Fix deadlock (#369)

clockworklabs · Oct 5, 2023 · 9020725 · 9020725
1 parent 1518baa
commit 9020725
Show file tree

Hide file tree

Showing 2 changed files with 9 additions and 0 deletions.
diff --git a/crates/client-api/src/routes/subscribe.rs b/crates/client-api/src/routes/subscribe.rs
@@ -274,6 +274,10 @@ async fn ws_client_actor(client: ClientConnection, mut ws: WebSocketStream, mut
     log::debug!("Client connection ended");
     sendrx.close();
 
+    // clear the queue before we go on to clean up, or else we can get a situation like:
+    // https://rust-lang.github.io/wg-async/vision/submitted_stories/status_quo/aws_engineer/solving_a_deadlock.html
+    handle_queue.clear();
+
     // ignore NoSuchModule; if the module's already closed, that's fine
     let _ = client.module.subscription().remove_subscriber(client.id);
     let _ = client

diff --git a/crates/core/src/util/future_queue.rs b/crates/core/src/util/future_queue.rs
@@ -39,6 +39,11 @@ where
     pub fn push_unpin(&mut self, item: T) {
         self.queue.push_back(item)
     }
+    pub fn clear(self: Pin<&mut Self>) {
+        let mut me = self.project();
+        me.queue.clear();
+        me.fut.set(Fuse::terminated());
+    }
 }
 
 impl<T, F, Fut> Stream for FutureQueue<T, F, Fut>