Struct tokio::sync::RwLockWriteGuard

pub struct RwLockWriteGuard<'a, T: ?Sized> { /* fields omitted */ }

This is supported on crate feature sync only.

RAII structure used to release the exclusive write access of a lock when dropped.

This structure is created by the write and method on RwLock.

Implementations

impl<'a, T: ?Sized> RwLockWriteGuard<'a, T>

pub fn map<F, U: ?Sized>(mut this: Self, f: F) -> RwLockWriteGuard<'a, U> where
    F: FnOnce(&mut T) -> &mut U, 

Make a new RwLockWriteGuard for a component of the locked data.

This operation cannot fail as the RwLockWriteGuard passed in already locked the data.

This is an associated function that needs to be used as RwLockWriteGuard::map(..). A method would interfere with methods of the same name on the contents of the locked data.

This is an asynchronous version of RwLockWriteGuard::map from the parking_lot crate.

Examples

use tokio::sync::{RwLock, RwLockWriteGuard};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);

let lock = RwLock::new(Foo(1));

{
    let mut mapped = RwLockWriteGuard::map(lock.write().await, |f| &mut f.0);
    *mapped = 2;
}

assert_eq!(Foo(2), *lock.read().await);

pub fn try_map<F, U: ?Sized>(
    mut this: Self,
    f: F
) -> Result<RwLockWriteGuard<'a, U>, Self> where
    F: FnOnce(&mut T) -> Option<&mut U>, 

Attempts to make a new RwLockWriteGuard for a component of the locked data. The original guard is returned if the closure returns None.

This operation cannot fail as the RwLockWriteGuard passed in already locked the data.

This is an associated function that needs to be used as RwLockWriteGuard::try_map(...). A method would interfere with methods of the same name on the contents of the locked data.

This is an asynchronous version of RwLockWriteGuard::try_map from the parking_lot crate.

Examples

use tokio::sync::{RwLock, RwLockWriteGuard};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Foo(u32);

let lock = RwLock::new(Foo(1));

{
    let guard = lock.write().await;
    let mut guard = RwLockWriteGuard::try_map(guard, |f| Some(&mut f.0)).expect("should not fail");
    *guard = 2;
}

assert_eq!(Foo(2), *lock.read().await);

Trait Implementations

impl<'a, T: ?Sized> Debug for RwLockWriteGuard<'a, T> where
    T: Debug, 

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

Formats the value using the given formatter.

impl<T: ?Sized> Deref for RwLockWriteGuard<'_, T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T: ?Sized> DerefMut for RwLockWriteGuard<'_, T>

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<'a, T: ?Sized> Display for RwLockWriteGuard<'a, T> where
    T: Display, 

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

Formats the value using the given formatter.

impl<'a, T: ?Sized> Drop for RwLockWriteGuard<'a, T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T: ?Sized> Send for RwLockWriteGuard<'_, T> where
    T: Send + Sync, 

impl<T: ?Sized> Sync for RwLockWriteGuard<'_, T> where
    T: Send + Sync,