ntex-util 2.14.0

Utilities for ntex framework
Documentation 
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
117

use std::{future::Future, mem, pin::Pin, task::Context, task::Poll};

use crate::future::MaybeDone;

/// Future for the `join` combinator, waiting for two futures to complete.
pub async fn join<A, B>(fut_a: A, fut_b: B) -> (A::Output, B::Output)
where
    A: Future,
    B: Future,
{
    Join {
        fut_a: MaybeDone::Pending(fut_a),
        fut_b: MaybeDone::Pending(fut_b),
    }
    .await
}

pin_project_lite::pin_project! {
    pub(crate) struct Join<A: Future, B: Future> {
        #[pin]
        fut_a: MaybeDone<A>,
        #[pin]
        fut_b: MaybeDone<B>,
    }
}

impl<A, B> Future for Join<A, B>
where
    A: Future,
    B: Future,
{
    type Output = (A::Output, B::Output);

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        let mut this = self.project();
        let mut all_done = true;
        all_done &= this.fut_a.as_mut().poll(cx).is_ready();
        all_done &= this.fut_b.as_mut().poll(cx).is_ready();
        if all_done {
            Poll::Ready((
                this.fut_a.take_output().unwrap(),
                this.fut_b.take_output().unwrap(),
            ))
        } else {
            Poll::Pending
        }
    }
}

/// Creates a future which represents a collection of the outputs of the futures
/// given.
pub async fn join_all<I>(i: I) -> Vec<<I::Item as Future>::Output>
where
    I: IntoIterator,
    I::Item: Future,
{
    let elems: Box<[_]> = i.into_iter().map(MaybeDone::Pending).collect();
    JoinAll {
        elems: elems.into(),
    }
    .await
}

pub(crate) struct JoinAll<T: Future> {
    elems: Pin<Box<[MaybeDone<T>]>>,
}

fn iter_pin_mut<T>(slice: Pin<&mut [T]>) -> impl Iterator<Item = Pin<&mut T>> {
    // Safety: `std` _could_ make this unsound if it were to decide Pin's
    // invariants aren't required to transmit through slices. Otherwise this has
    // the same safety as a normal field pin projection.
    unsafe { slice.get_unchecked_mut() }
        .iter_mut()
        .map(|t| unsafe { Pin::new_unchecked(t) })
}

impl<T> Future for JoinAll<T>
where
    T: Future,
{
    type Output = Vec<T::Output>;

    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        let mut all_done = true;

        for elem in iter_pin_mut(self.elems.as_mut()) {
            if elem.poll(cx).is_pending() {
                all_done = false;
            }
        }
        if all_done {
            let mut elems = mem::replace(&mut self.elems, Box::pin([]));
            let result = iter_pin_mut(elems.as_mut())
                .map(|e| e.take_output().unwrap())
                .collect();
            Poll::Ready(result)
        } else {
            Poll::Pending
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{future::Ready, time};

    #[ntex_macros::rt_test2]
    async fn join_tests() {
        let res = join(Ready::<_, ()>::Ok("test"), time::sleep(time::Millis(50))).await;
        assert_eq!(res, (Ok("test"), ()));

        let res =
            join_all([time::sleep(time::Millis(50)), time::sleep(time::Millis(60))]).await;
        assert_eq!(res, vec![(), ()]);
    }
}