),
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/// for example by passing it as an argument to the initial tasks.
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///
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/// This function requires `&'static mut self`. This means you have to store the
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/// Executor instance in a place where it'll live forever and grants you mutable
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/// access. There's a few ways to do this:
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///
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/// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe)
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/// - a `static mut` (unsafe)
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/// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe)
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pub fn start(&'static mut self, init: impl FnOnce(Spawner)) {
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unsafe {
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let executor = &self.inner;
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self.ctx.closure.write(Closure::new(move |_| {
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executor.poll();
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}));
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init(self.inner.spawner());
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}
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}
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}
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}
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