Struct tokio::sync::OwnedRwLockReadGuard
source · pub struct OwnedRwLockReadGuard<T: ?Sized, U: ?Sized = T> { /* private fields */ }
Expand description
Owned RAII structure used to release the shared read access of a lock when dropped.
This structure is created by the read_owned
method on
RwLock
.
Implementations§
source§impl<T: ?Sized, U: ?Sized> OwnedRwLockReadGuard<T, U>
impl<T: ?Sized, U: ?Sized> OwnedRwLockReadGuard<T, U>
sourcepub fn map<F, V: ?Sized>(this: Self, f: F) -> OwnedRwLockReadGuard<T, V>where
F: FnOnce(&U) -> &V,
pub fn map<F, V: ?Sized>(this: Self, f: F) -> OwnedRwLockReadGuard<T, V>where F: FnOnce(&U) -> &V,
Makes a new OwnedRwLockReadGuard
for a component of the locked data.
This operation cannot fail as the OwnedRwLockReadGuard
passed in
already locked the data.
This is an associated function that needs to be
used as OwnedRwLockReadGuard::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, OwnedRwLockReadGuard};
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);
let lock = Arc::new(RwLock::new(Foo(1)));
let guard = lock.read_owned().await;
let guard = OwnedRwLockReadGuard::map(guard, |f| &f.0);
assert_eq!(1, *guard);
sourcepub fn try_map<F, V: ?Sized>(
this: Self,
f: F
) -> Result<OwnedRwLockReadGuard<T, V>, Self>where
F: FnOnce(&U) -> Option<&V>,
pub fn try_map<F, V: ?Sized>( this: Self, f: F ) -> Result<OwnedRwLockReadGuard<T, V>, Self>where F: FnOnce(&U) -> Option<&V>,
Attempts to make a new OwnedRwLockReadGuard
for a component of the
locked data. The original guard is returned if the closure returns
None
.
This operation cannot fail as the OwnedRwLockReadGuard
passed in
already locked the data.
This is an associated function that needs to be used as
OwnedRwLockReadGuard::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, OwnedRwLockReadGuard};
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);
let lock = Arc::new(RwLock::new(Foo(1)));
let guard = lock.read_owned().await;
let guard = OwnedRwLockReadGuard::try_map(guard, |f| Some(&f.0)).expect("should not fail");
assert_eq!(1, *guard);