Struct tonic::transport::Channel

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pub struct Channel { /* private fields */ }
Expand description

A default batteries included transport channel.

This provides a fully featured http2 gRPC client based on hyper::Client and tower services.

§Multiplexing requests

Sending a request on a channel requires a &mut self and thus can only send one request in flight. This is intentional and is required to follow the Service contract from the tower library which this channel implementation is built on top of.

tower itself has a concept of poll_ready which is the main mechanism to apply back pressure. poll_ready takes a &mut self and when it returns Poll::Ready we know the Service is able to accept only one request before we must poll_ready again. Due to this fact any async fn that wants to poll for readiness and submit the request must have a &mut self reference.

To work around this and to ease the use of the channel, Channel provides a Clone implementation that is cheap. This is because at the very top level the channel is backed by a tower_buffer::Buffer which runs the connection in a background task and provides a mpsc channel interface. Due to this cloning the Channel type is cheap and encouraged.

Implementations§

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impl Channel

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pub fn builder(uri: Uri) -> Endpoint

Create an Endpoint builder that can create Channels.

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pub fn from_static(s: &'static str) -> Endpoint

Create an Endpoint from a static string.

Channel::from_static("https://example.com");
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pub fn from_shared(s: impl Into<Bytes>) -> Result<Endpoint, InvalidUri>

Create an Endpoint from shared bytes.

Channel::from_shared("https://example.com");
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pub fn balance_list(list: impl Iterator<Item = Endpoint>) -> Self

Balance a list of Endpoint’s.

This creates a Channel that will load balance across all the provided endpoints.

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pub fn balance_channel<K>( capacity: usize, ) -> (Self, Sender<Change<K, Endpoint>>)
where K: Hash + Eq + Send + Clone + 'static,

Balance a list of Endpoint’s.

This creates a Channel that will listen to a stream of change events and will add or remove provided endpoints.

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pub fn balance_channel_with_executor<K, E>( capacity: usize, executor: E, ) -> (Self, Sender<Change<K, Endpoint>>)
where K: Hash + Eq + Send + Clone + 'static, E: Executor<Pin<Box<dyn Future<Output = ()> + Send>>> + Send + Sync + 'static,

Balance a list of Endpoint’s.

This creates a Channel that will listen to a stream of change events and will add or remove provided endpoints.

The Channel will use the given executor to spawn async tasks.

Trait Implementations§

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impl Clone for Channel

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fn clone(&self) -> Channel

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for Channel

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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 Service<Request<UnsyncBoxBody<Bytes, Status>>> for Channel

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type Response = Response<Body>

Responses given by the service.
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type Error = Error

Errors produced by the service.
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type Future = ResponseFuture

The future response value.
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fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>>

Returns Poll::Ready(Ok(())) when the service is able to process requests. Read more
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fn call(&mut self, request: Request<BoxBody>) -> Self::Future

Process the request and return the response asynchronously. Read more

Auto Trait Implementations§

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> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit #126799)
Performs copy-assignment from self to dst. 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> FromRef<T> for T
where T: Clone,

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fn from_ref(input: &T) -> T

Converts to this type from a reference to the input type.
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impl<T, ReqBody, ResBody> GrpcService<ReqBody> for T
where T: Service<Request<ReqBody>, Response = Response<ResBody>>, <T as Service<Request<ReqBody>>>::Error: Into<Box<dyn Error + Sync + Send>>, ResBody: Body, <ResBody as Body>::Error: Into<Box<dyn Error + Sync + Send>>,

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type ResponseBody = ResBody

Responses body given by the service.
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type Error = <T as Service<Request<ReqBody>>>::Error

Errors produced by the service.
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type Future = <T as Service<Request<ReqBody>>>::Future

The future response value.
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fn poll_ready( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<(), <T as GrpcService<ReqBody>>::Error>>

Returns Ready when the service is able to process requests. Read more
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fn call( &mut self, request: Request<ReqBody>, ) -> <T as GrpcService<ReqBody>>::Future

Process the request and return the response asynchronously. 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<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<S, R> ServiceExt<R> for S
where S: Service<R>,

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fn into_make_service(self) -> IntoMakeService<S>

Convert this service into a MakeService, that is a Service whose response is another service. Read more
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impl<T, Request> ServiceExt<Request> for T
where T: Service<Request> + ?Sized,

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fn ready(&mut self) -> Ready<'_, Self, Request> ⓘ
where Self: Sized,

Yields a mutable reference to the service when it is ready to accept a request.
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fn ready_and(&mut self) -> Ready<'_, Self, Request> ⓘ
where Self: Sized,

👎Deprecated since 0.4.6: please use the ServiceExt::ready method instead
Yields a mutable reference to the service when it is ready to accept a request.
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fn ready_oneshot(self) -> ReadyOneshot<Self, Request> ⓘ
where Self: Sized,

Yields the service when it is ready to accept a request.
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fn oneshot(self, req: Request) -> Oneshot<Self, Request> ⓘ
where Self: Sized,

Consume this Service, calling with the providing request once it is ready.
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fn call_all<S>(self, reqs: S) -> CallAll<Self, S>
where Self: Sized, Self::Error: Into<Box<dyn Error + Sync + Send>>, S: Stream<Item = Request>,

Process all requests from the given Stream, and produce a Stream of their responses. Read more
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fn and_then<F>(self, f: F) -> AndThen<Self, F>
where Self: Sized, F: Clone,

Executes a new future after this service’s future resolves. This does not alter the behaviour of the poll_ready method. Read more
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fn map_response<F, Response>(self, f: F) -> MapResponse<Self, F>
where Self: Sized, F: FnOnce(Self::Response) -> Response + Clone,

Maps this service’s response value to a different value. This does not alter the behaviour of the poll_ready method. Read more
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fn map_err<F, Error>(self, f: F) -> MapErr<Self, F>
where Self: Sized, F: FnOnce(Self::Error) -> Error + Clone,

Maps this service’s error value to a different value. This does not alter the behaviour of the poll_ready method. Read more
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fn map_result<F, Response, Error>(self, f: F) -> MapResult<Self, F>
where Self: Sized, Error: From<Self::Error>, F: FnOnce(Result<Self::Response, Self::Error>) -> Result<Response, Error> + Clone,

Maps this service’s result type (Result<Self::Response, Self::Error>) to a different value, regardless of whether the future succeeds or fails. Read more
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fn map_request<F, NewRequest>(self, f: F) -> MapRequest<Self, F>
where Self: Sized, F: FnMut(NewRequest) -> Request,

Composes a function in front of the service. Read more
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fn then<F, Response, Error, Fut>(self, f: F) -> Then<Self, F>
where Self: Sized, Error: From<Self::Error>, F: FnOnce(Result<Self::Response, Self::Error>) -> Fut + Clone, Fut: Future<Output = Result<Response, Error>>,

Composes an asynchronous function after this service. Read more
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fn map_future<F, Fut, Response, Error>(self, f: F) -> MapFuture<Self, F>
where Self: Sized, F: FnMut(Self::Future) -> Fut, Error: From<Self::Error>, Fut: Future<Output = Result<Response, Error>>,

Composes a function that transforms futures produced by the service. Read more
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fn boxed(self) -> BoxService<Request, Self::Response, Self::Error>
where Self: Sized + Send + 'static, Self::Future: Send + 'static,

Convert the service into a Service + Send trait object. Read more
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fn boxed_clone(self) -> BoxCloneService<Request, Self::Response, Self::Error>
where Self: Sized + Clone + Send + 'static, Self::Future: Send + 'static,

Convert the service into a Service + Clone + Send trait object. Read more
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. 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<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