## PublishHandle

# Struct PublishHandle

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    pub struct PublishHandle { /* private fields */ }

Expand description

A handle that represents an in-flight publish operation.

This struct is a `Future`. You can `.await` it to get the final result of the publish call: either a server-assigned message ID `String` or an `Error` if the publish failed.

A `PublishHandle` is returned from every call to `Publisher::publish`

## §Example

    // publish() returns a handle immediately.
    let handle = publisher.publish(PubsubMessage::new().set_data("hello world"));

    // The handle can be awaited later to get the result.
    match handle.await {
        Ok(message_id) => println!("Message published with ID: {message_id}"),
        Err(e) => eprintln!("Failed to publish message: {e:?}"),
    }

## Trait Implementations§

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### impl Future for PublishHandle

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#### type Output = Result<String, Error>

The result of the publish operation.

- `Ok(String)`: The server-assigned message ID.
- `Err(Error)`: An error indicating the publish failed.

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#### 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

## Auto Trait Implementations§

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### impl Freeze for PublishHandle

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### impl !RefUnwindSafe for PublishHandle

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### impl Send for PublishHandle

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### impl Sync for PublishHandle

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### impl Unpin for PublishHandle

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### impl !UnwindSafe for PublishHandle

## 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> 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 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,

Turns a `Future<Output = T>` into a `TryFuture<Ok = T, Error = ()`>.
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#### fn never_error(self) -> NeverError<Self>
where Self: Sized,

Turns a `Future<Output = T>` into a `TryFuture<Ok = T, Error = Never`>.
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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> FutureExt for T
where T: Future + ?Sized,

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#### fn with_cancellation_token( self, cancellation_token: &CancellationToken, ) -> WithCancellationTokenFuture<'_, Self>
where Self: Sized,

Similar to [`CancellationToken::run_until_cancelled`], but with the advantage that it is easier to write fluent call chains. Read more
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#### fn with_cancellation_token_owned( self, cancellation_token: CancellationToken, ) -> WithCancellationTokenFutureOwned<Self>
where Self: Sized,

Similar to [`CancellationToken::run_until_cancelled_owned`], but with the advantage that it is easier to write fluent call chains. 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> IntoRequest<T> for T

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#### fn into_request(self) -> Request<T>

Wrap the input message `T` in a `tonic::Request`
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### impl<L> LayerExt<L> for L

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#### fn named_layer<S>(&self, service: S) -> Layered<<L as Layer<S>>::Service, S>
where L: Layer<S>,

Applies the layer to a service and wraps it in [`Layered`].
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### impl<T> PolicyExt for T
where T: ?Sized,

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#### fn and<P, B, E>(self, other: P) -> And<T, P>
where T: Policy<B, E>, P: Policy<B, E>,

Create a new `Policy` that returns [`Action::Follow`] only if `self` and `other` return `Action::Follow`. Read more
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#### fn or<P, B, E>(self, other: P) -> Or<T, P>
where T: Policy<B, E>, P: Policy<B, E>,

Create a new `Policy` that returns [`Action::Follow`] if either `self` or `other` returns `Action::Follow`. 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<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