1 | use std::cell::UnsafeCell; |
2 | use std::fmt; |
3 | use std::ops::Deref; |
4 | |
5 | /// `AtomicU32` providing an additional `unsync_load` function. |
6 | pub(crate) struct AtomicU32 { |
7 | inner: UnsafeCell<std::sync::atomic::AtomicU32>, |
8 | } |
9 | |
10 | unsafe impl Send for AtomicU32 {} |
11 | unsafe impl Sync for AtomicU32 {} |
12 | |
13 | impl AtomicU32 { |
14 | pub(crate) const fn new(val: u32) -> AtomicU32 { |
15 | let inner = UnsafeCell::new(std::sync::atomic::AtomicU32::new(val)); |
16 | AtomicU32 { inner } |
17 | } |
18 | |
19 | /// Performs an unsynchronized load. |
20 | /// |
21 | /// # Safety |
22 | /// |
23 | /// All mutations must have happened before the unsynchronized load. |
24 | /// Additionally, there must be no concurrent mutations. |
25 | pub(crate) unsafe fn unsync_load(&self) -> u32 { |
26 | // See <https://github.com/tokio-rs/tokio/issues/6155> |
27 | self.load(std::sync::atomic::Ordering::Relaxed) |
28 | } |
29 | } |
30 | |
31 | impl Deref for AtomicU32 { |
32 | type Target = std::sync::atomic::AtomicU32; |
33 | |
34 | fn deref(&self) -> &Self::Target { |
35 | // safety: it is always safe to access `&self` fns on the inner value as |
36 | // we never perform unsafe mutations. |
37 | unsafe { &*self.inner.get() } |
38 | } |
39 | } |
40 | |
41 | impl fmt::Debug for AtomicU32 { |
42 | fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { |
43 | self.deref().fmt(fmt) |
44 | } |
45 | } |
46 | |