Struct tokio::sync::OwnedRwLockMappedWriteGuard
source · 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.
Implementations§
source§impl<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>
pub fn map<F, V: ?Sized>(this: Self, f: F) -> OwnedRwLockMappedWriteGuard<T, 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>
pub fn try_map<F, V: ?Sized>( this: Self, f: F, ) -> Result<OwnedRwLockMappedWriteGuard<T, V>, Self>
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);
sourcepub fn rwlock(this: &Self) -> &Arc<RwLock<T>>
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)));