perf: only write state when data changes (#954)

* perf: avoid writing state when the controller did not actually update

#948 made me realize that the car data was being polled far less frequently than I thought as the underlying library was caching, but every time the coordinator fired, it would still callback all the listeners and write the state of all the entities which meant we ended up writing state every 10 seconds even if nothing has changed.

Keep track of when the controller was last updated in each entity and if it has not changed, we skip
the state write.

This reduced the number of calls to `async_write_ha_state` by 62% on my production HA instance!

* fix async_added_to_hass was being overridden and forgot to remove in pr

custom_components/tesla_custom/__init__.py

@@ -427,6 +427,7 @@ def __init__(
         self.update_vehicles = update_vehicles
         self._debounce_task = None
         self._last_update_time = None
+        self.last_controller_update_time: float | None = None
         self.assumed_state = True
 
         update_interval = timedelta(seconds=MIN_SCAN_INTERVAL)
@@ -477,8 +478,11 @@ async def _async_update_data(self):
             raise UpdateFailed(f"Error communicating with API: {err}") from err
         else:
             if vin := self.vin:
+                self.last_controller_update_time = controller.get_last_update_time(
+                    vin=vin
+                )
                 self.assumed_state = not controller.is_car_online(vin=vin) and (
-                    controller.get_last_update_time(vin=vin)
+                    self.last_controller_update_time
                     - controller.get_last_wake_up_time(vin=vin)
                     > controller.update_interval
                 )

custom_components/tesla_custom/base.py

@@ -1,5 +1,6 @@
 """Support for Tesla cars and energy sites."""
 
+from homeassistant.core import callback
 from homeassistant.helpers.entity import DeviceInfo
 from homeassistant.helpers.update_coordinator import CoordinatorEntity
 from homeassistant.util import slugify
@@ -29,12 +30,6 @@ def __init__(
         self._attr_name = self.type.capitalize()
         self._attr_entity_registry_enabled_default = self._enabled_by_default
 
-    async def async_added_to_hass(self) -> None:
-        """Register state update callback."""
-        self.async_on_remove(
-            self.coordinator.async_add_listener(self.async_write_ha_state)
-        )
-
 
 class TeslaCarEntity(TeslaBaseEntity):
     """Representation of a Tesla car device."""
@@ -61,6 +56,27 @@ def __init__(
             model=car.car_type,
             sw_version=car.car_version,
         )
+        self._last_update_success: bool | None = None
+        self._last_controller_update_time: float | None = None
+
+    @callback
+    def _handle_coordinator_update(self) -> None:
+        """Handle updated data from the coordinator."""
+        prev_last_update_success = self._last_update_success
+        prev_last_controller_update_time = self._last_controller_update_time
+        coordinator = self.coordinator
+        current_last_update_success = coordinator.last_update_success
+        current_last_controller_update_time = coordinator.last_controller_update_time
+        self._last_update_success = current_last_update_success
+        self._last_controller_update_time = current_last_controller_update_time
+        if (
+            prev_last_update_success == current_last_update_success
+            and prev_last_controller_update_time == current_last_controller_update_time
+        ):
+            # If there was no change in the last update success or time,
+            # avoid writing state to prevent unnecessary entity updates.
+            return
+        super()._handle_coordinator_update()
 
     async def update_controller(
         self, *, wake_if_asleep: bool = False, force: bool = True, blocking: bool = True