pub(crate) async fn grace_expired(started: Receiver<()>)Expand description
Resolves SHUTDOWN_GRACE after started fires, and never if it does
not.
The sender is dropped without sending when serving ends for any reason other than a signal — a bind that died, a listener that stopped accepting — and that must not be read as a shutdown whose grace has begun, so a closed channel pends here rather than starting the clock.