Fix mobile app dispatcher performance (#99647)

Fix mobile app thundering heard

The mobile_app would setup a dispatcher to listener for updates on
every entity and reject the ones that were not for the unique id
that it was intrested in.

Instead we now register for a signal per unique id since we were
previously generating O(entities*sensors*devices) callbacks which
was causing the event loop to stall when there were a large
number of mobile app users.

homeassistant/components/mobile_app/entity.py

@@ -1,6 +1,8 @@
 """A entity class for mobile_app."""
 from __future__ import annotations
 
+from typing import Any
+
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import ATTR_ICON, CONF_NAME, CONF_UNIQUE_ID, STATE_UNAVAILABLE
 from homeassistant.core import callback
@@ -36,7 +38,9 @@ class MobileAppEntity(RestoreEntity):
         """Register callbacks."""
         self.async_on_remove(
             async_dispatcher_connect(
-                self.hass, SIGNAL_SENSOR_UPDATE, self._handle_update
+                self.hass,
+                f"{SIGNAL_SENSOR_UPDATE}-{self._attr_unique_id}",
+                self._handle_update,
             )
         )
 
@@ -96,10 +100,7 @@ class MobileAppEntity(RestoreEntity):
         return self._config.get(ATTR_SENSOR_STATE) != STATE_UNAVAILABLE
 
     @callback
-    def _handle_update(self, incoming_id, data):
+    def _handle_update(self, data: dict[str, Any]) -> None:
         """Handle async event updates."""
-        if incoming_id != self._attr_unique_id:
-            return
-
-        self._config = {**self._config, **data}
+        self._config.update(data)
         self.async_write_ha_state()

homeassistant/components/mobile_app/webhook.py

@@ -607,7 +607,7 @@ async def webhook_register_sensor(
         if changes:
             entity_registry.async_update_entity(existing_sensor, **changes)
 
-        async_dispatcher_send(hass, SIGNAL_SENSOR_UPDATE, unique_store_key, data)
+        async_dispatcher_send(hass, f"{SIGNAL_SENSOR_UPDATE}-{unique_store_key}", data)
     else:
         data[CONF_UNIQUE_ID] = unique_store_key
         data[
@@ -693,8 +693,7 @@ async def webhook_update_sensor_states(
         sensor[CONF_WEBHOOK_ID] = config_entry.data[CONF_WEBHOOK_ID]
         async_dispatcher_send(
             hass,
-            SIGNAL_SENSOR_UPDATE,
-            unique_store_key,
+            f"{SIGNAL_SENSOR_UPDATE}-{unique_store_key}",
             sensor,
         )