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1 | // Copyright 2014 The Rust Project Developers. See the COPYRIGHT |
2 | // file at the top-level directory of this distribution and at | |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
5 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | |
6 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | |
7 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | |
8 | // option. This file may not be copied, modified, or distributed | |
9 | // except according to those terms. | |
10 | ||
1a4d82fc | 11 | use cell::UnsafeCell; |
9346a6ac | 12 | use fmt; |
b039eaaf | 13 | use mem; |
1a4d82fc | 14 | use ops::{Deref, DerefMut}; |
b039eaaf | 15 | use ptr; |
1a4d82fc | 16 | use sys_common::mutex as sys; |
9346a6ac | 17 | use sys_common::poison::{self, TryLockError, TryLockResult, LockResult}; |
1a4d82fc JJ |
18 | |
19 | /// A mutual exclusion primitive useful for protecting shared data | |
20 | /// | |
21 | /// This mutex will block threads waiting for the lock to become available. The | |
ea8adc8c | 22 | /// mutex can also be statically initialized or created via a [`new`] |
1a4d82fc JJ |
23 | /// constructor. Each mutex has a type parameter which represents the data that |
24 | /// it is protecting. The data can only be accessed through the RAII guards | |
ea8adc8c | 25 | /// returned from [`lock`] and [`try_lock`], which guarantees that the data is only |
1a4d82fc JJ |
26 | /// ever accessed when the mutex is locked. |
27 | /// | |
28 | /// # Poisoning | |
29 | /// | |
30 | /// The mutexes in this module implement a strategy called "poisoning" where a | |
31 | /// mutex is considered poisoned whenever a thread panics while holding the | |
cc61c64b | 32 | /// mutex. Once a mutex is poisoned, all other threads are unable to access the |
1a4d82fc JJ |
33 | /// data by default as it is likely tainted (some invariant is not being |
34 | /// upheld). | |
35 | /// | |
ea8adc8c XL |
36 | /// For a mutex, this means that the [`lock`] and [`try_lock`] methods return a |
37 | /// [`Result`] which indicates whether a mutex has been poisoned or not. Most | |
38 | /// usage of a mutex will simply [`unwrap()`] these results, propagating panics | |
1a4d82fc JJ |
39 | /// among threads to ensure that a possibly invalid invariant is not witnessed. |
40 | /// | |
41 | /// A poisoned mutex, however, does not prevent all access to the underlying | |
ea8adc8c | 42 | /// data. The [`PoisonError`] type has an [`into_inner`] method which will return |
1a4d82fc JJ |
43 | /// the guard that would have otherwise been returned on a successful lock. This |
44 | /// allows access to the data, despite the lock being poisoned. | |
45 | /// | |
ea8adc8c XL |
46 | /// [`new`]: #method.new |
47 | /// [`lock`]: #method.lock | |
48 | /// [`try_lock`]: #method.try_lock | |
49 | /// [`Result`]: ../../std/result/enum.Result.html | |
50 | /// [`unwrap()`]: ../../std/result/enum.Result.html#method.unwrap | |
51 | /// [`PoisonError`]: ../../std/sync/struct.PoisonError.html | |
52 | /// [`into_inner`]: ../../std/sync/struct.PoisonError.html#method.into_inner | |
53 | /// | |
1a4d82fc JJ |
54 | /// # Examples |
55 | /// | |
c34b1796 | 56 | /// ``` |
1a4d82fc | 57 | /// use std::sync::{Arc, Mutex}; |
85aaf69f | 58 | /// use std::thread; |
1a4d82fc JJ |
59 | /// use std::sync::mpsc::channel; |
60 | /// | |
c34b1796 | 61 | /// const N: usize = 10; |
1a4d82fc JJ |
62 | /// |
63 | /// // Spawn a few threads to increment a shared variable (non-atomically), and | |
64 | /// // let the main thread know once all increments are done. | |
65 | /// // | |
bd371182 | 66 | /// // Here we're using an Arc to share memory among threads, and the data inside |
1a4d82fc JJ |
67 | /// // the Arc is protected with a mutex. |
68 | /// let data = Arc::new(Mutex::new(0)); | |
69 | /// | |
70 | /// let (tx, rx) = channel(); | |
cc61c64b | 71 | /// for _ in 0..N { |
1a4d82fc | 72 | /// let (data, tx) = (data.clone(), tx.clone()); |
85aaf69f | 73 | /// thread::spawn(move || { |
92a42be0 | 74 | /// // The shared state can only be accessed once the lock is held. |
1a4d82fc JJ |
75 | /// // Our non-atomic increment is safe because we're the only thread |
76 | /// // which can access the shared state when the lock is held. | |
77 | /// // | |
78 | /// // We unwrap() the return value to assert that we are not expecting | |
bd371182 | 79 | /// // threads to ever fail while holding the lock. |
1a4d82fc JJ |
80 | /// let mut data = data.lock().unwrap(); |
81 | /// *data += 1; | |
82 | /// if *data == N { | |
83 | /// tx.send(()).unwrap(); | |
84 | /// } | |
85 | /// // the lock is unlocked here when `data` goes out of scope. | |
86 | /// }); | |
87 | /// } | |
88 | /// | |
89 | /// rx.recv().unwrap(); | |
90 | /// ``` | |
91 | /// | |
92 | /// To recover from a poisoned mutex: | |
93 | /// | |
c34b1796 | 94 | /// ``` |
1a4d82fc | 95 | /// use std::sync::{Arc, Mutex}; |
85aaf69f | 96 | /// use std::thread; |
1a4d82fc | 97 | /// |
85aaf69f | 98 | /// let lock = Arc::new(Mutex::new(0_u32)); |
1a4d82fc JJ |
99 | /// let lock2 = lock.clone(); |
100 | /// | |
85aaf69f | 101 | /// let _ = thread::spawn(move || -> () { |
1a4d82fc JJ |
102 | /// // This thread will acquire the mutex first, unwrapping the result of |
103 | /// // `lock` because the lock has not been poisoned. | |
7453a54e | 104 | /// let _guard = lock2.lock().unwrap(); |
1a4d82fc JJ |
105 | /// |
106 | /// // This panic while holding the lock (`_guard` is in scope) will poison | |
107 | /// // the mutex. | |
108 | /// panic!(); | |
109 | /// }).join(); | |
110 | /// | |
111 | /// // The lock is poisoned by this point, but the returned result can be | |
112 | /// // pattern matched on to return the underlying guard on both branches. | |
113 | /// let mut guard = match lock.lock() { | |
114 | /// Ok(guard) => guard, | |
c34b1796 | 115 | /// Err(poisoned) => poisoned.into_inner(), |
1a4d82fc JJ |
116 | /// }; |
117 | /// | |
118 | /// *guard += 1; | |
119 | /// ``` | |
85aaf69f | 120 | #[stable(feature = "rust1", since = "1.0.0")] |
d9579d0f | 121 | pub struct Mutex<T: ?Sized> { |
5bcae85e SL |
122 | // Note that this mutex is in a *box*, not inlined into the struct itself. |
123 | // Once a native mutex has been used once, its address can never change (it | |
124 | // can't be moved). This mutex type can be safely moved at any time, so to | |
cc61c64b | 125 | // ensure that the native mutex is used correctly we box the inner mutex to |
5bcae85e SL |
126 | // give it a constant address. |
127 | inner: Box<sys::Mutex>, | |
128 | poison: poison::Flag, | |
1a4d82fc JJ |
129 | data: UnsafeCell<T>, |
130 | } | |
131 | ||
c34b1796 AL |
132 | // these are the only places where `T: Send` matters; all other |
133 | // functionality works fine on a single thread. | |
92a42be0 | 134 | #[stable(feature = "rust1", since = "1.0.0")] |
d9579d0f | 135 | unsafe impl<T: ?Sized + Send> Send for Mutex<T> { } |
92a42be0 | 136 | #[stable(feature = "rust1", since = "1.0.0")] |
d9579d0f | 137 | unsafe impl<T: ?Sized + Send> Sync for Mutex<T> { } |
1a4d82fc | 138 | |
1a4d82fc JJ |
139 | /// An RAII implementation of a "scoped lock" of a mutex. When this structure is |
140 | /// dropped (falls out of scope), the lock will be unlocked. | |
141 | /// | |
cc61c64b | 142 | /// The data protected by the mutex can be accessed through this guard via its |
8bb4bdeb | 143 | /// [`Deref`] and [`DerefMut`] implementations. |
476ff2be | 144 | /// |
cc61c64b | 145 | /// This structure is created by the [`lock`] and [`try_lock`] methods on |
476ff2be SL |
146 | /// [`Mutex`]. |
147 | /// | |
8bb4bdeb XL |
148 | /// [`Deref`]: ../../std/ops/trait.Deref.html |
149 | /// [`DerefMut`]: ../../std/ops/trait.DerefMut.html | |
cc61c64b XL |
150 | /// [`lock`]: struct.Mutex.html#method.lock |
151 | /// [`try_lock`]: struct.Mutex.html#method.try_lock | |
476ff2be | 152 | /// [`Mutex`]: struct.Mutex.html |
94b46f34 | 153 | #[must_use = "if unused the Mutex will immediately unlock"] |
85aaf69f | 154 | #[stable(feature = "rust1", since = "1.0.0")] |
d9579d0f | 155 | pub struct MutexGuard<'a, T: ?Sized + 'a> { |
1a4d82fc JJ |
156 | // funny underscores due to how Deref/DerefMut currently work (they |
157 | // disregard field privacy). | |
5bcae85e | 158 | __lock: &'a Mutex<T>, |
1a4d82fc | 159 | __poison: poison::Guard, |
1a4d82fc JJ |
160 | } |
161 | ||
92a42be0 | 162 | #[stable(feature = "rust1", since = "1.0.0")] |
7cac9316 XL |
163 | impl<'a, T: ?Sized> !Send for MutexGuard<'a, T> { } |
164 | #[stable(feature = "mutexguard", since = "1.19.0")] | |
165 | unsafe impl<'a, T: ?Sized + Sync> Sync for MutexGuard<'a, T> { } | |
85aaf69f | 166 | |
c34b1796 | 167 | impl<T> Mutex<T> { |
1a4d82fc | 168 | /// Creates a new mutex in an unlocked state ready for use. |
32a655c1 SL |
169 | /// |
170 | /// # Examples | |
171 | /// | |
172 | /// ``` | |
173 | /// use std::sync::Mutex; | |
174 | /// | |
175 | /// let mutex = Mutex::new(0); | |
176 | /// ``` | |
85aaf69f | 177 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 178 | pub fn new(t: T) -> Mutex<T> { |
3157f602 | 179 | let mut m = Mutex { |
5bcae85e SL |
180 | inner: box sys::Mutex::new(), |
181 | poison: poison::Flag::new(), | |
1a4d82fc | 182 | data: UnsafeCell::new(t), |
3157f602 XL |
183 | }; |
184 | unsafe { | |
5bcae85e | 185 | m.inner.init(); |
1a4d82fc | 186 | } |
3157f602 | 187 | m |
1a4d82fc | 188 | } |
d9579d0f | 189 | } |
1a4d82fc | 190 | |
d9579d0f | 191 | impl<T: ?Sized> Mutex<T> { |
bd371182 | 192 | /// Acquires a mutex, blocking the current thread until it is able to do so. |
1a4d82fc | 193 | /// |
bd371182 | 194 | /// This function will block the local thread until it is available to acquire |
cc61c64b | 195 | /// the mutex. Upon returning, the thread is the only thread with the lock |
1a4d82fc JJ |
196 | /// held. An RAII guard is returned to allow scoped unlock of the lock. When |
197 | /// the guard goes out of scope, the mutex will be unlocked. | |
198 | /// | |
a7813a04 XL |
199 | /// The exact behavior on locking a mutex in the thread which already holds |
200 | /// the lock is left unspecified. However, this function will not return on | |
201 | /// the second call (it might panic or deadlock, for example). | |
202 | /// | |
7453a54e | 203 | /// # Errors |
1a4d82fc JJ |
204 | /// |
205 | /// If another user of this mutex panicked while holding the mutex, then | |
206 | /// this call will return an error once the mutex is acquired. | |
a7813a04 XL |
207 | /// |
208 | /// # Panics | |
209 | /// | |
210 | /// This function might panic when called if the lock is already held by | |
211 | /// the current thread. | |
32a655c1 SL |
212 | /// |
213 | /// # Examples | |
214 | /// | |
215 | /// ``` | |
216 | /// use std::sync::{Arc, Mutex}; | |
217 | /// use std::thread; | |
218 | /// | |
219 | /// let mutex = Arc::new(Mutex::new(0)); | |
220 | /// let c_mutex = mutex.clone(); | |
221 | /// | |
222 | /// thread::spawn(move || { | |
223 | /// *c_mutex.lock().unwrap() = 10; | |
224 | /// }).join().expect("thread::spawn failed"); | |
225 | /// assert_eq!(*mutex.lock().unwrap(), 10); | |
226 | /// ``` | |
85aaf69f | 227 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 228 | pub fn lock(&self) -> LockResult<MutexGuard<T>> { |
7453a54e | 229 | unsafe { |
94b46f34 | 230 | self.inner.raw_lock(); |
5bcae85e | 231 | MutexGuard::new(self) |
7453a54e | 232 | } |
1a4d82fc JJ |
233 | } |
234 | ||
235 | /// Attempts to acquire this lock. | |
236 | /// | |
ea8adc8c | 237 | /// If the lock could not be acquired at this time, then [`Err`] is returned. |
1a4d82fc JJ |
238 | /// Otherwise, an RAII guard is returned. The lock will be unlocked when the |
239 | /// guard is dropped. | |
240 | /// | |
241 | /// This function does not block. | |
242 | /// | |
7453a54e | 243 | /// # Errors |
1a4d82fc JJ |
244 | /// |
245 | /// If another user of this mutex panicked while holding the mutex, then | |
246 | /// this call will return failure if the mutex would otherwise be | |
247 | /// acquired. | |
32a655c1 | 248 | /// |
ea8adc8c XL |
249 | /// [`Err`]: ../../std/result/enum.Result.html#variant.Err |
250 | /// | |
32a655c1 SL |
251 | /// # Examples |
252 | /// | |
253 | /// ``` | |
254 | /// use std::sync::{Arc, Mutex}; | |
255 | /// use std::thread; | |
256 | /// | |
257 | /// let mutex = Arc::new(Mutex::new(0)); | |
258 | /// let c_mutex = mutex.clone(); | |
259 | /// | |
260 | /// thread::spawn(move || { | |
261 | /// let mut lock = c_mutex.try_lock(); | |
262 | /// if let Ok(ref mut mutex) = lock { | |
263 | /// **mutex = 10; | |
264 | /// } else { | |
265 | /// println!("try_lock failed"); | |
266 | /// } | |
267 | /// }).join().expect("thread::spawn failed"); | |
268 | /// assert_eq!(*mutex.lock().unwrap(), 10); | |
269 | /// ``` | |
85aaf69f | 270 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 271 | pub fn try_lock(&self) -> TryLockResult<MutexGuard<T>> { |
7453a54e | 272 | unsafe { |
5bcae85e SL |
273 | if self.inner.try_lock() { |
274 | Ok(MutexGuard::new(self)?) | |
7453a54e SL |
275 | } else { |
276 | Err(TryLockError::WouldBlock) | |
277 | } | |
1a4d82fc JJ |
278 | } |
279 | } | |
85aaf69f | 280 | |
cc61c64b | 281 | /// Determines whether the mutex is poisoned. |
85aaf69f | 282 | /// |
cc61c64b | 283 | /// If another thread is active, the mutex can still become poisoned at any |
32a655c1 | 284 | /// time. You should not trust a `false` value for program correctness |
85aaf69f | 285 | /// without additional synchronization. |
32a655c1 SL |
286 | /// |
287 | /// # Examples | |
288 | /// | |
289 | /// ``` | |
290 | /// use std::sync::{Arc, Mutex}; | |
291 | /// use std::thread; | |
292 | /// | |
293 | /// let mutex = Arc::new(Mutex::new(0)); | |
294 | /// let c_mutex = mutex.clone(); | |
295 | /// | |
296 | /// let _ = thread::spawn(move || { | |
297 | /// let _lock = c_mutex.lock().unwrap(); | |
298 | /// panic!(); // the mutex gets poisoned | |
299 | /// }).join(); | |
300 | /// assert_eq!(mutex.is_poisoned(), true); | |
301 | /// ``` | |
85aaf69f | 302 | #[inline] |
62682a34 | 303 | #[stable(feature = "sync_poison", since = "1.2.0")] |
85aaf69f | 304 | pub fn is_poisoned(&self) -> bool { |
5bcae85e | 305 | self.poison.get() |
85aaf69f | 306 | } |
b039eaaf SL |
307 | |
308 | /// Consumes this mutex, returning the underlying data. | |
309 | /// | |
7453a54e | 310 | /// # Errors |
b039eaaf SL |
311 | /// |
312 | /// If another user of this mutex panicked while holding the mutex, then | |
313 | /// this call will return an error instead. | |
32a655c1 SL |
314 | /// |
315 | /// # Examples | |
316 | /// | |
317 | /// ``` | |
318 | /// use std::sync::Mutex; | |
319 | /// | |
320 | /// let mutex = Mutex::new(0); | |
321 | /// assert_eq!(mutex.into_inner().unwrap(), 0); | |
322 | /// ``` | |
92a42be0 | 323 | #[stable(feature = "mutex_into_inner", since = "1.6.0")] |
b039eaaf SL |
324 | pub fn into_inner(self) -> LockResult<T> where T: Sized { |
325 | // We know statically that there are no outstanding references to | |
cc61c64b | 326 | // `self` so there's no need to lock the inner mutex. |
b039eaaf SL |
327 | // |
328 | // To get the inner value, we'd like to call `data.into_inner()`, | |
329 | // but because `Mutex` impl-s `Drop`, we can't move out of it, so | |
330 | // we'll have to destructure it manually instead. | |
331 | unsafe { | |
5bcae85e SL |
332 | // Like `let Mutex { inner, poison, data } = self`. |
333 | let (inner, poison, data) = { | |
334 | let Mutex { ref inner, ref poison, ref data } = self; | |
335 | (ptr::read(inner), ptr::read(poison), ptr::read(data)) | |
b039eaaf SL |
336 | }; |
337 | mem::forget(self); | |
5bcae85e SL |
338 | inner.destroy(); // Keep in sync with the `Drop` impl. |
339 | drop(inner); | |
b039eaaf | 340 | |
5bcae85e | 341 | poison::map_result(poison.borrow(), |_| data.into_inner()) |
b039eaaf SL |
342 | } |
343 | } | |
344 | ||
345 | /// Returns a mutable reference to the underlying data. | |
346 | /// | |
347 | /// Since this call borrows the `Mutex` mutably, no actual locking needs to | |
348 | /// take place---the mutable borrow statically guarantees no locks exist. | |
349 | /// | |
7453a54e | 350 | /// # Errors |
b039eaaf SL |
351 | /// |
352 | /// If another user of this mutex panicked while holding the mutex, then | |
353 | /// this call will return an error instead. | |
32a655c1 SL |
354 | /// |
355 | /// # Examples | |
356 | /// | |
357 | /// ``` | |
358 | /// use std::sync::Mutex; | |
359 | /// | |
360 | /// let mut mutex = Mutex::new(0); | |
361 | /// *mutex.get_mut().unwrap() = 10; | |
362 | /// assert_eq!(*mutex.lock().unwrap(), 10); | |
363 | /// ``` | |
92a42be0 | 364 | #[stable(feature = "mutex_get_mut", since = "1.6.0")] |
b039eaaf SL |
365 | pub fn get_mut(&mut self) -> LockResult<&mut T> { |
366 | // We know statically that there are no other references to `self`, so | |
cc61c64b | 367 | // there's no need to lock the inner mutex. |
b039eaaf | 368 | let data = unsafe { &mut *self.data.get() }; |
5bcae85e | 369 | poison::map_result(self.poison.borrow(), |_| data ) |
b039eaaf | 370 | } |
1a4d82fc JJ |
371 | } |
372 | ||
85aaf69f | 373 | #[stable(feature = "rust1", since = "1.0.0")] |
32a655c1 | 374 | unsafe impl<#[may_dangle] T: ?Sized> Drop for Mutex<T> { |
1a4d82fc JJ |
375 | fn drop(&mut self) { |
376 | // This is actually safe b/c we know that there is no further usage of | |
377 | // this mutex (it's up to the user to arrange for a mutex to get | |
378 | // dropped, that's not our job) | |
b039eaaf SL |
379 | // |
380 | // IMPORTANT: This code must be kept in sync with `Mutex::into_inner`. | |
5bcae85e | 381 | unsafe { self.inner.destroy() } |
1a4d82fc JJ |
382 | } |
383 | } | |
384 | ||
2c00a5a8 | 385 | #[stable(feature = "mutex_from", since = "1.24.0")] |
ff7c6d11 XL |
386 | impl<T> From<T> for Mutex<T> { |
387 | /// Creates a new mutex in an unlocked state ready for use. | |
388 | /// This is equivalent to [`Mutex::new`]. | |
389 | /// | |
390 | /// [`Mutex::new`]: #method.new | |
391 | fn from(t: T) -> Self { | |
392 | Mutex::new(t) | |
393 | } | |
394 | } | |
395 | ||
7cac9316 | 396 | #[stable(feature = "mutex_default", since = "1.10.0")] |
a7813a04 | 397 | impl<T: ?Sized + Default> Default for Mutex<T> { |
9e0c209e | 398 | /// Creates a `Mutex<T>`, with the `Default` value for T. |
a7813a04 XL |
399 | fn default() -> Mutex<T> { |
400 | Mutex::new(Default::default()) | |
401 | } | |
402 | } | |
403 | ||
c34b1796 | 404 | #[stable(feature = "rust1", since = "1.0.0")] |
7453a54e | 405 | impl<T: ?Sized + fmt::Debug> fmt::Debug for Mutex<T> { |
c34b1796 AL |
406 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
407 | match self.try_lock() { | |
abe05a73 | 408 | Ok(guard) => f.debug_struct("Mutex").field("data", &&*guard).finish(), |
c34b1796 | 409 | Err(TryLockError::Poisoned(err)) => { |
abe05a73 | 410 | f.debug_struct("Mutex").field("data", &&**err.get_ref()).finish() |
c34b1796 | 411 | }, |
abe05a73 XL |
412 | Err(TryLockError::WouldBlock) => { |
413 | struct LockedPlaceholder; | |
414 | impl fmt::Debug for LockedPlaceholder { | |
415 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { f.write_str("<locked>") } | |
416 | } | |
417 | ||
418 | f.debug_struct("Mutex").field("data", &LockedPlaceholder).finish() | |
419 | } | |
c34b1796 AL |
420 | } |
421 | } | |
422 | } | |
423 | ||
d9579d0f | 424 | impl<'mutex, T: ?Sized> MutexGuard<'mutex, T> { |
5bcae85e | 425 | unsafe fn new(lock: &'mutex Mutex<T>) -> LockResult<MutexGuard<'mutex, T>> { |
1a4d82fc JJ |
426 | poison::map_result(lock.poison.borrow(), |guard| { |
427 | MutexGuard { | |
428 | __lock: lock, | |
1a4d82fc | 429 | __poison: guard, |
1a4d82fc JJ |
430 | } |
431 | }) | |
432 | } | |
433 | } | |
434 | ||
85aaf69f | 435 | #[stable(feature = "rust1", since = "1.0.0")] |
d9579d0f | 436 | impl<'mutex, T: ?Sized> Deref for MutexGuard<'mutex, T> { |
1a4d82fc JJ |
437 | type Target = T; |
438 | ||
5bcae85e SL |
439 | fn deref(&self) -> &T { |
440 | unsafe { &*self.__lock.data.get() } | |
441 | } | |
1a4d82fc | 442 | } |
e9174d1e | 443 | |
85aaf69f | 444 | #[stable(feature = "rust1", since = "1.0.0")] |
d9579d0f | 445 | impl<'mutex, T: ?Sized> DerefMut for MutexGuard<'mutex, T> { |
5bcae85e SL |
446 | fn deref_mut(&mut self) -> &mut T { |
447 | unsafe { &mut *self.__lock.data.get() } | |
448 | } | |
1a4d82fc JJ |
449 | } |
450 | ||
85aaf69f | 451 | #[stable(feature = "rust1", since = "1.0.0")] |
d9579d0f | 452 | impl<'a, T: ?Sized> Drop for MutexGuard<'a, T> { |
1a4d82fc JJ |
453 | #[inline] |
454 | fn drop(&mut self) { | |
455 | unsafe { | |
456 | self.__lock.poison.done(&self.__poison); | |
94b46f34 | 457 | self.__lock.inner.raw_unlock(); |
1a4d82fc JJ |
458 | } |
459 | } | |
460 | } | |
461 | ||
8bb4bdeb | 462 | #[stable(feature = "std_debug", since = "1.16.0")] |
32a655c1 SL |
463 | impl<'a, T: ?Sized + fmt::Debug> fmt::Debug for MutexGuard<'a, T> { |
464 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
465 | f.debug_struct("MutexGuard") | |
466 | .field("lock", &self.__lock) | |
467 | .finish() | |
468 | } | |
469 | } | |
470 | ||
041b39d2 XL |
471 | #[stable(feature = "std_guard_impls", since = "1.20.0")] |
472 | impl<'a, T: ?Sized + fmt::Display> fmt::Display for MutexGuard<'a, T> { | |
473 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
474 | (**self).fmt(f) | |
475 | } | |
476 | } | |
477 | ||
d9579d0f | 478 | pub fn guard_lock<'a, T: ?Sized>(guard: &MutexGuard<'a, T>) -> &'a sys::Mutex { |
5bcae85e | 479 | &guard.__lock.inner |
1a4d82fc JJ |
480 | } |
481 | ||
d9579d0f | 482 | pub fn guard_poison<'a, T: ?Sized>(guard: &MutexGuard<'a, T>) -> &'a poison::Flag { |
1a4d82fc JJ |
483 | &guard.__lock.poison |
484 | } | |
485 | ||
c30ab7b3 | 486 | #[cfg(all(test, not(target_os = "emscripten")))] |
d9579d0f | 487 | mod tests { |
1a4d82fc | 488 | use sync::mpsc::channel; |
5bcae85e | 489 | use sync::{Arc, Mutex, Condvar}; |
b039eaaf | 490 | use sync::atomic::{AtomicUsize, Ordering}; |
85aaf69f | 491 | use thread; |
1a4d82fc | 492 | |
e9174d1e | 493 | struct Packet<T>(Arc<(Mutex<T>, Condvar)>); |
1a4d82fc | 494 | |
b039eaaf SL |
495 | #[derive(Eq, PartialEq, Debug)] |
496 | struct NonCopy(i32); | |
497 | ||
1a4d82fc JJ |
498 | #[test] |
499 | fn smoke() { | |
500 | let m = Mutex::new(()); | |
501 | drop(m.lock().unwrap()); | |
502 | drop(m.lock().unwrap()); | |
503 | } | |
504 | ||
1a4d82fc JJ |
505 | #[test] |
506 | fn lots_and_lots() { | |
c34b1796 AL |
507 | const J: u32 = 1000; |
508 | const K: u32 = 3; | |
1a4d82fc | 509 | |
5bcae85e SL |
510 | let m = Arc::new(Mutex::new(0)); |
511 | ||
512 | fn inc(m: &Mutex<u32>) { | |
85aaf69f | 513 | for _ in 0..J { |
5bcae85e | 514 | *m.lock().unwrap() += 1; |
1a4d82fc JJ |
515 | } |
516 | } | |
517 | ||
518 | let (tx, rx) = channel(); | |
85aaf69f | 519 | for _ in 0..K { |
1a4d82fc | 520 | let tx2 = tx.clone(); |
5bcae85e SL |
521 | let m2 = m.clone(); |
522 | thread::spawn(move|| { inc(&m2); tx2.send(()).unwrap(); }); | |
1a4d82fc | 523 | let tx2 = tx.clone(); |
5bcae85e SL |
524 | let m2 = m.clone(); |
525 | thread::spawn(move|| { inc(&m2); tx2.send(()).unwrap(); }); | |
1a4d82fc JJ |
526 | } |
527 | ||
528 | drop(tx); | |
85aaf69f | 529 | for _ in 0..2 * K { |
1a4d82fc JJ |
530 | rx.recv().unwrap(); |
531 | } | |
5bcae85e | 532 | assert_eq!(*m.lock().unwrap(), J * K * 2); |
1a4d82fc JJ |
533 | } |
534 | ||
535 | #[test] | |
536 | fn try_lock() { | |
537 | let m = Mutex::new(()); | |
538 | *m.try_lock().unwrap() = (); | |
539 | } | |
540 | ||
b039eaaf SL |
541 | #[test] |
542 | fn test_into_inner() { | |
543 | let m = Mutex::new(NonCopy(10)); | |
544 | assert_eq!(m.into_inner().unwrap(), NonCopy(10)); | |
545 | } | |
546 | ||
547 | #[test] | |
548 | fn test_into_inner_drop() { | |
549 | struct Foo(Arc<AtomicUsize>); | |
550 | impl Drop for Foo { | |
551 | fn drop(&mut self) { | |
552 | self.0.fetch_add(1, Ordering::SeqCst); | |
553 | } | |
554 | } | |
555 | let num_drops = Arc::new(AtomicUsize::new(0)); | |
556 | let m = Mutex::new(Foo(num_drops.clone())); | |
557 | assert_eq!(num_drops.load(Ordering::SeqCst), 0); | |
558 | { | |
559 | let _inner = m.into_inner().unwrap(); | |
560 | assert_eq!(num_drops.load(Ordering::SeqCst), 0); | |
561 | } | |
562 | assert_eq!(num_drops.load(Ordering::SeqCst), 1); | |
563 | } | |
564 | ||
565 | #[test] | |
566 | fn test_into_inner_poison() { | |
567 | let m = Arc::new(Mutex::new(NonCopy(10))); | |
568 | let m2 = m.clone(); | |
569 | let _ = thread::spawn(move || { | |
570 | let _lock = m2.lock().unwrap(); | |
571 | panic!("test panic in inner thread to poison mutex"); | |
572 | }).join(); | |
573 | ||
574 | assert!(m.is_poisoned()); | |
575 | match Arc::try_unwrap(m).unwrap().into_inner() { | |
576 | Err(e) => assert_eq!(e.into_inner(), NonCopy(10)), | |
577 | Ok(x) => panic!("into_inner of poisoned Mutex is Ok: {:?}", x), | |
578 | } | |
579 | } | |
580 | ||
581 | #[test] | |
582 | fn test_get_mut() { | |
583 | let mut m = Mutex::new(NonCopy(10)); | |
584 | *m.get_mut().unwrap() = NonCopy(20); | |
585 | assert_eq!(m.into_inner().unwrap(), NonCopy(20)); | |
586 | } | |
587 | ||
588 | #[test] | |
589 | fn test_get_mut_poison() { | |
590 | let m = Arc::new(Mutex::new(NonCopy(10))); | |
591 | let m2 = m.clone(); | |
592 | let _ = thread::spawn(move || { | |
593 | let _lock = m2.lock().unwrap(); | |
594 | panic!("test panic in inner thread to poison mutex"); | |
595 | }).join(); | |
596 | ||
597 | assert!(m.is_poisoned()); | |
598 | match Arc::try_unwrap(m).unwrap().get_mut() { | |
599 | Err(e) => assert_eq!(*e.into_inner(), NonCopy(10)), | |
600 | Ok(x) => panic!("get_mut of poisoned Mutex is Ok: {:?}", x), | |
601 | } | |
602 | } | |
603 | ||
1a4d82fc JJ |
604 | #[test] |
605 | fn test_mutex_arc_condvar() { | |
606 | let packet = Packet(Arc::new((Mutex::new(false), Condvar::new()))); | |
607 | let packet2 = Packet(packet.0.clone()); | |
608 | let (tx, rx) = channel(); | |
85aaf69f | 609 | let _t = thread::spawn(move|| { |
1a4d82fc JJ |
610 | // wait until parent gets in |
611 | rx.recv().unwrap(); | |
612 | let &(ref lock, ref cvar) = &*packet2.0; | |
613 | let mut lock = lock.lock().unwrap(); | |
614 | *lock = true; | |
615 | cvar.notify_one(); | |
616 | }); | |
617 | ||
618 | let &(ref lock, ref cvar) = &*packet.0; | |
619 | let mut lock = lock.lock().unwrap(); | |
620 | tx.send(()).unwrap(); | |
621 | assert!(!*lock); | |
622 | while !*lock { | |
623 | lock = cvar.wait(lock).unwrap(); | |
624 | } | |
625 | } | |
626 | ||
627 | #[test] | |
628 | fn test_arc_condvar_poison() { | |
85aaf69f | 629 | let packet = Packet(Arc::new((Mutex::new(1), Condvar::new()))); |
1a4d82fc JJ |
630 | let packet2 = Packet(packet.0.clone()); |
631 | let (tx, rx) = channel(); | |
632 | ||
85aaf69f | 633 | let _t = thread::spawn(move || -> () { |
1a4d82fc JJ |
634 | rx.recv().unwrap(); |
635 | let &(ref lock, ref cvar) = &*packet2.0; | |
636 | let _g = lock.lock().unwrap(); | |
637 | cvar.notify_one(); | |
638 | // Parent should fail when it wakes up. | |
639 | panic!(); | |
640 | }); | |
641 | ||
642 | let &(ref lock, ref cvar) = &*packet.0; | |
643 | let mut lock = lock.lock().unwrap(); | |
644 | tx.send(()).unwrap(); | |
645 | while *lock == 1 { | |
646 | match cvar.wait(lock) { | |
647 | Ok(l) => { | |
648 | lock = l; | |
649 | assert_eq!(*lock, 1); | |
650 | } | |
651 | Err(..) => break, | |
652 | } | |
653 | } | |
654 | } | |
655 | ||
656 | #[test] | |
657 | fn test_mutex_arc_poison() { | |
85aaf69f SL |
658 | let arc = Arc::new(Mutex::new(1)); |
659 | assert!(!arc.is_poisoned()); | |
1a4d82fc | 660 | let arc2 = arc.clone(); |
85aaf69f | 661 | let _ = thread::spawn(move|| { |
1a4d82fc JJ |
662 | let lock = arc2.lock().unwrap(); |
663 | assert_eq!(*lock, 2); | |
664 | }).join(); | |
665 | assert!(arc.lock().is_err()); | |
85aaf69f | 666 | assert!(arc.is_poisoned()); |
1a4d82fc JJ |
667 | } |
668 | ||
669 | #[test] | |
670 | fn test_mutex_arc_nested() { | |
671 | // Tests nested mutexes and access | |
672 | // to underlying data. | |
85aaf69f | 673 | let arc = Arc::new(Mutex::new(1)); |
1a4d82fc JJ |
674 | let arc2 = Arc::new(Mutex::new(arc)); |
675 | let (tx, rx) = channel(); | |
85aaf69f | 676 | let _t = thread::spawn(move|| { |
1a4d82fc JJ |
677 | let lock = arc2.lock().unwrap(); |
678 | let lock2 = lock.lock().unwrap(); | |
679 | assert_eq!(*lock2, 1); | |
680 | tx.send(()).unwrap(); | |
681 | }); | |
682 | rx.recv().unwrap(); | |
683 | } | |
684 | ||
685 | #[test] | |
686 | fn test_mutex_arc_access_in_unwind() { | |
85aaf69f | 687 | let arc = Arc::new(Mutex::new(1)); |
1a4d82fc | 688 | let arc2 = arc.clone(); |
85aaf69f | 689 | let _ = thread::spawn(move|| -> () { |
1a4d82fc | 690 | struct Unwinder { |
c34b1796 | 691 | i: Arc<Mutex<i32>>, |
1a4d82fc JJ |
692 | } |
693 | impl Drop for Unwinder { | |
694 | fn drop(&mut self) { | |
695 | *self.i.lock().unwrap() += 1; | |
696 | } | |
697 | } | |
698 | let _u = Unwinder { i: arc2 }; | |
699 | panic!(); | |
700 | }).join(); | |
701 | let lock = arc.lock().unwrap(); | |
702 | assert_eq!(*lock, 2); | |
703 | } | |
d9579d0f | 704 | |
b039eaaf SL |
705 | #[test] |
706 | fn test_mutex_unsized() { | |
707 | let mutex: &Mutex<[i32]> = &Mutex::new([1, 2, 3]); | |
708 | { | |
709 | let b = &mut *mutex.lock().unwrap(); | |
710 | b[0] = 4; | |
711 | b[2] = 5; | |
712 | } | |
713 | let comp: &[i32] = &[4, 2, 5]; | |
714 | assert_eq!(&*mutex.lock().unwrap(), comp); | |
715 | } | |
1a4d82fc | 716 | } |