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#[cfg(feature = "timer")] #[allow(deprecated)] use tokio_timer::Deadline; #[cfg(feature = "timer")] use tokio_timer::Timeout; use futures::Future; #[cfg(feature = "timer")] use std::time::{Duration, Instant}; /// An extension trait for `Future` that provides a variety of convenient /// combinator functions. /// /// Currently, there only is a [`timeout`] function, but this will increase /// over time. /// /// Users are not expected to implement this trait. All types that implement /// `Future` already implement `FutureExt`. /// /// This trait can be imported directly or via the Tokio prelude: `use /// tokio::prelude::*`. /// /// [`timeout`]: #method.timeout pub trait FutureExt: Future { /// Creates a new future which allows `self` until `timeout`. /// /// This combinator creates a new future which wraps the receiving future /// with a timeout. The returned future is allowed to execute until it /// completes or `timeout` has elapsed, whichever happens first. /// /// If the future completes before `timeout` then the future will resolve /// with that item. Otherwise the future will resolve to an error. /// /// The future is guaranteed to be polled at least once, even if `timeout` /// is set to zero. /// /// # Examples /// /// ``` /// # extern crate tokio; /// # extern crate futures; /// use tokio::prelude::*; /// use std::time::Duration; /// # use futures::future::{self, FutureResult}; /// /// # fn long_future() -> FutureResult<(), ()> { /// # future::ok(()) /// # } /// # /// # fn main() { /// let future = long_future() /// .timeout(Duration::from_secs(1)) /// .map_err(|e| println!("error = {:?}", e)); /// /// tokio::run(future); /// # } /// ``` #[cfg(feature = "timer")] fn timeout(self, timeout: Duration) -> Timeout<Self> where Self: Sized, { Timeout::new(self, timeout) } #[cfg(feature = "timer")] #[deprecated(since = "0.1.8", note = "use `timeout` instead")] #[allow(deprecated)] #[doc(hidden)] fn deadline(self, deadline: Instant) -> Deadline<Self> where Self: Sized, { Deadline::new(self, deadline) } } impl<T: ?Sized> FutureExt for T where T: Future {} #[cfg(test)] mod test { use super::*; use prelude::future; #[cfg(feature = "timer")] #[test] fn timeout_polls_at_least_once() { let base_future = future::result::<(), ()>(Ok(())); let timeouted_future = base_future.timeout(Duration::new(0, 0)); assert!(timeouted_future.wait().is_ok()); } }