Speed up generation of template states (#73728)

* Speed up generation of template states

* tweak

* cache

* cache hash

* weaken

* Revert "weaken"

This reverts commit 4856f500807c21aa1c9333d44fd53555bae7bb82.

* lower cache size as it tends to be the same ones over and over

* lower cache size as it tends to be the same ones over and over

* lower cache size as it tends to be the same ones over and over

* cover

* Update homeassistant/helpers/template.py

Co-authored-by: Paulus Schoutsen <paulus@home-assistant.io>

* id reuse is possible

* account for iterting all sensors

Co-authored-by: Paulus Schoutsen <paulus@home-assistant.io>

homeassistant/core.py

@@ -1110,6 +1110,13 @@ class State:
         self.domain, self.object_id = split_entity_id(self.entity_id)
         self._as_dict: ReadOnlyDict[str, Collection[Any]] | None = None
 
+    def __hash__(self) -> int:
+        """Make the state hashable.
+
+        State objects are effectively immutable.
+        """
+        return hash((id(self), self.last_updated))
+
     @property
     def name(self) -> str:
         """Name of this state."""

homeassistant/helpers/template.py

@@ -9,7 +9,7 @@ from collections.abc import Callable, Generator, Iterable
 from contextlib import contextmanager, suppress
 from contextvars import ContextVar
 from datetime import datetime, timedelta
-from functools import partial, wraps
+from functools import cache, lru_cache, partial, wraps
 import json
 import logging
 import math
@@ -98,6 +98,9 @@ template_cv: ContextVar[tuple[str, str] | None] = ContextVar(
     "template_cv", default=None
 )
 
+CACHED_TEMPLATE_STATES = 512
+EVAL_CACHE_SIZE = 512
+
 
 @bind_hass
 def attach(hass: HomeAssistant, obj: Any) -> None:
@@ -222,6 +225,9 @@ def _false(arg: str) -> bool:
     return False
 
 
+_cached_literal_eval = lru_cache(maxsize=EVAL_CACHE_SIZE)(literal_eval)
+
+
 class RenderInfo:
     """Holds information about a template render."""
 
@@ -318,6 +324,7 @@ class Template:
         "_exc_info",
         "_limited",
         "_strict",
+        "_hash_cache",
     )
 
     def __init__(self, template, hass=None):
@@ -333,6 +340,7 @@ class Template:
         self._exc_info = None
         self._limited = None
         self._strict = None
+        self._hash_cache: int = hash(self.template)
 
     @property
     def _env(self) -> TemplateEnvironment:
@@ -421,7 +429,7 @@ class Template:
     def _parse_result(self, render_result: str) -> Any:
         """Parse the result."""
         try:
-            result = literal_eval(render_result)
+            result = _cached_literal_eval(render_result)
 
             if type(result) in RESULT_WRAPPERS:
                 result = RESULT_WRAPPERS[type(result)](
@@ -618,16 +626,30 @@ class Template:
 
     def __hash__(self) -> int:
         """Hash code for template."""
-        return hash(self.template)
+        return self._hash_cache
 
     def __repr__(self) -> str:
         """Representation of Template."""
         return 'Template("' + self.template + '")'
 
 
+@cache
+def _domain_states(hass: HomeAssistant, name: str) -> DomainStates:
+    return DomainStates(hass, name)
+
+
+def _readonly(*args: Any, **kwargs: Any) -> Any:
+    """Raise an exception when a states object is modified."""
+    raise RuntimeError(f"Cannot modify template States object: {args} {kwargs}")
+
+
 class AllStates:
     """Class to expose all HA states as attributes."""
 
+    __setitem__ = _readonly
+    __delitem__ = _readonly
+    __slots__ = ("_hass",)
+
     def __init__(self, hass: HomeAssistant) -> None:
         """Initialize all states."""
         self._hass = hass
@@ -643,7 +665,7 @@ class AllStates:
         if not valid_entity_id(f"{name}.entity"):
             raise TemplateError(f"Invalid domain name '{name}'")
 
-        return DomainStates(self._hass, name)
+        return _domain_states(self._hass, name)
 
     # Jinja will try __getitem__ first and it avoids the need
     # to call is_safe_attribute
@@ -682,6 +704,11 @@ class AllStates:
 class DomainStates:
     """Class to expose a specific HA domain as attributes."""
 
+    __slots__ = ("_hass", "_domain")
+
+    __setitem__ = _readonly
+    __delitem__ = _readonly
+
     def __init__(self, hass: HomeAssistant, domain: str) -> None:
         """Initialize the domain states."""
         self._hass = hass
@@ -727,6 +754,9 @@ class TemplateStateBase(State):
 
     _state: State
 
+    __setitem__ = _readonly
+    __delitem__ = _readonly
+
     # Inheritance is done so functions that check against State keep working
     # pylint: disable=super-init-not-called
     def __init__(self, hass: HomeAssistant, collect: bool, entity_id: str) -> None:
@@ -865,10 +895,15 @@ def _collect_state(hass: HomeAssistant, entity_id: str) -> None:
         entity_collect.entities.add(entity_id)
 
 
+@lru_cache(maxsize=CACHED_TEMPLATE_STATES)
+def _template_state_no_collect(hass: HomeAssistant, state: State) -> TemplateState:
+    return TemplateState(hass, state, collect=False)
+
+
 def _state_generator(hass: HomeAssistant, domain: str | None) -> Generator:
     """State generator for a domain or all states."""
     for state in sorted(hass.states.async_all(domain), key=attrgetter("entity_id")):
-        yield TemplateState(hass, state, collect=False)
+        yield _template_state_no_collect(hass, state)
 
 
 def _get_state_if_valid(hass: HomeAssistant, entity_id: str) -> TemplateState | None:
@@ -882,6 +917,11 @@ def _get_state(hass: HomeAssistant, entity_id: str) -> TemplateState | None:
     return _get_template_state_from_state(hass, entity_id, hass.states.get(entity_id))
 
 
+@lru_cache(maxsize=CACHED_TEMPLATE_STATES)
+def _template_state(hass: HomeAssistant, state: State) -> TemplateState:
+    return TemplateState(hass, state)
+
+
 def _get_template_state_from_state(
     hass: HomeAssistant, entity_id: str, state: State | None
 ) -> TemplateState | None:
@@ -890,7 +930,7 @@ def _get_template_state_from_state(
         # access to the state properties in the state wrapper.
         _collect_state(hass, entity_id)
         return None
-    return TemplateState(hass, state)
+    return _template_state(hass, state)
 
 
 def _resolve_state(

tests/helpers/test_template.py

@@ -18,6 +18,7 @@ from homeassistant.const import (
     MASS_GRAMS,
     PRESSURE_PA,
     SPEED_KILOMETERS_PER_HOUR,
+    STATE_ON,
     TEMP_CELSIUS,
     VOLUME_LITERS,
 )
@@ -3831,3 +3832,12 @@ async def test_undefined_variable(hass, caplog):
         "Template variable warning: 'no_such_variable' is undefined when rendering '{{ no_such_variable }}'"
         in caplog.text
     )
+
+
+async def test_template_states_blocks_setitem(hass):
+    """Test we cannot setitem on TemplateStates."""
+    hass.states.async_set("light.new", STATE_ON)
+    state = hass.states.get("light.new")
+    template_state = template.TemplateState(hass, state, True)
+    with pytest.raises(RuntimeError):
+        template_state["any"] = "any"