From 07d1a16efd4930c23f565ff0b714d38ed9e36bd7 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Fri, 28 Apr 2023 21:15:39 +0200
Subject: [PATCH] Add as_dict cache to Context and Event (#92162)

---
 .../homeassistant/triggers/event.py           |  2 +-
 homeassistant/core.py                         | 44 ++++++++++++-------
 tests/components/recorder/test_models.py      |  4 +-
 3 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/homeassistant/components/homeassistant/triggers/event.py b/homeassistant/components/homeassistant/triggers/event.py
index d84b04c3652..d0e74d5b04e 100644
--- a/homeassistant/components/homeassistant/triggers/event.py
+++ b/homeassistant/components/homeassistant/triggers/event.py
@@ -91,7 +91,7 @@ async def async_attach_trigger(
             if event_data_schema:
                 event_data_schema(event.data)
             if event_context_schema:
-                event_context_schema(event.context.as_dict())
+                event_context_schema(dict(event.context.as_dict()))
         except vol.Invalid:
             # If event doesn't match, skip event
             return False
diff --git a/homeassistant/core.py b/homeassistant/core.py
index f7cfcf44205..48c69f35956 100644
--- a/homeassistant/core.py
+++ b/homeassistant/core.py
@@ -850,7 +850,7 @@ class HomeAssistant:
 class Context:
     """The context that triggered something."""
 
-    __slots__ = ("user_id", "parent_id", "id", "origin_event")
+    __slots__ = ("user_id", "parent_id", "id", "origin_event", "_as_dict")
 
     def __init__(
         self,
@@ -863,14 +863,23 @@ class Context:
         self.user_id = user_id
         self.parent_id = parent_id
         self.origin_event: Event | None = None
+        self._as_dict: ReadOnlyDict[str, str | None] | None = None
 
     def __eq__(self, other: Any) -> bool:
         """Compare contexts."""
         return bool(self.__class__ == other.__class__ and self.id == other.id)
 
-    def as_dict(self) -> dict[str, str | None]:
+    def as_dict(self) -> ReadOnlyDict[str, str | None]:
         """Return a dictionary representation of the context."""
-        return {"id": self.id, "parent_id": self.parent_id, "user_id": self.user_id}
+        if not self._as_dict:
+            self._as_dict = ReadOnlyDict(
+                {
+                    "id": self.id,
+                    "parent_id": self.parent_id,
+                    "user_id": self.user_id,
+                }
+            )
+        return self._as_dict
 
 
 class EventOrigin(enum.Enum):
@@ -887,7 +896,7 @@ class EventOrigin(enum.Enum):
 class Event:
     """Representation of an event within the bus."""
 
-    __slots__ = ["event_type", "data", "origin", "time_fired", "context"]
+    __slots__ = ("event_type", "data", "origin", "time_fired", "context", "_as_dict")
 
     def __init__(
         self,
@@ -905,19 +914,24 @@ class Event:
         self.context: Context = context or Context(
             id=ulid_util.ulid_at_time(dt_util.utc_to_timestamp(self.time_fired))
         )
+        self._as_dict: ReadOnlyDict[str, Any] | None = None
 
-    def as_dict(self) -> dict[str, Any]:
+    def as_dict(self) -> ReadOnlyDict[str, Any]:
         """Create a dict representation of this Event.
 
         Async friendly.
         """
-        return {
-            "event_type": self.event_type,
-            "data": dict(self.data),
-            "origin": str(self.origin.value),
-            "time_fired": self.time_fired.isoformat(),
-            "context": self.context.as_dict(),
-        }
+        if not self._as_dict:
+            self._as_dict = ReadOnlyDict(
+                {
+                    "event_type": self.event_type,
+                    "data": ReadOnlyDict(self.data),
+                    "origin": str(self.origin.value),
+                    "time_fired": self.time_fired.isoformat(),
+                    "context": self.context.as_dict(),
+                }
+            )
+        return self._as_dict
 
     def __repr__(self) -> str:
         """Return the representation."""
@@ -1189,7 +1203,7 @@ class State:
     object_id: Object id of this state.
     """
 
-    __slots__ = [
+    __slots__ = (
         "entity_id",
         "state",
         "attributes",
@@ -1200,7 +1214,7 @@ class State:
         "object_id",
         "_as_dict",
         "_as_compressed_state",
-    ]
+    )
 
     def __init__(
         self,
@@ -1265,7 +1279,7 @@ class State:
                     "attributes": self.attributes,
                     "last_changed": last_changed_isoformat,
                     "last_updated": last_updated_isoformat,
-                    "context": ReadOnlyDict(self.context.as_dict()),
+                    "context": self.context.as_dict(),
                 }
             )
         return self._as_dict
diff --git a/tests/components/recorder/test_models.py b/tests/components/recorder/test_models.py
index f47f1d3e78b..8797c153a7b 100644
--- a/tests/components/recorder/test_models.py
+++ b/tests/components/recorder/test_models.py
@@ -256,7 +256,9 @@ async def test_event_to_db_model() -> None:
     assert native.as_dict() == event.as_dict()
 
     native = Events.from_event(event).to_native()
-    event.data = {}
+    native.data = (
+        event.data
+    )  # data is not set by from_event as its in the event_data table
     native.event_type = event.event_type
     assert native.as_dict() == event.as_dict()