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https://github.com/bevyengine/bevy
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72f096c91e
# Objective - Contributes to #15460 ## Solution - Added the following features: - `std` (default) - `async_executor` (default) - `edge_executor` - `critical-section` - `portable-atomic` - Added [`edge-executor`](https://crates.io/crates/edge-executor) as a `no_std` alternative to `async-executor`. - Updated the `single_threaded_task_pool` to work in `no_std` environments by gating its reliance on `thread_local`. ## Testing - Added to `compile-check-no-std` CI command ## Notes - In previous iterations of this PR, a custom `async-executor` alternative was vendored in. This raised concerns around maintenance and testing. In this iteration, an existing version of that same vendoring is now used, but _only_ in `no_std` contexts. For existing `std` contexts, the original `async-executor` is used. - Due to the way statics work, certain `TaskPool` operations have added restrictions around `Send`/`Sync` in `no_std`. This is because there isn't a straightforward way to create a thread-local in `no_std`. If these added constraints pose an issue we can revisit this at a later date. - If a user enables both the `async_executor` and `edge_executor` features, we will default to using `async-executor`. Since enabling `async_executor` requires `std`, we can safely assume we are in an `std` context and use the original library. --------- Co-authored-by: Mike <2180432+hymm@users.noreply.github.com> Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
60 lines
2 KiB
Rust
60 lines
2 KiB
Rust
use core::{
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future::Future,
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pin::Pin,
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task::{Context, Poll},
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};
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/// Wraps `async_executor::Task`, a spawned future.
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///
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/// Tasks are also futures themselves and yield the output of the spawned future.
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///
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/// When a task is dropped, its gets canceled and won't be polled again. To cancel a task a bit
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/// more gracefully and wait until it stops running, use the [`Task::cancel()`] method.
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///
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/// Tasks that panic get immediately canceled. Awaiting a canceled task also causes a panic.
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#[derive(Debug)]
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#[must_use = "Tasks are canceled when dropped, use `.detach()` to run them in the background."]
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pub struct Task<T>(crate::executor::Task<T>);
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impl<T> Task<T> {
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/// Creates a new task from a given `async_executor::Task`
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pub fn new(task: crate::executor::Task<T>) -> Self {
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Self(task)
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}
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/// Detaches the task to let it keep running in the background. See
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/// `async_executor::Task::detach`
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pub fn detach(self) {
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self.0.detach();
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}
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/// Cancels the task and waits for it to stop running.
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///
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/// Returns the task's output if it was completed just before it got canceled, or [`None`] if
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/// it didn't complete.
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///
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/// While it's possible to simply drop the [`Task`] to cancel it, this is a cleaner way of
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/// canceling because it also waits for the task to stop running.
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///
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/// See `async_executor::Task::cancel`
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pub async fn cancel(self) -> Option<T> {
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self.0.cancel().await
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}
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/// Returns `true` if the current task is finished.
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///
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///
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/// Unlike poll, it doesn't resolve the final value, it just checks if the task has finished.
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/// Note that in a multithreaded environment, this task can be finished immediately after calling this function.
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pub fn is_finished(&self) -> bool {
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self.0.is_finished()
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}
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}
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impl<T> Future for Task<T> {
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type Output = T;
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fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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Pin::new(&mut self.0).poll(cx)
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}
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}
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