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);