summaryrefslogtreecommitdiffstats
path: root/vendor/gix-features/src/interrupt.rs
blob: dc7a2db170ff82dc0b9de92565ccdcc9cd46e5d3 (plain)
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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
//! Utilities to cause interruptions in common traits, like Read/Write and Iterator.
use std::{
    io,
    sync::atomic::{AtomicBool, Ordering},
};

/// A wrapper for an inner iterator which will check for interruptions on each iteration, stopping the iteration when
/// that is requested.
pub struct Iter<'a, I> {
    /// The actual iterator to yield elements from.
    pub inner: I,
    should_interrupt: &'a AtomicBool,
}

impl<'a, I> Iter<'a, I>
where
    I: Iterator,
{
    /// Create a new iterator over `inner` which checks for interruptions on each iteration on `should_interrupt`.
    ///
    /// Note that this means the consumer of the iterator data should also be able to access `should_interrupt` and
    /// consider it when producing the final result to avoid claiming success even though the operation is only partially
    /// complete.
    pub fn new(inner: I, should_interrupt: &'a AtomicBool) -> Self {
        Iter {
            inner,
            should_interrupt,
        }
    }
}

impl<'a, I> Iterator for Iter<'a, I>
where
    I: Iterator,
{
    type Item = I::Item;

    fn next(&mut self) -> Option<Self::Item> {
        if self.should_interrupt.load(Ordering::Relaxed) {
            return None;
        }
        self.inner.next()
    }
}

/// A wrapper for an inner iterator which will check for interruptions on each iteration.
pub struct IterWithErr<'a, I, EFN> {
    /// The actual iterator to yield elements from.
    pub inner: I,
    make_err: Option<EFN>,
    should_interrupt: &'a AtomicBool,
}

impl<'a, I, EFN, E> IterWithErr<'a, I, EFN>
where
    I: Iterator,
    EFN: FnOnce() -> E,
{
    /// Create a new iterator over `inner` which checks for interruptions on each iteration and calls `make_err()` to
    /// signal an interruption happened, causing no further items to be iterated from that point on.
    pub fn new(inner: I, make_err: EFN, should_interrupt: &'a AtomicBool) -> Self {
        IterWithErr {
            inner,
            make_err: Some(make_err),
            should_interrupt,
        }
    }
}

impl<'a, I, EFN, E> Iterator for IterWithErr<'a, I, EFN>
where
    I: Iterator,
    EFN: FnOnce() -> E,
{
    type Item = Result<I::Item, E>;

    fn next(&mut self) -> Option<Self::Item> {
        self.make_err.as_ref()?;
        if self.should_interrupt.load(Ordering::Relaxed) {
            return self.make_err.take().map(|f| Err(f()));
        }
        match self.inner.next() {
            Some(next) => Some(Ok(next)),
            None => {
                self.make_err = None;
                None
            }
        }
    }
}

/// A wrapper for implementors of [`std::io::Read`] or [`std::io::BufRead`] with interrupt support.
///
/// It fails a [read][std::io::Read::read] while an interrupt was requested.
pub struct Read<'a, R> {
    /// The actual implementor of [`std::io::Read`] to which interrupt support will be added.
    pub inner: R,
    /// The flag to trigger interruption
    pub should_interrupt: &'a AtomicBool,
}

impl<'a, R> io::Read for Read<'a, R>
where
    R: io::Read,
{
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        if self.should_interrupt.load(Ordering::Relaxed) {
            return Err(std::io::Error::new(std::io::ErrorKind::Other, "Interrupted"));
        }
        self.inner.read(buf)
    }
}

impl<'a, R> io::BufRead for Read<'a, R>
where
    R: io::BufRead,
{
    fn fill_buf(&mut self) -> io::Result<&[u8]> {
        self.inner.fill_buf()
    }

    fn consume(&mut self, amt: usize) {
        self.inner.consume(amt)
    }
}

/// A wrapper for implementors of [`std::io::Write`] with interrupt checks on each write call.
///
/// It fails a [write][std::io::Write::write] while an interrupt was requested.
pub struct Write<'a, W> {
    /// The actual implementor of [`std::io::Write`] to which interrupt support will be added.
    pub inner: W,
    /// The flag to trigger interruption
    pub should_interrupt: &'a AtomicBool,
}

impl<W> io::Write for Write<'_, W>
where
    W: std::io::Write,
{
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        if self.should_interrupt.load(Ordering::Relaxed) {
            return Err(std::io::Error::new(std::io::ErrorKind::Other, "Interrupted"));
        }
        self.inner.write(buf)
    }

    fn flush(&mut self) -> io::Result<()> {
        // Don't interrupt here, allow flushes to happen to prefer disk consistency.
        self.inner.flush()
    }
}

impl<W> io::Seek for Write<'_, W>
where
    W: std::io::Seek,
{
    fn seek(&mut self, pos: io::SeekFrom) -> io::Result<u64> {
        self.inner.seek(pos)
    }
}