pub struct BoxLayer<In, T, U, E> { /* private fields */ }
util
only.Expand description
A boxed Layer
trait object.
BoxLayer
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 BoxService
instances erasing the type of the
Service
produced by the wrapped Layer
.
Example
BoxLayer
can, for example, be useful to create layers dynamically that otherwise wouldn’t have
the same types. In this example, we include a Timeout
layer
only if an environment variable is set. We can use BoxLayer
to return a consistent type regardless of runtime configuration:
use std::time::Duration;
use tower::{Service, ServiceBuilder, BoxError, util::BoxLayer};
fn common_layer<S, T>() -> BoxLayer<S, T, S::Response, BoxError>
where
S: Service<T> + 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();
BoxLayer::new(layer)
} else {
let layer = builder
.map_err(Into::into)
.into_inner();
BoxLayer::new(layer)
}
}
Implementations
Trait Implementations
Auto Trait Implementations
impl<In, T, U, E> !RefUnwindSafe for BoxLayer<In, T, U, E>
impl<In, T, U, E> Send for BoxLayer<In, T, U, E>
impl<In, T, U, E> Sync for BoxLayer<In, T, U, E>
impl<In, T, U, E> Unpin for BoxLayer<In, T, U, E>
impl<In, T, U, E> !UnwindSafe for BoxLayer<In, T, U, E>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcepub fn borrow_mut(&mut self) -> &mut T
pub fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> Instrument for T
impl<T> Instrument for T
sourcefn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
sourcefn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcepub fn to_owned(&self) -> T
pub fn to_owned(&self) -> T
Creates owned data from borrowed data, usually by cloning. Read more
sourcepub fn clone_into(&self, target: &mut T)
pub fn clone_into(&self, target: &mut T)
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more
impl<V, T> VZip<V> for T where
V: MultiLane<T>,
impl<V, T> VZip<V> for T where
V: MultiLane<T>,
pub fn vzip(self) -> V
sourceimpl<T> WithSubscriber for T
impl<T> WithSubscriber for T
sourcefn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> where
S: Into<Dispatch>,
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
sourcefn with_current_subscriber(self) -> WithDispatch<Self>
fn with_current_subscriber(self) -> WithDispatch<Self>
Attaches the current default Subscriber
to this type, returning a
WithDispatch
wrapper. Read more