Cache Canary camera image (home-assistant#73923)

* Cache camera image

Cache camera image so a new image isn't generated each call.
Adds debug logging

* Apply suggestions from code review

code compression with walrus operator

Co-authored-by: Erik Montnemery <erik@montnemery.com>

* fix after walrus operator suggested tweak

fully use the live_stream_session variable in async_camera_image

* Invalidate cached image after 15 minutes

requested code change; invalidate cached image

* Removed unnecessary if statement

based on code review

* Image capture flow updates

now sets the image expiration upon getting an updated image
updates the cache image only when a new image is captured

Co-authored-by: Erik Montnemery <erik@montnemery.com>

homeassistant/components/canary/camera.py

@@ -2,6 +2,7 @@
 from __future__ import annotations
 
 from datetime import timedelta
+import logging
 from typing import Final
 
 from aiohttp.web import Request, StreamResponse
@@ -23,7 +24,7 @@
 from homeassistant.helpers.entity import DeviceInfo
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
 from homeassistant.helpers.update_coordinator import CoordinatorEntity
-from homeassistant.util import Throttle
+from homeassistant.util import dt as dt_util
 
 from .const import (
     CONF_FFMPEG_ARGUMENTS,
@@ -34,7 +35,7 @@
 )
 from .coordinator import CanaryDataUpdateCoordinator
 
-MIN_TIME_BETWEEN_SESSION_RENEW: Final = timedelta(seconds=90)
+FORCE_CAMERA_REFRESH_INTERVAL: Final = timedelta(minutes=15)
 
 PLATFORM_SCHEMA: Final = vol.All(
     cv.deprecated(CONF_FFMPEG_ARGUMENTS),
@@ -47,6 +48,8 @@
     ),
 )
 
+_LOGGER = logging.getLogger(__name__)
+
 
 async def async_setup_entry(
     hass: HomeAssistant,
@@ -105,6 +108,11 @@ def __init__(
             model=device.device_type["name"],
             name=device.name,
         )
+        self._image: bytes | None = None
+        self._expires_at = dt_util.utcnow()
+        _LOGGER.debug(
+            "%s %s has been initialized", self.name, device.device_type["name"]
+        )
 
     @property
     def location(self) -> Location:
@@ -125,17 +133,33 @@ async def async_camera_image(
         self, width: int | None = None, height: int | None = None
     ) -> bytes | None:
         """Return a still image response from the camera."""
-        await self.hass.async_add_executor_job(self.renew_live_stream_session)
-        live_stream_url = await self.hass.async_add_executor_job(
-            getattr, self._live_stream_session, "live_stream_url"
-        )
-        return await ffmpeg.async_get_image(
-            self.hass,
-            live_stream_url,
-            extra_cmd=self._ffmpeg_arguments,
-            width=width,
-            height=height,
-        )
+        utcnow = dt_util.utcnow()
+        if self._expires_at <= utcnow:
+            _LOGGER.debug("Grabbing a live view image from %s", self.name)
+            await self.hass.async_add_executor_job(self.renew_live_stream_session)
+
+            if (live_stream_session := self._live_stream_session) is None:
+                return None
+
+            if not (live_stream_url := live_stream_session.live_stream_url):
+                return None
+
+            image = await ffmpeg.async_get_image(
+                self.hass,
+                live_stream_url,
+                extra_cmd=self._ffmpeg_arguments,
+                width=width,
+                height=height,
+            )
+
+            if image:
+                self._image = image
+                self._expires_at = FORCE_CAMERA_REFRESH_INTERVAL + utcnow
+                _LOGGER.debug("Grabbed a live view image from %s", self.name)
+            await self.hass.async_add_executor_job(live_stream_session.stop_session)
+            _LOGGER.debug("Stopped live session from %s", self.name)
+
+        return self._image
 
     async def handle_async_mjpeg_stream(
         self, request: Request
@@ -161,9 +185,14 @@ async def handle_async_mjpeg_stream(
         finally:
             await stream.close()
 
-    @Throttle(MIN_TIME_BETWEEN_SESSION_RENEW)
     def renew_live_stream_session(self) -> None:
         """Renew live stream session."""
         self._live_stream_session = self.coordinator.canary.get_live_stream_session(
             self._device
         )
+
+        _LOGGER.debug(
+            "Live Stream URL for %s is %s",
+            self.name,
+            self._live_stream_session.live_stream_url,
+        )