Struct RwLockWriteGuard

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

RAII structure used to release the exclusive write access of a lock when dropped.

Implementations

impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T>

fn rwlock(s: &Self) -> &'a RwLock<R, T>

Returns a reference to the original reader-writer lock object.

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 RwLockWriteGuard passed in already locked the data.

This is an associated function that needs to be used as RwLockWriteGuard::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 RwLockWriteGuard passed in already locked the data.

This is an associated function that needs to be used as RwLockWriteGuard::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 RwLockWriteGuard passed in already locked the data.

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

fn unlocked<F, U>(s: &mut Self, f: F) -> U
where
    F: FnOnce() -> U,

Temporarily unlocks the RwLock to execute the given function.

This is safe because &mut guarantees that there exist no other references to the data protected by the RwLock.

impl<'a, R: RawRwLockDowngrade + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T>

fn downgrade(s: Self) -> RwLockReadGuard<'a, R, T>

Atomically downgrades a write lock into a read lock without allowing any writers to take exclusive access of the lock in the meantime.

Note that if there are any writers currently waiting to take the lock then other readers may not be able to acquire the lock even if it was downgraded.

impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> RwLockWriteGuard<'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 RwLockWriteGuard normally.

fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U
where
    F: FnOnce() -> U,

Temporarily unlocks the RwLock to execute the given function.

The RwLock is unlocked a fair unlock protocol.

This is safe because &mut guarantees that there exist no other references to the data protected by the RwLock.

fn bump(s: &mut Self)

Temporarily yields the RwLock to a waiting thread if there is one.

This method is functionally equivalent to calling unlock_fair followed by write, however it can be much more efficient in the case where there are no waiting threads.

impl<'a, R: RawRwLockUpgradeDowngrade + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T>

fn downgrade_to_upgradable(s: Self) -> RwLockUpgradableReadGuard<'a, R, T>

Atomically downgrades a write lock into an upgradable read lock without allowing any writers to take exclusive access of the lock in the meantime.

Note that if there are any writers currently waiting to take the lock then other readers may not be able to acquire the lock even if it was downgraded.

Trait Implementations

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

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

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

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

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

fn drop(&mut self)

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

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

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

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

impl<R: RawRwLock + Sync, T: Sync + ?Sized> Sync for RwLockWriteGuard<'_, R, T>

Auto Trait Implementations

impl<'a, R, T> !RefUnwindSafe for RwLockWriteGuard<'a, R, T>

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

impl<'a, R, T> Freeze for RwLockWriteGuard<'a, R, T> where &'a RwLock<R, T>: Freeze, PhantomData<(&'a mut T, <R as RawRwLock>::GuardMarker)>: Freeze, T: ?Sized,

impl<'a, R, T> Send for RwLockWriteGuard<'a, R, T> where &'a RwLock<R, T>: Send, PhantomData<(&'a mut T, <R as RawRwLock>::GuardMarker)>: Send, T: ?Sized,

impl<'a, R, T> Unpin for RwLockWriteGuard<'a, R, T> where &'a RwLock<R, T>: Unpin, PhantomData<(&'a mut T, <R as RawRwLock>::GuardMarker)>: Unpin, T: ?Sized,

impl<'a, R, T> UnsafeUnpin for RwLockWriteGuard<'a, R, T> where &'a RwLock<R, T>: UnsafeUnpin, PhantomData<(&'a mut T, <R as RawRwLock>::GuardMarker)>: UnsafeUnpin, T: ?Sized,

Blanket Implementations

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

type Target = T;

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

fn type_id(&self) -> TypeId

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

fn borrow(&self) -> &T

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

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

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

fn from(t: T) -> T

Returns the argument unchanged.

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

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

impl<T, U> TryInto<U> for RwLockWriteGuard<'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>