From fe997464b33e4279006d6bb7d5ecf0928633418a Mon Sep 17 00:00:00 2001
From: Giovanni Barillari <giovanni.barillari@sentry.io>
Date: Sat, 20 Jun 2026 17:48:42 +0200
Subject: [PATCH] Review ws teardown flow in ASGI proto

---
 src/asgi/io.rs | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/asgi/io.rs b/src/asgi/io.rs
index 5216a0df..9118ec84 100644
--- a/src/asgi/io.rs
+++ b/src/asgi/io.rs
@@ -355,6 +355,7 @@ pub(crate) struct ASGIWebsocketProtocol {
     init_tx: Arc<atomic::AtomicBool>,
     init_event: Arc<Notify>,
     closed: Arc<atomic::AtomicBool>,
+    teardown: Arc<Notify>,
 }
 
 impl ASGIWebsocketProtocol {
@@ -378,6 +379,7 @@ impl ASGIWebsocketProtocol {
             init_tx: Arc::new(false.into()),
             init_event: Arc::new(Notify::new()),
             closed: Arc::new(false.into()),
+            teardown: Arc::new(Notify::new()),
         }
     }
 
@@ -464,17 +466,22 @@ impl ASGIWebsocketProtocol {
     fn send_message<'p>(&self, py: Python<'p>, data: Message) -> PyResult<Bound<'p, PyAny>> {
         let transport = self.ws_tx.clone();
         let closed = self.closed.clone();
+        let teardown = self.teardown.clone();
 
         future_into_py_futlike(self.rt.clone(), py, async move {
             if let Some(ws) = &mut *(transport.lock().await) {
-                match ws.send(data).await {
-                    Ok(()) => return FutureResultToPy::None,
-                    _ => {
-                        if closed.load(atomic::Ordering::Acquire) {
-                            log::info!("Attempted to write to a closed websocket");
-                            return FutureResultToPy::None;
+                tokio::select! {
+                    biased;
+                    res = ws.send(data) => match res {
+                        Ok(()) => return FutureResultToPy::None,
+                        _ => {
+                            if closed.load(atomic::Ordering::Acquire) {
+                                log::info!("Attempted to write to a closed websocket");
+                                return FutureResultToPy::None;
+                            }
                         }
-                    }
+                    },
+                    () = teardown.notified() => return FutureResultToPy::None,
                 }
             }
             FutureResultToPy::Err(error_flow!("Transport not initialized or closed"))
@@ -510,11 +517,13 @@ impl ASGIWebsocketProtocol {
         Option<oneshot::Sender<WebsocketDetachedTransport>>,
         WebsocketDetachedTransport,
     ) {
-        let mut ws_rx = self.ws_rx.blocking_lock();
+        self.closed.store(true, atomic::Ordering::Release);
+        self.teardown.notify_one();
         let mut ws_tx = self.ws_tx.blocking_lock();
+        let ws_rx = self.ws_rx.try_lock().map_or(None, |mut guard| guard.take());
         (
             self.tx.lock().unwrap().take(),
-            WebsocketDetachedTransport::new(self.consumed(), ws_rx.take(), ws_tx.take(), None),
+            WebsocketDetachedTransport::new(self.consumed(), ws_rx, ws_tx.take(), None),
         )
     }
 }