Struct tokio::sync::OwnedRwLockMappedWriteGuard
source · [−]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.
Implementations
sourceimpl<T: ?Sized, U: ?Sized> OwnedRwLockMappedWriteGuard<T, U>
impl<T: ?Sized, U: ?Sized> OwnedRwLockMappedWriteGuard<T, U>
sourcepub fn map<F, V: ?Sized>(this: Self, f: F) -> OwnedRwLockMappedWriteGuard<T, V> where
F: FnOnce(&mut U) -> &mut V,
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);
sourcepub fn try_map<F, V: ?Sized>(
this: Self,
f: F
) -> Result<OwnedRwLockMappedWriteGuard<T, V>, Self> where
F: FnOnce(&mut U) -> Option<&mut V>,
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);
Trait Implementations
sourceimpl<T: ?Sized, U: ?Sized> Deref for OwnedRwLockMappedWriteGuard<T, U>
impl<T: ?Sized, U: ?Sized> Deref for OwnedRwLockMappedWriteGuard<T, U>
sourceimpl<T: ?Sized, U: ?Sized> DerefMut for OwnedRwLockMappedWriteGuard<T, U>
impl<T: ?Sized, U: ?Sized> DerefMut for OwnedRwLockMappedWriteGuard<T, U>
sourceimpl<T: ?Sized, U: ?Sized> Drop for OwnedRwLockMappedWriteGuard<T, U>
impl<T: ?Sized, U: ?Sized> Drop for OwnedRwLockMappedWriteGuard<T, U>
impl<T, U> Send for OwnedRwLockMappedWriteGuard<T, U> where
T: ?Sized + Send + Sync,
U: ?Sized + Send + Sync,
impl<T, U> Sync for OwnedRwLockMappedWriteGuard<T, U> where
T: ?Sized + Send + Sync,
U: ?Sized + Send + Sync,
Auto Trait Implementations
impl<T, U = T> !RefUnwindSafe for OwnedRwLockMappedWriteGuard<T, U>
impl<T: ?Sized, U: ?Sized> Unpin for OwnedRwLockMappedWriteGuard<T, U> where
T: Unpin,
impl<T, U = T> !UnwindSafe for OwnedRwLockMappedWriteGuard<T, U>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more