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use tokio::sync::broadcast;
/// The `Shutdown` struct listens for the signal and tracks that the signal has
/// been received. Callers may query for whether the shutdown signal has been
/// received or not.
pub struct Shutdown {
/// `true` if the shutdown signal has been received
shutdown: bool,
notify: broadcast::Sender<()>,
/// The receive half of the channel used to listen for shutdown.
watch: broadcast::Receiver<()>,
}
impl Clone for Shutdown {
fn clone(&self) -> Self {
let notify = self.notify.clone();
let watch = notify.subscribe();
Self {
shutdown: self.shutdown,
notify,
watch,
}
}
}
impl Default for Shutdown {
fn default() -> Self {
let (notify, watch) = broadcast::channel(1);
Self {
shutdown: false,
notify,
watch,
}
}
}
impl Shutdown {
/// Create a new `Shutdown` backed by the given `broadcast::Receiver`.
pub fn new(notify: broadcast::Sender<()>) -> Shutdown {
let watch = notify.subscribe();
Shutdown {
shutdown: false,
notify,
watch,
}
}
/// Returns `true` if the shutdown signal has been received.
pub fn is_shutdown(&self) -> bool {
self.shutdown
}
/// Receive the shutdown notice, waiting if necessary.
pub async fn recv(&mut self) {
// If the shutdown signal has already been received, then return
// immediately.
if self.shutdown {
return;
}
// Cannot receive a "lag error" as only one value is ever sent.
let _ = self.watch.recv().await;
// Remember that the signal has been received.
self.shutdown = true;
}
pub fn broadcast_shutdown(&mut self) {
self.notify.send(()).unwrap();
}
}