hyper/common/task.rs
use std::task::{Context, Poll};
/// A function to help "yield" a future, such that it is re-scheduled immediately.
///
/// Useful for spin counts, so a future doesn't hog too much time.
pub(crate) fn yield_now(cx: &mut Context<'_>) -> Poll<std::convert::Infallible> {
cx.waker().wake_by_ref();
Poll::Pending
}