Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 53 insertions, 0 deletions

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!");
+    }));
+}