musli_common/context/
access.rs

1use core::cell::Cell;
2
3/// Guarded access to some underlying state.
4pub(crate) struct Access {
5    state: Cell<isize>,
6}
7
8impl Access {
9    pub(crate) fn new() -> Self {
10        Self {
11            state: Cell::new(0),
12        }
13    }
14
15    #[inline]
16    pub(crate) fn shared(&self) -> Shared<'_> {
17        let state = self.state.get();
18
19        if state > 0 {
20            panic!("Context is exclusively held")
21        }
22
23        if state == isize::MIN {
24            crate::system::abort();
25        }
26
27        self.state.set(state - 1);
28
29        Shared { access: self }
30    }
31
32    #[inline]
33    pub(crate) fn exclusive(&self) -> Exlusive<'_> {
34        let state = self.state.get();
35
36        if state != 0 {
37            panic!("Context is already in shared use")
38        }
39
40        if state == isize::MIN {
41            crate::system::abort();
42        }
43
44        self.state.set(1);
45        Exlusive { access: self }
46    }
47}
48
49/// A shared access to some underlying state.
50pub(crate) struct Shared<'a> {
51    access: &'a Access,
52}
53
54impl Drop for Shared<'_> {
55    fn drop(&mut self) {
56        self.access.state.set(self.access.state.get() + 1);
57    }
58}
59
60/// An exclusive access to some underlying state.
61pub(crate) struct Exlusive<'a> {
62    access: &'a Access,
63}
64
65impl Drop for Exlusive<'_> {
66    fn drop(&mut self) {
67        self.access.state.set(0);
68    }
69}
musli_common/context/access.rs

musli_common/context/
access.rs
