Struct Task

pub struct Task<T>(/* private fields */);
Expand description

Wraps async_executor::Task, a spawned future.

Tasks are also futures themselves and yield the output of the spawned future.

When a task is dropped, its gets canceled and won’t be polled again. To cancel a task a bit more gracefully and wait until it stops running, use the Task::cancel() method.

Tasks that panic get immediately canceled. Awaiting a canceled task also causes a panic.

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impl<T> Task<T>

pub fn new(task: Task<T>) -> Task<T>

Creates a new task from a given async_executor::Task

pub fn detach(self)

Detaches the task to let it keep running in the background. See async_executor::Task::detach

pub async fn cancel(self) -> Option<T>

Cancels the task and waits for it to stop running.

Returns the task’s output if it was completed just before it got canceled, or None if it didn’t complete.

While it’s possible to simply drop the Task to cancel it, this is a cleaner way of canceling because it also waits for the task to stop running.

See async_executor::Task::cancel

pub fn is_finished(&self) -> bool

Returns true if the current task is finished.

Unlike poll, it doesn’t resolve the final value, it just checks if the task has finished. Note that in a multithreaded environment, this task can be finished immediately after calling this function.

Trait Implementations§

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impl<T> Debug for Task<T>
where T: Debug,

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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> Future for Task<T>

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type Output = T

The type of value produced on completion.
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fn poll( self: Pin<&mut Task<T>>, cx: &mut Context<'_>, ) -> Poll<<Task<T> as Future>::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

Auto Trait Implementations§

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impl<T> Freeze for Task<T>

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impl<T> RefUnwindSafe for Task<T>

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impl<T> Send for Task<T>
where T: Send,

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impl<T> Sync for Task<T>

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impl<T> Unpin for Task<T>

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impl<T> UnwindSafe for Task<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> CompatExt for T

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fn compat(self) -> Compat<T>

Applies the [Compat] adapter by value. Read more
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fn compat_ref(&self) -> Compat<&T>

Applies the [Compat] adapter by shared reference. Read more
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fn compat_mut(&mut self) -> Compat<&mut T>

Applies the [Compat] adapter by mutable reference. Read more
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impl<T> Downcast for T
where T: Any,

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fn into_any(self: Box<T>) -> Box<dyn Any>

Converts Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>, which can then be downcast into Box<dyn ConcreteType> where ConcreteType implements Trait.
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fn into_any_rc(self: Rc<T>) -> Rc<dyn Any>

Converts Rc<Trait> (where Trait: Downcast) to Rc<Any>, which can then be further downcast into Rc<ConcreteType> where ConcreteType implements Trait.
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fn as_any(&self) -> &(dyn Any + 'static)

Converts &Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &Any’s vtable from &Trait’s.
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fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Converts &mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &mut Any’s vtable from &mut Trait’s.
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impl<T> DowncastSend for T
where T: Any + Send,

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fn into_any_send(self: Box<T>) -> Box<dyn Any + Send>

Converts Box<Trait> (where Trait: DowncastSend) to Box<dyn Any + Send>, which can then be downcast into Box<ConcreteType> where ConcreteType implements Trait.
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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<F> FutureExt for F
where F: Future + ?Sized,

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

A convenience for calling Future::poll() on !Unpin types.
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fn or<F>(self, other: F) -> Or<Self, F>
where Self: Sized, F: Future<Output = Self::Output>,

Returns the result of self or other future, preferring self if both are ready. Read more
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fn race<F>(self, other: F) -> Race<Self, F>
where Self: Sized, F: Future<Output = Self::Output>,

Returns the result of self or other future, with no preference if both are ready. Read more
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fn catch_unwind(self) -> CatchUnwind<Self>
where Self: Sized + UnwindSafe,

Catches panics while polling the future. Read more
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fn boxed<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + Send + 'a>>
where Self: Sized + Send + 'a,

Boxes the future and changes its type to dyn Future + Send + 'a. Read more
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fn boxed_local<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 'a>>
where Self: Sized + 'a,

Boxes the future and changes its type to dyn Future + 'a. Read more
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impl<T> FutureExt for T
where T: Future + ?Sized,

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fn map<U, F>(self, f: F) -> Map<Self, F>
where F: FnOnce(Self::Output) -> U, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more
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fn map_into<U>(self) -> MapInto<Self, U>
where Self::Output: Into<U>, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more
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fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F>
where F: FnOnce(Self::Output) -> Fut, Fut: Future, Self: Sized,

Chain on a computation for when a future finished, passing the result of the future to the provided closure f. Read more
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fn left_future<B>(self) -> Either<Self, B>
where B: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the left-hand variant of that Either. Read more
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fn right_future<A>(self) -> Either<A, Self>
where A: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the right-hand variant of that Either. Read more
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fn into_stream(self) -> IntoStream<Self>
where Self: Sized,

Convert this future into a single element stream. Read more
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fn flatten(self) -> Flatten<Self>
where Self::Output: Future, Self: Sized,

Flatten the execution of this future when the output of this future is itself another future. Read more
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fn flatten_stream(self) -> FlattenStream<Self>
where Self::Output: Stream, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more
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fn fuse(self) -> Fuse<Self>
where Self: Sized,

Fuse a future such that poll will never again be called once it has completed. This method can be used to turn any Future into a FusedFuture. Read more
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fn inspect<F>(self, f: F) -> Inspect<Self, F>
where F: FnOnce(&Self::Output), Self: Sized,

Do something with the output of a future before passing it on. Read more
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fn catch_unwind(self) -> CatchUnwind<Self>
where Self: Sized + UnwindSafe,

Catches unwinding panics while polling the future. Read more
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fn shared(self) -> Shared<Self>
where Self: Sized, Self::Output: Clone,

Create a cloneable handle to this future where all handles will resolve to the same result. Read more
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fn remote_handle(self) -> (Remote<Self>, RemoteHandle<Self::Output>)
where Self: Sized,

Turn this future into a future that yields () on completion and sends its output to another future on a separate task. Read more
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fn boxed<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + Send + 'a>>
where Self: Sized + Send + 'a,

Wrap the future in a Box, pinning it. Read more
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fn boxed_local<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 'a>>
where Self: Sized + 'a,

Wrap the future in a Box, pinning it. Read more
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fn unit_error(self) -> UnitError<Self>
where Self: Sized,

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fn never_error(self) -> NeverError<Self>
where Self: Sized,

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fn poll_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>
where Self: Unpin,

A convenience for calling Future::poll on Unpin future types.
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fn now_or_never(self) -> Option<Self::Output>
where Self: Sized,

Evaluates and consumes the future, returning the resulting output if the future is ready after the first call to Future::poll. Read more
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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<F> IntoFuture for F
where F: Future,

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type Output = <F as Future>::Output

The output that the future will produce on completion.
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type IntoFuture = F

Which kind of future are we turning this into?
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fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more
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impl<T> Pointable for T

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const ALIGN: usize

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Same for T

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type Output = T

Should always be Self
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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<F, T, E> TryFuture for F
where F: Future<Output = Result<T, E>> + ?Sized,

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type Ok = T

The type of successful values yielded by this future
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type Error = E

The type of failures yielded by this future
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fn try_poll( self: Pin<&mut F>, cx: &mut Context<'_>, ) -> Poll<<F as Future>::Output>

Poll this TryFuture as if it were a Future. Read more
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impl<Fut> TryFutureExt for Fut
where Fut: TryFuture + ?Sized,

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fn flatten_sink<Item>(self) -> FlattenSink<Self, Self::Ok>
where Self::Ok: Sink<Item, Error = Self::Error>, Self: Sized,

Flattens the execution of this future when the successful result of this future is a [Sink]. Read more
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fn map_ok<T, F>(self, f: F) -> MapOk<Self, F>
where F: FnOnce(Self::Ok) -> T, Self: Sized,

Maps this future’s success value to a different value. Read more
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fn map_ok_or_else<T, E, F>(self, e: E, f: F) -> MapOkOrElse<Self, F, E>
where F: FnOnce(Self::Ok) -> T, E: FnOnce(Self::Error) -> T, Self: Sized,

Maps this future’s success value to a different value, and permits for error handling resulting in the same type. Read more
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fn map_err<E, F>(self, f: F) -> MapErr<Self, F>
where F: FnOnce(Self::Error) -> E, Self: Sized,

Maps this future’s error value to a different value. Read more
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fn err_into<E>(self) -> ErrInto<Self, E>
where Self: Sized, Self::Error: Into<E>,

Maps this future’s Error to a new error type using the Into trait. Read more
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fn ok_into<U>(self) -> OkInto<Self, U>
where Self: Sized, Self::Ok: Into<U>,

Maps this future’s Ok to a new type using the Into trait.
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fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F>
where F: FnOnce(Self::Ok) -> Fut, Fut: TryFuture<Error = Self::Error>, Self: Sized,

Executes another future after this one resolves successfully. The success value is passed to a closure to create this subsequent future. Read more
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fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F>
where F: FnOnce(Self::Error) -> Fut, Fut: TryFuture<Ok = Self::Ok>, Self: Sized,

Executes another future if this one resolves to an error. The error value is passed to a closure to create this subsequent future. Read more
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fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F>
where F: FnOnce(&Self::Ok), Self: Sized,

Do something with the success value of a future before passing it on. Read more
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fn inspect_err<F>(self, f: F) -> InspectErr<Self, F>
where F: FnOnce(&Self::Error), Self: Sized,

Do something with the error value of a future before passing it on. Read more
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fn try_flatten(self) -> TryFlatten<Self, Self::Ok>
where Self::Ok: TryFuture<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is another future. Read more
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fn try_flatten_stream(self) -> TryFlattenStream<Self>
where Self::Ok: TryStream<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more
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fn unwrap_or_else<F>(self, f: F) -> UnwrapOrElse<Self, F>
where Self: Sized, F: FnOnce(Self::Error) -> Self::Ok,

Unwraps this future’s output, producing a future with this future’s Ok type as its Output type. Read more
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fn into_future(self) -> IntoFuture<Self>
where Self: Sized,

Wraps a [TryFuture] into a type that implements Future. Read more
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fn try_poll_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<Self::Ok, Self::Error>>
where Self: Unpin,

A convenience method for calling [TryFuture::try_poll] on Unpin future types.
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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<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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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
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impl<T> ConditionalSend for T
where T: Send,

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impl<T> ConditionalSendFuture for T

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impl<T> ErasedDestructor for T
where T: 'static,

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impl<T> MaybeSendSync for T