try a new approach to resolve request cancellation

https://github.com/tiangolo/fastapi/discussions/11360

src/backend/base/langflow/main.py

@@ -32,6 +32,39 @@ from langflow.utils.logger import configure
 warnings.filterwarnings("ignore", category=PydanticDeprecatedSince20)
 
 
+class RequestCancelledMiddleware:
+    def __init__(self, app):
+        self.app = app
+
+    async def __call__(self, scope, receive, send):
+        if scope["type"] != "http":
+            await self.app(scope, receive, send)
+            return
+
+        # Let's make a shared queue for the request messages
+        queue = asyncio.Queue()
+
+        async def message_poller(sentinel, handler_task):
+            nonlocal queue
+            while True:
+                message = await receive()
+                if message["type"] == "http.disconnect":
+                    handler_task.cancel()
+                    return sentinel  # Break the loop
+
+                # Puts the message in the queue
+                await queue.put(message)
+
+        sentinel = object()
+        handler_task = asyncio.create_task(self.app(scope, queue.get, send))
+        asyncio.create_task(message_poller(sentinel, handler_task))
+
+        try:
+            return await handler_task
+        except asyncio.CancelledError:
+            logger.debug("Cancelling request due to disconnect")
+
+
 class JavaScriptMIMETypeMiddleware(BaseHTTPMiddleware):
     async def dispatch(self, request: Request, call_next):
         try:
@@ -96,6 +129,7 @@ def create_app():
         allow_headers=["*"],
     )
     app.add_middleware(JavaScriptMIMETypeMiddleware)
+    app.add_middleware(RequestCancelledMiddleware)
 
     @app.middleware("http")
     async def flatten_query_string_lists(request: Request, call_next):