pub struct OwnedRwLockMappedWriteGuard<T: ?Sized, U: ?Sized = T> { /* private fields */ }
Available on crate feature sync only.
Expand description

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§

source§

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

source

pub 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);

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);
source

pub 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);

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);

Trait Implementations§

source§

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

source§

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

Formats the value using the given formatter. Read more
source§

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

§

type Target = U

The resulting type after dereferencing.
source§

fn deref(&self) -> &U

Dereferences the value.
source§

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

source§

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

Mutably dereferences the value.
source§

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

source§

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

Formats the value using the given formatter. Read more
source§

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

source§

fn drop(&mut self)

Executes the destructor for this type. Read more
source§

impl<T, U> Send for OwnedRwLockMappedWriteGuard<T, U>where T: ?Sized + Send + Sync, U: ?Sized + Send + Sync,

source§

impl<T, U> Sync for OwnedRwLockMappedWriteGuard<T, U>where T: ?Sized + Send + Sync, U: ?Sized + Send + Sync,

Auto Trait Implementations§

§

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

§

impl<T: ?Sized, U: ?Sized> Unpin for OwnedRwLockMappedWriteGuard<T, U>where T: Unpin,

§

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

Blanket Implementations§

source§

impl<T> Any for Twhere T: 'static + ?Sized,

source§

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
source§

impl<T> Borrow<T> for Twhere T: ?Sized,

source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
source§

impl<T> BorrowMut<T> for Twhere T: ?Sized,

source§

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

Mutably borrows from an owned value. Read more
source§

impl<T> From<T> for T

source§

fn from(t: T) -> T

Returns the argument unchanged.

source§

impl<T> Instrument for T

source§

fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
source§

fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
source§

impl<T, U> Into<U> for Twhere U: From<T>,

source§

fn into(self) -> U

Calls U::from(self).

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

source§

impl<T> ToString for Twhere T: Display + ?Sized,

source§

default fn to_string(&self) -> String

Converts the given value to a String. Read more
source§

impl<T, U> TryFrom<U> for Twhere U: Into<T>,

§

type Error = Infallible

The type returned in the event of a conversion error.
source§

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

Performs the conversion.
source§

impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

§

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
source§

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

Performs the conversion.
source§

impl<T> WithSubscriber for T

source§

fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
source§

fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more