Mark database sessions that do not write data as read_only (#89600)

* Mark sessions that do not write data as read_only

* Mark sessions that do not write data as read_only

homeassistant/components/history/__init__.py

@@ -168,7 +168,7 @@ class HistoryPeriodView(HomeAssistantView):
         """Fetch significant stats from the database as json."""
         timer_start = time.perf_counter()
 
-        with session_scope(hass=hass) as session:
+        with session_scope(hass=hass, read_only=True) as session:
             states = history.get_significant_states_with_session(
                 hass,
                 session,

homeassistant/components/logbook/processor.py

@@ -150,7 +150,7 @@ class EventProcessor:
             #
             return result.yield_per(1024)
 
-        with session_scope(hass=self.hass) as session:
+        with session_scope(hass=self.hass, read_only=True) as session:
             metadata_ids: list[int] | None = None
             if self.entity_ids:
                 instance = get_instance(self.hass)

homeassistant/components/recorder/history/legacy.py

@@ -213,7 +213,7 @@ def get_significant_states(
     compressed_state_format: bool = False,
 ) -> MutableMapping[str, list[State | dict[str, Any]]]:
     """Wrap get_significant_states_with_session with an sql session."""
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         return get_significant_states_with_session(
             hass,
             session,
@@ -488,7 +488,7 @@ def state_changes_during_period(
     entity_id = entity_id.lower() if entity_id is not None else None
     entity_ids = [entity_id] if entity_id is not None else None
 
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         stmt = _state_changed_during_period_stmt(
             _schema_version(hass),
             start_time,
@@ -558,7 +558,7 @@ def get_last_state_changes(
     entity_id_lower = entity_id.lower()
     entity_ids = [entity_id_lower]
 
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         stmt = _get_last_state_changes_stmt(
             _schema_version(hass), number_of_states, entity_id_lower
         )

homeassistant/components/recorder/history/modern.py

@@ -115,7 +115,7 @@ def get_significant_states(
     compressed_state_format: bool = False,
 ) -> MutableMapping[str, list[State | dict[str, Any]]]:
     """Wrap get_significant_states_with_session with an sql session."""
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         return get_significant_states_with_session(
             hass,
             session,
@@ -360,7 +360,7 @@ def state_changes_during_period(
     entity_id = entity_id.lower() if entity_id is not None else None
     entity_ids = [entity_id] if entity_id is not None else None
 
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         metadata_id: int | None = None
         entity_id_to_metadata_id = None
         if entity_id:
@@ -424,7 +424,7 @@ def get_last_state_changes(
     entity_id_lower = entity_id.lower()
     entity_ids = [entity_id_lower]
 
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         instance = recorder.get_instance(hass)
         if not (metadata_id := instance.states_meta_manager.get(entity_id, session)):
             return {}

homeassistant/components/recorder/statistics.py

@@ -925,7 +925,7 @@ def get_metadata(
     statistic_source: str | None = None,
 ) -> dict[str, tuple[int, StatisticMetaData]]:
     """Return metadata for statistic_ids."""
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         return get_metadata_with_session(
             session,
             statistic_ids=statistic_ids,
@@ -985,7 +985,7 @@ def list_statistic_ids(
     statistic_ids_set = set(statistic_ids) if statistic_ids else None
 
     # Query the database
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         metadata = get_metadata_with_session(
             session, statistic_type=statistic_type, statistic_ids=statistic_ids
         )
@@ -1589,7 +1589,7 @@ def statistic_during_period(
 
     result: dict[str, Any] = {}
 
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         # Fetch metadata for the given statistic_id
         if not (
             metadata := get_metadata_with_session(session, statistic_ids=[statistic_id])
@@ -1814,7 +1814,7 @@ def statistics_during_period(
     If end_time is omitted, returns statistics newer than or equal to start_time.
     If statistic_ids is omitted, returns statistics for all statistics ids.
     """
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         return _statistics_during_period_with_session(
             hass,
             session,
@@ -1866,7 +1866,7 @@ def _get_last_statistics(
 ) -> dict[str, list[dict]]:
     """Return the last number_of_stats statistics for a given statistic_id."""
     statistic_ids = [statistic_id]
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         # Fetch metadata for the given statistic_id
         metadata = get_metadata_with_session(session, statistic_ids=statistic_ids)
         if not metadata:
@@ -1953,7 +1953,7 @@ def get_latest_short_term_statistics(
     metadata: dict[str, tuple[int, StatisticMetaData]] | None = None,
 ) -> dict[str, list[dict]]:
     """Return the latest short term statistics for a list of statistic_ids."""
-    with session_scope(hass=hass) as session:
+    with session_scope(hass=hass, read_only=True) as session:
         # Fetch metadata for the given statistic_ids
         if not metadata:
             metadata = get_metadata_with_session(session, statistic_ids=statistic_ids)

homeassistant/components/recorder/util.py

@@ -110,8 +110,14 @@ def session_scope(
     hass: HomeAssistant | None = None,
     session: Session | None = None,
     exception_filter: Callable[[Exception], bool] | None = None,
+    read_only: bool = False,
 ) -> Generator[Session, None, None]:
-    """Provide a transactional scope around a series of operations."""
+    """Provide a transactional scope around a series of operations.
+
+    read_only is used to indicate that the session is only used for reading
+    data and that no commit is required. It does not prevent the session
+    from writing and is not a security measure.
+    """
     if session is None and hass is not None:
         session = get_instance(hass).get_session()
 
@@ -121,7 +127,7 @@ def session_scope(
     need_rollback = False
     try:
         yield session
-        if session.get_transaction():
+        if session.get_transaction() and not read_only:
             need_rollback = True
             session.commit()
     except Exception as err:  # pylint: disable=broad-except