impl<T: ?Sized, U: ?Sized> OwnedRwLockMappedWriteGuard<T, U>

fn map<F, V: ?Sized>(this: Self, f: F) -> OwnedRwLockMappedWriteGuard<T, V>
where
    F: FnOnce(&mut U) -> &mut 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);

# #[tokio::main(flavor = "current_thread")]
# async fn main() {
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);
# }

fn try_map<F, V: ?Sized>(this: Self, f: F) -> Result<OwnedRwLockMappedWriteGuard<T, V>, Self>
where
    F: FnOnce(&mut U) -> Option<&mut V>,

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);

# #[tokio::main(flavor = "current_thread")]
# async fn main() {
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);
# }

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,
};

# #[tokio::main(flavor = "current_thread")]
# async fn main() {
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)));
# }