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
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
use std::fmt::Display;
use std::any::Any;
use std::time::{Instant, Duration};
use futures::Future;
use log::LogLevel;
use void::Void;
use log_error::LogError;
use until::Until;
use infallible::Infallible;
use finally::Finally;
use with_timeout::WithTimeout;
use first_ok2::FirstOk2;
use while_driving::WhileDriving;
use resume_unwind::ResumeUnwind;
use BoxFuture;
use BoxSendFuture;
/// Extension trait for `Future`.
pub trait FutureExt: Future + Sized {
/// Wraps a future into a boxed future, making type-checking easier at the expense of an extra
/// layer of indirection at runtime.
fn into_boxed(self) -> BoxFuture<Self::Item, Self::Error>
where
Self: 'static
{
Box::new(self)
}
fn into_send_boxed(self) -> BoxSendFuture<Self::Item, Self::Error>
where
Self: Send + 'static,
{
Box::new(self)
}
/// Run this future until some condition is met. If `condition` resolves before `self` then
/// `None` is returned.
///
/// # Example
/// ```rust
/// let my_future_with_timeout = my_future.until(Delay::new(Instant::now() + Duration::from_secs(1)));
/// ```
fn until<C>(self, condition: C) -> Until<Self, C>
where
C: Future<Item=()>,
Self::Error: From<C::Error>
{
Until::new(self, condition)
}
/// For futures which can't fail (ie. which have error type `Void`), cast the error type to
/// some inferred type.
fn infallible<E>(self) -> Infallible<Self, E>
where
Self: Future<Error=Void>
{
Infallible::new(self)
}
/// Take a future which returns `()` and log its error if it fails. The returned future cannot
/// fail and will always resolve to `()`.
fn log_error(self, level: LogLevel, description: &'static str) -> LogError<Self>
where
Self: Future<Item=()>,
Self::Error: Display,
{
LogError::new(self, level, description)
}
/// Executes the future and runs the provided callback when the future finishes. The callback
/// will also be run if the entire future is dropped.
fn finally<D>(self, on_drop: D) -> Finally<Self, D>
where
D: FnOnce()
{
Finally::new(self, on_drop)
}
/// Runs the future for the given duration, returning its value in an option, or returning
/// `None` if the timeout expires.
fn with_timeout(self, duration: Duration) -> WithTimeout<Self> {
WithTimeout::new(self, duration)
}
/// Runs the future until the given instant, returning its value in an option, or returning
/// `None` if the timeout expires.
fn with_timeout_at(self, instant: Instant) -> WithTimeout<Self> {
WithTimeout::new_at(self, instant)
}
/// Run two futures in parallel and yield the value of the first to return success. If both
/// futures fail, return both errors.
fn first_ok2<F>(self, other: F) -> FirstOk2<Self, F>
where
F: Future<Item = Self::Item>
{
FirstOk2::new(self, other)
}
/// Resolves `self` while driving `other` in parallel.
fn while_driving<F: Future>(self, other: F) -> WhileDriving<Self, F> {
WhileDriving::new(self, other)
}
/// Propogates the result of a `.catch_unwind`, panicking if the future resolves to an `Err`
fn resume_unwind(self) -> ResumeUnwind<Self>
where
Self: Future<Error=Box<Any + Send + 'static>>,
{
ResumeUnwind::new(self)
}
}
impl<T: Future + Sized> FutureExt for T {}