From 958f64f78705b4c6c922580bc9de9e4f798b49ef Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Mon, 30 Jun 2025 16:13:56 +0200
Subject: [PATCH 01/20] readd cancel on disconnect decorator

---
 .../src/simcore_service_api_server/api/routes/files.py          | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/services/api-server/src/simcore_service_api_server/api/routes/files.py b/services/api-server/src/simcore_service_api_server/api/routes/files.py
index 69f779f13e19..a220edacb232 100644
--- a/services/api-server/src/simcore_service_api_server/api/routes/files.py
+++ b/services/api-server/src/simcore_service_api_server/api/routes/files.py
@@ -287,6 +287,7 @@ async def upload_files(files: list[UploadFile] = FileParam(...)):
     response_model=ClientFileUploadData,
     responses=_FILE_STATUS_CODES,
 )
+@cancel_on_disconnect
 async def get_upload_links(
     request: Request,
     client_file: UserFileToProgramJob | UserFile,
@@ -421,6 +422,7 @@ async def abort_multipart_upload(
     response_model=OutputFile,
     responses=_FILE_STATUS_CODES,
 )
+@cancel_on_disconnect
 async def complete_multipart_upload(
     request: Request,
     file_id: UUID,

From 176775f365b7fa323a70a0d8622a140d0e8708b2 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Mon, 30 Jun 2025 16:15:54 +0200
Subject: [PATCH 02/20] add asyncio.Event for killing poller task

---
 .../src/servicelib/fastapi/requests_decorators.py     | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/packages/service-library/src/servicelib/fastapi/requests_decorators.py b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
index ae5f1ea047c6..f812437270c6 100644
--- a/packages/service-library/src/servicelib/fastapi/requests_decorators.py
+++ b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
@@ -13,8 +13,7 @@
 class _HandlerWithRequestArg(Protocol):
     __name__: str
 
-    async def __call__(self, request: Request, *args: Any, **kwargs: Any) -> Any:
-        ...
+    async def __call__(self, request: Request, *args: Any, **kwargs: Any) -> Any: ...
 
 
 def _validate_signature(handler: _HandlerWithRequestArg):
@@ -36,13 +35,15 @@ def _validate_signature(handler: _HandlerWithRequestArg):
 _POLL_INTERVAL_S: float = 0.01
 
 
-async def _disconnect_poller(request: Request, result: Any):
+async def _disconnect_poller(close_event: asyncio.Event, request: Request, result: Any):
     """
     Poll for a disconnect.
     If the request disconnects, stop polling and return.
     """
     while not await request.is_disconnected():
         await asyncio.sleep(_POLL_INTERVAL_S)
+        if close_event.is_set():
+            break
     return result
 
 
@@ -59,8 +60,9 @@ async def wrapper(request: Request, *args, **kwargs):
 
         # Create two tasks:
         # one to poll the request and check if the client disconnected
+        kill_poller_event = asyncio.Event()
         poller_task = asyncio.create_task(
-            _disconnect_poller(request, sentinel),
+            _disconnect_poller(kill_poller_event, request, sentinel),
             name=f"cancel_on_disconnect/poller/{handler.__name__}/{id(sentinel)}",
         )
         # , and another which is the request handler
@@ -72,6 +74,7 @@ async def wrapper(request: Request, *args, **kwargs):
         done, pending = await asyncio.wait(
             [poller_task, handler_task], return_when=asyncio.FIRST_COMPLETED
         )
+        kill_poller_event.set()
 
         # One has completed, cancel the other
         for t in pending:

From c376bab4e9c2b8a446544c47ea7db5b4a87f970f Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Mon, 30 Jun 2025 16:49:12 +0200
Subject: [PATCH 03/20] add comment

---
 .../src/servicelib/fastapi/requests_decorators.py              | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/packages/service-library/src/servicelib/fastapi/requests_decorators.py b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
index f812437270c6..f508ed6b3f9e 100644
--- a/packages/service-library/src/servicelib/fastapi/requests_decorators.py
+++ b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
@@ -60,6 +60,9 @@ async def wrapper(request: Request, *args, **kwargs):
 
         # Create two tasks:
         # one to poll the request and check if the client disconnected
+        # sometimes canceling a task doesn't cancel the task immediately. If the poller task is not "killed" immediately, the client doesn't
+        # get a response, and the request "hangs". For this reason, we use an event to signal the poller task to stop.
+        # See: https://github.com/ITISFoundation/osparc-issues/issues/1922
         kill_poller_event = asyncio.Event()
         poller_task = asyncio.create_task(
             _disconnect_poller(kill_poller_event, request, sentinel),

From 8812a8a29a0c067276ea873b318e7499c08bd75c Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Tue, 1 Jul 2025 07:02:36 +0200
Subject: [PATCH 04/20] add test for request handler `cancel_on_disconnect`
 @pcrespov

---
 .../tests/fastapi/test_request_decorators.py  | 168 +++++++-----------
 1 file changed, 61 insertions(+), 107 deletions(-)

diff --git a/packages/service-library/tests/fastapi/test_request_decorators.py b/packages/service-library/tests/fastapi/test_request_decorators.py
index 18f6267cf33a..4a5200cbe937 100644
--- a/packages/service-library/tests/fastapi/test_request_decorators.py
+++ b/packages/service-library/tests/fastapi/test_request_decorators.py
@@ -2,121 +2,75 @@
 # pylint: disable=unused-argument
 # pylint: disable=unused-variable
 
+
 import asyncio
-import subprocess
-import sys
-import time
-from collections.abc import Callable, Iterator
-from contextlib import contextmanager
-from pathlib import Path
-from typing import NamedTuple
+from collections.abc import Awaitable, Callable
+from typing import Any
+from unittest.mock import AsyncMock
 
 import pytest
-import requests
-from fastapi import FastAPI, Query, Request
+from fastapi import Request
 from servicelib.fastapi.requests_decorators import cancel_on_disconnect
 
-CURRENT_FILE = Path(sys.argv[0] if __name__ == "__main__" else __file__).resolve()
-CURRENT_DIR = CURRENT_FILE.parent
+POLLER_CLEANUP_DELAY_S = 100.0
+
 
+@pytest.fixture
+def long_running_poller_mock(
+    monkeypatch: pytest.MonkeyPatch,
+) -> Callable[[asyncio.Event, Request, Any], Awaitable]:
 
-mock_app = FastAPI(title="Disconnect example")
+    async def _mock_disconnect_poller(
+        close_event: asyncio.Event, request: Request, result: Any
+    ):
+        _mock_disconnect_poller.called = True
+        while not await request.is_disconnected():
+            await asyncio.sleep(0.01)
+            if close_event.is_set():
+                # Simulate a long cleanup procedure
+                await asyncio.sleep(POLLER_CLEANUP_DELAY_S)
+                break
+        return result
 
-MESSAGE_ON_HANDLER_CANCELLATION = "Request was cancelled!!"
+    monkeypatch.setattr(
+        "servicelib.fastapi.requests_decorators._disconnect_poller",
+        _mock_disconnect_poller,
+    )
+    return _mock_disconnect_poller
 
 
-@mock_app.get("/example")
-@cancel_on_disconnect
-async def example(
-    request: Request,
-    wait: float = Query(..., description="Time to wait, in seconds"),
+async def test_decorator_waits_for_poller_cleanup(
+    long_running_poller_mock: Callable[[asyncio.Event, Request, Any], Awaitable],
 ):
-    try:
-        print(f"Sleeping for {wait:.2f}")
-        await asyncio.sleep(wait)
-        print("Sleep not cancelled")
-        return f"I waited for {wait:.2f}s and now this is the result"
-    except asyncio.CancelledError:
-        print(MESSAGE_ON_HANDLER_CANCELLATION)
-        raise
-
-
-class ServerInfo(NamedTuple):
-    url: str
-    proc: subprocess.Popen
-
-
-@contextmanager
-def server_lifetime(port: int) -> Iterator[ServerInfo]:
-    with subprocess.Popen(
-        [
-            "uvicorn",
-            f"{CURRENT_FILE.stem}:mock_app",
-            "--port",
-            f"{port}",
-        ],
-        cwd=f"{CURRENT_DIR}",
-        stdout=subprocess.PIPE,
-        stderr=subprocess.PIPE,
-    ) as proc:
-
-        url = f"http://127.0.0.1:{port}"
-        print("\nStarted", proc.args)
-
-        # some time to start
-        time.sleep(2)
-
-        # checks started successfully
-        assert proc.stdout
-        assert not proc.poll(), proc.stdout.read().decode("utf-8")
-        print("server is up and waiting for requests...")
-        yield ServerInfo(url, proc)
-        print("server is closing...")
-        proc.terminate()
-        print("server terminated")
-
-
-def test_cancel_on_disconnect(get_unused_port: Callable[[], int]):
-
-    with server_lifetime(port=get_unused_port()) as server:
-        url, proc = server
-        print("--> testing server")
-        response = requests.get(f"{server.url}/example?wait=0", timeout=2)
-        print(response.url, "->", response.text)
-        response.raise_for_status()
-        print("<-- server responds")
-
-        print("--> testing server correctly cancels")
-        with pytest.raises(requests.exceptions.ReadTimeout):
-            response = requests.get(f"{server.url}/example?wait=2", timeout=0.5)
-        print("<-- testing server correctly cancels done")
-
-        print("--> testing server again")
-        # NOTE: the timeout here appears to be sensitive. if it is set <5 the test hangs from time to time
-        response = requests.get(f"{server.url}/example?wait=1", timeout=5)
-        print(response.url, "->", response.text)
-        response.raise_for_status()
-        print("<-- testing server again done")
-
-        # kill service
-        server.proc.terminate()
-        assert server.proc.stdout
-        server_log = server.proc.stdout.read().decode("utf-8")
-        print(
-            f"{server.url=} stdout",
-            "-" * 10,
-            "\n",
-            server_log,
-            "-" * 30,
-        )
-        # server.url=http://127.0.0.1:44077 stdout ----------
-        # Sleeping for 0.00
-        # Sleep not cancelled
-        # INFO:     127.0.0.1:35114 - "GET /example?wait=0 HTTP/1.1" 200 OK
-        # Sleeping for 2.00
-        # Exiting on cancellation
-        # Sleeping for 1.00
-        # Sleep not cancelled
-        # INFO:     127.0.0.1:35134 - "GET /example?wait=1 HTTP/1.1" 200 OK
-
-        assert MESSAGE_ON_HANDLER_CANCELLATION in server_log
+    """
+    Tests that the decorator's wrapper waits for the poller task to finish
+    its cleanup, even if the handler finishes first, without needing a full server.
+    """
+    long_running_poller_mock.called = False
+    handler_was_called = False
+
+    @cancel_on_disconnect
+    async def my_handler(request: Request):
+        nonlocal handler_was_called
+        handler_was_called = True
+        await asyncio.sleep(0.1)  # Simulate quick work
+        return "Success"
+
+    # Mock a fastapi.Request object
+    mock_request = AsyncMock(spec=Request)
+    mock_request.is_disconnected.return_value = False
+
+    # ---
+    tasks_before = asyncio.all_tasks()
+
+    # Call the decorated handler
+    _ = await my_handler(mock_request)
+
+    tasks_after = asyncio.all_tasks()
+    # ---
+
+    assert handler_was_called
+    assert long_running_poller_mock.called == True
+
+    # Check that no background tasks were left orphaned
+    assert tasks_before == tasks_after

From a80f4e199e6085b21869cfe6be9f55b972e66a9a Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Tue, 1 Jul 2025 07:12:02 +0200
Subject: [PATCH 05/20] use taskgroup for error handling

---
 .../servicelib/fastapi/requests_decorators.py | 106 ++++++------------
 1 file changed, 34 insertions(+), 72 deletions(-)

diff --git a/packages/service-library/src/servicelib/fastapi/requests_decorators.py b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
index f508ed6b3f9e..062494d30a1d 100644
--- a/packages/service-library/src/servicelib/fastapi/requests_decorators.py
+++ b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
@@ -29,96 +29,58 @@ def _validate_signature(handler: _HandlerWithRequestArg):
 
 
 #
-# cancel_on_disconnect/disconnect_poller based
-# on https://github.com/RedRoserade/fastapi-disconnect-example/blob/main/app.py
+# cancel_on_disconnect based on TaskGroup
 #
 _POLL_INTERVAL_S: float = 0.01
 
 
-async def _disconnect_poller(close_event: asyncio.Event, request: Request, result: Any):
+class _ClientDisconnectedError(Exception):
+    """Internal exception raised by the poller task when the client disconnects."""
+
+
+async def _disconnect_poller_for_task_group(request: Request):
     """
-    Poll for a disconnect.
-    If the request disconnects, stop polling and return.
+    Polls for client disconnection and raises _ClientDisconnectedError if it occurs.
     """
     while not await request.is_disconnected():
         await asyncio.sleep(_POLL_INTERVAL_S)
-        if close_event.is_set():
-            break
-    return result
+    raise _ClientDisconnectedError()
 
 
 def cancel_on_disconnect(handler: _HandlerWithRequestArg):
     """
-    After client disconnects, handler gets cancelled in ~<3 secs
+    Decorator that cancels the request handler if the client disconnects.
+
+    Uses a TaskGroup to manage the handler and a poller task concurrently.
+    If the client disconnects, the poller raises an exception, which is
+    caught and translated into a 503 Service Unavailable response.
     """
 
     _validate_signature(handler)
 
     @wraps(handler)
     async def wrapper(request: Request, *args, **kwargs):
-        sentinel = object()
-
-        # Create two tasks:
-        # one to poll the request and check if the client disconnected
-        # sometimes canceling a task doesn't cancel the task immediately. If the poller task is not "killed" immediately, the client doesn't
-        # get a response, and the request "hangs". For this reason, we use an event to signal the poller task to stop.
-        # See: https://github.com/ITISFoundation/osparc-issues/issues/1922
-        kill_poller_event = asyncio.Event()
-        poller_task = asyncio.create_task(
-            _disconnect_poller(kill_poller_event, request, sentinel),
-            name=f"cancel_on_disconnect/poller/{handler.__name__}/{id(sentinel)}",
-        )
-        # , and another which is the request handler
-        handler_task = asyncio.create_task(
-            handler(request, *args, **kwargs),
-            name=f"cancel_on_disconnect/handler/{handler.__name__}/{id(sentinel)}",
-        )
-
-        done, pending = await asyncio.wait(
-            [poller_task, handler_task], return_when=asyncio.FIRST_COMPLETED
-        )
-        kill_poller_event.set()
-
-        # One has completed, cancel the other
-        for t in pending:
-            t.cancel()
-
-            try:
-                await asyncio.wait_for(t, timeout=3)
-
-            except asyncio.CancelledError:
-                pass
-            except Exception:  # pylint: disable=broad-except
-                if t is handler_task:
-                    raise
-            finally:
-                assert t.done()  # nosec
-
-        # Return the result if the handler finished first
-        if handler_task in done:
-            assert poller_task.done()  # nosec
-            return await handler_task
-
-        # Otherwise, raise an exception. This is not exactly needed,
-        # but it will prevent validation errors if your request handler
-        # is supposed to return something.
-        logger.warning(
-            "Request %s %s cancelled since client %s disconnected:\n - %s\n - %s",
-            request.method,
-            request.url,
-            request.client,
-            f"{poller_task=}",
-            f"{handler_task=}",
-        )
-
-        assert poller_task.done()  # nosec
-        assert handler_task.done()  # nosec
-
-        # NOTE: uvicorn server fails with 499
-        raise HTTPException(
-            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
-            detail=f"client disconnected from {request=}",
-        )
+        try:
+            async with asyncio.TaskGroup() as tg:
+                handler_task = tg.create_task(handler(request, *args, **kwargs))
+                tg.create_task(_disconnect_poller_for_task_group(request))
+
+            return handler_task.result()
+
+        except* _ClientDisconnectedError as eg:
+            logger.info(
+                "Request %s %s cancelled since client %s disconnected.",
+                request.method,
+                request.url,
+                request.client,
+            )
+            raise HTTPException(
+                status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
+                detail="Client disconnected",
+            ) from eg
+
+        except* Exception as eg:
+            raise eg.exceptions[0]
 
     return wrapper
 

From 60e99d04c61dec0efcaf28f0ed897dac2ed2877d Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Tue, 1 Jul 2025 07:47:44 +0200
Subject: [PATCH 06/20] add old names to tasks

---
 .../src/servicelib/fastapi/requests_decorators.py     | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/packages/service-library/src/servicelib/fastapi/requests_decorators.py b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
index 062494d30a1d..70c938aa77b5 100644
--- a/packages/service-library/src/servicelib/fastapi/requests_decorators.py
+++ b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
@@ -60,10 +60,17 @@ def cancel_on_disconnect(handler: _HandlerWithRequestArg):
 
     @wraps(handler)
     async def wrapper(request: Request, *args, **kwargs):
+        sentinel = object()
         try:
             async with asyncio.TaskGroup() as tg:
-                handler_task = tg.create_task(handler(request, *args, **kwargs))
-                tg.create_task(_disconnect_poller_for_task_group(request))
+                handler_task = tg.create_task(
+                    handler(request, *args, **kwargs),
+                    name=f"cancel_on_disconnect/handler/{handler.__name__}/{id(sentinel)}",
+                )
+                tg.create_task(
+                    _disconnect_poller_for_task_group(request),
+                    name=f"cancel_on_disconnect/poller/{handler.__name__}/{id(sentinel)}",
+                )
 
             return handler_task.result()
 

From e6c42f71d12bc820b59a652c7d07b5b837d015a8 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Tue, 1 Jul 2025 15:33:36 +0200
Subject: [PATCH 07/20] use event to kill poller task to be sure it terminates

---
 .../servicelib/fastapi/requests_decorators.py  | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/packages/service-library/src/servicelib/fastapi/requests_decorators.py b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
index 70c938aa77b5..2cdf373f7c52 100644
--- a/packages/service-library/src/servicelib/fastapi/requests_decorators.py
+++ b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
@@ -38,12 +38,16 @@ class _ClientDisconnectedError(Exception):
     """Internal exception raised by the poller task when the client disconnects."""
 
 
-async def _disconnect_poller_for_task_group(request: Request):
+async def _disconnect_poller_for_task_group(
+    close_event: asyncio.Event, request: Request
+):
     """
     Polls for client disconnection and raises _ClientDisconnectedError if it occurs.
     """
     while not await request.is_disconnected():
         await asyncio.sleep(_POLL_INTERVAL_S)
+        if close_event.is_set():
+            return
     raise _ClientDisconnectedError()
 
 
@@ -61,16 +65,20 @@ def cancel_on_disconnect(handler: _HandlerWithRequestArg):
     @wraps(handler)
     async def wrapper(request: Request, *args, **kwargs):
         sentinel = object()
+        kill_poller_task_event = asyncio.Event()
         try:
             async with asyncio.TaskGroup() as tg:
+
+                tg.create_task(
+                    _disconnect_poller_for_task_group(kill_poller_task_event, request),
+                    name=f"cancel_on_disconnect/poller/{handler.__name__}/{id(sentinel)}",
+                )
                 handler_task = tg.create_task(
                     handler(request, *args, **kwargs),
                     name=f"cancel_on_disconnect/handler/{handler.__name__}/{id(sentinel)}",
                 )
-                tg.create_task(
-                    _disconnect_poller_for_task_group(request),
-                    name=f"cancel_on_disconnect/poller/{handler.__name__}/{id(sentinel)}",
-                )
+                await handler_task
+                kill_poller_task_event.set()
 
             return handler_task.result()
 

From 1229fa333f1f7a38a409c6467f74fd7fcab4df7a Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Wed, 2 Jul 2025 09:15:51 +0200
Subject: [PATCH 08/20] pylint

---
 .../src/servicelib/fastapi/requests_decorators.py               | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/service-library/src/servicelib/fastapi/requests_decorators.py b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
index 2cdf373f7c52..daf4922fc182 100644
--- a/packages/service-library/src/servicelib/fastapi/requests_decorators.py
+++ b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
@@ -95,7 +95,7 @@ async def wrapper(request: Request, *args, **kwargs):
             ) from eg
 
         except* Exception as eg:
-            raise eg.exceptions[0]
+            raise eg.exceptions[0]  # pylint: disable=no-member
 
     return wrapper
 

From 4cbc9dc0845eb41439e23f49ee32411aef7fcf9e Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Wed, 2 Jul 2025 09:19:56 +0200
Subject: [PATCH 09/20] fix test

---
 .../tests/fastapi/test_request_decorators.py     | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/packages/service-library/tests/fastapi/test_request_decorators.py b/packages/service-library/tests/fastapi/test_request_decorators.py
index 4a5200cbe937..19f899fad9d6 100644
--- a/packages/service-library/tests/fastapi/test_request_decorators.py
+++ b/packages/service-library/tests/fastapi/test_request_decorators.py
@@ -5,7 +5,6 @@
 
 import asyncio
 from collections.abc import Awaitable, Callable
-from typing import Any
 from unittest.mock import AsyncMock
 
 import pytest
@@ -18,29 +17,24 @@
 @pytest.fixture
 def long_running_poller_mock(
     monkeypatch: pytest.MonkeyPatch,
-) -> Callable[[asyncio.Event, Request, Any], Awaitable]:
+) -> Callable[[asyncio.Event, Request], Awaitable]:
 
-    async def _mock_disconnect_poller(
-        close_event: asyncio.Event, request: Request, result: Any
-    ):
+    async def _mock_disconnect_poller(close_event: asyncio.Event, request: Request):
         _mock_disconnect_poller.called = True
         while not await request.is_disconnected():
-            await asyncio.sleep(0.01)
+            await asyncio.sleep(2)
             if close_event.is_set():
-                # Simulate a long cleanup procedure
-                await asyncio.sleep(POLLER_CLEANUP_DELAY_S)
                 break
-        return result
 
     monkeypatch.setattr(
-        "servicelib.fastapi.requests_decorators._disconnect_poller",
+        "servicelib.fastapi.requests_decorators._disconnect_poller_for_task_group",
         _mock_disconnect_poller,
     )
     return _mock_disconnect_poller
 
 
 async def test_decorator_waits_for_poller_cleanup(
-    long_running_poller_mock: Callable[[asyncio.Event, Request, Any], Awaitable],
+    long_running_poller_mock: Callable[[asyncio.Event, Request], Awaitable],
 ):
     """
     Tests that the decorator's wrapper waits for the poller task to finish

From e22808ab71a4f5e4a747f6861b051cca052b4276 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Fri, 4 Jul 2025 14:23:31 +0200
Subject: [PATCH 10/20] @pcrespov readd comments

---
 .../src/servicelib/fastapi/requests_decorators.py              | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/packages/service-library/src/servicelib/fastapi/requests_decorators.py b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
index daf4922fc182..9f88406b33a3 100644
--- a/packages/service-library/src/servicelib/fastapi/requests_decorators.py
+++ b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
@@ -67,12 +67,15 @@ async def wrapper(request: Request, *args, **kwargs):
         sentinel = object()
         kill_poller_task_event = asyncio.Event()
         try:
+            # Create two tasks in a TaskGroup
             async with asyncio.TaskGroup() as tg:
 
+                # One to poll the `Request` object to check for client disconnection
                 tg.create_task(
                     _disconnect_poller_for_task_group(kill_poller_task_event, request),
                     name=f"cancel_on_disconnect/poller/{handler.__name__}/{id(sentinel)}",
                 )
+                # The other to run the actual request handler
                 handler_task = tg.create_task(
                     handler(request, *args, **kwargs),
                     name=f"cancel_on_disconnect/handler/{handler.__name__}/{id(sentinel)}",

From 5399294d2bdbf8cd471039fd587e90b5b312350b Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Fri, 4 Jul 2025 14:29:51 +0200
Subject: [PATCH 11/20] readd old tests

---
 .../tests/fastapi/test_request_decorators.py  | 120 +++++++++++++++++-
 1 file changed, 118 insertions(+), 2 deletions(-)

diff --git a/packages/service-library/tests/fastapi/test_request_decorators.py b/packages/service-library/tests/fastapi/test_request_decorators.py
index 19f899fad9d6..49646047169d 100644
--- a/packages/service-library/tests/fastapi/test_request_decorators.py
+++ b/packages/service-library/tests/fastapi/test_request_decorators.py
@@ -4,16 +4,132 @@
 
 
 import asyncio
-from collections.abc import Awaitable, Callable
+import subprocess
+import sys
+import time
+from collections.abc import Awaitable, Callable, Iterator
+from contextlib import contextmanager
+from pathlib import Path
+from typing import NamedTuple
 from unittest.mock import AsyncMock
 
 import pytest
-from fastapi import Request
+import requests
+from fastapi import FastAPI, Query, Request
 from servicelib.fastapi.requests_decorators import cancel_on_disconnect
 
 POLLER_CLEANUP_DELAY_S = 100.0
 
 
+CURRENT_FILE = Path(sys.argv[0] if __name__ == "__main__" else __file__).resolve()
+CURRENT_DIR = CURRENT_FILE.parent
+
+
+mock_app = FastAPI(title="Disconnect example")
+
+MESSAGE_ON_HANDLER_CANCELLATION = "Request was cancelled!!"
+
+
+@mock_app.get("/example")
+@cancel_on_disconnect
+async def example(
+    request: Request,
+    wait: float = Query(..., description="Time to wait, in seconds"),
+):
+    try:
+        print(f"Sleeping for {wait:.2f}")
+        await asyncio.sleep(wait)
+        print("Sleep not cancelled")
+        return f"I waited for {wait:.2f}s and now this is the result"
+    except asyncio.CancelledError:
+        print(MESSAGE_ON_HANDLER_CANCELLATION)
+        raise
+
+
+class ServerInfo(NamedTuple):
+    url: str
+    proc: subprocess.Popen
+
+
+@contextmanager
+def server_lifetime(port: int) -> Iterator[ServerInfo]:
+    with subprocess.Popen(
+        [
+            "uvicorn",
+            f"{CURRENT_FILE.stem}:mock_app",
+            "--port",
+            f"{port}",
+        ],
+        cwd=f"{CURRENT_DIR}",
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+    ) as proc:
+
+        url = f"http://127.0.0.1:{port}"
+        print("\nStarted", proc.args)
+
+        # some time to start
+        time.sleep(2)
+
+        # checks started successfully
+        assert proc.stdout
+        assert not proc.poll(), proc.stdout.read().decode("utf-8")
+        print("server is up and waiting for requests...")
+        yield ServerInfo(url, proc)
+        print("server is closing...")
+        proc.terminate()
+        print("server terminated")
+
+
+def test_cancel_on_disconnect(get_unused_port: Callable[[], int]):
+
+    with server_lifetime(port=get_unused_port()) as server:
+        url, proc = server
+        print("--> testing server")
+        response = requests.get(f"{server.url}/example?wait=0", timeout=2)
+        print(response.url, "->", response.text)
+        response.raise_for_status()
+        print("<-- server responds")
+
+        print("--> testing server correctly cancels")
+        with pytest.raises(requests.exceptions.ReadTimeout):
+            response = requests.get(f"{server.url}/example?wait=2", timeout=0.5)
+        print("<-- testing server correctly cancels done")
+
+        print("--> testing server again")
+        # NOTE: the timeout here appears to be sensitive. if it is set <5 the test hangs from time to time
+        response = requests.get(f"{server.url}/example?wait=1", timeout=5)
+        print(response.url, "->", response.text)
+        response.raise_for_status()
+        print("<-- testing server again done")
+
+        # kill service
+        server.proc.terminate()
+        assert server.proc.stdout
+        server_log = server.proc.stdout.read().decode("utf-8")
+        print(
+            f"{server.url=} stdout",
+            "-" * 10,
+            "\n",
+            server_log,
+            "-" * 30,
+        )
+        # server.url=http://127.0.0.1:44077 stdout ----------
+        # Sleeping for 0.00
+        # Sleep not cancelled
+        # INFO:     127.0.0.1:35114 - "GET /example?wait=0 HTTP/1.1" 200 OK
+        # Sleeping for 2.00
+        # Exiting on cancellation
+        # Sleeping for 1.00
+        # Sleep not cancelled
+        # INFO:     127.0.0.1:35134 - "GET /example?wait=1 HTTP/1.1" 200 OK
+
+        assert MESSAGE_ON_HANDLER_CANCELLATION in server_log
+
+
+# ===================================================================================================
+
+
 @pytest.fixture
 def long_running_poller_mock(
     monkeypatch: pytest.MonkeyPatch,

From 97afe884816bdb30f1d81b21cdede15b8786de43 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Fri, 4 Jul 2025 14:30:15 +0200
Subject: [PATCH 12/20] readd

---
 .../service-library/tests/fastapi/test_request_decorators.py   | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/packages/service-library/tests/fastapi/test_request_decorators.py b/packages/service-library/tests/fastapi/test_request_decorators.py
index 49646047169d..d711a930631a 100644
--- a/packages/service-library/tests/fastapi/test_request_decorators.py
+++ b/packages/service-library/tests/fastapi/test_request_decorators.py
@@ -127,9 +127,6 @@ def test_cancel_on_disconnect(get_unused_port: Callable[[], int]):
         assert MESSAGE_ON_HANDLER_CANCELLATION in server_log
 
 
-# ===================================================================================================
-
-
 @pytest.fixture
 def long_running_poller_mock(
     monkeypatch: pytest.MonkeyPatch,

From 373ad5c6b512c74dd4e779fede62028e533f79f1 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Fri, 4 Jul 2025 15:19:16 +0200
Subject: [PATCH 13/20] factor out core funcionality into run_until_cancelled

---
 .../src/servicelib/async_utils.py             | 59 ++++++++++++++++++-
 .../servicelib/fastapi/requests_decorators.py | 55 ++++-------------
 2 files changed, 69 insertions(+), 45 deletions(-)

diff --git a/packages/service-library/src/servicelib/async_utils.py b/packages/service-library/src/servicelib/async_utils.py
index d2c62ba55ffb..424156acfdb6 100644
--- a/packages/service-library/src/servicelib/async_utils.py
+++ b/packages/service-library/src/servicelib/async_utils.py
@@ -1,7 +1,7 @@
 import asyncio
 import logging
 from collections import deque
-from collections.abc import Awaitable, Callable
+from collections.abc import Awaitable, Callable, Coroutine
 from contextlib import suppress
 from dataclasses import dataclass
 from functools import wraps
@@ -210,3 +210,60 @@ async def worker(in_q: Queue[QueueElement], out_q: Queue) -> None:
         return wrapper
 
     return decorator
+
+
+TaskCancelCallback = Callable[[], Awaitable[bool]]
+_POLL_INTERVAL_S: float = 0.01
+
+
+class TaskCancelled(Exception):
+    """Internal exception raised by the poller task when the client disconnects."""
+
+
+async def _poller_for_task_group(
+    close_event: asyncio.Event, cancel_awaitable: TaskCancelCallback
+):
+    """
+    Polls for cancellation via the callback and raises TaskCancelled if it occurs.
+    """
+    while not await cancel_awaitable():
+        await asyncio.sleep(_POLL_INTERVAL_S)
+        if close_event.is_set():
+            return
+    raise TaskCancelled()
+
+
+async def run_until_cancelled(
+    *, coro: Coroutine, cancel_callback: TaskCancelCallback
+) -> Any:
+    """
+    Runs the given coroutine until it completes or cancellation is requested.
+
+    This function executes the provided coroutine and periodically checks the given
+    cancel_callback. If cancellation is requested (i.e., cancel_callback returns True),
+    the coroutine is cancelled and a TaskCancelled exception is raised. If the coroutine
+    completes first, its result (or exception) is returned/reraised.
+    """
+    sentinel = object()
+    close_poller_event = asyncio.Event()
+    try:
+        # Create two tasks in a TaskGroup
+        async with asyncio.TaskGroup() as tg:
+
+            # One to poll for cancellation
+            tg.create_task(
+                _poller_for_task_group(close_poller_event, cancel_callback),
+                name=f"run_until_cancelled/poller/{coro.__name__}/{id(sentinel)}",
+            )
+            # The other to run the actual coroutine
+            coro_task = tg.create_task(
+                coro,
+                name=f"run_until_cancelled/coroutine/{coro.__name__}/{id(sentinel)}",
+            )
+            await coro_task
+            close_poller_event.set()
+
+        return coro_task.result()
+
+    except* Exception as eg:
+        raise eg.exceptions[0]  # pylint: disable=no-member
diff --git a/packages/service-library/src/servicelib/fastapi/requests_decorators.py b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
index 9f88406b33a3..761c81be7061 100644
--- a/packages/service-library/src/servicelib/fastapi/requests_decorators.py
+++ b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
@@ -1,4 +1,3 @@
-import asyncio
 import inspect
 import logging
 from functools import wraps
@@ -7,6 +6,8 @@
 from fastapi import Request, status
 from fastapi.exceptions import HTTPException
 
+from ..async_utils import TaskCancelled, run_until_cancelled
+
 logger = logging.getLogger(__name__)
 
 
@@ -31,24 +32,6 @@ def _validate_signature(handler: _HandlerWithRequestArg):
 #
 # cancel_on_disconnect based on TaskGroup
 #
-_POLL_INTERVAL_S: float = 0.01
-
-
-class _ClientDisconnectedError(Exception):
-    """Internal exception raised by the poller task when the client disconnects."""
-
-
-async def _disconnect_poller_for_task_group(
-    close_event: asyncio.Event, request: Request
-):
-    """
-    Polls for client disconnection and raises _ClientDisconnectedError if it occurs.
-    """
-    while not await request.is_disconnected():
-        await asyncio.sleep(_POLL_INTERVAL_S)
-        if close_event.is_set():
-            return
-    raise _ClientDisconnectedError()
 
 
 def cancel_on_disconnect(handler: _HandlerWithRequestArg):
@@ -64,28 +47,15 @@ def cancel_on_disconnect(handler: _HandlerWithRequestArg):
 
     @wraps(handler)
     async def wrapper(request: Request, *args, **kwargs):
-        sentinel = object()
-        kill_poller_task_event = asyncio.Event()
+
         try:
-            # Create two tasks in a TaskGroup
-            async with asyncio.TaskGroup() as tg:
-
-                # One to poll the `Request` object to check for client disconnection
-                tg.create_task(
-                    _disconnect_poller_for_task_group(kill_poller_task_event, request),
-                    name=f"cancel_on_disconnect/poller/{handler.__name__}/{id(sentinel)}",
-                )
-                # The other to run the actual request handler
-                handler_task = tg.create_task(
-                    handler(request, *args, **kwargs),
-                    name=f"cancel_on_disconnect/handler/{handler.__name__}/{id(sentinel)}",
-                )
-                await handler_task
-                kill_poller_task_event.set()
-
-            return handler_task.result()
-
-        except* _ClientDisconnectedError as eg:
+            await run_until_cancelled(
+                coro=handler(request, *args, **kwargs),
+                cancel_callback=request.is_disconnected,
+            )
+
+        except TaskCancelled as exc:
+
             logger.info(
                 "Request %s %s cancelled since client %s disconnected.",
                 request.method,
@@ -95,10 +65,7 @@ async def wrapper(request: Request, *args, **kwargs):
             raise HTTPException(
                 status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
                 detail="Client disconnected",
-            ) from eg
-
-        except* Exception as eg:
-            raise eg.exceptions[0]  # pylint: disable=no-member
+            ) from exc
 
     return wrapper
 

From ef3911e50c7d9d08ed30a13562cb7f1fa8900d81 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Fri, 4 Jul 2025 15:27:11 +0200
Subject: [PATCH 14/20] fix tests

---
 .../service-library/tests/fastapi/test_request_decorators.py    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/service-library/tests/fastapi/test_request_decorators.py b/packages/service-library/tests/fastapi/test_request_decorators.py
index d711a930631a..2b271b6219f0 100644
--- a/packages/service-library/tests/fastapi/test_request_decorators.py
+++ b/packages/service-library/tests/fastapi/test_request_decorators.py
@@ -140,7 +140,7 @@ async def _mock_disconnect_poller(close_event: asyncio.Event, request: Request):
                 break
 
     monkeypatch.setattr(
-        "servicelib.fastapi.requests_decorators._disconnect_poller_for_task_group",
+        "servicelib.async_utils._poller_for_task_group",
         _mock_disconnect_poller,
     )
     return _mock_disconnect_poller

From a626a294a583869e6e74f39905301af3286f5186 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Fri, 4 Jul 2025 22:11:27 +0200
Subject: [PATCH 15/20] ensure function decorator works on local deployment

---
 packages/service-library/src/servicelib/async_utils.py |  2 +-
 .../src/servicelib/fastapi/requests_decorators.py      | 10 +++++++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/packages/service-library/src/servicelib/async_utils.py b/packages/service-library/src/servicelib/async_utils.py
index 424156acfdb6..68fda7dff267 100644
--- a/packages/service-library/src/servicelib/async_utils.py
+++ b/packages/service-library/src/servicelib/async_utils.py
@@ -230,7 +230,7 @@ async def _poller_for_task_group(
         await asyncio.sleep(_POLL_INTERVAL_S)
         if close_event.is_set():
             return
-    raise TaskCancelled()
+    raise TaskCancelled
 
 
 async def run_until_cancelled(
diff --git a/packages/service-library/src/servicelib/fastapi/requests_decorators.py b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
index 761c81be7061..b9c6f4941202 100644
--- a/packages/service-library/src/servicelib/fastapi/requests_decorators.py
+++ b/packages/service-library/src/servicelib/fastapi/requests_decorators.py
@@ -1,6 +1,6 @@
 import inspect
 import logging
-from functools import wraps
+from functools import partial, wraps
 from typing import Any, Protocol
 
 from fastapi import Request, status
@@ -34,6 +34,10 @@ def _validate_signature(handler: _HandlerWithRequestArg):
 #
 
 
+async def _is_client_disconnected(request: Request):
+    return await request.is_disconnected()
+
+
 def cancel_on_disconnect(handler: _HandlerWithRequestArg):
     """
     Decorator that cancels the request handler if the client disconnects.
@@ -49,9 +53,9 @@ def cancel_on_disconnect(handler: _HandlerWithRequestArg):
     async def wrapper(request: Request, *args, **kwargs):
 
         try:
-            await run_until_cancelled(
+            return await run_until_cancelled(
                 coro=handler(request, *args, **kwargs),
-                cancel_callback=request.is_disconnected,
+                cancel_callback=partial(_is_client_disconnected, request),
             )
 
         except TaskCancelled as exc:

From edd826e5f63a0d193071370277539a0dc238bafe Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Fri, 4 Jul 2025 23:18:06 +0200
Subject: [PATCH 16/20] migrate middleware to new implementation

---
 .../src/servicelib/async_utils.py             | 17 +++--
 .../fastapi/cancellation_middleware.py        | 68 +++++++++----------
 2 files changed, 44 insertions(+), 41 deletions(-)

diff --git a/packages/service-library/src/servicelib/async_utils.py b/packages/service-library/src/servicelib/async_utils.py
index 68fda7dff267..896fa13be214 100644
--- a/packages/service-library/src/servicelib/async_utils.py
+++ b/packages/service-library/src/servicelib/async_utils.py
@@ -7,6 +7,8 @@
 from functools import wraps
 from typing import TYPE_CHECKING, Any, ParamSpec, TypeVar
 
+from pydantic import NonNegativeFloat
+
 from . import tracing
 from .utils_profiling_middleware import dont_profile, is_profiling, profile_context
 
@@ -221,20 +223,25 @@ class TaskCancelled(Exception):
 
 
 async def _poller_for_task_group(
-    close_event: asyncio.Event, cancel_awaitable: TaskCancelCallback
+    close_event: asyncio.Event,
+    cancel_awaitable: TaskCancelCallback,
+    poll_interval: NonNegativeFloat,
 ):
     """
     Polls for cancellation via the callback and raises TaskCancelled if it occurs.
     """
     while not await cancel_awaitable():
-        await asyncio.sleep(_POLL_INTERVAL_S)
+        await asyncio.sleep(poll_interval)
         if close_event.is_set():
             return
     raise TaskCancelled
 
 
 async def run_until_cancelled(
-    *, coro: Coroutine, cancel_callback: TaskCancelCallback
+    *,
+    coro: Coroutine,
+    cancel_callback: TaskCancelCallback,
+    poll_interval: NonNegativeFloat = _POLL_INTERVAL_S,
 ) -> Any:
     """
     Runs the given coroutine until it completes or cancellation is requested.
@@ -252,7 +259,9 @@ async def run_until_cancelled(
 
             # One to poll for cancellation
             tg.create_task(
-                _poller_for_task_group(close_poller_event, cancel_callback),
+                _poller_for_task_group(
+                    close_poller_event, cancel_callback, poll_interval
+                ),
                 name=f"run_until_cancelled/poller/{coro.__name__}/{id(sentinel)}",
             )
             # The other to run the actual coroutine
diff --git a/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py b/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py
index 8116869af5db..3d69c72d8ab1 100644
--- a/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py
+++ b/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py
@@ -1,7 +1,8 @@
 import asyncio
 import logging
-from typing import NoReturn
+from functools import partial
 
+from servicelib.async_utils import TaskCancelled, run_until_cancelled
 from starlette.requests import Request
 from starlette.types import ASGIApp, Message, Receive, Scope, Send
 
@@ -10,29 +11,23 @@
 _logger = logging.getLogger(__name__)
 
 
-class _TerminateTaskGroupError(Exception):
-    pass
-
-
-async def _message_poller(
-    request: Request, queue: asyncio.Queue, receive: Receive
-) -> NoReturn:
-    while True:
-        message = await receive()
-        if message["type"] == "http.disconnect":
-            _logger.debug(
-                "client disconnected, terminating request to %s!", request.url
-            )
-            raise _TerminateTaskGroupError
-
-        # Puts the message in the queue
-        await queue.put(message)
-
-
 async def _handler(
     app: ASGIApp, scope: Scope, queue: asyncio.Queue[Message], send: Send
 ) -> None:
-    return await app(scope, queue.get, send)
+    await app(scope, queue.get, send)
+
+
+async def _is_client_disconnected(
+    receive: Receive, queue: asyncio.Queue[Message], request: Request
+) -> bool:
+    message = await receive()
+    if message["type"] == "http.disconnect":
+        _logger.debug("client disconnected, terminating request to %s!", request.url)
+        return True
+
+    # Puts the message in the queue
+    await queue.put(message)
+    return False
 
 
 class RequestCancellationMiddleware:
@@ -58,23 +53,22 @@ async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
             return
 
         # Let's make a shared queue for the request messages
-        queue: asyncio.Queue[Message] = asyncio.Queue()
         request = Request(scope)
+        queue: asyncio.Queue[Message] = asyncio.Queue()
 
         with log_context(_logger, logging.DEBUG, f"cancellable request {request.url}"):
             try:
-                async with asyncio.TaskGroup() as tg:
-                    handler_task = tg.create_task(
-                        _handler(self.app, scope, queue, send)
-                    )
-                    poller_task = tg.create_task(
-                        _message_poller(request, queue, receive)
-                    )
-                    await handler_task
-                    poller_task.cancel()
-            except* _TerminateTaskGroupError:
-                if not handler_task.done():
-                    _logger.info(
-                        "The client disconnected. request to %s was cancelled.",
-                        request.url,
-                    )
+                await run_until_cancelled(
+                    coro=_handler(self.app, scope, queue, send),
+                    cancel_callback=partial(
+                        _is_client_disconnected, receive, queue, request
+                    ),
+                    poll_interval=0.0,
+                )
+                return
+
+            except TaskCancelled:
+                _logger.info(
+                    "The client disconnected. request to %s was cancelled.",
+                    request.url,
+                )

From 241a0e9565a626e2b81ebabda0829c16cdf2cc45 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Fri, 4 Jul 2025 23:32:52 +0200
Subject: [PATCH 17/20] improve types

---
 packages/service-library/src/servicelib/async_utils.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/packages/service-library/src/servicelib/async_utils.py b/packages/service-library/src/servicelib/async_utils.py
index 896fa13be214..c8892fba010a 100644
--- a/packages/service-library/src/servicelib/async_utils.py
+++ b/packages/service-library/src/servicelib/async_utils.py
@@ -7,8 +7,6 @@
 from functools import wraps
 from typing import TYPE_CHECKING, Any, ParamSpec, TypeVar
 
-from pydantic import NonNegativeFloat
-
 from . import tracing
 from .utils_profiling_middleware import dont_profile, is_profiling, profile_context
 
@@ -225,7 +223,7 @@ class TaskCancelled(Exception):
 async def _poller_for_task_group(
     close_event: asyncio.Event,
     cancel_awaitable: TaskCancelCallback,
-    poll_interval: NonNegativeFloat,
+    poll_interval: float,
 ):
     """
     Polls for cancellation via the callback and raises TaskCancelled if it occurs.
@@ -241,7 +239,7 @@ async def run_until_cancelled(
     *,
     coro: Coroutine,
     cancel_callback: TaskCancelCallback,
-    poll_interval: NonNegativeFloat = _POLL_INTERVAL_S,
+    poll_interval: float = _POLL_INTERVAL_S,
 ) -> Any:
     """
     Runs the given coroutine until it completes or cancellation is requested.

From 431df54c0d72496e382132a1c7f1ab13adfd6655 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Mon, 7 Jul 2025 06:25:55 +0200
Subject: [PATCH 18/20] fix request cancellation test

---
 .../tests/fastapi/test_request_decorators.py      | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/packages/service-library/tests/fastapi/test_request_decorators.py b/packages/service-library/tests/fastapi/test_request_decorators.py
index 2b271b6219f0..968534c36383 100644
--- a/packages/service-library/tests/fastapi/test_request_decorators.py
+++ b/packages/service-library/tests/fastapi/test_request_decorators.py
@@ -16,6 +16,7 @@
 import pytest
 import requests
 from fastapi import FastAPI, Query, Request
+from servicelib.async_utils import TaskCancelCallback
 from servicelib.fastapi.requests_decorators import cancel_on_disconnect
 
 POLLER_CLEANUP_DELAY_S = 100.0
@@ -130,11 +131,15 @@ def test_cancel_on_disconnect(get_unused_port: Callable[[], int]):
 @pytest.fixture
 def long_running_poller_mock(
     monkeypatch: pytest.MonkeyPatch,
-) -> Callable[[asyncio.Event, Request], Awaitable]:
+) -> Callable[[asyncio.Event, TaskCancelCallback, float], Awaitable]:
 
-    async def _mock_disconnect_poller(close_event: asyncio.Event, request: Request):
+    async def _mock_disconnect_poller(
+        close_event: asyncio.Event,
+        cancel_awaitable: TaskCancelCallback,
+        poll_interval: float,
+    ):
         _mock_disconnect_poller.called = True
-        while not await request.is_disconnected():
+        while not await cancel_awaitable():
             await asyncio.sleep(2)
             if close_event.is_set():
                 break
@@ -147,7 +152,9 @@ async def _mock_disconnect_poller(close_event: asyncio.Event, request: Request):
 
 
 async def test_decorator_waits_for_poller_cleanup(
-    long_running_poller_mock: Callable[[asyncio.Event, Request], Awaitable],
+    long_running_poller_mock: Callable[
+        [asyncio.Event, TaskCancelCallback, float], Awaitable
+    ],
 ):
     """
     Tests that the decorator's wrapper waits for the poller task to finish

From fe5b4ca6b023420fafca37c222deed47b15f1b02 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Mon, 7 Jul 2025 06:43:49 +0200
Subject: [PATCH 19/20] improve naming

---
 packages/service-library/src/servicelib/async_utils.py    | 8 ++++----
 .../src/servicelib/fastapi/cancellation_middleware.py     | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/packages/service-library/src/servicelib/async_utils.py b/packages/service-library/src/servicelib/async_utils.py
index c8892fba010a..0229495442be 100644
--- a/packages/service-library/src/servicelib/async_utils.py
+++ b/packages/service-library/src/servicelib/async_utils.py
@@ -223,13 +223,13 @@ class TaskCancelled(Exception):
 async def _poller_for_task_group(
     close_event: asyncio.Event,
     cancel_awaitable: TaskCancelCallback,
-    poll_interval: float,
+    poll_interval_s: float,
 ):
     """
     Polls for cancellation via the callback and raises TaskCancelled if it occurs.
     """
     while not await cancel_awaitable():
-        await asyncio.sleep(poll_interval)
+        await asyncio.sleep(poll_interval_s)
         if close_event.is_set():
             return
     raise TaskCancelled
@@ -239,7 +239,7 @@ async def run_until_cancelled(
     *,
     coro: Coroutine,
     cancel_callback: TaskCancelCallback,
-    poll_interval: float = _POLL_INTERVAL_S,
+    poll_interval_s: float = _POLL_INTERVAL_S,
 ) -> Any:
     """
     Runs the given coroutine until it completes or cancellation is requested.
@@ -258,7 +258,7 @@ async def run_until_cancelled(
             # One to poll for cancellation
             tg.create_task(
                 _poller_for_task_group(
-                    close_poller_event, cancel_callback, poll_interval
+                    close_poller_event, cancel_callback, poll_interval_s
                 ),
                 name=f"run_until_cancelled/poller/{coro.__name__}/{id(sentinel)}",
             )
diff --git a/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py b/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py
index 3d69c72d8ab1..fe62d6af7930 100644
--- a/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py
+++ b/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py
@@ -63,7 +63,7 @@ async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
                     cancel_callback=partial(
                         _is_client_disconnected, receive, queue, request
                     ),
-                    poll_interval=0.0,
+                    poll_interval_s=0.0,
                 )
                 return
 

From 62808a82931eba020f64346e5c38495919499bd0 Mon Sep 17 00:00:00 2001
From: Mads Bisgaard <bisgaard@itis.swiss>
Date: Mon, 7 Jul 2025 07:10:00 +0200
Subject: [PATCH 20/20] Revert "improve naming"

This reverts commit fe5b4ca6b023420fafca37c222deed47b15f1b02.
---
 packages/service-library/src/servicelib/async_utils.py    | 8 ++++----
 .../src/servicelib/fastapi/cancellation_middleware.py     | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/packages/service-library/src/servicelib/async_utils.py b/packages/service-library/src/servicelib/async_utils.py
index 0229495442be..c8892fba010a 100644
--- a/packages/service-library/src/servicelib/async_utils.py
+++ b/packages/service-library/src/servicelib/async_utils.py
@@ -223,13 +223,13 @@ class TaskCancelled(Exception):
 async def _poller_for_task_group(
     close_event: asyncio.Event,
     cancel_awaitable: TaskCancelCallback,
-    poll_interval_s: float,
+    poll_interval: float,
 ):
     """
     Polls for cancellation via the callback and raises TaskCancelled if it occurs.
     """
     while not await cancel_awaitable():
-        await asyncio.sleep(poll_interval_s)
+        await asyncio.sleep(poll_interval)
         if close_event.is_set():
             return
     raise TaskCancelled
@@ -239,7 +239,7 @@ async def run_until_cancelled(
     *,
     coro: Coroutine,
     cancel_callback: TaskCancelCallback,
-    poll_interval_s: float = _POLL_INTERVAL_S,
+    poll_interval: float = _POLL_INTERVAL_S,
 ) -> Any:
     """
     Runs the given coroutine until it completes or cancellation is requested.
@@ -258,7 +258,7 @@ async def run_until_cancelled(
             # One to poll for cancellation
             tg.create_task(
                 _poller_for_task_group(
-                    close_poller_event, cancel_callback, poll_interval_s
+                    close_poller_event, cancel_callback, poll_interval
                 ),
                 name=f"run_until_cancelled/poller/{coro.__name__}/{id(sentinel)}",
             )
diff --git a/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py b/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py
index fe62d6af7930..3d69c72d8ab1 100644
--- a/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py
+++ b/packages/service-library/src/servicelib/fastapi/cancellation_middleware.py
@@ -63,7 +63,7 @@ async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
                     cancel_callback=partial(
                         _is_client_disconnected, receive, queue, request
                     ),
-                    poll_interval_s=0.0,
+                    poll_interval=0.0,
                 )
                 return