]>
Commit | Line | Data |
---|---|---|
532ac7d7 XL |
1 | use crate::cell::UnsafeCell; |
2 | use crate::fmt; | |
3 | use crate::mem; | |
4 | use crate::ops::{Deref, DerefMut}; | |
5 | use crate::ptr; | |
6 | use crate::sys_common::mutex as sys; | |
dfeec247 | 7 | use crate::sys_common::poison::{self, LockResult, TryLockError, TryLockResult}; |
1a4d82fc JJ |
8 | |
9 | /// A mutual exclusion primitive useful for protecting shared data | |
10 | /// | |
11 | /// This mutex will block threads waiting for the lock to become available. The | |
ea8adc8c | 12 | /// mutex can also be statically initialized or created via a [`new`] |
1a4d82fc JJ |
13 | /// constructor. Each mutex has a type parameter which represents the data that |
14 | /// it is protecting. The data can only be accessed through the RAII guards | |
ea8adc8c | 15 | /// returned from [`lock`] and [`try_lock`], which guarantees that the data is only |
1a4d82fc JJ |
16 | /// ever accessed when the mutex is locked. |
17 | /// | |
18 | /// # Poisoning | |
19 | /// | |
20 | /// The mutexes in this module implement a strategy called "poisoning" where a | |
21 | /// mutex is considered poisoned whenever a thread panics while holding the | |
cc61c64b | 22 | /// mutex. Once a mutex is poisoned, all other threads are unable to access the |
1a4d82fc JJ |
23 | /// data by default as it is likely tainted (some invariant is not being |
24 | /// upheld). | |
25 | /// | |
ea8adc8c XL |
26 | /// For a mutex, this means that the [`lock`] and [`try_lock`] methods return a |
27 | /// [`Result`] which indicates whether a mutex has been poisoned or not. Most | |
28 | /// usage of a mutex will simply [`unwrap()`] these results, propagating panics | |
1a4d82fc JJ |
29 | /// among threads to ensure that a possibly invalid invariant is not witnessed. |
30 | /// | |
31 | /// A poisoned mutex, however, does not prevent all access to the underlying | |
ea8adc8c | 32 | /// data. The [`PoisonError`] type has an [`into_inner`] method which will return |
1a4d82fc JJ |
33 | /// the guard that would have otherwise been returned on a successful lock. This |
34 | /// allows access to the data, despite the lock being poisoned. | |
35 | /// | |
ea8adc8c XL |
36 | /// [`new`]: #method.new |
37 | /// [`lock`]: #method.lock | |
38 | /// [`try_lock`]: #method.try_lock | |
39 | /// [`Result`]: ../../std/result/enum.Result.html | |
40 | /// [`unwrap()`]: ../../std/result/enum.Result.html#method.unwrap | |
41 | /// [`PoisonError`]: ../../std/sync/struct.PoisonError.html | |
42 | /// [`into_inner`]: ../../std/sync/struct.PoisonError.html#method.into_inner | |
43 | /// | |
1a4d82fc JJ |
44 | /// # Examples |
45 | /// | |
c34b1796 | 46 | /// ``` |
1a4d82fc | 47 | /// use std::sync::{Arc, Mutex}; |
85aaf69f | 48 | /// use std::thread; |
1a4d82fc JJ |
49 | /// use std::sync::mpsc::channel; |
50 | /// | |
c34b1796 | 51 | /// const N: usize = 10; |
1a4d82fc JJ |
52 | /// |
53 | /// // Spawn a few threads to increment a shared variable (non-atomically), and | |
54 | /// // let the main thread know once all increments are done. | |
55 | /// // | |
bd371182 | 56 | /// // Here we're using an Arc to share memory among threads, and the data inside |
1a4d82fc JJ |
57 | /// // the Arc is protected with a mutex. |
58 | /// let data = Arc::new(Mutex::new(0)); | |
59 | /// | |
60 | /// let (tx, rx) = channel(); | |
cc61c64b | 61 | /// for _ in 0..N { |
a1dfa0c6 | 62 | /// let (data, tx) = (Arc::clone(&data), tx.clone()); |
85aaf69f | 63 | /// thread::spawn(move || { |
92a42be0 | 64 | /// // The shared state can only be accessed once the lock is held. |
1a4d82fc JJ |
65 | /// // Our non-atomic increment is safe because we're the only thread |
66 | /// // which can access the shared state when the lock is held. | |
67 | /// // | |
68 | /// // We unwrap() the return value to assert that we are not expecting | |
bd371182 | 69 | /// // threads to ever fail while holding the lock. |
1a4d82fc JJ |
70 | /// let mut data = data.lock().unwrap(); |
71 | /// *data += 1; | |
72 | /// if *data == N { | |
73 | /// tx.send(()).unwrap(); | |
74 | /// } | |
75 | /// // the lock is unlocked here when `data` goes out of scope. | |
76 | /// }); | |
77 | /// } | |
78 | /// | |
79 | /// rx.recv().unwrap(); | |
80 | /// ``` | |
81 | /// | |
82 | /// To recover from a poisoned mutex: | |
83 | /// | |
c34b1796 | 84 | /// ``` |
1a4d82fc | 85 | /// use std::sync::{Arc, Mutex}; |
85aaf69f | 86 | /// use std::thread; |
1a4d82fc | 87 | /// |
85aaf69f | 88 | /// let lock = Arc::new(Mutex::new(0_u32)); |
1a4d82fc JJ |
89 | /// let lock2 = lock.clone(); |
90 | /// | |
85aaf69f | 91 | /// let _ = thread::spawn(move || -> () { |
1a4d82fc JJ |
92 | /// // This thread will acquire the mutex first, unwrapping the result of |
93 | /// // `lock` because the lock has not been poisoned. | |
7453a54e | 94 | /// let _guard = lock2.lock().unwrap(); |
1a4d82fc JJ |
95 | /// |
96 | /// // This panic while holding the lock (`_guard` is in scope) will poison | |
97 | /// // the mutex. | |
98 | /// panic!(); | |
99 | /// }).join(); | |
100 | /// | |
101 | /// // The lock is poisoned by this point, but the returned result can be | |
102 | /// // pattern matched on to return the underlying guard on both branches. | |
103 | /// let mut guard = match lock.lock() { | |
104 | /// Ok(guard) => guard, | |
c34b1796 | 105 | /// Err(poisoned) => poisoned.into_inner(), |
1a4d82fc JJ |
106 | /// }; |
107 | /// | |
108 | /// *guard += 1; | |
109 | /// ``` | |
85aaf69f | 110 | #[stable(feature = "rust1", since = "1.0.0")] |
f9f354fc | 111 | #[cfg_attr(not(test), rustc_diagnostic_item = "mutex_type")] |
d9579d0f | 112 | pub struct Mutex<T: ?Sized> { |
5bcae85e SL |
113 | // Note that this mutex is in a *box*, not inlined into the struct itself. |
114 | // Once a native mutex has been used once, its address can never change (it | |
115 | // can't be moved). This mutex type can be safely moved at any time, so to | |
cc61c64b | 116 | // ensure that the native mutex is used correctly we box the inner mutex to |
5bcae85e SL |
117 | // give it a constant address. |
118 | inner: Box<sys::Mutex>, | |
119 | poison: poison::Flag, | |
1a4d82fc JJ |
120 | data: UnsafeCell<T>, |
121 | } | |
122 | ||
c34b1796 AL |
123 | // these are the only places where `T: Send` matters; all other |
124 | // functionality works fine on a single thread. | |
92a42be0 | 125 | #[stable(feature = "rust1", since = "1.0.0")] |
dfeec247 | 126 | unsafe impl<T: ?Sized + Send> Send for Mutex<T> {} |
92a42be0 | 127 | #[stable(feature = "rust1", since = "1.0.0")] |
dfeec247 | 128 | unsafe impl<T: ?Sized + Send> Sync for Mutex<T> {} |
1a4d82fc | 129 | |
1a4d82fc JJ |
130 | /// An RAII implementation of a "scoped lock" of a mutex. When this structure is |
131 | /// dropped (falls out of scope), the lock will be unlocked. | |
132 | /// | |
cc61c64b | 133 | /// The data protected by the mutex can be accessed through this guard via its |
8bb4bdeb | 134 | /// [`Deref`] and [`DerefMut`] implementations. |
476ff2be | 135 | /// |
cc61c64b | 136 | /// This structure is created by the [`lock`] and [`try_lock`] methods on |
476ff2be SL |
137 | /// [`Mutex`]. |
138 | /// | |
8bb4bdeb XL |
139 | /// [`Deref`]: ../../std/ops/trait.Deref.html |
140 | /// [`DerefMut`]: ../../std/ops/trait.DerefMut.html | |
cc61c64b XL |
141 | /// [`lock`]: struct.Mutex.html#method.lock |
142 | /// [`try_lock`]: struct.Mutex.html#method.try_lock | |
476ff2be | 143 | /// [`Mutex`]: struct.Mutex.html |
94b46f34 | 144 | #[must_use = "if unused the Mutex will immediately unlock"] |
85aaf69f | 145 | #[stable(feature = "rust1", since = "1.0.0")] |
d9579d0f | 146 | pub struct MutexGuard<'a, T: ?Sized + 'a> { |
60c5eb7d XL |
147 | lock: &'a Mutex<T>, |
148 | poison: poison::Guard, | |
1a4d82fc JJ |
149 | } |
150 | ||
92a42be0 | 151 | #[stable(feature = "rust1", since = "1.0.0")] |
dfeec247 | 152 | impl<T: ?Sized> !Send for MutexGuard<'_, T> {} |
7cac9316 | 153 | #[stable(feature = "mutexguard", since = "1.19.0")] |
dfeec247 | 154 | unsafe impl<T: ?Sized + Sync> Sync for MutexGuard<'_, T> {} |
85aaf69f | 155 | |
c34b1796 | 156 | impl<T> Mutex<T> { |
1a4d82fc | 157 | /// Creates a new mutex in an unlocked state ready for use. |
32a655c1 SL |
158 | /// |
159 | /// # Examples | |
160 | /// | |
161 | /// ``` | |
162 | /// use std::sync::Mutex; | |
163 | /// | |
164 | /// let mutex = Mutex::new(0); | |
165 | /// ``` | |
85aaf69f | 166 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 167 | pub fn new(t: T) -> Mutex<T> { |
3157f602 | 168 | let mut m = Mutex { |
5bcae85e SL |
169 | inner: box sys::Mutex::new(), |
170 | poison: poison::Flag::new(), | |
1a4d82fc | 171 | data: UnsafeCell::new(t), |
3157f602 XL |
172 | }; |
173 | unsafe { | |
5bcae85e | 174 | m.inner.init(); |
1a4d82fc | 175 | } |
3157f602 | 176 | m |
1a4d82fc | 177 | } |
d9579d0f | 178 | } |
1a4d82fc | 179 | |
d9579d0f | 180 | impl<T: ?Sized> Mutex<T> { |
bd371182 | 181 | /// Acquires a mutex, blocking the current thread until it is able to do so. |
1a4d82fc | 182 | /// |
bd371182 | 183 | /// This function will block the local thread until it is available to acquire |
cc61c64b | 184 | /// the mutex. Upon returning, the thread is the only thread with the lock |
1a4d82fc JJ |
185 | /// held. An RAII guard is returned to allow scoped unlock of the lock. When |
186 | /// the guard goes out of scope, the mutex will be unlocked. | |
187 | /// | |
a7813a04 XL |
188 | /// The exact behavior on locking a mutex in the thread which already holds |
189 | /// the lock is left unspecified. However, this function will not return on | |
190 | /// the second call (it might panic or deadlock, for example). | |
191 | /// | |
7453a54e | 192 | /// # Errors |
1a4d82fc JJ |
193 | /// |
194 | /// If another user of this mutex panicked while holding the mutex, then | |
195 | /// this call will return an error once the mutex is acquired. | |
a7813a04 XL |
196 | /// |
197 | /// # Panics | |
198 | /// | |
199 | /// This function might panic when called if the lock is already held by | |
200 | /// the current thread. | |
32a655c1 SL |
201 | /// |
202 | /// # Examples | |
203 | /// | |
204 | /// ``` | |
205 | /// use std::sync::{Arc, Mutex}; | |
206 | /// use std::thread; | |
207 | /// | |
208 | /// let mutex = Arc::new(Mutex::new(0)); | |
209 | /// let c_mutex = mutex.clone(); | |
210 | /// | |
211 | /// thread::spawn(move || { | |
212 | /// *c_mutex.lock().unwrap() = 10; | |
213 | /// }).join().expect("thread::spawn failed"); | |
214 | /// assert_eq!(*mutex.lock().unwrap(), 10); | |
215 | /// ``` | |
85aaf69f | 216 | #[stable(feature = "rust1", since = "1.0.0")] |
532ac7d7 | 217 | pub fn lock(&self) -> LockResult<MutexGuard<'_, T>> { |
7453a54e | 218 | unsafe { |
94b46f34 | 219 | self.inner.raw_lock(); |
5bcae85e | 220 | MutexGuard::new(self) |
7453a54e | 221 | } |
1a4d82fc JJ |
222 | } |
223 | ||
224 | /// Attempts to acquire this lock. | |
225 | /// | |
ea8adc8c | 226 | /// If the lock could not be acquired at this time, then [`Err`] is returned. |
1a4d82fc JJ |
227 | /// Otherwise, an RAII guard is returned. The lock will be unlocked when the |
228 | /// guard is dropped. | |
229 | /// | |
230 | /// This function does not block. | |
231 | /// | |
7453a54e | 232 | /// # Errors |
1a4d82fc JJ |
233 | /// |
234 | /// If another user of this mutex panicked while holding the mutex, then | |
235 | /// this call will return failure if the mutex would otherwise be | |
236 | /// acquired. | |
32a655c1 | 237 | /// |
ea8adc8c XL |
238 | /// [`Err`]: ../../std/result/enum.Result.html#variant.Err |
239 | /// | |
32a655c1 SL |
240 | /// # Examples |
241 | /// | |
242 | /// ``` | |
243 | /// use std::sync::{Arc, Mutex}; | |
244 | /// use std::thread; | |
245 | /// | |
246 | /// let mutex = Arc::new(Mutex::new(0)); | |
247 | /// let c_mutex = mutex.clone(); | |
248 | /// | |
249 | /// thread::spawn(move || { | |
250 | /// let mut lock = c_mutex.try_lock(); | |
251 | /// if let Ok(ref mut mutex) = lock { | |
252 | /// **mutex = 10; | |
253 | /// } else { | |
254 | /// println!("try_lock failed"); | |
255 | /// } | |
256 | /// }).join().expect("thread::spawn failed"); | |
257 | /// assert_eq!(*mutex.lock().unwrap(), 10); | |
258 | /// ``` | |
85aaf69f | 259 | #[stable(feature = "rust1", since = "1.0.0")] |
532ac7d7 | 260 | pub fn try_lock(&self) -> TryLockResult<MutexGuard<'_, T>> { |
7453a54e | 261 | unsafe { |
5bcae85e SL |
262 | if self.inner.try_lock() { |
263 | Ok(MutexGuard::new(self)?) | |
7453a54e SL |
264 | } else { |
265 | Err(TryLockError::WouldBlock) | |
266 | } | |
1a4d82fc JJ |
267 | } |
268 | } | |
85aaf69f | 269 | |
cc61c64b | 270 | /// Determines whether the mutex is poisoned. |
85aaf69f | 271 | /// |
cc61c64b | 272 | /// If another thread is active, the mutex can still become poisoned at any |
32a655c1 | 273 | /// time. You should not trust a `false` value for program correctness |
85aaf69f | 274 | /// without additional synchronization. |
32a655c1 SL |
275 | /// |
276 | /// # Examples | |
277 | /// | |
278 | /// ``` | |
279 | /// use std::sync::{Arc, Mutex}; | |
280 | /// use std::thread; | |
281 | /// | |
282 | /// let mutex = Arc::new(Mutex::new(0)); | |
283 | /// let c_mutex = mutex.clone(); | |
284 | /// | |
285 | /// let _ = thread::spawn(move || { | |
286 | /// let _lock = c_mutex.lock().unwrap(); | |
287 | /// panic!(); // the mutex gets poisoned | |
288 | /// }).join(); | |
289 | /// assert_eq!(mutex.is_poisoned(), true); | |
290 | /// ``` | |
85aaf69f | 291 | #[inline] |
62682a34 | 292 | #[stable(feature = "sync_poison", since = "1.2.0")] |
85aaf69f | 293 | pub fn is_poisoned(&self) -> bool { |
5bcae85e | 294 | self.poison.get() |
85aaf69f | 295 | } |
b039eaaf SL |
296 | |
297 | /// Consumes this mutex, returning the underlying data. | |
298 | /// | |
7453a54e | 299 | /// # Errors |
b039eaaf SL |
300 | /// |
301 | /// If another user of this mutex panicked while holding the mutex, then | |
302 | /// this call will return an error instead. | |
32a655c1 SL |
303 | /// |
304 | /// # Examples | |
305 | /// | |
306 | /// ``` | |
307 | /// use std::sync::Mutex; | |
308 | /// | |
309 | /// let mutex = Mutex::new(0); | |
310 | /// assert_eq!(mutex.into_inner().unwrap(), 0); | |
311 | /// ``` | |
92a42be0 | 312 | #[stable(feature = "mutex_into_inner", since = "1.6.0")] |
dfeec247 XL |
313 | pub fn into_inner(self) -> LockResult<T> |
314 | where | |
315 | T: Sized, | |
316 | { | |
b039eaaf | 317 | // We know statically that there are no outstanding references to |
cc61c64b | 318 | // `self` so there's no need to lock the inner mutex. |
b039eaaf SL |
319 | // |
320 | // To get the inner value, we'd like to call `data.into_inner()`, | |
321 | // but because `Mutex` impl-s `Drop`, we can't move out of it, so | |
322 | // we'll have to destructure it manually instead. | |
323 | unsafe { | |
5bcae85e SL |
324 | // Like `let Mutex { inner, poison, data } = self`. |
325 | let (inner, poison, data) = { | |
326 | let Mutex { ref inner, ref poison, ref data } = self; | |
327 | (ptr::read(inner), ptr::read(poison), ptr::read(data)) | |
b039eaaf SL |
328 | }; |
329 | mem::forget(self); | |
dfeec247 | 330 | inner.destroy(); // Keep in sync with the `Drop` impl. |
5bcae85e | 331 | drop(inner); |
b039eaaf | 332 | |
5bcae85e | 333 | poison::map_result(poison.borrow(), |_| data.into_inner()) |
b039eaaf SL |
334 | } |
335 | } | |
336 | ||
337 | /// Returns a mutable reference to the underlying data. | |
338 | /// | |
339 | /// Since this call borrows the `Mutex` mutably, no actual locking needs to | |
9fa01778 | 340 | /// take place -- the mutable borrow statically guarantees no locks exist. |
b039eaaf | 341 | /// |
7453a54e | 342 | /// # Errors |
b039eaaf SL |
343 | /// |
344 | /// If another user of this mutex panicked while holding the mutex, then | |
345 | /// this call will return an error instead. | |
32a655c1 SL |
346 | /// |
347 | /// # Examples | |
348 | /// | |
349 | /// ``` | |
350 | /// use std::sync::Mutex; | |
351 | /// | |
352 | /// let mut mutex = Mutex::new(0); | |
353 | /// *mutex.get_mut().unwrap() = 10; | |
354 | /// assert_eq!(*mutex.lock().unwrap(), 10); | |
355 | /// ``` | |
92a42be0 | 356 | #[stable(feature = "mutex_get_mut", since = "1.6.0")] |
b039eaaf SL |
357 | pub fn get_mut(&mut self) -> LockResult<&mut T> { |
358 | // We know statically that there are no other references to `self`, so | |
cc61c64b | 359 | // there's no need to lock the inner mutex. |
b039eaaf | 360 | let data = unsafe { &mut *self.data.get() }; |
dfeec247 | 361 | poison::map_result(self.poison.borrow(), |_| data) |
b039eaaf | 362 | } |
1a4d82fc JJ |
363 | } |
364 | ||
85aaf69f | 365 | #[stable(feature = "rust1", since = "1.0.0")] |
32a655c1 | 366 | unsafe impl<#[may_dangle] T: ?Sized> Drop for Mutex<T> { |
1a4d82fc JJ |
367 | fn drop(&mut self) { |
368 | // This is actually safe b/c we know that there is no further usage of | |
369 | // this mutex (it's up to the user to arrange for a mutex to get | |
370 | // dropped, that's not our job) | |
b039eaaf SL |
371 | // |
372 | // IMPORTANT: This code must be kept in sync with `Mutex::into_inner`. | |
5bcae85e | 373 | unsafe { self.inner.destroy() } |
1a4d82fc JJ |
374 | } |
375 | } | |
376 | ||
2c00a5a8 | 377 | #[stable(feature = "mutex_from", since = "1.24.0")] |
ff7c6d11 XL |
378 | impl<T> From<T> for Mutex<T> { |
379 | /// Creates a new mutex in an unlocked state ready for use. | |
380 | /// This is equivalent to [`Mutex::new`]. | |
48663c56 XL |
381 | /// |
382 | /// [`Mutex::new`]: ../../std/sync/struct.Mutex.html#method.new | |
ff7c6d11 XL |
383 | fn from(t: T) -> Self { |
384 | Mutex::new(t) | |
385 | } | |
386 | } | |
387 | ||
7cac9316 | 388 | #[stable(feature = "mutex_default", since = "1.10.0")] |
a7813a04 | 389 | impl<T: ?Sized + Default> Default for Mutex<T> { |
9e0c209e | 390 | /// Creates a `Mutex<T>`, with the `Default` value for T. |
a7813a04 XL |
391 | fn default() -> Mutex<T> { |
392 | Mutex::new(Default::default()) | |
393 | } | |
394 | } | |
395 | ||
c34b1796 | 396 | #[stable(feature = "rust1", since = "1.0.0")] |
7453a54e | 397 | impl<T: ?Sized + fmt::Debug> fmt::Debug for Mutex<T> { |
532ac7d7 | 398 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
c34b1796 | 399 | match self.try_lock() { |
abe05a73 | 400 | Ok(guard) => f.debug_struct("Mutex").field("data", &&*guard).finish(), |
c34b1796 | 401 | Err(TryLockError::Poisoned(err)) => { |
abe05a73 | 402 | f.debug_struct("Mutex").field("data", &&**err.get_ref()).finish() |
dfeec247 | 403 | } |
abe05a73 XL |
404 | Err(TryLockError::WouldBlock) => { |
405 | struct LockedPlaceholder; | |
406 | impl fmt::Debug for LockedPlaceholder { | |
532ac7d7 XL |
407 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
408 | f.write_str("<locked>") | |
409 | } | |
abe05a73 XL |
410 | } |
411 | ||
412 | f.debug_struct("Mutex").field("data", &LockedPlaceholder).finish() | |
413 | } | |
c34b1796 AL |
414 | } |
415 | } | |
416 | } | |
417 | ||
d9579d0f | 418 | impl<'mutex, T: ?Sized> MutexGuard<'mutex, T> { |
5bcae85e | 419 | unsafe fn new(lock: &'mutex Mutex<T>) -> LockResult<MutexGuard<'mutex, T>> { |
74b04a01 | 420 | poison::map_result(lock.poison.borrow(), |guard| MutexGuard { lock, poison: guard }) |
1a4d82fc JJ |
421 | } |
422 | } | |
423 | ||
85aaf69f | 424 | #[stable(feature = "rust1", since = "1.0.0")] |
9fa01778 | 425 | impl<T: ?Sized> Deref for MutexGuard<'_, T> { |
1a4d82fc JJ |
426 | type Target = T; |
427 | ||
5bcae85e | 428 | fn deref(&self) -> &T { |
60c5eb7d | 429 | unsafe { &*self.lock.data.get() } |
5bcae85e | 430 | } |
1a4d82fc | 431 | } |
e9174d1e | 432 | |
85aaf69f | 433 | #[stable(feature = "rust1", since = "1.0.0")] |
9fa01778 | 434 | impl<T: ?Sized> DerefMut for MutexGuard<'_, T> { |
5bcae85e | 435 | fn deref_mut(&mut self) -> &mut T { |
60c5eb7d | 436 | unsafe { &mut *self.lock.data.get() } |
5bcae85e | 437 | } |
1a4d82fc JJ |
438 | } |
439 | ||
85aaf69f | 440 | #[stable(feature = "rust1", since = "1.0.0")] |
9fa01778 | 441 | impl<T: ?Sized> Drop for MutexGuard<'_, T> { |
1a4d82fc JJ |
442 | #[inline] |
443 | fn drop(&mut self) { | |
444 | unsafe { | |
60c5eb7d XL |
445 | self.lock.poison.done(&self.poison); |
446 | self.lock.inner.raw_unlock(); | |
1a4d82fc JJ |
447 | } |
448 | } | |
449 | } | |
450 | ||
8bb4bdeb | 451 | #[stable(feature = "std_debug", since = "1.16.0")] |
9fa01778 | 452 | impl<T: ?Sized + fmt::Debug> fmt::Debug for MutexGuard<'_, T> { |
532ac7d7 | 453 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
9fa01778 | 454 | fmt::Debug::fmt(&**self, f) |
32a655c1 SL |
455 | } |
456 | } | |
457 | ||
041b39d2 | 458 | #[stable(feature = "std_guard_impls", since = "1.20.0")] |
9fa01778 | 459 | impl<T: ?Sized + fmt::Display> fmt::Display for MutexGuard<'_, T> { |
532ac7d7 | 460 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
041b39d2 XL |
461 | (**self).fmt(f) |
462 | } | |
463 | } | |
464 | ||
d9579d0f | 465 | pub fn guard_lock<'a, T: ?Sized>(guard: &MutexGuard<'a, T>) -> &'a sys::Mutex { |
60c5eb7d | 466 | &guard.lock.inner |
1a4d82fc JJ |
467 | } |
468 | ||
d9579d0f | 469 | pub fn guard_poison<'a, T: ?Sized>(guard: &MutexGuard<'a, T>) -> &'a poison::Flag { |
60c5eb7d | 470 | &guard.lock.poison |
1a4d82fc JJ |
471 | } |
472 | ||
c30ab7b3 | 473 | #[cfg(all(test, not(target_os = "emscripten")))] |
d9579d0f | 474 | mod tests { |
532ac7d7 | 475 | use crate::sync::atomic::{AtomicUsize, Ordering}; |
dfeec247 XL |
476 | use crate::sync::mpsc::channel; |
477 | use crate::sync::{Arc, Condvar, Mutex}; | |
532ac7d7 | 478 | use crate::thread; |
1a4d82fc | 479 | |
e9174d1e | 480 | struct Packet<T>(Arc<(Mutex<T>, Condvar)>); |
1a4d82fc | 481 | |
b039eaaf SL |
482 | #[derive(Eq, PartialEq, Debug)] |
483 | struct NonCopy(i32); | |
484 | ||
1a4d82fc JJ |
485 | #[test] |
486 | fn smoke() { | |
487 | let m = Mutex::new(()); | |
488 | drop(m.lock().unwrap()); | |
489 | drop(m.lock().unwrap()); | |
490 | } | |
491 | ||
1a4d82fc JJ |
492 | #[test] |
493 | fn lots_and_lots() { | |
c34b1796 AL |
494 | const J: u32 = 1000; |
495 | const K: u32 = 3; | |
1a4d82fc | 496 | |
5bcae85e SL |
497 | let m = Arc::new(Mutex::new(0)); |
498 | ||
499 | fn inc(m: &Mutex<u32>) { | |
85aaf69f | 500 | for _ in 0..J { |
5bcae85e | 501 | *m.lock().unwrap() += 1; |
1a4d82fc JJ |
502 | } |
503 | } | |
504 | ||
505 | let (tx, rx) = channel(); | |
85aaf69f | 506 | for _ in 0..K { |
1a4d82fc | 507 | let tx2 = tx.clone(); |
5bcae85e | 508 | let m2 = m.clone(); |
dfeec247 XL |
509 | thread::spawn(move || { |
510 | inc(&m2); | |
511 | tx2.send(()).unwrap(); | |
512 | }); | |
1a4d82fc | 513 | let tx2 = tx.clone(); |
5bcae85e | 514 | let m2 = m.clone(); |
dfeec247 XL |
515 | thread::spawn(move || { |
516 | inc(&m2); | |
517 | tx2.send(()).unwrap(); | |
518 | }); | |
1a4d82fc JJ |
519 | } |
520 | ||
521 | drop(tx); | |
85aaf69f | 522 | for _ in 0..2 * K { |
1a4d82fc JJ |
523 | rx.recv().unwrap(); |
524 | } | |
5bcae85e | 525 | assert_eq!(*m.lock().unwrap(), J * K * 2); |
1a4d82fc JJ |
526 | } |
527 | ||
528 | #[test] | |
529 | fn try_lock() { | |
530 | let m = Mutex::new(()); | |
531 | *m.try_lock().unwrap() = (); | |
532 | } | |
533 | ||
b039eaaf SL |
534 | #[test] |
535 | fn test_into_inner() { | |
536 | let m = Mutex::new(NonCopy(10)); | |
537 | assert_eq!(m.into_inner().unwrap(), NonCopy(10)); | |
538 | } | |
539 | ||
540 | #[test] | |
541 | fn test_into_inner_drop() { | |
542 | struct Foo(Arc<AtomicUsize>); | |
543 | impl Drop for Foo { | |
544 | fn drop(&mut self) { | |
545 | self.0.fetch_add(1, Ordering::SeqCst); | |
546 | } | |
547 | } | |
548 | let num_drops = Arc::new(AtomicUsize::new(0)); | |
549 | let m = Mutex::new(Foo(num_drops.clone())); | |
550 | assert_eq!(num_drops.load(Ordering::SeqCst), 0); | |
551 | { | |
552 | let _inner = m.into_inner().unwrap(); | |
553 | assert_eq!(num_drops.load(Ordering::SeqCst), 0); | |
554 | } | |
555 | assert_eq!(num_drops.load(Ordering::SeqCst), 1); | |
556 | } | |
557 | ||
558 | #[test] | |
559 | fn test_into_inner_poison() { | |
560 | let m = Arc::new(Mutex::new(NonCopy(10))); | |
561 | let m2 = m.clone(); | |
562 | let _ = thread::spawn(move || { | |
563 | let _lock = m2.lock().unwrap(); | |
564 | panic!("test panic in inner thread to poison mutex"); | |
dfeec247 XL |
565 | }) |
566 | .join(); | |
b039eaaf SL |
567 | |
568 | assert!(m.is_poisoned()); | |
569 | match Arc::try_unwrap(m).unwrap().into_inner() { | |
570 | Err(e) => assert_eq!(e.into_inner(), NonCopy(10)), | |
571 | Ok(x) => panic!("into_inner of poisoned Mutex is Ok: {:?}", x), | |
572 | } | |
573 | } | |
574 | ||
575 | #[test] | |
576 | fn test_get_mut() { | |
577 | let mut m = Mutex::new(NonCopy(10)); | |
578 | *m.get_mut().unwrap() = NonCopy(20); | |
579 | assert_eq!(m.into_inner().unwrap(), NonCopy(20)); | |
580 | } | |
581 | ||
582 | #[test] | |
583 | fn test_get_mut_poison() { | |
584 | let m = Arc::new(Mutex::new(NonCopy(10))); | |
585 | let m2 = m.clone(); | |
586 | let _ = thread::spawn(move || { | |
587 | let _lock = m2.lock().unwrap(); | |
588 | panic!("test panic in inner thread to poison mutex"); | |
dfeec247 XL |
589 | }) |
590 | .join(); | |
b039eaaf SL |
591 | |
592 | assert!(m.is_poisoned()); | |
593 | match Arc::try_unwrap(m).unwrap().get_mut() { | |
594 | Err(e) => assert_eq!(*e.into_inner(), NonCopy(10)), | |
595 | Ok(x) => panic!("get_mut of poisoned Mutex is Ok: {:?}", x), | |
596 | } | |
597 | } | |
598 | ||
1a4d82fc JJ |
599 | #[test] |
600 | fn test_mutex_arc_condvar() { | |
601 | let packet = Packet(Arc::new((Mutex::new(false), Condvar::new()))); | |
602 | let packet2 = Packet(packet.0.clone()); | |
603 | let (tx, rx) = channel(); | |
dfeec247 | 604 | let _t = thread::spawn(move || { |
1a4d82fc JJ |
605 | // wait until parent gets in |
606 | rx.recv().unwrap(); | |
607 | let &(ref lock, ref cvar) = &*packet2.0; | |
608 | let mut lock = lock.lock().unwrap(); | |
609 | *lock = true; | |
610 | cvar.notify_one(); | |
611 | }); | |
612 | ||
613 | let &(ref lock, ref cvar) = &*packet.0; | |
614 | let mut lock = lock.lock().unwrap(); | |
615 | tx.send(()).unwrap(); | |
616 | assert!(!*lock); | |
617 | while !*lock { | |
618 | lock = cvar.wait(lock).unwrap(); | |
619 | } | |
620 | } | |
621 | ||
622 | #[test] | |
623 | fn test_arc_condvar_poison() { | |
85aaf69f | 624 | let packet = Packet(Arc::new((Mutex::new(1), Condvar::new()))); |
1a4d82fc JJ |
625 | let packet2 = Packet(packet.0.clone()); |
626 | let (tx, rx) = channel(); | |
627 | ||
85aaf69f | 628 | let _t = thread::spawn(move || -> () { |
1a4d82fc JJ |
629 | rx.recv().unwrap(); |
630 | let &(ref lock, ref cvar) = &*packet2.0; | |
631 | let _g = lock.lock().unwrap(); | |
632 | cvar.notify_one(); | |
633 | // Parent should fail when it wakes up. | |
634 | panic!(); | |
635 | }); | |
636 | ||
637 | let &(ref lock, ref cvar) = &*packet.0; | |
638 | let mut lock = lock.lock().unwrap(); | |
639 | tx.send(()).unwrap(); | |
640 | while *lock == 1 { | |
641 | match cvar.wait(lock) { | |
642 | Ok(l) => { | |
643 | lock = l; | |
644 | assert_eq!(*lock, 1); | |
645 | } | |
646 | Err(..) => break, | |
647 | } | |
648 | } | |
649 | } | |
650 | ||
651 | #[test] | |
652 | fn test_mutex_arc_poison() { | |
85aaf69f SL |
653 | let arc = Arc::new(Mutex::new(1)); |
654 | assert!(!arc.is_poisoned()); | |
1a4d82fc | 655 | let arc2 = arc.clone(); |
dfeec247 | 656 | let _ = thread::spawn(move || { |
1a4d82fc JJ |
657 | let lock = arc2.lock().unwrap(); |
658 | assert_eq!(*lock, 2); | |
dfeec247 XL |
659 | }) |
660 | .join(); | |
1a4d82fc | 661 | assert!(arc.lock().is_err()); |
85aaf69f | 662 | assert!(arc.is_poisoned()); |
1a4d82fc JJ |
663 | } |
664 | ||
665 | #[test] | |
666 | fn test_mutex_arc_nested() { | |
667 | // Tests nested mutexes and access | |
668 | // to underlying data. | |
85aaf69f | 669 | let arc = Arc::new(Mutex::new(1)); |
1a4d82fc JJ |
670 | let arc2 = Arc::new(Mutex::new(arc)); |
671 | let (tx, rx) = channel(); | |
dfeec247 | 672 | let _t = thread::spawn(move || { |
1a4d82fc JJ |
673 | let lock = arc2.lock().unwrap(); |
674 | let lock2 = lock.lock().unwrap(); | |
675 | assert_eq!(*lock2, 1); | |
676 | tx.send(()).unwrap(); | |
677 | }); | |
678 | rx.recv().unwrap(); | |
679 | } | |
680 | ||
681 | #[test] | |
682 | fn test_mutex_arc_access_in_unwind() { | |
85aaf69f | 683 | let arc = Arc::new(Mutex::new(1)); |
1a4d82fc | 684 | let arc2 = arc.clone(); |
dfeec247 | 685 | let _ = thread::spawn(move || -> () { |
1a4d82fc | 686 | struct Unwinder { |
c34b1796 | 687 | i: Arc<Mutex<i32>>, |
1a4d82fc JJ |
688 | } |
689 | impl Drop for Unwinder { | |
690 | fn drop(&mut self) { | |
691 | *self.i.lock().unwrap() += 1; | |
692 | } | |
693 | } | |
694 | let _u = Unwinder { i: arc2 }; | |
695 | panic!(); | |
dfeec247 XL |
696 | }) |
697 | .join(); | |
1a4d82fc JJ |
698 | let lock = arc.lock().unwrap(); |
699 | assert_eq!(*lock, 2); | |
700 | } | |
d9579d0f | 701 | |
b039eaaf SL |
702 | #[test] |
703 | fn test_mutex_unsized() { | |
704 | let mutex: &Mutex<[i32]> = &Mutex::new([1, 2, 3]); | |
705 | { | |
706 | let b = &mut *mutex.lock().unwrap(); | |
707 | b[0] = 4; | |
708 | b[2] = 5; | |
709 | } | |
710 | let comp: &[i32] = &[4, 2, 5]; | |
711 | assert_eq!(&*mutex.lock().unwrap(), comp); | |
712 | } | |
1a4d82fc | 713 | } |