From 8d2daaa694074b7a676a368c788c316676914267 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Wed, 21 Jun 2023 22:23:35 +0200
Subject: [PATCH] Limit cache size of EntityValues (#94983)

---
 homeassistant/helpers/entity_values.py | 19 +++++++++++++------
 tests/helpers/test_entity_values.py    |  7 +++++--
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/homeassistant/helpers/entity_values.py b/homeassistant/helpers/entity_values.py
index d489a4b1d37..fe4a4249c54 100644
--- a/homeassistant/helpers/entity_values.py
+++ b/homeassistant/helpers/entity_values.py
@@ -3,14 +3,24 @@ from __future__ import annotations
 
 from collections import OrderedDict
 import fnmatch
+from functools import lru_cache
 import re
 from typing import Any
 
 from homeassistant.core import split_entity_id
 
+_MAX_EXPECTED_ENTITIES = 16384
+
 
 class EntityValues:
-    """Class to store entity id based values."""
+    """Class to store entity id based values.
+
+    This class is expected to only be used infrequently
+    as it caches all entity ids up to _MAX_EXPECTED_ENTITIES.
+
+    The cache includes `self` so it is important to
+    only use this in places where usage of `EntityValues` is immortal.
+    """
 
     def __init__(
         self,
@@ -19,7 +29,6 @@ class EntityValues:
         glob: dict[str, dict[str, str]] | None = None,
     ) -> None:
         """Initialize an EntityConfigDict."""
-        self._cache: dict[str, dict[str, str]] = {}
         self._exact = exact
         self._domain = domain
 
@@ -32,13 +41,11 @@ class EntityValues:
 
         self._glob = compiled
 
+    @lru_cache(maxsize=_MAX_EXPECTED_ENTITIES)
     def get(self, entity_id: str) -> dict[str, str]:
         """Get config for an entity id."""
-        if entity_id in self._cache:
-            return self._cache[entity_id]
-
         domain, _ = split_entity_id(entity_id)
-        result = self._cache[entity_id] = {}
+        result: dict[str, str] = {}
 
         if self._domain is not None and domain in self._domain:
             result.update(self._domain[domain])
diff --git a/tests/helpers/test_entity_values.py b/tests/helpers/test_entity_values.py
index f953ec0ba9e..1ac8e480f51 100644
--- a/tests/helpers/test_entity_values.py
+++ b/tests/helpers/test_entity_values.py
@@ -10,9 +10,12 @@ def test_override_single_value() -> None:
     """Test values with exact match."""
     store = EV({ent: {"key": "value"}})
     assert store.get(ent) == {"key": "value"}
-    assert len(store._cache) == 1
+    assert store.get.cache_info().currsize == 1
+    assert store.get.cache_info().misses == 1
     assert store.get(ent) == {"key": "value"}
-    assert len(store._cache) == 1
+    assert store.get.cache_info().currsize == 1
+    assert store.get.cache_info().misses == 1
+    assert store.get.cache_info().hits == 1
 
 
 def test_override_by_domain() -> None: