Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

3 files changed, 174 insertions, 0 deletions

diff --git a/third_party/rust/async-task/examples/spawn-local.rs b/third_party/rust/async-task/examples/spawn-local.rs
new file mode 100644
index 0000000000..a9da1b4de9
--- /dev/null
+++ b/third_party/rust/async-task/examples/spawn-local.rs
@@ -0,0 +1,73 @@
+//! 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());
+}
diff --git a/third_party/rust/async-task/examples/spawn-on-thread.rs b/third_party/rust/async-task/examples/spawn-on-thread.rs
new file mode 100644
index 0000000000..b0ec2f20a7
--- /dev/null
+++ b/third_party/rust/async-task/examples/spawn-on-thread.rs
@@ -0,0 +1,53 @@
+//! 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!");
+    }));
+}
diff --git a/third_party/rust/async-task/examples/spawn.rs b/third_party/rust/async-task/examples/spawn.rs
new file mode 100644
index 0000000000..3a648114c9
--- /dev/null
+++ b/third_party/rust/async-task/examples/spawn.rs
@@ -0,0 +1,48 @@
+//! 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);
+}