attempt to fix webserver lockup (#2788)

core/startos/Cargo.toml

@@ -198,7 +198,7 @@ tokio-util = { version = "0.7.9", features = ["io"] }
 torut = { git = "https://github.com/Start9Labs/torut.git", branch = "update/dependencies", features = [
   "serialize",
 ] }
-tower-service = "0.3.2"
+tower-service = "0.3.3"
 tracing = "0.1.39"
 tracing-error = "0.2.0"
 tracing-futures = "0.2.5"

core/startos/src/net/web_server.rs

@@ -7,7 +7,7 @@ use axum::extract::Request;
 use axum::Router;
 use axum_server::Handle;
 use bytes::Bytes;
-use futures::future::ready;
+use futures::future::{ready, BoxFuture};
 use futures::FutureExt;
 use helpers::NonDetachingJoinHandle;
 use tokio::sync::{oneshot, watch};
@@ -30,8 +30,39 @@ impl SwappableRouter {
     }
 }
 
-#[derive(Clone)]
-pub struct SwappableRouterService(watch::Receiver<Router>);
+pub struct SwappableRouterService {
+    router: watch::Receiver<Router>,
+    changed: Option<BoxFuture<'static, ()>>,
+}
+impl SwappableRouterService {
+    fn router(&self) -> Router {
+        self.router.borrow().clone()
+    }
+    fn changed(&mut self, cx: &mut std::task::Context<'_>) -> Poll<()> {
+        let mut changed = if let Some(changed) = self.changed.take() {
+            changed
+        } else {
+            let mut router = self.router.clone();
+            async move {
+                router.changed().await;
+            }
+            .boxed()
+        };
+        if changed.poll_unpin(cx).is_ready() {
+            return Poll::Ready(());
+        }
+        self.changed = Some(changed);
+        Poll::Pending
+    }
+}
+impl Clone for SwappableRouterService {
+    fn clone(&self) -> Self {
+        Self {
+            router: self.router.clone(),
+            changed: None,
+        }
+    }
+}
 impl<B> tower_service::Service<Request<B>> for SwappableRouterService
 where
     B: axum::body::HttpBody<Data = Bytes> + Send + 'static,
@@ -42,15 +73,13 @@ where
     type Future = <Router as tower_service::Service<Request<B>>>::Future;
     #[inline]
     fn poll_ready(&mut self, cx: &mut std::task::Context<'_>) -> Poll<Result<(), Self::Error>> {
-        let mut changed = self.0.changed().boxed();
-        if changed.poll_unpin(cx).is_ready() {
+        if self.changed(cx).is_ready() {
             return Poll::Ready(Ok(()));
         }
-        drop(changed);
-        tower_service::Service::<Request<B>>::poll_ready(&mut self.0.borrow().clone(), cx)
+        tower_service::Service::<Request<B>>::poll_ready(&mut self.router(), cx)
     }
     fn call(&mut self, req: Request<B>) -> Self::Future {
-        self.0.borrow().clone().call(req)
+        self.router().call(req)
     }
 }
 
@@ -66,7 +95,10 @@ impl<T> tower_service::Service<T> for SwappableRouter {
         Poll::Ready(Ok(()))
     }
     fn call(&mut self, _: T) -> Self::Future {
-        ready(Ok(SwappableRouterService(self.0.subscribe())))
+        ready(Ok(SwappableRouterService {
+            router: self.0.subscribe(),
+            changed: None,
+        }))
     }
 }