pub struct MappedMutexGuard<'a, T>
where T: 'a + ?Sized,
{ data: NonNull<T>, inner: &'a Mutex, poison_flag: &'a Flag, poison: Guard, _variance: PhantomData<&'a mut T>, }
🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)
Expand description

An RAII mutex guard returned by MutexGuard::map, which can point to a subfield of the protected data. When this structure is dropped (falls out of scope), the lock will be unlocked.

The main difference between MappedMutexGuard and MutexGuard is that the former cannot be used with Condvar, since that could introduce soundness issues if the locked object is modified by another thread while the Mutex is unlocked.

The data protected by the mutex can be accessed through this guard via its Deref and DerefMut implementations.

This structure is created by the map and try_map methods on MutexGuard.

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§data: NonNull<T>
🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)
§inner: &'a Mutex
🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)
§poison_flag: &'a Flag
🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)
§poison: Guard
🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)
§_variance: PhantomData<&'a mut T>
🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)

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impl<'a, T> MappedMutexGuard<'a, T>
where T: ?Sized,

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

🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)

Makes a MappedMutexGuard for a component of the borrowed data, e.g. an enum variant.

The Mutex is already locked, so this cannot fail.

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

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

🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)

Makes a MappedMutexGuard for a component of the borrowed data. The original guard is returned as an Err(...) if the closure returns None.

The Mutex is already locked, so this cannot fail.

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

Trait Implementations§

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impl<T> Debug for MappedMutexGuard<'_, T>
where T: Debug + ?Sized,

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

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

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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<T> DerefMut for MappedMutexGuard<'_, T>
where T: ?Sized,

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

Mutably dereferences the value.
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impl<T> Display for MappedMutexGuard<'_, T>
where T: Display + ?Sized,

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

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

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fn drop(&mut self)

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

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

Auto Trait Implementations§

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impl<'a, T: ?Sized> Freeze for MappedMutexGuard<'a, T>

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impl<'a, T: ?Sized> RefUnwindSafe for MappedMutexGuard<'a, T>
where T: RefUnwindSafe,

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

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

Blanket Implementations§

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impl<T> Any for T
where 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 T
where 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 T
where 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 T
where 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 T
where 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 T
where 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 T
where 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