pub async fn yield_once()Expand description
Runtime-agnostic single-yield future. Returns Pending once then
resolves to Ready(()) on the next poll, with wake_by_ref driving
the re-poll. Works under any executor (pollster, tokio, smol,
futures::executor).
Used by the default SyncWaiter::wait_async impl and by per-backend
overrides for their fast-path yield-spin loops.