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