From 20c93656d18b50c17c85b7a1e234276fb1444f27 Mon Sep 17 00:00:00 2001
From: "patchback[bot]" <45432694+patchback[bot]@users.noreply.github.com>
Date: Sun, 8 May 2022 22:06:02 +0000
Subject: [PATCH] Fix asyncio.CancelledError again (#6719) (#6727) (#6741)

* Fix asyncio.CancelledError again (#6719)

`asyncio.CancelledError()` on peer disconnection have been removed by #4080,
but #4415 re-introduced it silently.

`self._waiter.cancel()` and `self._task_handler.cancel()` were added by #4415,
but #4415 in fact only needed `self._waiter.cancel()` (proof below).

So I propose to remove `self._task_handler.cancel()`, both #4080 and #4415 will
be fixed.

To test that I re-resolved #4080 I used:
```py
async def handle(request):
    try:
        await asyncio.sleep(5)
        await request.text()
    except BaseException as e:
        print(f'base exception {type(e).__name__}')
    return web.Response(text='toto')
```
```console
curl -X POST -H "Content-Type: text/plain" --data "bouh" localhost:8080
```
I kill the curl request before the 5 seconds of sleep.
Before this PR I have the following error right after killing the curl:
```console
$ python -Wall -X dev test.py
======== Running on http://0.0.0.0:8080 ========
(Press CTRL+C to quit)
base exception CancelledError
```

After this commit I have the following error, but only after the 5 seconds
sleep:
```console
$ python -Wall -X dev test.py
======== Running on http://0.0.0.0:8080 ========
(Press CTRL+C to quit)
base exception ConnectionResetError
```

To test that I didn't re-introduce #4415 I use a basic `handle` and 30
`curl localhost:8080`:

- Before this commit no issue
- If I remove `self._task_handler.cancel()` no issue
- If I remove both `self._task_handler.cancel()` and `self._waiter.cancel()`:

  ```console
  $ python -Wall -X dev test.py
  ======== Running on http://0.0.0.0:8080 ========
  (Press CTRL+C to quit)
  Task was destroyed but it is pending!
  task: <Task pending name='Task-4' coro=<RequestHandler.start() done, defined at ...
  Task was destroyed but it is pending!
  ...
  ```

So it's OK to remove only `self._task_handler.cancel()`.

There is no documentation or tests to be updated because #4080 already did that
part.

However I guess that for a few people it might be seen as a breaking change,
I'm not sure.

Tested on master and on v3.8.1.

fixes #6719

* Update 6719.bugfix

Co-authored-by: Sam Bull <aa6bs0@sambull.org>
(cherry picked from commit adeece3c1826b150f129e198f69e78a469901b5e)

Co-authored-by: Hoel IRIS <hoel.iris@gmail.com>
---
 CHANGES/6719.bugfix     | 1 +
 aiohttp/web_protocol.py | 2 --
 2 files changed, 1 insertion(+), 2 deletions(-)
 create mode 100644 CHANGES/6719.bugfix

diff --git a/CHANGES/6719.bugfix b/CHANGES/6719.bugfix
new file mode 100644
index 0000000000..b42ccca255
--- /dev/null
+++ b/CHANGES/6719.bugfix
@@ -0,0 +1 @@
+Fix regression where ``asyncio.CancelledError`` occurs on client disconnection.
diff --git a/aiohttp/web_protocol.py b/aiohttp/web_protocol.py
index f103b1672e..10a9608018 100644
--- a/aiohttp/web_protocol.py
+++ b/aiohttp/web_protocol.py
@@ -299,8 +299,6 @@ def connection_lost(self, exc: Optional[BaseException]) -> None:
                 exc = ConnectionResetError("Connection lost")
             self._current_request._cancel(exc)
 
-        if self._task_handler is not None:
-            self._task_handler.cancel()
         if self._waiter is not None:
             self._waiter.cancel()