Serialize amcrest snapshot commands and bump PyPI package to 1.2.4 (#21664)

* Serialize snapshot commands and bump amcrest package to 1.2.4

Attempting to send a snapshot command when a previous one hasn't finished will result in warnings and/or errors. This can happen when the camera picture is clicked on in the frontend, resulting in the thread that updates the thumbnail in the background every 10 seconds to sometimes collide with the thread that updates the large picture in the foreground quickly. An automation that calls the camera.snapshot service in yet another thread can make the situation worse. Fix by adding a thread lock to serialize snapshot commands. Also bump the amcrest package to 1.2.4 which fixes error handling in the command method and improves performance by reusing requests sessions.

* Update amcrest package to 1.2.4

homeassistant/components/amcrest/__init__.py

@@ -13,7 +13,7 @@ from homeassistant.const import (
 from homeassistant.helpers import discovery
 import homeassistant.helpers.config_validation as cv
 
-REQUIREMENTS = ['amcrest==1.2.3']
+REQUIREMENTS = ['amcrest==1.2.4']
 DEPENDENCIES = ['ffmpeg']
 
 _LOGGER = logging.getLogger(__name__)

homeassistant/components/amcrest/camera.py

@@ -1,5 +1,9 @@
 """Support for Amcrest IP cameras."""
 import logging
+import threading
+
+from requests import RequestException
+from urllib3.exceptions import ReadTimeoutError
 
 from homeassistant.components.amcrest import (
     DATA_AMCREST, STREAM_SOURCE_LIST, TIMEOUT)
@@ -43,12 +47,18 @@ class AmcrestCam(Camera):
         self._stream_source = amcrest.stream_source
         self._resolution = amcrest.resolution
         self._token = self._auth = amcrest.authentication
+        self._snapshot_lock = threading.Lock()
 
     def camera_image(self):
         """Return a still image response from the camera."""
+        with self._snapshot_lock:
+            try:
                 # Send the request to snap a picture and return raw jpg data
-        response = self._camera.snapshot(channel=self._resolution)
-        return response.data
+                return self._camera.snapshot(channel=self._resolution).data
+            except (RequestException, ReadTimeoutError, ValueError) as error:
+                _LOGGER.error(
+                    'Could not get camera image due to error %s', error)
+                return None
 
     async def handle_async_mjpeg_stream(self, request):
         """Return an MJPEG stream."""

requirements_all.txt

@@ -152,7 +152,7 @@ alarmdecoder==1.13.2
 alpha_vantage==2.1.0
 
 # homeassistant.components.amcrest
-amcrest==1.2.3
+amcrest==1.2.4
 
 # homeassistant.components.switch.anel_pwrctrl
 anel_pwrctrl-homeassistant==0.0.1.dev2