Change template loop detection strategy to allow self-referencing updates when there are multiple templates (#39943)

homeassistant/components/template/template_entity.py

@@ -5,6 +5,7 @@ from typing import Any, Callable, List, Optional, Union
 
 import voluptuous as vol
 
+from homeassistant.const import ATTR_ENTITY_ID
 from homeassistant.core import EVENT_HOMEASSISTANT_START, CoreState, callback
 from homeassistant.exceptions import TemplateError
 import homeassistant.helpers.config_validation as cv
@@ -121,7 +122,6 @@ class TemplateEntity(Entity):
         """Template Entity."""
         self._template_attrs = {}
         self._async_update = None
-        self._async_update_entity_ids_filter = None
         self._attribute_templates = attribute_templates
         self._attributes = {}
         self._availability_template = availability_template
@@ -130,6 +130,7 @@ class TemplateEntity(Entity):
         self._entity_picture_template = entity_picture_template
         self._icon = None
         self._entity_picture = None
+        self._self_ref_update_count = 0
 
     @property
     def should_poll(self):
@@ -223,18 +224,34 @@ class TemplateEntity(Entity):
         updates: List[TrackTemplateResult],
     ) -> None:
         """Call back the results to the attributes."""
+
         if event:
             self.async_set_context(event.context)
 
+        entity_id = event and event.data.get(ATTR_ENTITY_ID)
+
+        if entity_id and entity_id == self.entity_id:
+            self._self_ref_update_count += 1
+        else:
+            self._self_ref_update_count = 0
+
+        # If we need to make this less sensitive in the future,
+        # change the '>=' to a '>' here.
+        if self._self_ref_update_count >= len(self._template_attrs):
+            for update in updates:
+                _LOGGER.warning(
+                    "Template loop detected while processing event: %s, skipping template render for Template[%s]",
+                    event,
+                    update.template.template,
+                )
+            return
+
         for update in updates:
             for attr in self._template_attrs[update.template]:
                 attr.handle_result(
                     event, update.template, update.last_result, update.result
                 )
 
-        if self._async_update_entity_ids_filter:
-            self._async_update_entity_ids_filter({self.entity_id})
-
         if self._async_update:
             self.async_write_ha_state()
 
@@ -249,12 +266,8 @@ class TemplateEntity(Entity):
         )
         self.async_on_remove(result_info.async_remove)
         result_info.async_refresh()
-        result_info.async_update_entity_ids_filter({self.entity_id})
         self.async_write_ha_state()
         self._async_update = result_info.async_refresh
-        self._async_update_entity_ids_filter = (
-            result_info.async_update_entity_ids_filter
-        )
 
     async def async_added_to_hass(self) -> None:
         """Run when entity about to be added to hass."""