Struct MappedRwLockWriteGuard

#[must_use = "if unused the RwLock will immediately unlock"]
pub struct MappedRwLockWriteGuard<'a, R: RawRwLock, T: ?Sized> { /* private fields */ }

An RAII write lock guard returned by RwLockWriteGuard::map, which can point to a subfield of the protected data.

The main difference between MappedRwLockWriteGuard and RwLockWriteGuard 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: RawRwLock + 'a, T: ?Sized + 'a> MappedRwLockWriteGuard<'a, R, T>

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

Make a new MappedRwLockWriteGuard for a component of the locked data.

This operation cannot fail as the MappedRwLockWriteGuard passed in already locked the data.

This is an associated function that needs to be used as MappedRwLockWriteGuard::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<MappedRwLockWriteGuard<'a, R, U>, Self>
where
    F: FnOnce(&mut T) -> Option<&mut U>,

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

This operation cannot fail as the MappedRwLockWriteGuard passed in already locked the data.

This is an associated function that needs to be used as MappedRwLockWriteGuard::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<MappedRwLockWriteGuard<'a, R, U>, (Self, E)>
where
    F: FnOnce(&mut T) -> Result<&mut U, E>,

Attempts to make a new MappedRwLockWriteGuard 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 MappedRwLockWriteGuard passed in already locked the data.

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

impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> MappedRwLockWriteGuard<'a, R, T>

fn unlock_fair(s: Self)

Unlocks the RwLock using a fair unlock protocol.

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

Trait Implementations

impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for MappedRwLockWriteGuard<'a, R, T>

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

impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> DerefMut for MappedRwLockWriteGuard<'a, R, T>

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

impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Drop for MappedRwLockWriteGuard<'a, R, T>

fn drop(&mut self)

impl<'a, R: RawRwLock + 'a, T: ?Sized + Send + 'a> Send for MappedRwLockWriteGuard<'a, R, T> where R::GuardMarker: Send,

impl<'a, R: RawRwLock + 'a, T: ?Sized + Sync + 'a> Sync for MappedRwLockWriteGuard<'a, R, T>

impl<'a, R: RawRwLock + 'a, T: Debug + ?Sized + 'a> Debug for MappedRwLockWriteGuard<'a, R, T>

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

impl<'a, R: RawRwLock + 'a, T: Display + ?Sized + 'a> Display for MappedRwLockWriteGuard<'a, R, T>

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

Auto Trait Implementations

impl<'a, R, T> !UnwindSafe for MappedRwLockWriteGuard<'a, R, T>

impl<'a, R, T> Freeze for MappedRwLockWriteGuard<'a, R, T> where &'a R: Freeze, *mut T: Freeze, PhantomData<&'a mut T>: Freeze, T: ?Sized,

impl<'a, R, T> RefUnwindSafe for MappedRwLockWriteGuard<'a, R, T> where &'a R: RefUnwindSafe, *mut T: RefUnwindSafe, PhantomData<&'a mut T>: RefUnwindSafe, T: ?Sized,

impl<'a, R, T> Unpin for MappedRwLockWriteGuard<'a, R, T> where &'a R: Unpin, *mut T: Unpin, PhantomData<&'a mut T>: Unpin, T: ?Sized,

impl<'a, R, T> UnsafeUnpin for MappedRwLockWriteGuard<'a, R, T> where &'a R: UnsafeUnpin, *mut T: UnsafeUnpin, PhantomData<&'a mut T>: UnsafeUnpin, T: ?Sized,

Blanket Implementations

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

type Target = T;

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

fn type_id(&self) -> TypeId

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

fn borrow(&self) -> &T

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

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

impl<T> From<T> for MappedRwLockWriteGuard<'a, R, T>

fn from(t: T) -> T

Returns the argument unchanged.

impl<T, U> Into<U> for MappedRwLockWriteGuard<'a, R, 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 MappedRwLockWriteGuard<'a, R, T> where U: Into<T>,

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

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

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