sled/
fastlock.rs

1use std::{
2    cell::UnsafeCell,
3    ops::{Deref, DerefMut},
4    sync::atomic::{
5        AtomicBool,
6        Ordering::{Acquire, Release},
7    },
8};
9
10pub struct FastLockGuard<'a, T> {
11    mu: &'a FastLock<T>,
12}
13
14impl<'a, T> Drop for FastLockGuard<'a, T> {
15    fn drop(&mut self) {
16        assert!(self.mu.lock.swap(false, Release));
17    }
18}
19
20impl<'a, T> Deref for FastLockGuard<'a, T> {
21    type Target = T;
22
23    fn deref(&self) -> &T {
24        #[allow(unsafe_code)]
25        unsafe {
26            &*self.mu.inner.get()
27        }
28    }
29}
30
31impl<'a, T> DerefMut for FastLockGuard<'a, T> {
32    fn deref_mut(&mut self) -> &mut T {
33        #[allow(unsafe_code)]
34        unsafe {
35            &mut *self.mu.inner.get()
36        }
37    }
38}
39
40pub struct FastLock<T> {
41    lock: AtomicBool,
42    inner: UnsafeCell<T>,
43}
44
45impl<T> FastLock<T> {
46    pub fn new(inner: T) -> FastLock<T> {
47        FastLock { lock: AtomicBool::new(false), inner: UnsafeCell::new(inner) }
48    }
49
50    pub fn try_lock(&self) -> Option<FastLockGuard<'_, T>> {
51        let lock_result = self.lock.compare_and_swap(false, true, Acquire);
52
53        // `compare_and_swap` returns the last value if successful,
54        // otherwise the current value. If we succeed, it should return false.
55        let success = !lock_result;
56
57        if success { Some(FastLockGuard { mu: self }) } else { None }
58    }
59}
sled/fastlock.rs

sled/
fastlock.rs
