1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
// SPDX-License-Identifier: Apache-2.0 OR MIT
// inspired by <https://github.com/nbdd0121/pin-init/blob/trunk/examples/pthread_mutex.rs>
#![allow(clippy::undocumented_unsafe_blocks)]
#![cfg_attr(feature = "alloc", feature(allocator_api))]
#[cfg(not(windows))]
mod pthread_mtx {
#[cfg(feature = "alloc")]
use core::alloc::AllocError;
use core::{
cell::UnsafeCell,
marker::PhantomPinned,
mem::MaybeUninit,
ops::{Deref, DerefMut},
pin::Pin,
};
use pin_init::*;
use std::convert::Infallible;
#[pin_data(PinnedDrop)]
pub struct PThreadMutex<T> {
#[pin]
raw: UnsafeCell<libc::pthread_mutex_t>,
data: UnsafeCell<T>,
#[pin]
pin: PhantomPinned,
}
unsafe impl<T: Send> Send for PThreadMutex<T> {}
unsafe impl<T: Send> Sync for PThreadMutex<T> {}
#[pinned_drop]
impl<T> PinnedDrop for PThreadMutex<T> {
fn drop(self: Pin<&mut Self>) {
unsafe {
libc::pthread_mutex_destroy(self.raw.get());
}
}
}
#[derive(Debug)]
pub enum Error {
#[expect(dead_code)]
IO(std::io::Error),
Alloc,
}
impl From<Infallible> for Error {
fn from(e: Infallible) -> Self {
match e {}
}
}
#[cfg(feature = "alloc")]
impl From<AllocError> for Error {
fn from(_: AllocError) -> Self {
Self::Alloc
}
}
impl<T> PThreadMutex<T> {
pub fn new(data: T) -> impl PinInit<Self, Error> {
fn init_raw() -> impl PinInit<UnsafeCell<libc::pthread_mutex_t>, Error> {
let init = |slot: *mut UnsafeCell<libc::pthread_mutex_t>| {
// we can cast, because `UnsafeCell` has the same layout as T.
let slot: *mut libc::pthread_mutex_t = slot.cast();
let mut attr = MaybeUninit::uninit();
let attr = attr.as_mut_ptr();
// SAFETY: ptr is valid
let ret = unsafe { libc::pthread_mutexattr_init(attr) };
if ret != 0 {
return Err(Error::IO(std::io::Error::from_raw_os_error(ret)));
}
// SAFETY: attr is initialized
let ret = unsafe {
libc::pthread_mutexattr_settype(attr, libc::PTHREAD_MUTEX_NORMAL)
};
if ret != 0 {
// SAFETY: attr is initialized
unsafe { libc::pthread_mutexattr_destroy(attr) };
return Err(Error::IO(std::io::Error::from_raw_os_error(ret)));
}
// SAFETY: slot is valid
unsafe { slot.write(libc::PTHREAD_MUTEX_INITIALIZER) };
// SAFETY: attr and slot are valid ptrs and attr is initialized
let ret = unsafe { libc::pthread_mutex_init(slot, attr) };
// SAFETY: attr was initialized
unsafe { libc::pthread_mutexattr_destroy(attr) };
if ret != 0 {
return Err(Error::IO(std::io::Error::from_raw_os_error(ret)));
}
Ok(())
};
// SAFETY: mutex has been initialized
unsafe { pin_init_from_closure(init) }
}
try_pin_init!(Self {
data: UnsafeCell::new(data),
raw <- init_raw(),
pin: PhantomPinned,
}? Error)
}
pub fn lock(&self) -> PThreadMutexGuard<'_, T> {
// SAFETY: raw is always initialized
unsafe { libc::pthread_mutex_lock(self.raw.get()) };
PThreadMutexGuard { mtx: self }
}
}
pub struct PThreadMutexGuard<'a, T> {
mtx: &'a PThreadMutex<T>,
}
impl<T> Drop for PThreadMutexGuard<'_, T> {
fn drop(&mut self) {
// SAFETY: raw is always initialized
unsafe { libc::pthread_mutex_unlock(self.mtx.raw.get()) };
}
}
impl<T> Deref for PThreadMutexGuard<'_, T> {
type Target = T;
fn deref(&self) -> &Self::Target {
unsafe { &*self.mtx.data.get() }
}
}
impl<T> DerefMut for PThreadMutexGuard<'_, T> {
fn deref_mut(&mut self) -> &mut Self::Target {
unsafe { &mut *self.mtx.data.get() }
}
}
}
#[cfg_attr(test, test)]
fn main() {
#[cfg(all(any(feature = "std", feature = "alloc"), not(windows)))]
{
use core::pin::Pin;
use pin_init::*;
use pthread_mtx::*;
use std::{
sync::Arc,
thread::{sleep, Builder},
time::Duration,
};
let mtx: Pin<Arc<PThreadMutex<usize>>> = Arc::try_pin_init(PThreadMutex::new(0)).unwrap();
let mut handles = vec![];
let thread_count = 20;
let workload = 1_000_000;
for i in 0..thread_count {
let mtx = mtx.clone();
handles.push(
Builder::new()
.name(format!("worker #{i}"))
.spawn(move || {
for _ in 0..workload {
*mtx.lock() += 1;
}
println!("{i} halfway");
sleep(Duration::from_millis((i as u64) * 10));
for _ in 0..workload {
*mtx.lock() += 1;
}
println!("{i} finished");
})
.expect("should not fail"),
);
}
for h in handles {
h.join().expect("thread panicked");
}
println!("{:?}", &*mtx.lock());
assert_eq!(*mtx.lock(), workload * thread_count * 2);
}
}
|
