swansong 0.3.4

Graceful Shutdown
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
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146

use crate::{Guard, Inner};
use event_listener::EventListener;
use std::{
    ops::{Deref, DerefMut},
    sync::{Arc, Weak},
};

#[cfg(any(feature = "tokio", feature = "futures-io"))]
mod async_read;
#[cfg(any(feature = "tokio", feature = "futures-io"))]
mod async_write;

mod future;
mod iterator;
mod stream;

pin_project_lite::pin_project! {
    /// A wrapper type that implements Stream when wrapping a [`Stream`] and [`Future`] when wrapping a
    /// Future
    ///
    /// When the associated [`Swansong`][crate::Swansong] is stopped with
    /// [`Swansong::shut_down`][crate::Swansong::shut_down] or all clones of the [`Swansong`] have dropped,
    /// the Future or Stream within this Stop will wake and return `Poll::Ready(None)` on next poll,
    /// regardless of where it is being polled.
    #[derive(Debug)]
    pub struct Interrupt<T> {
        inner: WeakInner,
        #[pin]
        wrapped_type: T,
        guard: Option<Guard>,
        stop_listener: StopListener,
    }
}

impl<T: Eq> Eq for Interrupt<T> {}

impl<T, U> PartialEq<Interrupt<U>> for Interrupt<T>
where
    T: PartialEq<U>,
{
    fn eq(&self, other: &Interrupt<U>) -> bool {
        self.inner.ptr_eq(&other.inner) && self.wrapped_type == other.wrapped_type
    }
}

impl<T> Interrupt<T> {
    pub(crate) fn new(inner: &Arc<Inner>, wrapped_type: T) -> Self {
        Self {
            inner: WeakInner(Arc::downgrade(inner)),
            wrapped_type,
            guard: None,
            stop_listener: StopListener(None),
        }
    }

    /// Chainable setter to delay shutdown until this wrapper type has dropped.
    #[must_use]
    pub fn guarded(mut self) -> Self {
        if let Some(inner) = self.inner.upgrade() {
            self.guard = Some(Guard::new(&inner));
        }
        self
    }

    /// Take the wrapped type out of this Interrupt.
    ///
    /// If the interrupt is guarded with [`Interrupt::guarded`], this will decrement the guard count.
    pub fn into_inner(self) -> T {
        self.wrapped_type
    }

    pub(crate) fn is_stopped(&self) -> bool {
        self.inner.is_stopped()
    }

    #[cfg(any(feature = "futures-io", feature = "tokio"))]
    pub(crate) fn is_stopped_relaxed(&self) -> bool {
        self.inner.is_stopped_relaxed()
    }
}

impl<T> Deref for Interrupt<T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        &self.wrapped_type
    }
}

impl<T> DerefMut for Interrupt<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.wrapped_type
    }
}

#[derive(Debug)]
struct WeakInner(Weak<Inner>);
impl Deref for WeakInner {
    type Target = Weak<Inner>;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl WeakInner {
    fn is_stopped(&self) -> bool {
        self.upgrade().as_deref().is_none_or(Inner::is_stopped)
    }
    fn is_stopped_relaxed(&self) -> bool {
        self.upgrade()
            .as_deref()
            .is_none_or(Inner::is_stopped_relaxed)
    }
}

#[derive(Debug)]
struct StopListener(Option<EventListener>);
impl StopListener {
    fn listen(&mut self, weak_inner: &WeakInner) -> Option<&mut EventListener> {
        let Self(listener) = self;
        if let Some(listener) = listener {
            return Some(listener);
        }
        let inner = weak_inner.upgrade()?;
        let listener = listener.insert(inner.listen_stop());
        if inner.is_stopped() {
            log::trace!("inner was stopped after registering new listener");
            None
        } else {
            log::trace!("registered new listener");
            Some(listener)
        }
    }
}
impl Deref for StopListener {
    type Target = Option<EventListener>;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl DerefMut for StopListener {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}