ed3ecda91d
# Objective In some scenarios it can be useful to check if a task has been finished without polling it. I added a function called `is_finished` to check if a task has been finished. ## Solution Since `async_task` supports it out of the box, it is just a simple wrapper function. ---
62 lines
2.0 KiB
Rust
62 lines
2.0 KiB
Rust
use std::{
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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 [`cancel()`][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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/// Wraps `async_executor::Task`
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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>(async_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: async_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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