Fix `poll_close` returning WouldBlock error kind

src/lib.rs

@@ -217,6 +217,7 @@ where
 #[derive(Debug)]
 pub struct WebSocketStream<S> {
     inner: WebSocket<AllowStd<S>>,
+    closing: bool,
 }
 
 impl<S> WebSocketStream<S> {
@@ -250,7 +251,10 @@ impl<S> WebSocketStream<S> {
     }
 
     pub(crate) fn new(ws: WebSocket<AllowStd<S>>) -> Self {
-        WebSocketStream { inner: ws }
+        WebSocketStream {
+            inner: ws,
+            closing: false,
+        }
     }
 
     fn with_context<F, R>(&mut self, ctx: Option<(ContextWaker, &mut Context<'_>)>, f: F) -> R
@@ -336,9 +340,7 @@ where
     fn start_send(mut self: Pin<&mut Self>, item: Message) -> Result<(), Self::Error> {
         match (*self).with_context(None, |s| s.write_message(item)) {
             Ok(()) => Ok(()),
-            Err(::tungstenite::Error::Io(ref err))
+            Err(::tungstenite::Error::Io(err)) if err.kind() == std::io::ErrorKind::WouldBlock => {
-                if err.kind() == std::io::ErrorKind::WouldBlock =>
-            {
                 // the message was accepted and queued
                 // isn't an error.
                 Ok(())
@@ -355,15 +357,37 @@ where
     }
 
     fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        if self.closing {
+            // After queing it, we call `write_pending` to drive the close handshake to completion.
+            match (*self).with_context(Some((ContextWaker::Write, cx)), |s| s.write_pending()) {
+                Ok(()) => Poll::Ready(Ok(())),
+                Err(::tungstenite::Error::ConnectionClosed) => Poll::Ready(Ok(())),
+                Err(::tungstenite::Error::Io(err))
+                    if err.kind() == std::io::ErrorKind::WouldBlock =>
+                {
+                    trace!("WouldBlock");
+                    Poll::Pending
+                }
+                Err(err) => Poll::Ready(Err(err)),
+            }
+        } else {
             match (*self).with_context(Some((ContextWaker::Write, cx)), |s| s.close(None)) {
                 Ok(()) => Poll::Ready(Ok(())),
                 Err(::tungstenite::Error::ConnectionClosed) => Poll::Ready(Ok(())),
+                Err(::tungstenite::Error::Io(err))
+                    if err.kind() == std::io::ErrorKind::WouldBlock =>
+                {
+                    trace!("WouldBlock");
+                    self.closing = true;
+                    Poll::Pending
+                }
                 Err(err) => {
                     debug!("websocket close error: {}", err);
                     Poll::Ready(Err(err))
                 }
             }
         }
+    }
 }
 
 #[cfg(any(