Struct tokio::sync::RwLockMappedWriteGuard
source · [−]pub struct RwLockMappedWriteGuard<'a, T: ?Sized> { /* private fields */ }
sync
only.Expand description
RAII structure used to release the exclusive write access of a lock when dropped.
This structure is created by mapping an RwLockWriteGuard
. It is a
separate type from RwLockWriteGuard
to disallow downgrading a mapped
guard, since doing so can cause undefined behavior.
Implementations
sourceimpl<'a, T: ?Sized> RwLockMappedWriteGuard<'a, T>
impl<'a, T: ?Sized> RwLockMappedWriteGuard<'a, T>
sourcepub fn map<F, U: ?Sized>(this: Self, f: F) -> RwLockMappedWriteGuard<'a, U>where
F: FnOnce(&mut T) -> &mut U,
pub fn map<F, U: ?Sized>(this: Self, f: F) -> RwLockMappedWriteGuard<'a, U>where
F: FnOnce(&mut T) -> &mut U,
Makes a new RwLockMappedWriteGuard
for a component of the locked data.
This operation cannot fail as the RwLockMappedWriteGuard
passed in already
locked the data.
This is an associated function that needs to be used as
RwLockMappedWriteGuard::map(..)
. A method would interfere with methods
of the same name on the contents of the locked data.
This is an asynchronous version of RwLockWriteGuard::map
from the
parking_lot
crate.
Examples
use tokio::sync::{RwLock, RwLockWriteGuard};
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);
let lock = RwLock::new(Foo(1));
{
let mut mapped = RwLockWriteGuard::map(lock.write().await, |f| &mut f.0);
*mapped = 2;
}
assert_eq!(Foo(2), *lock.read().await);
sourcepub fn try_map<F, U: ?Sized>(
this: Self,
f: F
) -> Result<RwLockMappedWriteGuard<'a, U>, Self>where
F: FnOnce(&mut T) -> Option<&mut U>,
pub fn try_map<F, U: ?Sized>(
this: Self,
f: F
) -> Result<RwLockMappedWriteGuard<'a, U>, Self>where
F: FnOnce(&mut T) -> Option<&mut U>,
Attempts to make a new RwLockMappedWriteGuard
for a component of
the locked data. The original guard is returned if the closure returns
None
.
This operation cannot fail as the RwLockMappedWriteGuard
passed in already
locked the data.
This is an associated function that needs to be
used as RwLockMappedWriteGuard::try_map(...)
. A method would interfere
with methods of the same name on the contents of the locked data.
This is an asynchronous version of RwLockWriteGuard::try_map
from
the parking_lot
crate.
Examples
use tokio::sync::{RwLock, RwLockWriteGuard};
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);
let lock = RwLock::new(Foo(1));
{
let guard = lock.write().await;
let mut guard = RwLockWriteGuard::try_map(guard, |f| Some(&mut f.0)).expect("should not fail");
*guard = 2;
}
assert_eq!(Foo(2), *lock.read().await);
Trait Implementations
sourceimpl<'a, T: ?Sized> Debug for RwLockMappedWriteGuard<'a, T>where
T: Debug,
impl<'a, T: ?Sized> Debug for RwLockMappedWriteGuard<'a, T>where
T: Debug,
sourceimpl<T: ?Sized> Deref for RwLockMappedWriteGuard<'_, T>
impl<T: ?Sized> Deref for RwLockMappedWriteGuard<'_, T>
sourceimpl<T: ?Sized> DerefMut for RwLockMappedWriteGuard<'_, T>
impl<T: ?Sized> DerefMut for RwLockMappedWriteGuard<'_, T>
sourceimpl<'a, T: ?Sized> Display for RwLockMappedWriteGuard<'a, T>where
T: Display,
impl<'a, T: ?Sized> Display for RwLockMappedWriteGuard<'a, T>where
T: Display,
sourceimpl<'a, T: ?Sized> Drop for RwLockMappedWriteGuard<'a, T>
impl<'a, T: ?Sized> Drop for RwLockMappedWriteGuard<'a, T>
impl<T> Send for RwLockMappedWriteGuard<'_, T>where
T: ?Sized + Send + Sync,
impl<T> Sync for RwLockMappedWriteGuard<'_, T>where
T: ?Sized + Send + Sync,
Auto Trait Implementations
impl<'a, T> !RefUnwindSafe for RwLockMappedWriteGuard<'a, T>
impl<'a, T: ?Sized> Unpin for RwLockMappedWriteGuard<'a, T>
impl<'a, T> !UnwindSafe for RwLockMappedWriteGuard<'a, T>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
sourceimpl<T> Instrument for T
impl<T> Instrument for T
sourcefn instrument(self, span: Span) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T>where
T: Future, type Output = <T as Future>::Output;
fn instrument(self, span: Span) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T>where
T: Future, type Output = <T as Future>::Output;
T: Future, type Output = <T as Future>::Output;
sourcefn in_current_span(self) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T>where
T: Future, type Output = <T as Future>::Output;
fn in_current_span(self) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T>where
T: Future, type Output = <T as Future>::Output;
T: Future, type Output = <T as Future>::Output;
sourceimpl<T> WithSubscriber for T
impl<T> WithSubscriber for T
sourcefn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T>where
T: Future, type Output = <T as Future>::Output;
where
S: Into<Dispatch>,
fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T>where
T: Future, type Output = <T as Future>::Output;
where
S: Into<Dispatch>,
T: Future, type Output = <T as Future>::Output;
sourcefn with_current_subscriber(self) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T>where
T: Future, type Output = <T as Future>::Output;
fn with_current_subscriber(self) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T>where
T: Future, type Output = <T as Future>::Output;
T: Future, type Output = <T as Future>::Output;