Struct TaskLocalFuture

pub struct TaskLocalFuture<T, F>where
    T: 'static,
{ /* private fields */ }

Available on crate feature rt only.

A future that sets a value T of a task local for the future F during its execution.

The value of the task-local must be 'static and will be dropped on the completion of the future.

Created by the function LocalKey::scope.

Examples

tokio::task_local! {
    static NUMBER: u32;
}

NUMBER.scope(1, async move {
    println!("task local value: {}", NUMBER.get());
}).await;

Implementations

impl<T, F> TaskLocalFuture<T, F>
where T: 'static,

pub fn take_value(self: Pin<&mut Self>) -> Option<T>

Returns the value stored in the task local by this TaskLocalFuture.

The function returns:

Some(T) if the task local value exists.
None if the task local value has already been taken.

Note that this function attempts to take the task local value even if the future has not yet completed. In that case, the value will no longer be available via the task local after the call to take_value.

Examples

tokio::task_local! {
    static KEY: u32;
}

let fut = KEY.scope(42, async {
    // Do some async work
});

let mut pinned = Box::pin(fut);

// Complete the TaskLocalFuture
let _ = pinned.as_mut().await;

// And here, we can take task local value
let value = pinned.as_mut().take_value();

assert_eq!(value, Some(42));

Trait Implementations

impl<T, F> Debug for TaskLocalFuture<T, F>
where T: Debug + 'static,

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

Formats the value using the given formatter. Read more

impl<T: 'static, F> Drop for TaskLocalFuture<T, F>

fn drop(&mut self)

Executes the destructor for this type. Read more

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned. Read more

impl<T: 'static, F: Future> Future for TaskLocalFuture<T, F>

type Output = <F as Future>::Output

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. Read more

impl<'pin, T, F> Unpin for TaskLocalFuture<T, F>
where PinnedFieldsOf<Origin<'__pin, T, F>>: Unpin, T: 'static,

Auto Trait Implementations

impl<T, F> !UnsafeUnpin for TaskLocalFuture<T, F>

impl<T, F> Freeze for TaskLocalFuture<T, F>
where T: Freeze, F: Freeze,

impl<T, F> RefUnwindSafe for TaskLocalFuture<T, F>
where T: RefUnwindSafe, F: RefUnwindSafe,

impl<T, F> Send for TaskLocalFuture<T, F>
where T: Send, F: Send,

impl<T, F> Sync for TaskLocalFuture<T, F>
where T: Sync, F: Sync,

impl<T, F> UnwindSafe for TaskLocalFuture<T, F>
where T: UnwindSafe, F: UnwindSafe,

Blanket Implementations

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

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

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

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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

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

Mutably borrows from an owned value. Read more

impl<T> From<T> for T

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> Instrument for T

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

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

fn in_current_span(self) -> Instrumented<Self> ⓘ

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

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

fn into(self) -> U

Calls U::from(self).

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

impl<F> IntoFuture for F
where F: Future,

type Output = <F as Future>::Output

The output that the future will produce on completion.

type IntoFuture = F

Which kind of future are we turning this into?

fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more

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

type Error = Infallible

The type returned in the event of a conversion error.

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

Performs the conversion.

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

type Error = >::Error

The type returned in the event of a conversion error.

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

Performs the conversion.

impl<T> WithSubscriber for T

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

fn with_current_subscriber(self) -> WithDispatch<Self> ⓘ

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

Struct TaskLocalFuture

Examples

Implementations

impl<T, F> TaskLocalFuture<T, F>where T: 'static,

pub fn take_value(self: Pin<&mut Self>) -> Option<T>

Examples

Trait Implementations

impl<T, F> Debug for TaskLocalFuture<T, F>where T: Debug + 'static,

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

impl<T: 'static, F> Drop for TaskLocalFuture<T, F>

fn drop(&mut self)

fn pin_drop(self: Pin<&mut Self>)

impl<T: 'static, F: Future> Future for TaskLocalFuture<T, F>

type Output = <F as Future>::Output

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

impl<'__pin, T, F> Unpin for TaskLocalFuture<T, F>where PinnedFieldsOf<__Origin<'__pin, T, F>>: Unpin, T: 'static,

Auto Trait Implementations

impl<T, F> !UnsafeUnpin for TaskLocalFuture<T, F>

impl<T, F> Freeze for TaskLocalFuture<T, F>where T: Freeze, F: Freeze,

impl<T, F> RefUnwindSafe for TaskLocalFuture<T, F>where T: RefUnwindSafe, F: RefUnwindSafe,

impl<T, F> Send for TaskLocalFuture<T, F>where T: Send, F: Send,

impl<T, F> Sync for TaskLocalFuture<T, F>where T: Sync, F: Sync,

impl<T, F> UnwindSafe for TaskLocalFuture<T, F>where T: UnwindSafe, F: UnwindSafe,

Blanket Implementations

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

fn type_id(&self) -> TypeId

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

fn borrow(&self) -> &T

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

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

impl<T> From<T> for T

fn from(t: T) -> T

impl<T> Instrument for T

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

fn in_current_span(self) -> Instrumented<Self> ⓘ

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

fn into(self) -> U

impl<F> IntoFuture for Fwhere F: Future,

type Output = <F as Future>::Output

type IntoFuture = F

fn into_future(self) -> <F as IntoFuture>::IntoFuture

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

type Error = Infallible

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

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

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

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

impl<T> WithSubscriber for T

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

fn with_current_subscriber(self) -> WithDispatch<Self> ⓘ

impl<T, F> TaskLocalFuture<T, F>
where T: 'static,

impl<T, F> Debug for TaskLocalFuture<T, F>
where T: Debug + 'static,

impl<'pin, T, F> Unpin for TaskLocalFuture<T, F>
where PinnedFieldsOf<Origin<'__pin, T, F>>: Unpin, T: 'static,

impl<T, F> Freeze for TaskLocalFuture<T, F>
where T: Freeze, F: Freeze,

impl<T, F> RefUnwindSafe for TaskLocalFuture<T, F>
where T: RefUnwindSafe, F: RefUnwindSafe,

impl<T, F> Send for TaskLocalFuture<T, F>
where T: Send, F: Send,

impl<T, F> Sync for TaskLocalFuture<T, F>
where T: Sync, F: Sync,

impl<T, F> UnwindSafe for TaskLocalFuture<T, F>
where T: UnwindSafe, F: UnwindSafe,

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

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

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

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

impl<F> IntoFuture for F
where F: Future,

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

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

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