1 | //! Abstracts over sync primitive implementations. |
2 | //! |
3 | //! Optionally, we allow the Rust standard library's `RwLock` to be replaced |
4 | //! with the `parking_lot` crate's implementation. This may provide improved |
5 | //! performance in some cases. However, the `parking_lot` dependency is an |
6 | //! opt-in feature flag. Because `parking_lot::RwLock` has a slightly different |
7 | //! API than `std::sync::RwLock` (it does not support poisoning on panics), we |
8 | //! wrap it with a type that provides the same method signatures. This allows us |
9 | //! to transparently swap `parking_lot` in without changing code at the callsite. |
10 | #[allow (unused_imports)] // may be used later; |
11 | pub(crate) use std::sync::{LockResult, PoisonError, TryLockResult}; |
12 | |
13 | #[cfg (not(feature = "parking_lot" ))] |
14 | pub(crate) use std::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard}; |
15 | |
16 | #[cfg (feature = "parking_lot" )] |
17 | pub(crate) use self::parking_lot_impl::*; |
18 | |
19 | #[cfg (feature = "parking_lot" )] |
20 | mod parking_lot_impl { |
21 | pub(crate) use parking_lot::{RwLockReadGuard, RwLockWriteGuard}; |
22 | use std::sync::{LockResult, TryLockError, TryLockResult}; |
23 | |
24 | #[derive (Debug)] |
25 | pub(crate) struct RwLock<T> { |
26 | inner: parking_lot::RwLock<T>, |
27 | } |
28 | |
29 | impl<T> RwLock<T> { |
30 | pub(crate) fn new(val: T) -> Self { |
31 | Self { |
32 | inner: parking_lot::RwLock::new(val), |
33 | } |
34 | } |
35 | |
36 | #[inline ] |
37 | pub(crate) fn get_mut(&mut self) -> LockResult<&mut T> { |
38 | Ok(self.inner.get_mut()) |
39 | } |
40 | |
41 | #[inline ] |
42 | pub(crate) fn read(&self) -> LockResult<RwLockReadGuard<'_, T>> { |
43 | Ok(self.inner.read()) |
44 | } |
45 | |
46 | #[inline ] |
47 | #[allow (dead_code)] // may be used later; |
48 | pub(crate) fn try_read(&self) -> TryLockResult<RwLockReadGuard<'_, T>> { |
49 | self.inner.try_read().ok_or(TryLockError::WouldBlock) |
50 | } |
51 | |
52 | #[inline ] |
53 | pub(crate) fn write(&self) -> LockResult<RwLockWriteGuard<'_, T>> { |
54 | Ok(self.inner.write()) |
55 | } |
56 | } |
57 | } |
58 | |