# Struct lock_api::RwLockUpgradableReadGuard [−] [src]

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

RAII structure used to release the upgradable read access of a lock when dropped.

## Implementations

### `impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T>` [src]

#### `pub fn rwlock(s: &Self) -> &'a RwLock<R, T>` [src]

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

#### `pub fn unlocked<F, U>(s: &mut Self, f: F) -> U where
F: FnOnce() -> U,` [src]

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`.

#### `pub fn upgrade(s: Self) -> RwLockWriteGuard<'a, R, T>` [src]

Atomically upgrades an upgradable read lock lock into a exclusive write lock, blocking the current thread until it can be acquired.

#### `pub fn try_upgrade(s: Self) -> Result<RwLockWriteGuard<'a, R, T>, Self>` [src]

Tries to atomically upgrade an upgradable read lock into a exclusive write lock.

If the access could not be granted at this time, then the current guard is returned.

### `impl<'a, R: RawRwLockUpgradeFair + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T>` [src]

#### `pub fn unlock_fair(s: Self)` [src]

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 `RwLockUpgradableReadGuard` normally.

#### `pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U where
F: FnOnce() -> U,` [src]

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`.

#### `pub fn bump(s: &mut Self)` [src]

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

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

### `impl<'a, R: RawRwLockUpgradeDowngrade + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T>` [src]

#### `pub fn downgrade(s: Self) -> RwLockReadGuard<'a, R, T>` [src]

Atomically downgrades an upgradable read lock lock into a shared 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: RawRwLockUpgradeTimed + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T>` [src]

#### `pub fn try_upgrade_for(
s: Self,
timeout: R::Duration
) -> Result<RwLockWriteGuard<'a, R, T>, Self>` [src]

Tries to atomically upgrade an upgradable read lock into a exclusive write lock, until a timeout is reached.

If the access could not be granted before the timeout expires, then the current guard is returned.

#### `pub fn try_upgrade_until(
s: Self,
timeout: R::Instant
) -> Result<RwLockWriteGuard<'a, R, T>, Self>` [src]

Tries to atomically upgrade an upgradable read lock into a exclusive write lock, until a timeout is reached.

If the access could not be granted before the timeout expires, then the current guard is returned.

## Trait Implementations

### `impl<'a, R: RawRwLockUpgrade + 'a, T: Debug + ?Sized + 'a> Debug for RwLockUpgradableReadGuard<'a, R, T>` [src]

#### `fn fmt(&self, f: &mut Formatter<'_>) -> Result` [src]

Formats the value using the given formatter. Read more

### `impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> Deref for RwLockUpgradableReadGuard<'a, R, T>` [src]

#### `type Target = T`

The resulting type after dereferencing.

#### `fn deref(&self) -> &T` [src]

Dereferences the value.

### `impl<'a, R: RawRwLockUpgrade + 'a, T: Display + ?Sized + 'a> Display for RwLockUpgradableReadGuard<'a, R, T>` [src]

#### `fn fmt(&self, f: &mut Formatter<'_>) -> Result` [src]

Formats the value using the given formatter. Read more

### `impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> Drop for RwLockUpgradableReadGuard<'a, R, T>` [src]

#### `fn drop(&mut self)` [src]

Executes the destructor for this type. Read more

### `impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + Sync + 'a> Sync for RwLockUpgradableReadGuard<'a, R, T>` [src]

## Auto Trait Implementations

### `impl<'a, R, T: ?Sized> Send for RwLockUpgradableReadGuard<'a, R, T> where
R: Sync,
T: Send + Sync,
<R as RawRwLock>::GuardMarker: Send,`

### `impl<'a, R, T: ?Sized> Unpin for RwLockUpgradableReadGuard<'a, R, T> where
<R as RawRwLock>::GuardMarker: Unpin,`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.