Struct MappedReentrantMutexGuard

#[must_use = "if unused the ReentrantMutex will immediately unlock"]
pub struct MappedReentrantMutexGuard<'a, R: RawMutex, G: GetThreadId, T: ?Sized> { /* private fields */ }

An RAII mutex guard returned by ReentrantMutexGuard::map, which can point to a subfield of the protected data.

The main difference between MappedReentrantMutexGuard and ReentrantMutexGuard is that the former doesn't support temporarily unlocking and re-locking, since that could introduce soundness issues if the locked object is modified by another thread.

Implementations

impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> MappedReentrantMutexGuard<'a, R, G, T>

fn map<U: ?Sized, F>(s: Self, f: F) -> MappedReentrantMutexGuard<'a, R, G, U>
where
    F: FnOnce(&T) -> &U,

Makes a new MappedReentrantMutexGuard for a component of the locked data.

This operation cannot fail as the MappedReentrantMutexGuard passed in already locked the mutex.

This is an associated function that needs to be used as MappedReentrantMutexGuard::map(...). A method would interfere with methods of the same name on the contents of the locked data.

fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedReentrantMutexGuard<'a, R, G, U>, Self>
where
    F: FnOnce(&T) -> Option<&U>,

Attempts to make a new MappedReentrantMutexGuard for a component of the locked data. The original guard is return if the closure returns None.

This operation cannot fail as the MappedReentrantMutexGuard passed in already locked the mutex.

This is an associated function that needs to be used as MappedReentrantMutexGuard::try_map(...). A method would interfere with methods of the same name on the contents of the locked data.

fn try_map_or_err<U: ?Sized, F, E>(s: Self, f: F) -> Result<MappedReentrantMutexGuard<'a, R, G, U>, (Self, E)>
where
    F: FnOnce(&T) -> Result<&U, E>,

Attempts to make a new MappedReentrantMutexGuard for a component of the locked data. The original guard is returned alongside arbitrary user data if the closure returns Err.

This operation cannot fail as the MappedReentrantMutexGuard passed in already locked the mutex.

This is an associated function that needs to be used as MappedReentrantMutexGuard::try_map_or_err(...). A method would interfere with methods of the same name on the contents of the locked data.

impl<'a, R: RawMutexFair + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> MappedReentrantMutexGuard<'a, R, G, T>

fn unlock_fair(s: Self)

Unlocks the mutex using a fair unlock protocol.

By default, mutexes are unfair and allow the current thread to re-lock the mutex before another has the chance to acquire the lock, even if that thread has been blocked on the mutex for a long time. This is the default because it allows much higher throughput as it avoids forcing a context switch on every mutex unlock. This can result in one thread acquiring a mutex many more times than other threads.

However in some cases it can be beneficial to ensure fairness by forcing the lock to pass on to a waiting thread if there is one. This is done by using this method instead of dropping the ReentrantMutexGuard normally.

Trait Implementations

impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Deref for MappedReentrantMutexGuard<'a, R, G, T>

type Target = T;
fn deref(&self) -> &T

impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Drop for MappedReentrantMutexGuard<'a, R, G, T>

fn drop(&mut self)

impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: Debug + ?Sized + 'a> Debug for MappedReentrantMutexGuard<'a, R, G, T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: Display + ?Sized + 'a> Display for MappedReentrantMutexGuard<'a, R, G, T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

impl<'a, R: RawMutex + Sync + 'a, G: GetThreadId + Sync + 'a, T: ?Sized + Sync + 'a> Sync for MappedReentrantMutexGuard<'a, R, G, T>

Auto Trait Implementations

impl<'a, R, G, T> !RefUnwindSafe for MappedReentrantMutexGuard<'a, R, G, T>

impl<'a, R, G, T> !Send for MappedReentrantMutexGuard<'a, R, G, T>

impl<'a, R, G, T> !UnwindSafe for MappedReentrantMutexGuard<'a, R, G, T>

impl<'a, R, G, T> Freeze for MappedReentrantMutexGuard<'a, R, G, T> where &'a RawReentrantMutex<R, G>: Freeze, *const T: Freeze, PhantomData<&'a T>: Freeze, T: ?Sized,

impl<'a, R, G, T> Unpin for MappedReentrantMutexGuard<'a, R, G, T> where &'a RawReentrantMutex<R, G>: Unpin, *const T: Unpin, PhantomData<&'a T>: Unpin, T: ?Sized,

impl<'a, R, G, T> UnsafeUnpin for MappedReentrantMutexGuard<'a, R, G, T> where &'a RawReentrantMutex<R, G>: UnsafeUnpin, *const T: UnsafeUnpin, PhantomData<&'a T>: UnsafeUnpin, T: ?Sized,

Blanket Implementations

impl<P, T> Receiver for MappedReentrantMutexGuard<'a, R, G, T> where P: Deref<Target = T> + ?Sized, T: ?Sized,

type Target = T;

impl<T> Any for MappedReentrantMutexGuard<'a, R, G, T> where T: 'static + ?Sized,

fn type_id(&self) -> TypeId

impl<T> Borrow<T> for MappedReentrantMutexGuard<'a, R, G, T> where T: ?Sized,

fn borrow(&self) -> &T

impl<T> BorrowMut<T> for MappedReentrantMutexGuard<'a, R, G, T> where T: ?Sized,

fn borrow_mut(&mut self) -> &mut T

impl<T> From<T> for MappedReentrantMutexGuard<'a, R, G, T>

fn from(t: T) -> T

Returns the argument unchanged.

impl<T, U> Into<U> for MappedReentrantMutexGuard<'a, R, G, T> where U: From<T>,

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

impl<T, U> TryFrom<U> for MappedReentrantMutexGuard<'a, R, G, T> where U: Into<T>,

type Error = never;
fn try_from(value: U) -> Result<T, never>

impl<T, U> TryInto<U> for MappedReentrantMutexGuard<'a, R, G, T> where U: TryFrom<T>,

type Error = <U as TryFrom<T>>::Error;
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>