Fixed #33738 -- Allowed handling ASGI http.disconnect in long-lived requests.

django/core/handlers/asgi.py

@@ -1,3 +1,4 @@
+import asyncio
 import logging
 import sys
 import tempfile
@@ -177,15 +178,49 @@ class ASGIHandler(base.BaseHandler):
             body_file.close()
             await self.send_response(error_response, send)
             return
-        # Get the response, using the async mode of BaseHandler.
+        # Try to catch a disconnect while getting response.
+        tasks = [
+            asyncio.create_task(self.run_get_response(request)),
+            asyncio.create_task(self.listen_for_disconnect(receive)),
+        ]
+        done, pending = await asyncio.wait(tasks, return_when=asyncio.FIRST_COMPLETED)
+        done, pending = done.pop(), pending.pop()
+        # Allow views to handle cancellation.
+        pending.cancel()
+        try:
+            await pending
+        except asyncio.CancelledError:
+            # Task re-raised the CancelledError as expected.
+            pass
+        try:
+            response = done.result()
+        except RequestAborted:
+            body_file.close()
+            return
+        except AssertionError:
+            body_file.close()
+            raise
+        # Send the response.
+        await self.send_response(response, send)
+
+    async def listen_for_disconnect(self, receive):
+        """Listen for disconnect from the client."""
+        message = await receive()
+        if message["type"] == "http.disconnect":
+            raise RequestAborted()
+        # This should never happen.
+        assert False, "Invalid ASGI message after request body: %s" % message["type"]
+
+    async def run_get_response(self, request):
+        """Get async response."""
+        # Use the async mode of BaseHandler.
         response = await self.get_response_async(request)
         response._handler_class = self.__class__
         # Increase chunk size on file responses (ASGI servers handles low-level
         # chunking).
         if isinstance(response, FileResponse):
             response.block_size = self.chunk_size
-        # Send the response.
-        await self.send_response(response, send)
+        return response
 
     async def read_body(self, receive):
         """Reads an HTTP body from an ASGI connection."""