Struct tokio::sync::RwLockReadGuard

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pub struct RwLockReadGuard<'a, T: ?Sized> { /* private fields */ }
Available on crate feature sync only.
Expand description

RAII structure used to release the shared read access of a lock when dropped.

This structure is created by the read method on RwLock.

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

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

Makes a new RwLockReadGuard for a component of the locked data.

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

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

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

Examples
use tokio::sync::{RwLock, RwLockReadGuard};

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

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

let guard = lock.read().await;
let guard = RwLockReadGuard::map(guard, |f| &f.0);

assert_eq!(1, *guard);
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pub fn try_map<F, U: ?Sized>( this: Self, f: F ) -> Result<RwLockReadGuard<'a, U>, Self>where F: FnOnce(&T) -> Option<&U>,

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

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

This is an associated function that needs to be used as RwLockReadGuard::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 RwLockReadGuard::try_map from the parking_lot crate.

Examples
use tokio::sync::{RwLock, RwLockReadGuard};

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

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

let guard = lock.read().await;
let guard = RwLockReadGuard::try_map(guard, |f| Some(&f.0)).expect("should not fail");

assert_eq!(1, *guard);

Trait Implementations§

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

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

Formats the value using the given formatter. Read more
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impl<T: ?Sized> Deref for RwLockReadGuard<'_, T>

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type Target = T

The resulting type after dereferencing.
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fn deref(&self) -> &T

Dereferences the value.
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impl<'a, T> Display for RwLockReadGuard<'a, T>where T: Display + ?Sized,

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

Formats the value using the given formatter. Read more
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impl<'a, T: ?Sized> Drop for RwLockReadGuard<'a, T>

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fn drop(&mut self)

Executes the destructor for this type. Read more
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impl<T> Send for RwLockReadGuard<'_, T>where T: ?Sized + Sync,

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

Auto Trait Implementations§

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impl<'a, T> !RefUnwindSafe for RwLockReadGuard<'a, T>

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impl<'a, T: ?Sized> Unpin for RwLockReadGuard<'a, T>

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impl<'a, T> !UnwindSafe for RwLockReadGuard<'a, T>

Blanket Implementations§

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

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

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

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> WithSubscriber for T

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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
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fn with_current_subscriber(self) -> WithDispatch<Self>

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