Shield async httpx call in generic (#47852)

* Shield async httpx call

* Don't set last_url/last_image on cancellation

* Add test

homeassistant/components/generic/camera.py

@@ -125,32 +125,45 @@ class GenericCamera(Camera):
         ).result()
 
     async def async_camera_image(self):
+        """Wrap _async_camera_image with an asyncio.shield."""
+        # Shield the request because of https://github.com/encode/httpx/issues/1461
+        try:
+            self._last_url, self._last_image = await asyncio.shield(
+                self._async_camera_image()
+            )
+        except asyncio.CancelledError as err:
+            _LOGGER.warning("Timeout getting camera image from %s", self._name)
+            raise err
+        return self._last_image
+
+    async def _async_camera_image(self):
         """Return a still image response from the camera."""
         try:
             url = self._still_image_url.async_render(parse_result=False)
         except TemplateError as err:
             _LOGGER.error("Error parsing template %s: %s", self._still_image_url, err)
-            return self._last_image
+            return self._last_url, self._last_image
 
         if url == self._last_url and self._limit_refetch:
-            return self._last_image
-
+            return self._last_url, self._last_image
+        response = None
         try:
             async_client = get_async_client(self.hass, verify_ssl=self.verify_ssl)
             response = await async_client.get(
                 url, auth=self._auth, timeout=GET_IMAGE_TIMEOUT
             )
             response.raise_for_status()
-            self._last_image = response.content
+            image = response.content
         except httpx.TimeoutException:
             _LOGGER.error("Timeout getting camera image from %s", self._name)
-            return self._last_image
+            return self._last_url, self._last_image
         except (httpx.RequestError, httpx.HTTPStatusError) as err:
             _LOGGER.error("Error getting new camera image from %s: %s", self._name, err)
-            return self._last_image
-
-        self._last_url = url
-        return self._last_image
+            return self._last_url, self._last_image
+        finally:
+            if response:
+                await response.aclose()
+        return url, image
 
     @property
     def name(self):

tests/components/generic/test_camera.py

@@ -3,6 +3,7 @@ import asyncio
 from os import path
 from unittest.mock import patch
 
+import httpx
 import respx
 
 from homeassistant import config as hass_config
@@ -407,5 +408,56 @@ async def test_reloading(hass, hass_client):
     assert body == "hello world"
 
 
+@respx.mock
+async def test_timeout_cancelled(hass, hass_client):
+    """Test that timeouts and cancellations return last image."""
+
+    respx.get("http://example.com").respond(text="hello world")
+
+    await async_setup_component(
+        hass,
+        "camera",
+        {
+            "camera": {
+                "name": "config_test",
+                "platform": "generic",
+                "still_image_url": "http://example.com",
+                "username": "user",
+                "password": "pass",
+            }
+        },
+    )
+    await hass.async_block_till_done()
+
+    client = await hass_client()
+
+    resp = await client.get("/api/camera_proxy/camera.config_test")
+
+    assert resp.status == 200
+    assert respx.calls.call_count == 1
+    assert await resp.text() == "hello world"
+
+    respx.get("http://example.com").respond(text="not hello world")
+
+    with patch(
+        "homeassistant.components.generic.camera.GenericCamera._async_camera_image",
+        side_effect=asyncio.CancelledError(),
+    ):
+        resp = await client.get("/api/camera_proxy/camera.config_test")
+        assert respx.calls.call_count == 1
+        assert resp.status == 500
+
+    respx.get("http://example.com").side_effect = [
+        httpx.RequestError,
+        httpx.TimeoutException,
+    ]
+
+    for total_calls in range(2, 4):
+        resp = await client.get("/api/camera_proxy/camera.config_test")
+        assert respx.calls.call_count == total_calls
+        assert resp.status == 200
+        assert await resp.text() == "hello world"
+
+
 def _get_fixtures_base_path():
     return path.dirname(path.dirname(path.dirname(__file__)))