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Commit | Line | Data |
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1a4d82fc JJ |
1 | //! Generic support for building blocking abstractions. |
2 | ||
60c5eb7d | 3 | use crate::mem; |
532ac7d7 XL |
4 | use crate::sync::atomic::{AtomicBool, Ordering}; |
5 | use crate::sync::Arc; | |
60c5eb7d | 6 | use crate::thread::{self, Thread}; |
532ac7d7 | 7 | use crate::time::Instant; |
1a4d82fc JJ |
8 | |
9 | struct Inner { | |
10 | thread: Thread, | |
11 | woken: AtomicBool, | |
12 | } | |
13 | ||
14 | unsafe impl Send for Inner {} | |
15 | unsafe impl Sync for Inner {} | |
16 | ||
17 | #[derive(Clone)] | |
18 | pub struct SignalToken { | |
19 | inner: Arc<Inner>, | |
20 | } | |
21 | ||
22 | pub struct WaitToken { | |
23 | inner: Arc<Inner>, | |
1a4d82fc JJ |
24 | } |
25 | ||
85aaf69f SL |
26 | impl !Send for WaitToken {} |
27 | ||
28 | impl !Sync for WaitToken {} | |
29 | ||
1a4d82fc | 30 | pub fn tokens() -> (WaitToken, SignalToken) { |
60c5eb7d XL |
31 | let inner = Arc::new(Inner { thread: thread::current(), woken: AtomicBool::new(false) }); |
32 | let wait_token = WaitToken { inner: inner.clone() }; | |
33 | let signal_token = SignalToken { inner }; | |
1a4d82fc JJ |
34 | (wait_token, signal_token) |
35 | } | |
36 | ||
37 | impl SignalToken { | |
38 | pub fn signal(&self) -> bool { | |
39 | let wake = !self.inner.woken.compare_and_swap(false, true, Ordering::SeqCst); | |
40 | if wake { | |
41 | self.inner.thread.unpark(); | |
42 | } | |
43 | wake | |
44 | } | |
45 | ||
9fa01778 | 46 | /// Converts to an unsafe usize value. Useful for storing in a pipe's state |
1a4d82fc JJ |
47 | /// flag. |
48 | #[inline] | |
c34b1796 | 49 | pub unsafe fn cast_to_usize(self) -> usize { |
1a4d82fc JJ |
50 | mem::transmute(self.inner) |
51 | } | |
52 | ||
9fa01778 | 53 | /// Converts from an unsafe usize value. Useful for retrieving a pipe's state |
1a4d82fc JJ |
54 | /// flag. |
55 | #[inline] | |
c34b1796 | 56 | pub unsafe fn cast_from_usize(signal_ptr: usize) -> SignalToken { |
1a4d82fc JJ |
57 | SignalToken { inner: mem::transmute(signal_ptr) } |
58 | } | |
1a4d82fc JJ |
59 | } |
60 | ||
61 | impl WaitToken { | |
62 | pub fn wait(self) { | |
63 | while !self.inner.woken.load(Ordering::SeqCst) { | |
85aaf69f | 64 | thread::park() |
1a4d82fc JJ |
65 | } |
66 | } | |
3157f602 | 67 | |
9fa01778 | 68 | /// Returns `true` if we wake up normally. |
3157f602 XL |
69 | pub fn wait_max_until(self, end: Instant) -> bool { |
70 | while !self.inner.woken.load(Ordering::SeqCst) { | |
71 | let now = Instant::now(); | |
72 | if now >= end { | |
73 | return false; | |
74 | } | |
75 | thread::park_timeout(end - now) | |
76 | } | |
77 | true | |
78 | } | |
1a4d82fc | 79 | } |