Struct tokio::sync::OwnedRwLockWriteGuard
source · [−]pub struct OwnedRwLockWriteGuard<T: ?Sized> { /* private fields */ }
Expand description
Owned RAII structure used to release the exclusive write access of a lock when dropped.
This structure is created by the write_owned
method
on RwLock
.
Implementations
sourceimpl<T: ?Sized> OwnedRwLockWriteGuard<T>
impl<T: ?Sized> OwnedRwLockWriteGuard<T>
sourcepub fn map<F, U: ?Sized>(this: Self, f: F) -> OwnedRwLockMappedWriteGuard<T, U> where
F: FnOnce(&mut T) -> &mut U,
pub fn map<F, U: ?Sized>(this: Self, f: F) -> OwnedRwLockMappedWriteGuard<T, U> where
F: FnOnce(&mut T) -> &mut U,
Makes a new OwnedRwLockMappedWriteGuard
for a component of the locked
data.
This operation cannot fail as the OwnedRwLockWriteGuard
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, U: ?Sized>(
this: Self,
f: F
) -> Result<OwnedRwLockMappedWriteGuard<T, U>, Self> where
F: FnOnce(&mut T) -> Option<&mut U>,
pub fn try_map<F, U: ?Sized>(
this: Self,
f: F
) -> Result<OwnedRwLockMappedWriteGuard<T, U>, Self> where
F: FnOnce(&mut T) -> Option<&mut U>,
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 OwnedRwLockWriteGuard
passed in
already locked the data.
This is an associated function that needs to be
used as OwnedRwLockWriteGuard::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);
sourcepub fn into_mapped(this: Self) -> OwnedRwLockMappedWriteGuard<T>
pub fn into_mapped(this: Self) -> OwnedRwLockMappedWriteGuard<T>
Converts this OwnedRwLockWriteGuard
into an
OwnedRwLockMappedWriteGuard
. This method can be used to store a
non-mapped guard in a struct field that expects a mapped guard.
This is equivalent to calling OwnedRwLockWriteGuard::map(guard, |me| me)
.
sourcepub fn downgrade(self) -> OwnedRwLockReadGuard<T>
pub fn downgrade(self) -> OwnedRwLockReadGuard<T>
Atomically downgrades a write lock into a read lock without allowing any writers to take exclusive access of the lock in the meantime.
Note: This won’t necessarily allow any additional readers to acquire
locks, since RwLock
is fair and it is possible that a writer is next
in line.
Returns an RAII guard which will drop this read access of the RwLock
when dropped.
Examples
let lock = Arc::new(RwLock::new(1));
let n = lock.clone().write_owned().await;
let cloned_lock = lock.clone();
let handle = tokio::spawn(async move {
*cloned_lock.write_owned().await = 2;
});
let n = n.downgrade();
assert_eq!(*n, 1, "downgrade is atomic");
drop(n);
handle.await.unwrap();
assert_eq!(*lock.read().await, 2, "second writer obtained write lock");
Trait Implementations
sourceimpl<T: ?Sized> Debug for OwnedRwLockWriteGuard<T> where
T: Debug,
impl<T: ?Sized> Debug for OwnedRwLockWriteGuard<T> where
T: Debug,
sourceimpl<T: ?Sized> Deref for OwnedRwLockWriteGuard<T>
impl<T: ?Sized> Deref for OwnedRwLockWriteGuard<T>
sourceimpl<T: ?Sized> DerefMut for OwnedRwLockWriteGuard<T>
impl<T: ?Sized> DerefMut for OwnedRwLockWriteGuard<T>
sourceimpl<T: ?Sized> Display for OwnedRwLockWriteGuard<T> where
T: Display,
impl<T: ?Sized> Display for OwnedRwLockWriteGuard<T> where
T: Display,
sourceimpl<T: ?Sized> Drop for OwnedRwLockWriteGuard<T>
impl<T: ?Sized> Drop for OwnedRwLockWriteGuard<T>
impl<T> Send for OwnedRwLockWriteGuard<T> where
T: ?Sized + Send + Sync,
impl<T> Sync for OwnedRwLockWriteGuard<T> where
T: ?Sized + Send + Sync,
Auto Trait Implementations
impl<T> !RefUnwindSafe for OwnedRwLockWriteGuard<T>
impl<T: ?Sized> Unpin for OwnedRwLockWriteGuard<T> where
T: Unpin,
impl<T> !UnwindSafe for OwnedRwLockWriteGuard<T>
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