make StreamExt::timeout(d).next() behave like future::timeout(d, s.next())

src/stream/stream/timeout.rs

@@ -18,31 +18,36 @@ pin_project! {
         stream: S,
         #[pin]
         delay: Timer,
+        duration: Duration,
     }
 }
 
 impl<S: Stream> Timeout<S> {
     pub(crate) fn new(stream: S, dur: Duration) -> Self {
         let delay = timer_after(dur);
 
-        Self { stream, delay }
+        Self { stream, delay, duration: dur }
     }
 }
 
 impl<S: Stream> Stream for Timeout<S> {
     type Item = Result<S::Item, TimeoutError>;
 
     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
-        let this = self.project();
+        let mut this = self.project();
 
-        match this.stream.poll_next(cx) {
+        let r = match this.stream.poll_next(cx) {
             Poll::Ready(Some(v)) => Poll::Ready(Some(Ok(v))),
             Poll::Ready(None) => Poll::Ready(None),
-            Poll::Pending => match this.delay.poll(cx) {
+            Poll::Pending => match this.delay.as_mut().poll(cx) {
                 Poll::Ready(_) => Poll::Ready(Some(Err(TimeoutError { _private: () }))),
-                Poll::Pending => Poll::Pending,
+                Poll::Pending => return Poll::Pending,
             },
-        }
+        };
+
+        *this.delay.as_mut() = timer_after(*this.duration);
+
+        r
     }
 }