Struct lock_api::RwLockWriteGuard

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pub struct RwLockWriteGuard<'a, R: RawRwLock + 'a, T: ?Sized + 'a> { /* private fields */ }

Expand description

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

Implementations§

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

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

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

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pub 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.

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pub 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::map(...). A method would interfere with methods of the same name on the contents of the locked data.

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pub fn unlocked<F, U>(s: &mut Self, f: F) -> Uwhere
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.

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

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pub 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.

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

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pub 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.

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

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pub 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.

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pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> Uwhere
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.

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pub 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.