tower::util

Struct BoxCloneServiceLayer

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pub struct BoxCloneServiceLayer<In, T, U, E> { /* private fields */ }
Available on crate feature util only.
Expand description

A Clone + Send boxed Layer.

BoxCloneServiceLayer turns a layer into a trait object, allowing both the Layer itself and the output Service to be dynamic, while having consistent types.

This Layer produces BoxCloneService instances erasing the type of the Service produced by the wrapped Layer.

This is similar to BoxLayer except the layer and resulting service implements Clone.

§Example

BoxCloneServiceLayer can, for example, be useful to create layers dynamically that otherwise wouldn’t have the same types, when the underlying service must be clone (for example, when building a MakeService) In this example, we include a Timeout layer only if an environment variable is set. We can use BoxCloneService to return a consistent type regardless of runtime configuration:

use std::time::Duration;
use tower::{Service, ServiceBuilder, BoxError};
use tower::util::{BoxCloneServiceLayer, BoxCloneService};


fn common_layer<S, T>() -> BoxCloneServiceLayer<S, T, S::Response, BoxError>
where
    S: Service<T> + Clone + Send + 'static,
    S::Future: Send + 'static,
    S::Error: Into<BoxError> + 'static,
{
    let builder = ServiceBuilder::new()
        .concurrency_limit(100);

    if std::env::var("SET_TIMEOUT").is_ok() {
        let layer = builder
            .timeout(Duration::from_secs(30))
            .into_inner();

        BoxCloneServiceLayer::new(layer)
    } else {
        let layer = builder
            .map_err(Into::into)
            .into_inner();

        BoxCloneServiceLayer::new(layer)
    }
}

// We can clone the layer (this is true of BoxLayer as well)
let boxed_clone_layer = common_layer();

let cloned_layer = boxed_clone_layer.clone();

// Using the `BoxCloneServiceLayer` we can create a `BoxCloneService`
let service: BoxCloneService<Request, Response, BoxError> = ServiceBuilder::new().layer(boxed_clone_layer)
     .service_fn(|req: Request| async {
        Ok::<_, BoxError>(Response::new())
    });


// And we can still clone the service
let cloned_service = service.clone();

Implementations§

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impl<In, T, U, E> BoxCloneServiceLayer<In, T, U, E>

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pub fn new<L>(inner_layer: L) -> Self
where L: Layer<In> + Send + Sync + 'static, L::Service: Service<T, Response = U, Error = E> + Send + Clone + 'static, <L::Service as Service<T>>::Future: Send + 'static,

Create a new BoxCloneServiceLayer.

Trait Implementations§

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impl<In, T, U, E> Clone for BoxCloneServiceLayer<In, T, U, E>

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fn clone(&self) -> Self

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<In, T, U, E> Debug for BoxCloneServiceLayer<In, T, U, E>

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

Formats the value using the given formatter. Read more
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impl<In, T, U, E> Layer<In> for BoxCloneServiceLayer<In, T, U, E>

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type Service = BoxCloneService<T, U, E>

The wrapped service
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fn layer(&self, inner: In) -> Self::Service

Wrap the given service with the middleware, returning a new service that has been decorated with the middleware.

Auto Trait Implementations§

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impl<In, T, U, E> Freeze for BoxCloneServiceLayer<In, T, U, E>

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impl<In, T, U, E> !RefUnwindSafe for BoxCloneServiceLayer<In, T, U, E>

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impl<In, T, U, E> Send for BoxCloneServiceLayer<In, T, U, E>

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impl<In, T, U, E> Sync for BoxCloneServiceLayer<In, T, U, E>

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impl<In, T, U, E> Unpin for BoxCloneServiceLayer<In, T, U, E>

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impl<In, T, U, E> !UnwindSafe for BoxCloneServiceLayer<In, T, U, E>

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)
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, 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> 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.

Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 16 bytes