Shield service call from cancellation on REST API connection loss (#102657)

* Shield service call from cancellation on connection loss

* add test for timeout

* Apply suggestions from code review

* Apply suggestions from code review

* fix merge

* Apply suggestions from code review

homeassistant/components/api/__init__.py

@@ -1,6 +1,6 @@
 """Rest API for Home Assistant."""
 import asyncio
-from asyncio import timeout
+from asyncio import shield, timeout
 from collections.abc import Collection
 from functools import lru_cache
 from http import HTTPStatus
@@ -62,6 +62,7 @@ ATTR_VERSION = "version"
 DOMAIN = "api"
 STREAM_PING_PAYLOAD = "ping"
 STREAM_PING_INTERVAL = 50  # seconds
+SERVICE_WAIT_TIMEOUT = 10
 
 CONFIG_SCHEMA = cv.empty_config_schema(DOMAIN)
 
@@ -388,11 +389,17 @@ class APIDomainServicesView(HomeAssistantView):
         )
 
         try:
-            await hass.services.async_call(
+            async with timeout(SERVICE_WAIT_TIMEOUT):
+                # shield the service call from cancellation on connection drop
+                await shield(
+                    hass.services.async_call(
                         domain, service, data, blocking=True, context=context
                     )
+                )
         except (vol.Invalid, ServiceNotFound) as ex:
             raise HTTPBadRequest() from ex
+        except TimeoutError:
+            pass
         finally:
             cancel_listen()
 

tests/components/api/test_init.py

@@ -352,6 +352,31 @@ async def test_api_call_service_with_data(
     assert state["attributes"] == {"data": 1}
 
 
+async def test_api_call_service_timeout(
+    hass: HomeAssistant, mock_api_client: TestClient
+) -> None:
+    """Test if the API does not fail on long running services."""
+    test_value = []
+
+    fut = hass.loop.create_future()
+
+    async def listener(service_call):
+        """Wait and return after mock_api_client.post finishes."""
+        value = await fut
+        test_value.append(value)
+
+    hass.services.async_register("test_domain", "test_service", listener)
+
+    with patch("homeassistant.components.api.SERVICE_WAIT_TIMEOUT", 0):
+        await mock_api_client.post("/api/services/test_domain/test_service")
+        assert len(test_value) == 0
+        fut.set_result(1)
+        await hass.async_block_till_done()
+
+    assert len(test_value) == 1
+    assert test_value[0] == 1
+
+
 async def test_api_template(hass: HomeAssistant, mock_api_client: TestClient) -> None:
     """Test the template API."""
     hass.states.async_set("sensor.temperature", 10)