1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
|
//! A sequence of asynchronous values.
#[cfg(feature = "timer")]
use std::time::Duration;
#[cfg(feature = "timer")]
use crate::timer::{throttle::Throttle, Timeout};
#[doc(inline)]
pub use futures_core::Stream;
#[doc(inline)]
pub use futures_util::stream::{empty, iter, once, pending, poll_fn, repeat, unfold};
/// An extension trait for `Stream` that provides a variety of convenient
/// combinator functions.
///
/// Currently, there are only [`timeout`] and [`throttle`] functions, but
/// this will increase over time.
///
/// Users are not expected to implement this trait. All types that implement
/// `Stream` already implement `StreamExt`.
///
/// This trait can be imported directly or via the Tokio prelude: `use
/// tokio::prelude::*`.
///
/// [`throttle`]: method.throttle
/// [`timeout`]: method.timeout
pub trait StreamExt: Stream {
/// Throttle down the stream by enforcing a fixed delay between items.
///
/// Errors are also delayed.
#[cfg(feature = "timer")]
fn throttle(self, duration: Duration) -> Throttle<Self>
where
Self: Sized,
{
Throttle::new(self, duration)
}
/// Creates a new stream which allows `self` until `timeout`.
///
/// This combinator creates a new stream which wraps the receiving stream
/// with a timeout. For each item, the returned stream is allowed to execute
/// until it completes or `timeout` has elapsed, whichever happens first.
///
/// If an item completes before `timeout` then the stream will yield
/// with that item. Otherwise the stream will yield to an error.
///
/// # Examples
///
/// ```
/// use tokio::prelude::*;
///
/// use std::time::Duration;
///
/// # fn slow_stream() -> impl Stream<Item = ()> {
/// # tokio::stream::empty()
/// # }
/// #
/// # async fn dox() {
/// let mut stream = slow_stream()
/// .timeout(Duration::from_secs(1));
///
/// while let Some(value) = stream.next().await {
/// println!("value = {:?}", value);
/// }
/// # }
/// ```
#[cfg(feature = "timer")]
fn timeout(self, timeout: Duration) -> Timeout<Self>
where
Self: Sized,
{
Timeout::new(self, timeout)
}
}
impl<T: ?Sized> StreamExt for T where T: Stream {}
|