Struct `OwnedRwLockMappedWriteGuard`

struct OwnedRwLockMappedWriteGuard<T: ?Sized, U: ?Sized = T> { ... }

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

`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]
# 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]
# 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]
# 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)));
# }

`impl<P, T> Receiver for OwnedRwLockMappedWriteGuard<T, U>`

`impl<T> Any for OwnedRwLockMappedWriteGuard<T, U>`

fn type_id(self: &Self) -> TypeId

`impl<T> Borrow for OwnedRwLockMappedWriteGuard<T, U>`

fn borrow(self: &Self) -> &T

`impl<T> BorrowMut for OwnedRwLockMappedWriteGuard<T, U>`

fn borrow_mut(self: &mut Self) -> &mut T

`impl<T> From for OwnedRwLockMappedWriteGuard<T, U>`

fn from(t: T) -> T: Returns the argument unchanged.

`impl<T> ToString for OwnedRwLockMappedWriteGuard<T, U>`

fn to_string(self: &Self) -> String

`impl<T, U = T> RefUnwindSafe for OwnedRwLockMappedWriteGuard<T, U>`

`impl<T, U = T> UnwindSafe for OwnedRwLockMappedWriteGuard<T, U>`

`impl<T, U> Freeze for OwnedRwLockMappedWriteGuard<T, U>`

`impl<T, U> Into for OwnedRwLockMappedWriteGuard<T, U>`

fn into(self: Self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

`impl<T, U> Send for OwnedRwLockMappedWriteGuard<T, U>`

`impl<T, U> Sync for OwnedRwLockMappedWriteGuard<T, U>`

`impl<T, U> TryFrom for OwnedRwLockMappedWriteGuard<T, U>`

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

`impl<T, U> TryInto for OwnedRwLockMappedWriteGuard<T, U>`

fn try_into(self: Self) -> Result<U, <U as TryFrom<T>>::Error>

`impl<T, U> Unpin for OwnedRwLockMappedWriteGuard<T, U>`

`impl<T, U> UnsafeUnpin for OwnedRwLockMappedWriteGuard<T, U>`

`impl<T: ?Sized, U> Debug for OwnedRwLockMappedWriteGuard<T, U>`

fn fmt(self: &Self, f: &mut Formatter<'_>) -> Result

`impl<T: ?Sized, U> Display for OwnedRwLockMappedWriteGuard<T, U>`

fn fmt(self: &Self, f: &mut Formatter<'_>) -> Result

`impl<T: ?Sized, U: ?Sized> Deref for OwnedRwLockMappedWriteGuard<T, U>`

fn deref(self: &Self) -> &U

`impl<T: ?Sized, U: ?Sized> DerefMut for OwnedRwLockMappedWriteGuard<T, U>`

fn deref_mut(self: &mut Self) -> &mut U

`impl<T: ?Sized, U: ?Sized> Drop for OwnedRwLockMappedWriteGuard<T, U>`

fn drop(self: &mut Self)