Function timeout 

pub fn timeout<T, U>(dur: U, future: T) -> Timeout<T> 
where
    T: Future,
    U: Into<Millis>,

Requires a future to complete before dur has elapsed.

If the future completes before the duration has elapsed, then the completed value is returned. Otherwise, an error is returned and the future is canceled. A zero duration still represents an active timeout of at least one timer tick; use timeout_checked to disable the timeout with zero.