Struct spin::RwLockUpgradeableGuard

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pub struct RwLockUpgradeableGuard<'a, T: 'a + ?Sized> { /* private fields */ }
Expand description

A guard from which the protected data can be read, and can be upgraded to a writable guard if needed

No writers or other upgradeable guards can exist while this is in scope. New reader creation is prevented (to alleviate writer starvation) but there may be existing readers when the lock is acquired.

When the guard falls out of scope it will release the lock.

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impl<'rwlock, T: ?Sized> RwLockUpgradeableGuard<'rwlock, T>

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pub fn upgrade(self) -> RwLockWriteGuard<'rwlock, T>

Upgrades an upgradeable lock guard to a writable lock guard.

let mylock = spin::RwLock::new(0);

let upgradeable = mylock.upgradeable_read(); // Readable, but not yet writable
let writable = upgradeable.upgrade();
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pub fn try_upgrade(self) -> Result<RwLockWriteGuard<'rwlock, T>, Self>

Tries to upgrade an upgradeable lock guard to a writable lock guard.

let mylock = spin::RwLock::new(0);
let upgradeable = mylock.upgradeable_read(); // Readable, but not yet writable

match upgradeable.try_upgrade() {
    Ok(writable) => /* upgrade successful - use writable lock guard */ (),
    Err(upgradeable) => /* upgrade unsuccessful */ (),
};
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pub fn downgrade(self) -> RwLockReadGuard<'rwlock, T>

Downgrades the upgradeable lock guard to a readable, shared lock guard. Cannot fail and is guaranteed not to spin.

let mylock = spin::RwLock::new(1);

let upgradeable = mylock.upgradeable_read();
assert!(mylock.try_read().is_none());
assert_eq!(*upgradeable, 1);

let readable = upgradeable.downgrade(); // This is guaranteed not to spin
assert!(mylock.try_read().is_some());
assert_eq!(*readable, 1);

Trait Implementations§

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impl<'a, T: Debug + 'a + ?Sized> Debug for RwLockUpgradeableGuard<'a, T>

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

Formats the value using the given formatter. Read more
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impl<'rwlock, T: ?Sized> Deref for RwLockUpgradeableGuard<'rwlock, T>

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type Target = T

The resulting type after dereferencing.
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fn deref(&self) -> &T

Dereferences the value.
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impl<'rwlock, T: ?Sized> Drop for RwLockUpgradeableGuard<'rwlock, T>

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fn drop(&mut self)

Executes the destructor for this type. Read more

Auto Trait Implementations§

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impl<'a, T> Freeze for RwLockUpgradeableGuard<'a, T>
where T: ?Sized,

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impl<'a, T> RefUnwindSafe for RwLockUpgradeableGuard<'a, T>
where T: RefUnwindSafe + ?Sized,

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impl<'a, T> !Send for RwLockUpgradeableGuard<'a, T>

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impl<'a, T> !Sync for RwLockUpgradeableGuard<'a, T>

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impl<'a, T> Unpin for RwLockUpgradeableGuard<'a, T>
where T: ?Sized,

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impl<'a, T> !UnwindSafe for RwLockUpgradeableGuard<'a, T>

Blanket Implementations§

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

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

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.