reconnect: Fix maker error to return in future

tower-reconnect/src/future.rs

@@ -1,5 +1,5 @@
 use crate::Error;
-use pin_project::pin_project;
+use pin_project::{pin_project, project};
 use std::{
     future::Future,
     pin::Pin,
@@ -9,25 +9,51 @@ use std::{
 /// Future that resolves to the response or failure to connect.
 #[pin_project]
 #[derive(Debug)]
-pub struct ResponseFuture<F> {
+pub struct ResponseFuture<F, E> {
     #[pin]
-    inner: F,
+    inner: Inner<F, E>,
 }
 
-impl<F> ResponseFuture<F> {
+#[pin_project]
+#[derive(Debug)]
+enum Inner<F, E> {
+    Future(#[pin] F),
+    Error(Option<E>),
+}
+
+impl<F, E> ResponseFuture<F, E> {
     pub(crate) fn new(inner: F) -> Self {
-        ResponseFuture { inner }
+        ResponseFuture {
+            inner: Inner::Future(inner),
+        }
+    }
+
+    pub(crate) fn error(error: E) -> Self {
+        ResponseFuture {
+            inner: Inner::Error(Some(error)),
+        }
     }
 }
 
-impl<F, T, E> Future for ResponseFuture<F>
+impl<F, T, E, ME> Future for ResponseFuture<F, ME>
 where
     F: Future<Output = Result<T, E>>,
     E: Into<Error>,
+    ME: Into<Error>,
 {
     type Output = Result<T, Error>;
 
+    #[project]
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        self.project().inner.poll(cx).map_err(Into::into)
+        //self.project().inner.poll(cx).map_err(Into::into)
+        let me = self.project();
+        #[project]
+        match me.inner.project() {
+            Inner::Future(fut) => fut.poll(cx).map_err(Into::into),
+            Inner::Error(e) => {
+                let e = e.take().expect("Polled after ready.").into();
+                Poll::Ready(Err(e))
+            }
+        }
     }
 }

tower-reconnect/src/lib.rs

@@ -24,9 +24,10 @@ where
     mk_service: M,
     state: State<M::Future, M::Response>,
     target: Target,
+    error: Option<M::Error>,
 }
 
-type Error = Box<dyn std::error::Error + Send + Sync>;
+type Error = Box<dyn std::error::Error + Send + Sync + 'static>;
 
 #[derive(Debug)]
 enum State<F, S> {
@@ -51,6 +52,7 @@ where
             mk_service,
             state: State::Idle,
             target,
+            error: None,
         }
     }
 
@@ -60,6 +62,7 @@ where
             mk_service,
             state: State::Connected(init_conn),
             target,
+            error: None,
         }
     }
 }
@@ -74,14 +77,11 @@ where
 {
     type Response = S::Response;
     type Error = Error;
-    type Future = ResponseFuture<S::Future>;
+    type Future = ResponseFuture<S::Future, M::Error>;
 
     fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
-        let ret;
-        let mut state;
-
         loop {
-            match self.state {
+            match &mut self.state {
                 State::Idle => {
                     trace!("poll_ready; idle");
                     match self.mk_service.poll_ready(cx) {
@@ -100,16 +100,16 @@ where
                     trace!("poll_ready; connecting");
                     match Pin::new(f).poll(cx) {
                         Poll::Ready(Ok(service)) => {
-                            state = State::Connected(service);
+                            self.state = State::Connected(service);
                         }
                         Poll::Pending => {
                             trace!("poll_ready; not ready");
                             return Poll::Pending;
                         }
                         Poll::Ready(Err(e)) => {
                             trace!("poll_ready; error");
-                            state = State::Idle;
-                            ret = Err(e.into());
+                            self.state = State::Idle;
+                            self.error = Some(e.into());
                             break;
                         }
                     }
@@ -127,20 +127,21 @@ where
                         }
                         Poll::Ready(Err(_)) => {
                             trace!("poll_ready; error");
-                            state = State::Idle;
+                            self.state = State::Idle;
                         }
                     }
                 }
             }
-
-            self.state = state;
         }
 
-        self.state = state;
-        Poll::Ready(ret)
+        Poll::Ready(Ok(()))
     }
 
     fn call(&mut self, request: Request) -> Self::Future {
+        if let Some(error) = self.error.take() {
+            return ResponseFuture::error(error);
+        }
+
         let service = match self.state {
             State::Connected(ref mut service) => service,
             _ => panic!("service not ready; poll_ready must be called first"),