Vendor dependencies for 0.3.0 release

vendor/async-task/examples/spawn-local.rs

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+//! A simple single-threaded executor that can spawn non-`Send` futures.
+
+use std::cell::Cell;
+use std::future::Future;
+use std::rc::Rc;
+
+use async_task::{Runnable, Task};
+
+thread_local! {
+    // A queue that holds scheduled tasks.
+    static QUEUE: (flume::Sender<Runnable>, flume::Receiver<Runnable>) = flume::unbounded();
+}
+
+/// Spawns a future on the executor.
+fn spawn<F, T>(future: F) -> Task<T>
+where
+    F: Future<Output = T> + 'static,
+    T: 'static,
+{
+    // Create a task that is scheduled by pushing itself into the queue.
+    let schedule = |runnable| QUEUE.with(|(s, _)| s.send(runnable).unwrap());
+    let (runnable, task) = async_task::spawn_local(future, schedule);
+
+    // Schedule the task by pushing it into the queue.
+    runnable.schedule();
+
+    task
+}
+
+/// Runs a future to completion.
+fn run<F, T>(future: F) -> T
+where
+    F: Future<Output = T> + 'static,
+    T: 'static,
+{
+    // Spawn a task that sends its result through a channel.
+    let (s, r) = flume::unbounded();
+    spawn(async move { drop(s.send(future.await)) }).detach();
+
+    loop {
+        // If the original task has completed, return its result.
+        if let Ok(val) = r.try_recv() {
+            return val;
+        }
+
+        // Otherwise, take a task from the queue and run it.
+        QUEUE.with(|(_, r)| r.recv().unwrap().run());
+    }
+}
+
+fn main() {
+    let val = Rc::new(Cell::new(0));
+
+    // Run a future that increments a non-`Send` value.
+    run({
+        let val = val.clone();
+        async move {
+            // Spawn a future that increments the value.
+            let task = spawn({
+                let val = val.clone();
+                async move {
+                    val.set(dbg!(val.get()) + 1);
+                }
+            });
+
+            val.set(dbg!(val.get()) + 1);
+            task.await;
+        }
+    });
+
+    // The value should be 2 at the end of the program.
+    dbg!(val.get());
+}

vendor/async-task/examples/spawn-on-thread.rs

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+//! A function that runs a future to completion on a dedicated thread.
+
+use std::future::Future;
+use std::sync::Arc;
+use std::thread;
+
+use async_task::Task;
+use smol::future;
+
+/// Spawns a future on a new dedicated thread.
+///
+/// The returned task can be used to await the output of the future.
+fn spawn_on_thread<F, T>(future: F) -> Task<T>
+where
+    F: Future<Output = T> + Send + 'static,
+    T: Send + 'static,
+{
+    // Create a channel that holds the task when it is scheduled for running.
+    let (sender, receiver) = flume::unbounded();
+    let sender = Arc::new(sender);
+    let s = Arc::downgrade(&sender);
+
+    // Wrap the future into one that disconnects the channel on completion.
+    let future = async move {
+        // When the inner future completes, the sender gets dropped and disconnects the channel.
+        let _sender = sender;
+        future.await
+    };
+
+    // Create a task that is scheduled by sending it into the channel.
+    let schedule = move |runnable| s.upgrade().unwrap().send(runnable).unwrap();
+    let (runnable, task) = async_task::spawn(future, schedule);
+
+    // Schedule the task by sending it into the channel.
+    runnable.schedule();
+
+    // Spawn a thread running the task to completion.
+    thread::spawn(move || {
+        // Keep taking the task from the channel and running it until completion.
+        for runnable in receiver {
+            runnable.run();
+        }
+    });
+
+    task
+}
+
+fn main() {
+    // Spawn a future on a dedicated thread.
+    future::block_on(spawn_on_thread(async {
+        println!("Hello, world!");
+    }));
+}

vendor/async-task/examples/spawn.rs

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

vendor/async-task/examples/with-metadata.rs

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+//! A single threaded executor that uses shortest-job-first scheduling.
+
+use std::cell::RefCell;
+use std::collections::BinaryHeap;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use std::thread;
+use std::time::{Duration, Instant};
+use std::{cell::Cell, future::Future};
+
+use async_task::{Builder, Runnable, Task};
+use pin_project_lite::pin_project;
+use smol::{channel, future};
+
+struct ByDuration(Runnable<DurationMetadata>);
+
+impl ByDuration {
+    fn duration(&self) -> Duration {
+        self.0.metadata().inner.get()
+    }
+}
+
+impl PartialEq for ByDuration {
+    fn eq(&self, other: &Self) -> bool {
+        self.duration() == other.duration()
+    }
+}
+
+impl Eq for ByDuration {}
+
+impl PartialOrd for ByDuration {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for ByDuration {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.duration().cmp(&other.duration()).reverse()
+    }
+}
+
+pin_project! {
+    #[must_use = "futures do nothing unless you `.await` or poll them"]
+    struct MeasureRuntime<'a, F> {
+        #[pin]
+        f: F,
+        duration: &'a Cell<Duration>
+    }
+}
+
+impl<'a, F: Future> Future for MeasureRuntime<'a, F> {
+    type Output = F::Output;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = self.project();
+        let duration_cell: &Cell<Duration> = this.duration;
+        let start = Instant::now();
+        let res = F::poll(this.f, cx);
+        let new_duration = Instant::now() - start;
+        duration_cell.set(duration_cell.get() / 2 + new_duration / 2);
+        res
+    }
+}
+
+pub struct DurationMetadata {
+    inner: Cell<Duration>,
+}
+
+thread_local! {
+    // A queue that holds scheduled tasks.
+    static QUEUE: RefCell<BinaryHeap<ByDuration>> = RefCell::new(BinaryHeap::new());
+}
+
+fn make_future_fn<'a, F>(
+    future: F,
+) -> impl (FnOnce(&'a DurationMetadata) -> MeasureRuntime<'a, F>) {
+    move |duration_meta| MeasureRuntime {
+        f: future,
+        duration: &duration_meta.inner,
+    }
+}
+
+fn ensure_safe_schedule<F: Send + Sync + 'static>(f: F) -> F {
+    f
+}
+
+/// Spawns a future on the executor.
+pub fn spawn<F, T>(future: F) -> Task<T, DurationMetadata>
+where
+    F: Future<Output = T> + 'static,
+    T: 'static,
+{
+    let spawn_thread_id = thread::current().id();
+    // Create a task that is scheduled by pushing it into the queue.
+    let schedule = ensure_safe_schedule(move |runnable| {
+        if thread::current().id() != spawn_thread_id {
+            panic!("Task would be run on a different thread than spawned on.");
+        }
+        QUEUE.with(move |queue| queue.borrow_mut().push(ByDuration(runnable)));
+    });
+    let future_fn = make_future_fn(future);
+    let (runnable, task) = unsafe {
+        Builder::new()
+            .metadata(DurationMetadata {
+                inner: Cell::new(Duration::default()),
+            })
+            .spawn_unchecked(future_fn, schedule)
+    };
+
+    // Schedule the task by pushing it into the queue.
+    runnable.schedule();
+
+    task
+}
+
+pub fn block_on<F>(future: F)
+where
+    F: Future<Output = ()> + 'static,
+{
+    let task = spawn(future);
+    while !task.is_finished() {
+        let Some(runnable) = QUEUE.with(|queue| queue.borrow_mut().pop()) else {
+            thread::yield_now();
+            continue;
+        };
+        runnable.0.run();
+    }
+}
+
+fn main() {
+    // Spawn a future and await its result.
+    block_on(async {
+        let (sender, receiver) = channel::bounded(1);
+        let world = spawn(async move {
+            receiver.recv().await.unwrap();
+            println!("world.")
+        });
+        let hello = spawn(async move {
+            sender.send(()).await.unwrap();
+            print!("Hello, ")
+        });
+        future::zip(hello, world).await;
+    });
+}