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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());
}
}
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