Struct tokio::sync::OwnedRwLockMappedWriteGuard

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pub struct OwnedRwLockMappedWriteGuard<T: ?Sized, U: ?Sized = T> { /* private fields */ }
Expand description

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

This structure is created by mapping an OwnedRwLockWriteGuard. It is a separate type from OwnedRwLockWriteGuard to disallow downgrading a mapped guard, since doing so can cause undefined behavior.

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impl<T: ?Sized, U: ?Sized> OwnedRwLockMappedWriteGuard<T, U>

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pub fn map<F, V: ?Sized>(this: Self, f: F) -> OwnedRwLockMappedWriteGuard<T, V>
where F: FnOnce(&mut U) -> &mut V,

Makes a new OwnedRwLockMappedWriteGuard for a component of the locked data.

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

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

§Examples
use std::sync::Arc;
use tokio::sync::{RwLock, OwnedRwLockWriteGuard};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);

let lock = Arc::new(RwLock::new(Foo(1)));

{
    let lock = Arc::clone(&lock);
    let mut mapped = OwnedRwLockWriteGuard::map(lock.write_owned().await, |f| &mut f.0);
    *mapped = 2;
}

assert_eq!(Foo(2), *lock.read().await);
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pub fn try_map<F, V: ?Sized>( this: Self, f: F ) -> Result<OwnedRwLockMappedWriteGuard<T, V>, Self>
where F: FnOnce(&mut U) -> Option<&mut V>,

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

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

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

§Examples
use std::sync::Arc;
use tokio::sync::{RwLock, OwnedRwLockWriteGuard};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);

let lock = Arc::new(RwLock::new(Foo(1)));

{
    let guard = Arc::clone(&lock).write_owned().await;
    let mut guard = OwnedRwLockWriteGuard::try_map(guard, |f| Some(&mut f.0)).expect("should not fail");
    *guard = 2;
}

assert_eq!(Foo(2), *lock.read().await);
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pub fn rwlock(this: &Self) -> &Arc<RwLock<T>>

Returns a reference to the original Arc<RwLock>.

§Examples
use std::sync::Arc;
use tokio::sync::{
    RwLock,
    OwnedRwLockWriteGuard,
    OwnedRwLockMappedWriteGuard,
};

let lock = Arc::new(RwLock::new(1));

let guard = lock.clone().write_owned().await;
let guard = OwnedRwLockWriteGuard::map(guard, |x| x);
assert!(Arc::ptr_eq(&lock, OwnedRwLockMappedWriteGuard::rwlock(&guard)));

Trait Implementations§

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impl<T: ?Sized, U> Debug for OwnedRwLockMappedWriteGuard<T, U>
where U: Debug + ?Sized,

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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<T: ?Sized, U: ?Sized> Deref for OwnedRwLockMappedWriteGuard<T, U>

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type Target = U

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

Dereferences the value.
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impl<T: ?Sized, U: ?Sized> DerefMut for OwnedRwLockMappedWriteGuard<T, U>

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

Mutably dereferences the value.
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impl<T: ?Sized, U> Display for OwnedRwLockMappedWriteGuard<T, U>
where U: Display + ?Sized,

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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<T: ?Sized, U: ?Sized> Drop for OwnedRwLockMappedWriteGuard<T, U>

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fn drop(&mut self)

Executes the destructor for this type. Read more
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impl<T, U> Send for OwnedRwLockMappedWriteGuard<T, U>
where T: ?Sized + Send + Sync, U: ?Sized + Send + Sync,

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impl<T, U> Sync for OwnedRwLockMappedWriteGuard<T, U>
where T: ?Sized + Send + Sync, U: ?Sized + Send + Sync,

Auto Trait Implementations§

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impl<T, U> Freeze for OwnedRwLockMappedWriteGuard<T, U>
where T: ?Sized, U: ?Sized,

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impl<T, U = T> !RefUnwindSafe for OwnedRwLockMappedWriteGuard<T, U>

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impl<T, U> Unpin for OwnedRwLockMappedWriteGuard<T, U>
where T: Unpin + ?Sized, U: ?Sized,

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impl<T, U = T> !UnwindSafe for OwnedRwLockMappedWriteGuard<T, U>

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> ToString for T
where T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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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.