tower/tower/src/discover/list.rs

65 lines
1.5 KiB
Rust

use super::{error::Never, Change, Discover};
use pin_project::pin_project;
use std::iter::{Enumerate, IntoIterator};
use std::{
pin::Pin,
task::{Context, Poll},
};
use tower_service::Service;
/// Static service discovery based on a predetermined list of services.
///
/// `ServiceList` is created with an initial list of services. The discovery
/// process will yield this list once and do nothing after.
#[pin_project]
#[derive(Debug)]
pub struct ServiceList<T>
where
T: IntoIterator,
{
inner: Enumerate<T::IntoIter>,
}
impl<T, U> ServiceList<T>
where
T: IntoIterator<Item = U>,
{
#[allow(missing_docs)]
pub fn new<Request>(services: T) -> ServiceList<T>
where
U: Service<Request>,
{
ServiceList {
inner: services.into_iter().enumerate(),
}
}
}
impl<T, U> Discover for ServiceList<T>
where
T: IntoIterator<Item = U>,
{
type Key = usize;
type Service = U;
type Error = Never;
fn poll_discover(
self: Pin<&mut Self>,
_: &mut Context<'_>,
) -> Poll<Result<Change<Self::Key, Self::Service>, Self::Error>> {
match self.project().inner.next() {
Some((i, service)) => Poll::Ready(Ok(Change::Insert(i, service))),
None => Poll::Pending,
}
}
}
// check that List can be directly over collections
#[cfg(test)]
#[allow(dead_code)]
type ListVecTest<T> = ServiceList<Vec<T>>;
#[cfg(test)]
#[allow(dead_code)]
type ListVecIterTest<T> = ServiceList<::std::vec::IntoIter<T>>;