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49 lines
1.2 KiB
49 lines
1.2 KiB
4 months ago
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//! A simple single-threaded executor.
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use std::future::Future;
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use std::panic::catch_unwind;
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use std::thread;
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use async_task::{Runnable, Task};
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use once_cell::sync::Lazy;
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use smol::future;
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/// Spawns a future on the executor.
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fn spawn<F, T>(future: F) -> Task<T>
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where
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F: Future<Output = T> + Send + 'static,
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T: Send + 'static,
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{
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// A queue that holds scheduled tasks.
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static QUEUE: Lazy<flume::Sender<Runnable>> = Lazy::new(|| {
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let (sender, receiver) = flume::unbounded::<Runnable>();
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// Start the executor thread.
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thread::spawn(|| {
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for runnable in receiver {
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// Ignore panics inside futures.
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let _ignore_panic = catch_unwind(|| runnable.run());
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}
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});
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sender
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});
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// Create a task that is scheduled by pushing it into the queue.
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let schedule = |runnable| QUEUE.send(runnable).unwrap();
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let (runnable, task) = async_task::spawn(future, schedule);
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// Schedule the task by pushing it into the queue.
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runnable.schedule();
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task
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}
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fn main() {
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// Spawn a future and await its result.
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let task = spawn(async {
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println!("Hello, world!");
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});
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future::block_on(task);
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}
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