diff options
20 files changed, 682 insertions, 32 deletions
diff --git a/library/std/src/sync/mod.rs b/library/std/src/sync/mod.rs index e67b4f6f22f..6ef3bf25cf6 100644 --- a/library/std/src/sync/mod.rs +++ b/library/std/src/sync/mod.rs @@ -225,6 +225,8 @@ pub use self::poison::{MappedMutexGuard, MappedRwLockReadGuard, MappedRwLockWrit pub mod mpmc; pub mod mpsc; +#[unstable(feature = "sync_nonpoison", issue = "134645")] +pub mod nonpoison; #[unstable(feature = "sync_poison_mod", issue = "134646")] pub mod poison; diff --git a/library/std/src/sync/nonpoison.rs b/library/std/src/sync/nonpoison.rs new file mode 100644 index 00000000000..2bbf226dc2c --- /dev/null +++ b/library/std/src/sync/nonpoison.rs @@ -0,0 +1,37 @@ +//! Non-poisoning synchronous locks. +//! +//! The difference from the locks in the [`poison`] module is that the locks in this module will not +//! become poisoned when a thread panics while holding a guard. +//! +//! [`poison`]: super::poison + +use crate::fmt; + +/// A type alias for the result of a nonblocking locking method. +#[unstable(feature = "sync_nonpoison", issue = "134645")] +pub type TryLockResult<Guard> = Result<Guard, WouldBlock>; + +/// A lock could not be acquired at this time because the operation would otherwise block. +#[unstable(feature = "sync_nonpoison", issue = "134645")] +pub struct WouldBlock; + +#[unstable(feature = "sync_nonpoison", issue = "134645")] +impl fmt::Debug for WouldBlock { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + "WouldBlock".fmt(f) + } +} + +#[unstable(feature = "sync_nonpoison", issue = "134645")] +impl fmt::Display for WouldBlock { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + "try_lock failed because the operation would block".fmt(f) + } +} + +#[unstable(feature = "mapped_lock_guards", issue = "117108")] +pub use self::mutex::MappedMutexGuard; +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +pub use self::mutex::{Mutex, MutexGuard}; + +mod mutex; diff --git a/library/std/src/sync/nonpoison/mutex.rs b/library/std/src/sync/nonpoison/mutex.rs new file mode 100644 index 00000000000..b6861c78f00 --- /dev/null +++ b/library/std/src/sync/nonpoison/mutex.rs @@ -0,0 +1,611 @@ +use crate::cell::UnsafeCell; +use crate::fmt; +use crate::marker::PhantomData; +use crate::mem::{self, ManuallyDrop}; +use crate::ops::{Deref, DerefMut}; +use crate::ptr::NonNull; +use crate::sync::nonpoison::{TryLockResult, WouldBlock}; +use crate::sys::sync as sys; + +/// A mutual exclusion primitive useful for protecting shared data that does not keep track of +/// lock poisoning. +/// +/// For more information about mutexes, check out the documentation for the poisoning variant of +/// this lock at [`poison::Mutex`]. +/// +/// [`poison::Mutex`]: crate::sync::poison::Mutex +/// +/// # Examples +/// +/// Note that this `Mutex` does **not** propagate threads that panic while holding the lock via +/// poisoning. If you need this functionality, see [`poison::Mutex`]. +/// +/// ``` +/// #![feature(nonpoison_mutex)] +/// +/// use std::thread; +/// use std::sync::{Arc, nonpoison::Mutex}; +/// +/// let mutex = Arc::new(Mutex::new(0u32)); +/// let mut handles = Vec::new(); +/// +/// for n in 0..10 { +/// let m = Arc::clone(&mutex); +/// let handle = thread::spawn(move || { +/// let mut guard = m.lock(); +/// *guard += 1; +/// panic!("panic from thread {n} {guard}") +/// }); +/// handles.push(handle); +/// } +/// +/// for h in handles { +/// let _ = h.join(); +/// } +/// +/// println!("Finished, locked {} times", mutex.lock()); +/// ``` +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +#[cfg_attr(not(test), rustc_diagnostic_item = "NonPoisonMutex")] +pub struct Mutex<T: ?Sized> { + inner: sys::Mutex, + data: UnsafeCell<T>, +} + +/// `T` must be `Send` for a [`Mutex`] to be `Send` because it is possible to acquire +/// the owned `T` from the `Mutex` via [`into_inner`]. +/// +/// [`into_inner`]: Mutex::into_inner +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +unsafe impl<T: ?Sized + Send> Send for Mutex<T> {} + +/// `T` must be `Send` for [`Mutex`] to be `Sync`. +/// This ensures that the protected data can be accessed safely from multiple threads +/// without causing data races or other unsafe behavior. +/// +/// [`Mutex<T>`] provides mutable access to `T` to one thread at a time. However, it's essential +/// for `T` to be `Send` because it's not safe for non-`Send` structures to be accessed in +/// this manner. For instance, consider [`Rc`], a non-atomic reference counted smart pointer, +/// which is not `Send`. With `Rc`, we can have multiple copies pointing to the same heap +/// allocation with a non-atomic reference count. If we were to use `Mutex<Rc<_>>`, it would +/// only protect one instance of `Rc` from shared access, leaving other copies vulnerable +/// to potential data races. +/// +/// Also note that it is not necessary for `T` to be `Sync` as `&T` is only made available +/// to one thread at a time if `T` is not `Sync`. +/// +/// [`Rc`]: crate::rc::Rc +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +unsafe impl<T: ?Sized + Send> Sync for Mutex<T> {} + +/// An RAII implementation of a "scoped lock" of a mutex. When this structure is +/// dropped (falls out of scope), the lock will be unlocked. +/// +/// The data protected by the mutex can be accessed through this guard via its +/// [`Deref`] and [`DerefMut`] implementations. +/// +/// This structure is created by the [`lock`] and [`try_lock`] methods on +/// [`Mutex`]. +/// +/// [`lock`]: Mutex::lock +/// [`try_lock`]: Mutex::try_lock +#[must_use = "if unused the Mutex will immediately unlock"] +#[must_not_suspend = "holding a MutexGuard across suspend \ + points can cause deadlocks, delays, \ + and cause Futures to not implement `Send`"] +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +#[clippy::has_significant_drop] +#[cfg_attr(not(test), rustc_diagnostic_item = "NonPoisonMutexGuard")] +pub struct MutexGuard<'a, T: ?Sized + 'a> { + lock: &'a Mutex<T>, +} + +/// A [`MutexGuard`] is not `Send` to maximize platform portablity. +/// +/// On platforms that use POSIX threads (commonly referred to as pthreads) there is a requirement to +/// release mutex locks on the same thread they were acquired. +/// For this reason, [`MutexGuard`] must not implement `Send` to prevent it being dropped from +/// another thread. +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T: ?Sized> !Send for MutexGuard<'_, T> {} + +/// `T` must be `Sync` for a [`MutexGuard<T>`] to be `Sync` +/// because it is possible to get a `&T` from `&MutexGuard` (via `Deref`). +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +unsafe impl<T: ?Sized + Sync> Sync for MutexGuard<'_, T> {} + +// FIXME(nonpoison_condvar): Use this link instead: [`Condvar`]: crate::sync::nonpoison::Condvar +/// An RAII mutex guard returned by `MutexGuard::map`, which can point to a +/// subfield of the protected data. When this structure is dropped (falls out +/// of scope), the lock will be unlocked. +/// +/// The main difference between `MappedMutexGuard` and [`MutexGuard`] is that the +/// former cannot be used with [`Condvar`], since that could introduce soundness issues if the +/// locked object is modified by another thread while the `Mutex` is unlocked. +/// +/// The data protected by the mutex can be accessed through this guard via its +/// [`Deref`] and [`DerefMut`] implementations. +/// +/// This structure is created by the [`map`] and [`filter_map`] methods on +/// [`MutexGuard`]. +/// +/// [`map`]: MutexGuard::map +/// [`filter_map`]: MutexGuard::filter_map +/// [`Condvar`]: crate::sync::Condvar +#[must_use = "if unused the Mutex will immediately unlock"] +#[must_not_suspend = "holding a MappedMutexGuard across suspend \ + points can cause deadlocks, delays, \ + and cause Futures to not implement `Send`"] +#[unstable(feature = "mapped_lock_guards", issue = "117108")] +// #[unstable(feature = "nonpoison_mutex", issue = "134645")] +#[clippy::has_significant_drop] +pub struct MappedMutexGuard<'a, T: ?Sized + 'a> { + // NB: we use a pointer instead of `&'a mut T` to avoid `noalias` violations, because a + // `MappedMutexGuard` argument doesn't hold uniqueness for its whole scope, only until it drops. + // `NonNull` is covariant over `T`, so we add a `PhantomData<&'a mut T>` field + // below for the correct variance over `T` (invariance). + data: NonNull<T>, + inner: &'a sys::Mutex, + _variance: PhantomData<&'a mut T>, +} + +#[unstable(feature = "mapped_lock_guards", issue = "117108")] +// #[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T: ?Sized> !Send for MappedMutexGuard<'_, T> {} +#[unstable(feature = "mapped_lock_guards", issue = "117108")] +// #[unstable(feature = "nonpoison_mutex", issue = "134645")] +unsafe impl<T: ?Sized + Sync> Sync for MappedMutexGuard<'_, T> {} + +impl<T> Mutex<T> { + /// Creates a new mutex in an unlocked state ready for use. + /// + /// # Examples + /// + /// ``` + /// #![feature(nonpoison_mutex)] + /// + /// use std::sync::nonpoison::Mutex; + /// + /// let mutex = Mutex::new(0); + /// ``` + #[unstable(feature = "nonpoison_mutex", issue = "134645")] + #[inline] + pub const fn new(t: T) -> Mutex<T> { + Mutex { inner: sys::Mutex::new(), data: UnsafeCell::new(t) } + } + + /// Returns the contained value by cloning it. + /// + /// # Examples + /// + /// ``` + /// #![feature(nonpoison_mutex)] + /// #![feature(lock_value_accessors)] + /// + /// use std::sync::nonpoison::Mutex; + /// + /// let mut mutex = Mutex::new(7); + /// + /// assert_eq!(mutex.get_cloned(), 7); + /// ``` + #[unstable(feature = "lock_value_accessors", issue = "133407")] + // #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn get_cloned(&self) -> T + where + T: Clone, + { + self.lock().clone() + } + + /// Sets the contained value. + /// + /// # Examples + /// + /// ``` + /// #![feature(nonpoison_mutex)] + /// #![feature(lock_value_accessors)] + /// + /// use std::sync::nonpoison::Mutex; + /// + /// let mut mutex = Mutex::new(7); + /// + /// assert_eq!(mutex.get_cloned(), 7); + /// mutex.set(11); + /// assert_eq!(mutex.get_cloned(), 11); + /// ``` + #[unstable(feature = "lock_value_accessors", issue = "133407")] + // #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn set(&self, value: T) { + if mem::needs_drop::<T>() { + // If the contained value has a non-trivial destructor, we + // call that destructor after the lock has been released. + drop(self.replace(value)) + } else { + *self.lock() = value; + } + } + + /// Replaces the contained value with `value`, and returns the old contained value. + /// + /// # Examples + /// + /// ``` + /// #![feature(nonpoison_mutex)] + /// #![feature(lock_value_accessors)] + /// + /// use std::sync::nonpoison::Mutex; + /// + /// let mut mutex = Mutex::new(7); + /// + /// assert_eq!(mutex.replace(11), 7); + /// assert_eq!(mutex.get_cloned(), 11); + /// ``` + #[unstable(feature = "lock_value_accessors", issue = "133407")] + // #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn replace(&self, value: T) -> T { + let mut guard = self.lock(); + mem::replace(&mut *guard, value) + } +} + +impl<T: ?Sized> Mutex<T> { + /// Acquires a mutex, blocking the current thread until it is able to do so. + /// + /// This function will block the local thread until it is available to acquire + /// the mutex. Upon returning, the thread is the only thread with the lock + /// held. An RAII guard is returned to allow scoped unlock of the lock. When + /// the guard goes out of scope, the mutex will be unlocked. + /// + /// The exact behavior on locking a mutex in the thread which already holds + /// the lock is left unspecified. However, this function will not return on + /// the second call (it might panic or deadlock, for example). + /// + /// # Panics + /// + /// This function might panic when called if the lock is already held by + /// the current thread. + /// + /// # Examples + /// + /// ``` + /// #![feature(nonpoison_mutex)] + /// + /// use std::sync::{Arc, nonpoison::Mutex}; + /// use std::thread; + /// + /// let mutex = Arc::new(Mutex::new(0)); + /// let c_mutex = Arc::clone(&mutex); + /// + /// thread::spawn(move || { + /// *c_mutex.lock() = 10; + /// }).join().expect("thread::spawn failed"); + /// assert_eq!(*mutex.lock(), 10); + /// ``` + #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn lock(&self) -> MutexGuard<'_, T> { + unsafe { + self.inner.lock(); + MutexGuard::new(self) + } + } + + /// Attempts to acquire this lock. + /// + /// This function does not block. If the lock could not be acquired at this time, then + /// [`WouldBlock`] is returned. Otherwise, an RAII guard is returned. + /// + /// The lock will be unlocked when the guard is dropped. + /// + /// # Errors + /// + /// If the mutex could not be acquired because it is already locked, then this call will return + /// the [`WouldBlock`] error. + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Arc, Mutex}; + /// use std::thread; + /// + /// let mutex = Arc::new(Mutex::new(0)); + /// let c_mutex = Arc::clone(&mutex); + /// + /// thread::spawn(move || { + /// let mut lock = c_mutex.try_lock(); + /// if let Ok(ref mut mutex) = lock { + /// **mutex = 10; + /// } else { + /// println!("try_lock failed"); + /// } + /// }).join().expect("thread::spawn failed"); + /// assert_eq!(*mutex.lock().unwrap(), 10); + /// ``` + #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn try_lock(&self) -> TryLockResult<MutexGuard<'_, T>> { + unsafe { if self.inner.try_lock() { Ok(MutexGuard::new(self)) } else { Err(WouldBlock) } } + } + + /// Consumes this mutex, returning the underlying data. + /// + /// # Examples + /// + /// ``` + /// #![feature(nonpoison_mutex)] + /// + /// use std::sync::nonpoison::Mutex; + /// + /// let mutex = Mutex::new(0); + /// assert_eq!(mutex.into_inner(), 0); + /// ``` + #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn into_inner(self) -> T + where + T: Sized, + { + self.data.into_inner() + } + + /// Returns a mutable reference to the underlying data. + /// + /// Since this call borrows the `Mutex` mutably, no actual locking needs to + /// take place -- the mutable borrow statically guarantees no locks exist. + /// + /// # Examples + /// + /// ``` + /// #![feature(nonpoison_mutex)] + /// + /// use std::sync::nonpoison::Mutex; + /// + /// let mut mutex = Mutex::new(0); + /// *mutex.get_mut() = 10; + /// assert_eq!(*mutex.lock(), 10); + /// ``` + #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn get_mut(&mut self) -> &mut T { + self.data.get_mut() + } + + /// Returns a raw pointer to the underlying data. + /// + /// The returned pointer is always non-null and properly aligned, but it is + /// the user's responsibility to ensure that any reads and writes through it + /// are properly synchronized to avoid data races, and that it is not read + /// or written through after the mutex is dropped. + #[unstable(feature = "mutex_data_ptr", issue = "140368")] + // #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn data_ptr(&self) -> *mut T { + self.data.get() + } +} + +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T> From<T> for Mutex<T> { + /// Creates a new mutex in an unlocked state ready for use. + /// This is equivalent to [`Mutex::new`]. + fn from(t: T) -> Self { + Mutex::new(t) + } +} + +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T: ?Sized + Default> Default for Mutex<T> { + /// Creates a `Mutex<T>`, with the `Default` value for T. + fn default() -> Mutex<T> { + Mutex::new(Default::default()) + } +} + +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T: ?Sized + fmt::Debug> fmt::Debug for Mutex<T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let mut d = f.debug_struct("Mutex"); + match self.try_lock() { + Ok(guard) => { + d.field("data", &&*guard); + } + Err(WouldBlock) => { + d.field("data", &"<locked>"); + } + } + d.finish_non_exhaustive() + } +} + +impl<'mutex, T: ?Sized> MutexGuard<'mutex, T> { + unsafe fn new(lock: &'mutex Mutex<T>) -> MutexGuard<'mutex, T> { + return MutexGuard { lock }; + } +} + +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T: ?Sized> Deref for MutexGuard<'_, T> { + type Target = T; + + fn deref(&self) -> &T { + unsafe { &*self.lock.data.get() } + } +} + +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T: ?Sized> DerefMut for MutexGuard<'_, T> { + fn deref_mut(&mut self) -> &mut T { + unsafe { &mut *self.lock.data.get() } + } +} + +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T: ?Sized> Drop for MutexGuard<'_, T> { + #[inline] + fn drop(&mut self) { + unsafe { + self.lock.inner.unlock(); + } + } +} + +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T: ?Sized + fmt::Debug> fmt::Debug for MutexGuard<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Debug::fmt(&**self, f) + } +} + +#[unstable(feature = "nonpoison_mutex", issue = "134645")] +impl<T: ?Sized + fmt::Display> fmt::Display for MutexGuard<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} + +impl<'a, T: ?Sized> MutexGuard<'a, T> { + /// Makes a [`MappedMutexGuard`] for a component of the borrowed data, e.g. + /// an enum variant. + /// + /// The `Mutex` is already locked, so this cannot fail. + /// + /// This is an associated function that needs to be used as + /// `MutexGuard::map(...)`. A method would interfere with methods of the + /// same name on the contents of the `MutexGuard` used through `Deref`. + #[unstable(feature = "mapped_lock_guards", issue = "117108")] + // #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn map<U, F>(orig: Self, f: F) -> MappedMutexGuard<'a, U> + where + F: FnOnce(&mut T) -> &mut U, + U: ?Sized, + { + // SAFETY: the conditions of `MutexGuard::new` were satisfied when the original guard + // was created, and have been upheld throughout `map` and/or `filter_map`. + // The signature of the closure guarantees that it will not "leak" the lifetime of the reference + // passed to it. If the closure panics, the guard will be dropped. + let data = NonNull::from(f(unsafe { &mut *orig.lock.data.get() })); + let orig = ManuallyDrop::new(orig); + MappedMutexGuard { data, inner: &orig.lock.inner, _variance: PhantomData } + } + + /// Makes a [`MappedMutexGuard`] for a component of the borrowed data. The + /// original guard is returned as an `Err(...)` if the closure returns + /// `None`. + /// + /// The `Mutex` is already locked, so this cannot fail. + /// + /// This is an associated function that needs to be used as + /// `MutexGuard::filter_map(...)`. A method would interfere with methods of the + /// same name on the contents of the `MutexGuard` used through `Deref`. + #[unstable(feature = "mapped_lock_guards", issue = "117108")] + // #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn filter_map<U, F>(orig: Self, f: F) -> Result<MappedMutexGuard<'a, U>, Self> + where + F: FnOnce(&mut T) -> Option<&mut U>, + U: ?Sized, + { + // SAFETY: the conditions of `MutexGuard::new` were satisfied when the original guard + // was created, and have been upheld throughout `map` and/or `filter_map`. + // The signature of the closure guarantees that it will not "leak" the lifetime of the reference + // passed to it. If the closure panics, the guard will be dropped. + match f(unsafe { &mut *orig.lock.data.get() }) { + Some(data) => { + let data = NonNull::from(data); + let orig = ManuallyDrop::new(orig); + Ok(MappedMutexGuard { data, inner: &orig.lock.inner, _variance: PhantomData }) + } + None => Err(orig), + } + } +} + +#[unstable(feature = "mapped_lock_guards", issue = "117108")] +impl<T: ?Sized> Deref for MappedMutexGuard<'_, T> { + type Target = T; + + fn deref(&self) -> &T { + unsafe { self.data.as_ref() } + } +} + +#[unstable(feature = "mapped_lock_guards", issue = "117108")] +impl<T: ?Sized> DerefMut for MappedMutexGuard<'_, T> { + fn deref_mut(&mut self) -> &mut T { + unsafe { self.data.as_mut() } + } +} + +#[unstable(feature = "mapped_lock_guards", issue = "117108")] +impl<T: ?Sized> Drop for MappedMutexGuard<'_, T> { + #[inline] + fn drop(&mut self) { + unsafe { + self.inner.unlock(); + } + } +} + +#[unstable(feature = "mapped_lock_guards", issue = "117108")] +impl<T: ?Sized + fmt::Debug> fmt::Debug for MappedMutexGuard<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Debug::fmt(&**self, f) + } +} + +#[unstable(feature = "mapped_lock_guards", issue = "117108")] +impl<T: ?Sized + fmt::Display> fmt::Display for MappedMutexGuard<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} + +impl<'a, T: ?Sized> MappedMutexGuard<'a, T> { + /// Makes a [`MappedMutexGuard`] for a component of the borrowed data, e.g. + /// an enum variant. + /// + /// The `Mutex` is already locked, so this cannot fail. + /// + /// This is an associated function that needs to be used as + /// `MappedMutexGuard::map(...)`. A method would interfere with methods of the + /// same name on the contents of the `MutexGuard` used through `Deref`. + #[unstable(feature = "mapped_lock_guards", issue = "117108")] + // #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn map<U, F>(mut orig: Self, f: F) -> MappedMutexGuard<'a, U> + where + F: FnOnce(&mut T) -> &mut U, + U: ?Sized, + { + // SAFETY: the conditions of `MutexGuard::new` were satisfied when the original guard + // was created, and have been upheld throughout `map` and/or `filter_map`. + // The signature of the closure guarantees that it will not "leak" the lifetime of the reference + // passed to it. If the closure panics, the guard will be dropped. + let data = NonNull::from(f(unsafe { orig.data.as_mut() })); + let orig = ManuallyDrop::new(orig); + MappedMutexGuard { data, inner: orig.inner, _variance: PhantomData } + } + + /// Makes a [`MappedMutexGuard`] for a component of the borrowed data. The + /// original guard is returned as an `Err(...)` if the closure returns + /// `None`. + /// + /// The `Mutex` is already locked, so this cannot fail. + /// + /// This is an associated function that needs to be used as + /// `MappedMutexGuard::filter_map(...)`. A method would interfere with methods of the + /// same name on the contents of the `MutexGuard` used through `Deref`. + #[unstable(feature = "mapped_lock_guards", issue = "117108")] + // #[unstable(feature = "nonpoison_mutex", issue = "134645")] + pub fn filter_map<U, F>(mut orig: Self, f: F) -> Result<MappedMutexGuard<'a, U>, Self> + where + F: FnOnce(&mut T) -> Option<&mut U>, + U: ?Sized, + { + // SAFETY: the conditions of `MutexGuard::new` were satisfied when the original guard + // was created, and have been upheld throughout `map` and/or `filter_map`. + // The signature of the closure guarantees that it will not "leak" the lifetime of the reference + // passed to it. If the closure panics, the guard will be dropped. + match f(unsafe { orig.data.as_mut() }) { + Some(data) => { + let data = NonNull::from(data); + let orig = ManuallyDrop::new(orig); + Ok(MappedMutexGuard { data, inner: orig.inner, _variance: PhantomData }) + } + None => Err(orig), + } + } +} diff --git a/tests/ui/async-await/issue-64130-non-send-future-diags.stderr b/tests/ui/async-await/issue-64130-non-send-future-diags.stderr index d28807e223b..beaf8e9c96d 100644 --- a/tests/ui/async-await/issue-64130-non-send-future-diags.stderr +++ b/tests/ui/async-await/issue-64130-non-send-future-diags.stderr @@ -4,12 +4,12 @@ error: future cannot be sent between threads safely LL | is_send(foo()); | ^^^^^ future returned by `foo` is not `Send` | - = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `MutexGuard<'_, u32>` + = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `std::sync::MutexGuard<'_, u32>` note: future is not `Send` as this value is used across an await --> $DIR/issue-64130-non-send-future-diags.rs:17:11 | LL | let g = x.lock().unwrap(); - | - has type `MutexGuard<'_, u32>` which is not `Send` + | - has type `std::sync::MutexGuard<'_, u32>` which is not `Send` LL | baz().await; | ^^^^^ await occurs here, with `g` maybe used later note: required by a bound in `is_send` diff --git a/tests/ui/async-await/issue-71137.stderr b/tests/ui/async-await/issue-71137.stderr index 8739c22a310..d567e3f2063 100644 --- a/tests/ui/async-await/issue-71137.stderr +++ b/tests/ui/async-await/issue-71137.stderr @@ -4,12 +4,12 @@ error: future cannot be sent between threads safely LL | fake_spawn(wrong_mutex()); | ^^^^^^^^^^^^^ future returned by `wrong_mutex` is not `Send` | - = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `MutexGuard<'_, i32>` + = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `std::sync::MutexGuard<'_, i32>` note: future is not `Send` as this value is used across an await --> $DIR/issue-71137.rs:14:26 | LL | let mut guard = m.lock().unwrap(); - | --------- has type `MutexGuard<'_, i32>` which is not `Send` + | --------- has type `std::sync::MutexGuard<'_, i32>` which is not `Send` LL | (async { "right"; }).await; | ^^^^^ await occurs here, with `mut guard` maybe used later note: required by a bound in `fake_spawn` diff --git a/tests/ui/async-await/issues/issue-67893.rs b/tests/ui/async-await/issues/issue-67893.rs index 73cce38c94a..2020abe7a5a 100644 --- a/tests/ui/async-await/issues/issue-67893.rs +++ b/tests/ui/async-await/issues/issue-67893.rs @@ -7,5 +7,5 @@ fn g(_: impl Send) {} fn main() { g(issue_67893::run()) - //~^ ERROR `MutexGuard<'_, ()>` cannot be sent between threads safely + //~^ ERROR `std::sync::MutexGuard<'_, ()>` cannot be sent between threads safely } diff --git a/tests/ui/async-await/issues/issue-67893.stderr b/tests/ui/async-await/issues/issue-67893.stderr index c01237255b8..34f28dd53c7 100644 --- a/tests/ui/async-await/issues/issue-67893.stderr +++ b/tests/ui/async-await/issues/issue-67893.stderr @@ -1,8 +1,8 @@ -error[E0277]: `MutexGuard<'_, ()>` cannot be sent between threads safely +error[E0277]: `std::sync::MutexGuard<'_, ()>` cannot be sent between threads safely --> $DIR/issue-67893.rs:9:7 | LL | g(issue_67893::run()) - | - ^^^^^^^^^^^^^^^^^^ `MutexGuard<'_, ()>` cannot be sent between threads safely + | - ^^^^^^^^^^^^^^^^^^ `std::sync::MutexGuard<'_, ()>` cannot be sent between threads safely | | | required by a bound introduced by this call | @@ -11,7 +11,7 @@ LL | g(issue_67893::run()) LL | pub async fn run() { | ------------------ within this `impl Future<Output = ()>` | - = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `MutexGuard<'_, ()>` + = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `std::sync::MutexGuard<'_, ()>` note: required because it's used within this `async` fn body --> $DIR/auxiliary/issue_67893.rs:9:20 | diff --git a/tests/ui/lint/must_not_suspend/mutex.rs b/tests/ui/lint/must_not_suspend/mutex.rs index d14f7130b4c..8dd4cc17615 100644 --- a/tests/ui/lint/must_not_suspend/mutex.rs +++ b/tests/ui/lint/must_not_suspend/mutex.rs @@ -5,7 +5,7 @@ async fn other() {} pub async fn uhoh(m: std::sync::Mutex<()>) { - let _guard = m.lock().unwrap(); //~ ERROR `MutexGuard` held across + let _guard = m.lock().unwrap(); //~ ERROR `std::sync::MutexGuard` held across other().await; } diff --git a/tests/ui/lint/must_not_suspend/mutex.stderr b/tests/ui/lint/must_not_suspend/mutex.stderr index ca53a753150..0db1f2575b1 100644 --- a/tests/ui/lint/must_not_suspend/mutex.stderr +++ b/tests/ui/lint/must_not_suspend/mutex.stderr @@ -1,4 +1,4 @@ -error: `MutexGuard` held across a suspend point, but should not be +error: `std::sync::MutexGuard` held across a suspend point, but should not be --> $DIR/mutex.rs:8:9 | LL | let _guard = m.lock().unwrap(); diff --git a/tests/ui/privacy/private-field-access-in-mutex-54062.rs b/tests/ui/privacy/private-field-access-in-mutex-54062.rs index f145f9c3e52..c957e0bc7e8 100644 --- a/tests/ui/privacy/private-field-access-in-mutex-54062.rs +++ b/tests/ui/privacy/private-field-access-in-mutex-54062.rs @@ -8,7 +8,7 @@ fn main() {} fn testing(test: Test) { let _ = test.comps.inner.try_lock(); - //~^ ERROR: field `inner` of struct `Mutex` is private + //~^ ERROR: field `inner` of struct `std::sync::Mutex` is private } // https://github.com/rust-lang/rust/issues/54062 diff --git a/tests/ui/privacy/private-field-access-in-mutex-54062.stderr b/tests/ui/privacy/private-field-access-in-mutex-54062.stderr index 14244107597..f7f84640648 100644 --- a/tests/ui/privacy/private-field-access-in-mutex-54062.stderr +++ b/tests/ui/privacy/private-field-access-in-mutex-54062.stderr @@ -1,4 +1,4 @@ -error[E0616]: field `inner` of struct `Mutex` is private +error[E0616]: field `inner` of struct `std::sync::Mutex` is private --> $DIR/private-field-access-in-mutex-54062.rs:10:24 | LL | let _ = test.comps.inner.try_lock(); diff --git a/tests/ui/suggestions/inner_type.fixed b/tests/ui/suggestions/inner_type.fixed index 3dc939d6b5c..175a2a02acd 100644 --- a/tests/ui/suggestions/inner_type.fixed +++ b/tests/ui/suggestions/inner_type.fixed @@ -25,7 +25,7 @@ fn main() { let another_item = std::sync::Mutex::new(Struct { p: 42_u32 }); another_item.lock().unwrap().method(); - //~^ ERROR no method named `method` found for struct `Mutex` in the current scope [E0599] + //~^ ERROR no method named `method` found for struct `std::sync::Mutex` in the current scope [E0599] //~| HELP use `.lock().unwrap()` to borrow the `Struct<u32>`, blocking the current thread until it can be acquired let another_item = std::sync::RwLock::new(Struct { p: 42_u32 }); diff --git a/tests/ui/suggestions/inner_type.rs b/tests/ui/suggestions/inner_type.rs index 81a05c25311..ab021414f56 100644 --- a/tests/ui/suggestions/inner_type.rs +++ b/tests/ui/suggestions/inner_type.rs @@ -25,7 +25,7 @@ fn main() { let another_item = std::sync::Mutex::new(Struct { p: 42_u32 }); another_item.method(); - //~^ ERROR no method named `method` found for struct `Mutex` in the current scope [E0599] + //~^ ERROR no method named `method` found for struct `std::sync::Mutex` in the current scope [E0599] //~| HELP use `.lock().unwrap()` to borrow the `Struct<u32>`, blocking the current thread until it can be acquired let another_item = std::sync::RwLock::new(Struct { p: 42_u32 }); diff --git a/tests/ui/suggestions/inner_type.stderr b/tests/ui/suggestions/inner_type.stderr index 5ac3d04f104..67ebb5789b7 100644 --- a/tests/ui/suggestions/inner_type.stderr +++ b/tests/ui/suggestions/inner_type.stderr @@ -30,11 +30,11 @@ help: use `.borrow_mut()` to mutably borrow the `Struct<u32>`, panicking if any LL | other_item.borrow_mut().some_mutable_method(); | +++++++++++++ -error[E0599]: no method named `method` found for struct `Mutex` in the current scope +error[E0599]: no method named `method` found for struct `std::sync::Mutex` in the current scope --> $DIR/inner_type.rs:27:18 | LL | another_item.method(); - | ^^^^^^ method not found in `Mutex<Struct<u32>>` + | ^^^^^^ method not found in `std::sync::Mutex<Struct<u32>>` | note: the method `method` exists on the type `Struct<u32>` --> $DIR/inner_type.rs:9:5 diff --git a/tests/ui/sync/mutexguard-sync.stderr b/tests/ui/sync/mutexguard-sync.stderr index 1501a793d5e..ab9983c1f2c 100644 --- a/tests/ui/sync/mutexguard-sync.stderr +++ b/tests/ui/sync/mutexguard-sync.stderr @@ -8,7 +8,7 @@ LL | test_sync(guard); | = help: the trait `Sync` is not implemented for `Cell<i32>` = note: if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI32` instead - = note: required for `MutexGuard<'_, Cell<i32>>` to implement `Sync` + = note: required for `std::sync::MutexGuard<'_, Cell<i32>>` to implement `Sync` note: required by a bound in `test_sync` --> $DIR/mutexguard-sync.rs:5:17 | diff --git a/tests/ui/traits/const-traits/span-bug-issue-121418.stderr b/tests/ui/traits/const-traits/span-bug-issue-121418.stderr index 92cfecd0540..f31129d9cb7 100644 --- a/tests/ui/traits/const-traits/span-bug-issue-121418.stderr +++ b/tests/ui/traits/const-traits/span-bug-issue-121418.stderr @@ -14,8 +14,8 @@ error[E0277]: the size for values of type `(dyn T + 'static)` cannot be known at LL | pub const fn new() -> std::sync::Mutex<dyn T> {} | ^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time | - = help: within `Mutex<(dyn T + 'static)>`, the trait `Sized` is not implemented for `(dyn T + 'static)` -note: required because it appears within the type `Mutex<(dyn T + 'static)>` + = help: within `std::sync::Mutex<(dyn T + 'static)>`, the trait `Sized` is not implemented for `(dyn T + 'static)` +note: required because it appears within the type `std::sync::Mutex<(dyn T + 'static)>` --> $SRC_DIR/std/src/sync/poison/mutex.rs:LL:COL = note: the return type of a function must have a statically known size @@ -27,7 +27,7 @@ LL | pub const fn new() -> std::sync::Mutex<dyn T> {} | | | implicitly returns `()` as its body has no tail or `return` expression | - = note: expected struct `Mutex<(dyn T + 'static)>` + = note: expected struct `std::sync::Mutex<(dyn T + 'static)>` found unit type `()` error: aborting due to 3 previous errors diff --git a/tests/ui/typeck/assign-non-lval-derefmut.fixed b/tests/ui/typeck/assign-non-lval-derefmut.fixed index 6ecec574f2e..e6f97a9e86c 100644 --- a/tests/ui/typeck/assign-non-lval-derefmut.fixed +++ b/tests/ui/typeck/assign-non-lval-derefmut.fixed @@ -5,11 +5,11 @@ fn main() { *x.lock().unwrap() = 2; //~^ ERROR invalid left-hand side of assignment *x.lock().unwrap() += 1; - //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>` + //~^ ERROR binary assignment operation `+=` cannot be applied to type `std::sync::MutexGuard<'_, usize>` let mut y = x.lock().unwrap(); *y = 2; //~^ ERROR mismatched types *y += 1; - //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>` + //~^ ERROR binary assignment operation `+=` cannot be applied to type `std::sync::MutexGuard<'_, usize>` } diff --git a/tests/ui/typeck/assign-non-lval-derefmut.rs b/tests/ui/typeck/assign-non-lval-derefmut.rs index ac1be913e2a..a53a52c7e4d 100644 --- a/tests/ui/typeck/assign-non-lval-derefmut.rs +++ b/tests/ui/typeck/assign-non-lval-derefmut.rs @@ -5,11 +5,11 @@ fn main() { x.lock().unwrap() = 2; //~^ ERROR invalid left-hand side of assignment x.lock().unwrap() += 1; - //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>` + //~^ ERROR binary assignment operation `+=` cannot be applied to type `std::sync::MutexGuard<'_, usize>` let mut y = x.lock().unwrap(); y = 2; //~^ ERROR mismatched types y += 1; - //~^ ERROR binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>` + //~^ ERROR binary assignment operation `+=` cannot be applied to type `std::sync::MutexGuard<'_, usize>` } diff --git a/tests/ui/typeck/assign-non-lval-derefmut.stderr b/tests/ui/typeck/assign-non-lval-derefmut.stderr index 16fb1e9c5c3..f57b5abe2ee 100644 --- a/tests/ui/typeck/assign-non-lval-derefmut.stderr +++ b/tests/ui/typeck/assign-non-lval-derefmut.stderr @@ -11,15 +11,15 @@ help: consider dereferencing here to assign to the mutably borrowed value LL | *x.lock().unwrap() = 2; | + -error[E0368]: binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>` +error[E0368]: binary assignment operation `+=` cannot be applied to type `std::sync::MutexGuard<'_, usize>` --> $DIR/assign-non-lval-derefmut.rs:7:5 | LL | x.lock().unwrap() += 1; | -----------------^^^^^ | | - | cannot use `+=` on type `MutexGuard<'_, usize>` + | cannot use `+=` on type `std::sync::MutexGuard<'_, usize>` | -note: the foreign item type `MutexGuard<'_, usize>` doesn't implement `AddAssign<{integer}>` +note: the foreign item type `std::sync::MutexGuard<'_, usize>` doesn't implement `AddAssign<{integer}>` --> $SRC_DIR/std/src/sync/poison/mutex.rs:LL:COL | = note: not implement `AddAssign<{integer}>` @@ -36,22 +36,22 @@ LL | let mut y = x.lock().unwrap(); LL | y = 2; | ^ expected `MutexGuard<'_, usize>`, found integer | - = note: expected struct `MutexGuard<'_, usize>` + = note: expected struct `std::sync::MutexGuard<'_, usize>` found type `{integer}` help: consider dereferencing here to assign to the mutably borrowed value | LL | *y = 2; | + -error[E0368]: binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>` +error[E0368]: binary assignment operation `+=` cannot be applied to type `std::sync::MutexGuard<'_, usize>` --> $DIR/assign-non-lval-derefmut.rs:13:5 | LL | y += 1; | -^^^^^ | | - | cannot use `+=` on type `MutexGuard<'_, usize>` + | cannot use `+=` on type `std::sync::MutexGuard<'_, usize>` | -note: the foreign item type `MutexGuard<'_, usize>` doesn't implement `AddAssign<{integer}>` +note: the foreign item type `std::sync::MutexGuard<'_, usize>` doesn't implement `AddAssign<{integer}>` --> $SRC_DIR/std/src/sync/poison/mutex.rs:LL:COL | = note: not implement `AddAssign<{integer}>` diff --git a/tests/ui/typeck/deref-multi.stderr b/tests/ui/typeck/deref-multi.stderr index 02513853c48..c4fa49e43ef 100644 --- a/tests/ui/typeck/deref-multi.stderr +++ b/tests/ui/typeck/deref-multi.stderr @@ -63,7 +63,7 @@ LL | x.lock().unwrap() | ^^^^^^^^^^^^^^^^^ expected `i32`, found `MutexGuard<'_, &i32>` | = note: expected type `i32` - found struct `MutexGuard<'_, &i32>` + found struct `std::sync::MutexGuard<'_, &i32>` help: consider dereferencing the type | LL | **x.lock().unwrap() |