Rename storage classes (#12913)

30 files changed, 592 insertions, 484 deletions

diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index 7a91544119..b700cbbfa1 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -22,7 +22,7 @@ from synapse.events import EventBase
 from synapse.types import JsonDict, StateMap
 
 if TYPE_CHECKING:
-    from synapse.storage import Storage
+    from synapse.storage.controllers import StorageControllers
     from synapse.storage.databases.main import DataStore
     from synapse.storage.state import StateFilter
 
@@ -84,7 +84,7 @@ class EventContext:
             incomplete state.
     """
 
-    _storage: "Storage"
+    _storage: "StorageControllers"
     rejected: Union[Literal[False], str] = False
     _state_group: Optional[int] = None
     state_group_before_event: Optional[int] = None
@@ -97,7 +97,7 @@ class EventContext:
 
     @staticmethod
     def with_state(
-        storage: "Storage",
+        storage: "StorageControllers",
         state_group: Optional[int],
         state_group_before_event: Optional[int],
         state_delta_due_to_event: Optional[StateMap[str]],
@@ -117,7 +117,7 @@ class EventContext:
 
     @staticmethod
     def for_outlier(
-        storage: "Storage",
+        storage: "StorageControllers",
     ) -> "EventContext":
         """Return an EventContext instance suitable for persisting an outlier event"""
         return EventContext(storage=storage)
@@ -147,7 +147,7 @@ class EventContext:
         }
 
     @staticmethod
-    def deserialize(storage: "Storage", input: JsonDict) -> "EventContext":
+    def deserialize(storage: "StorageControllers", input: JsonDict) -> "EventContext":
         """Converts a dict that was produced by `serialize` back into a
         EventContext.
 
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 5b227b85fd..3ecede22d9 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -109,7 +109,6 @@ class FederationServer(FederationBase):
         super().__init__(hs)
 
         self.handler = hs.get_federation_handler()
-        self.storage = hs.get_storage()
         self._spam_checker = hs.get_spam_checker()
         self._federation_event_handler = hs.get_federation_event_handler()
         self.state = hs.get_state_handler()
diff --git a/synapse/handlers/admin.py b/synapse/handlers/admin.py
index 50e34743b7..d4fe7df533 100644
--- a/synapse/handlers/admin.py
+++ b/synapse/handlers/admin.py
@@ -30,8 +30,8 @@ logger = logging.getLogger(__name__)
 class AdminHandler:
     def __init__(self, hs: "HomeServer"):
         self.store = hs.get_datastores().main
-        self.storage = hs.get_storage()
-        self.state_storage = self.storage.state
+        self._storage_controllers = hs.get_storage_controllers()
+        self._state_storage_controller = self._storage_controllers.state
 
     async def get_whois(self, user: UserID) -> JsonDict:
         connections = []
@@ -197,7 +197,9 @@ class AdminHandler:
 
                 from_key = events[-1].internal_metadata.after
 
-                events = await filter_events_for_client(self.storage, user_id, events)
+                events = await filter_events_for_client(
+                    self._storage_controllers, user_id, events
+                )
 
                 writer.write_events(room_id, events)
 
@@ -233,7 +235,9 @@ class AdminHandler:
             for event_id in extremities:
                 if not event_to_unseen_prevs[event_id]:
                     continue
-                state = await self.state_storage.get_state_for_event(event_id)
+                state = await self._state_storage_controller.get_state_for_event(
+                    event_id
+                )
                 writer.write_state(room_id, event_id, state)
 
         return writer.finished()
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 2a56473dc6..72faf2ee38 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -71,7 +71,7 @@ class DeviceWorkerHandler:
         self.store = hs.get_datastores().main
         self.notifier = hs.get_notifier()
         self.state = hs.get_state_handler()
-        self.state_storage = hs.get_storage().state
+        self._state_storage = hs.get_storage_controllers().state
         self._auth_handler = hs.get_auth_handler()
         self.server_name = hs.hostname
 
@@ -204,7 +204,7 @@ class DeviceWorkerHandler:
                 continue
 
             # mapping from event_id -> state_dict
-            prev_state_ids = await self.state_storage.get_state_ids_for_events(
+            prev_state_ids = await self._state_storage.get_state_ids_for_events(
                 event_ids
             )
 
diff --git a/synapse/handlers/events.py b/synapse/handlers/events.py
index cb7e0ca7a8..ac13340d3a 100644
--- a/synapse/handlers/events.py
+++ b/synapse/handlers/events.py
@@ -139,7 +139,7 @@ class EventStreamHandler:
 class EventHandler:
     def __init__(self, hs: "HomeServer"):
         self.store = hs.get_datastores().main
-        self.storage = hs.get_storage()
+        self._storage_controllers = hs.get_storage_controllers()
 
     async def get_event(
         self,
@@ -177,7 +177,7 @@ class EventHandler:
         is_peeking = user.to_string() not in users
 
         filtered = await filter_events_for_client(
-            self.storage, user.to_string(), [event], is_peeking=is_peeking
+            self._storage_controllers, user.to_string(), [event], is_peeking=is_peeking
         )
 
         if not filtered:
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index c8233270d7..80ee7e7b4e 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -125,8 +125,8 @@ class FederationHandler:
         self.hs = hs
 
         self.store = hs.get_datastores().main
-        self.storage = hs.get_storage()
-        self.state_storage = self.storage.state
+        self._storage_controllers = hs.get_storage_controllers()
+        self._state_storage_controller = self._storage_controllers.state
         self.federation_client = hs.get_federation_client()
         self.state_handler = hs.get_state_handler()
         self.server_name = hs.hostname
@@ -324,7 +324,7 @@ class FederationHandler:
             # We set `check_history_visibility_only` as we might otherwise get false
             # positives from users having been erased.
             filtered_extremities = await filter_events_for_server(
-                self.storage,
+                self._storage_controllers,
                 self.server_name,
                 events_to_check,
                 redact=False,
@@ -660,7 +660,7 @@ class FederationHandler:
         # in the invitee's sync stream. It is stripped out for all other local users.
         event.unsigned["knock_room_state"] = stripped_room_state["knock_state_events"]
 
-        context = EventContext.for_outlier(self.storage)
+        context = EventContext.for_outlier(self._storage_controllers)
         stream_id = await self._federation_event_handler.persist_events_and_notify(
             event.room_id, [(event, context)]
         )
@@ -849,7 +849,7 @@ class FederationHandler:
             )
         )
 
-        context = EventContext.for_outlier(self.storage)
+        context = EventContext.for_outlier(self._storage_controllers)
         await self._federation_event_handler.persist_events_and_notify(
             event.room_id, [(event, context)]
         )
@@ -878,7 +878,7 @@ class FederationHandler:
 
         await self.federation_client.send_leave(host_list, event)
 
-        context = EventContext.for_outlier(self.storage)
+        context = EventContext.for_outlier(self._storage_controllers)
         stream_id = await self._federation_event_handler.persist_events_and_notify(
             event.room_id, [(event, context)]
         )
@@ -1027,7 +1027,7 @@ class FederationHandler:
         if event.internal_metadata.outlier:
             raise NotFoundError("State not known at event %s" % (event_id,))
 
-        state_groups = await self.state_storage.get_state_groups_ids(
+        state_groups = await self._state_storage_controller.get_state_groups_ids(
             room_id, [event_id]
         )
 
@@ -1078,7 +1078,9 @@ class FederationHandler:
             ],
         )
 
-        events = await filter_events_for_server(self.storage, origin, events)
+        events = await filter_events_for_server(
+            self._storage_controllers, origin, events
+        )
 
         return events
 
@@ -1109,7 +1111,9 @@ class FederationHandler:
             if not in_room:
                 raise AuthError(403, "Host not in room.")
 
-            events = await filter_events_for_server(self.storage, origin, [event])
+            events = await filter_events_for_server(
+                self._storage_controllers, origin, [event]
+            )
             event = events[0]
             return event
         else:
@@ -1138,7 +1142,7 @@ class FederationHandler:
         )
 
         missing_events = await filter_events_for_server(
-            self.storage, origin, missing_events
+            self._storage_controllers, origin, missing_events
         )
 
         return missing_events
@@ -1480,9 +1484,11 @@ class FederationHandler:
                 # clear the lazy-loading flag.
                 logger.info("Updating current state for %s", room_id)
                 assert (
-                    self.storage.persistence is not None
+                    self._storage_controllers.persistence is not None
                 ), "TODO(faster_joins): support for workers"
-                await self.storage.persistence.update_current_state(room_id)
+                await self._storage_controllers.persistence.update_current_state(
+                    room_id
+                )
 
                 logger.info("Clearing partial-state flag for %s", room_id)
                 success = await self.store.clear_partial_state_room(room_id)
diff --git a/synapse/handlers/federation_event.py b/synapse/handlers/federation_event.py
index a1361af272..b908674529 100644
--- a/synapse/handlers/federation_event.py
+++ b/synapse/handlers/federation_event.py
@@ -98,8 +98,8 @@ class FederationEventHandler:
 
     def __init__(self, hs: "HomeServer"):
         self._store = hs.get_datastores().main
-        self._storage = hs.get_storage()
-        self._state_storage = self._storage.state
+        self._storage_controllers = hs.get_storage_controllers()
+        self._state_storage_controller = self._storage_controllers.state
 
         self._state_handler = hs.get_state_handler()
         self._event_creation_handler = hs.get_event_creation_handler()
@@ -535,7 +535,9 @@ class FederationEventHandler:
                 )
                 return
             await self._store.update_state_for_partial_state_event(event, context)
-            self._state_storage.notify_event_un_partial_stated(event.event_id)
+            self._state_storage_controller.notify_event_un_partial_stated(
+                event.event_id
+            )
 
     async def backfill(
         self, dest: str, room_id: str, limit: int, extremities: Collection[str]
@@ -835,7 +837,9 @@ class FederationEventHandler:
 
         try:
             # Get the state of the events we know about
-            ours = await self._state_storage.get_state_groups_ids(room_id, seen)
+            ours = await self._state_storage_controller.get_state_groups_ids(
+                room_id, seen
+            )
 
             # state_maps is a list of mappings from (type, state_key) to event_id
             state_maps: List[StateMap[str]] = list(ours.values())
@@ -1436,7 +1440,7 @@ class FederationEventHandler:
                 # we're not bothering about room state, so flag the event as an outlier.
                 event.internal_metadata.outlier = True
 
-                context = EventContext.for_outlier(self._storage)
+                context = EventContext.for_outlier(self._storage_controllers)
                 try:
                     validate_event_for_room_version(room_version_obj, event)
                     check_auth_rules_for_event(room_version_obj, event, auth)
@@ -1613,7 +1617,7 @@ class FederationEventHandler:
             # given state at the event. This should correctly handle cases
             # like bans, especially with state res v2.
 
-            state_sets_d = await self._state_storage.get_state_groups_ids(
+            state_sets_d = await self._state_storage_controller.get_state_groups_ids(
                 event.room_id, extrem_ids
             )
             state_sets: List[StateMap[str]] = list(state_sets_d.values())
@@ -1885,7 +1889,7 @@ class FederationEventHandler:
 
         # create a new state group as a delta from the existing one.
         prev_group = context.state_group
-        state_group = await self._state_storage.store_state_group(
+        state_group = await self._state_storage_controller.store_state_group(
             event.event_id,
             event.room_id,
             prev_group=prev_group,
@@ -1894,7 +1898,7 @@ class FederationEventHandler:
         )
 
         return EventContext.with_state(
-            storage=self._storage,
+            storage=self._storage_controllers,
             state_group=state_group,
             state_group_before_event=context.state_group_before_event,
             state_delta_due_to_event=state_updates,
@@ -1984,11 +1988,14 @@ class FederationEventHandler:
                 )
             return result["max_stream_id"]
         else:
-            assert self._storage.persistence
+            assert self._storage_controllers.persistence
 
             # Note that this returns the events that were persisted, which may not be
             # the same as were passed in if some were deduplicated due to transaction IDs.
-            events, max_stream_token = await self._storage.persistence.persist_events(
+            (
+                events,
+                max_stream_token,
+            ) = await self._storage_controllers.persistence.persist_events(
                 event_and_contexts, backfilled=backfilled
             )
 
diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index fbdbeeedfd..d2b489e816 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -67,8 +67,8 @@ class InitialSyncHandler:
             ]
         ] = ResponseCache(hs.get_clock(), "initial_sync_cache")
         self._event_serializer = hs.get_event_client_serializer()
-        self.storage = hs.get_storage()
-        self.state_storage = self.storage.state
+        self._storage_controllers = hs.get_storage_controllers()
+        self._state_storage_controller = self._storage_controllers.state
 
     async def snapshot_all_rooms(
         self,
@@ -198,7 +198,8 @@ class InitialSyncHandler:
                         event.stream_ordering,
                     )
                     deferred_room_state = run_in_background(
-                        self.state_storage.get_state_for_events, [event.event_id]
+                        self._state_storage_controller.get_state_for_events,
+                        [event.event_id],
                     ).addCallback(
                         lambda states: cast(StateMap[EventBase], states[event.event_id])
                     )
@@ -218,7 +219,7 @@ class InitialSyncHandler:
                 ).addErrback(unwrapFirstError)
 
                 messages = await filter_events_for_client(
-                    self.storage, user_id, messages
+                    self._storage_controllers, user_id, messages
                 )
 
                 start_token = now_token.copy_and_replace(StreamKeyType.ROOM, token)
@@ -355,7 +356,9 @@ class InitialSyncHandler:
         member_event_id: str,
         is_peeking: bool,
     ) -> JsonDict:
-        room_state = await self.state_storage.get_state_for_event(member_event_id)
+        room_state = await self._state_storage_controller.get_state_for_event(
+            member_event_id
+        )
 
         limit = pagin_config.limit if pagin_config else None
         if limit is None:
@@ -369,7 +372,7 @@ class InitialSyncHandler:
         )
 
         messages = await filter_events_for_client(
-            self.storage, user_id, messages, is_peeking=is_peeking
+            self._storage_controllers, user_id, messages, is_peeking=is_peeking
         )
 
         start_token = StreamToken.START.copy_and_replace(StreamKeyType.ROOM, token)
@@ -474,7 +477,7 @@ class InitialSyncHandler:
         )
 
         messages = await filter_events_for_client(
-            self.storage, user_id, messages, is_peeking=is_peeking
+            self._storage_controllers, user_id, messages, is_peeking=is_peeking
         )
 
         start_token = now_token.copy_and_replace(StreamKeyType.ROOM, token)
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 38b71a2c96..f377769071 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -84,8 +84,8 @@ class MessageHandler:
         self.clock = hs.get_clock()
         self.state = hs.get_state_handler()
         self.store = hs.get_datastores().main
-        self.storage = hs.get_storage()
-        self.state_storage = self.storage.state
+        self._storage_controllers = hs.get_storage_controllers()
+        self._state_storage_controller = self._storage_controllers.state
         self._event_serializer = hs.get_event_client_serializer()
         self._ephemeral_events_enabled = hs.config.server.enable_ephemeral_messages
 
@@ -132,7 +132,7 @@ class MessageHandler:
             assert (
                 membership_event_id is not None
             ), "check_user_in_room_or_world_readable returned invalid data"
-            room_state = await self.state_storage.get_state_for_events(
+            room_state = await self._state_storage_controller.get_state_for_events(
                 [membership_event_id], StateFilter.from_types([key])
             )
             data = room_state[membership_event_id].get(key)
@@ -193,7 +193,7 @@ class MessageHandler:
 
             # check whether the user is in the room at that time to determine
             # whether they should be treated as peeking.
-            state_map = await self.state_storage.get_state_for_event(
+            state_map = await self._state_storage_controller.get_state_for_event(
                 last_event.event_id,
                 StateFilter.from_types([(EventTypes.Member, user_id)]),
             )
@@ -206,7 +206,7 @@ class MessageHandler:
             is_peeking = not joined
 
             visible_events = await filter_events_for_client(
-                self.storage,
+                self._storage_controllers,
                 user_id,
                 [last_event],
                 filter_send_to_client=False,
@@ -214,8 +214,10 @@ class MessageHandler:
             )
 
             if visible_events:
-                room_state_events = await self.state_storage.get_state_for_events(
-                    [last_event.event_id], state_filter=state_filter
+                room_state_events = (
+                    await self._state_storage_controller.get_state_for_events(
+                        [last_event.event_id], state_filter=state_filter
+                    )
                 )
                 room_state: Mapping[Any, EventBase] = room_state_events[
                     last_event.event_id
@@ -244,8 +246,10 @@ class MessageHandler:
                 assert (
                     membership_event_id is not None
                 ), "check_user_in_room_or_world_readable returned invalid data"
-                room_state_events = await self.state_storage.get_state_for_events(
-                    [membership_event_id], state_filter=state_filter
+                room_state_events = (
+                    await self._state_storage_controller.get_state_for_events(
+                        [membership_event_id], state_filter=state_filter
+                    )
                 )
                 room_state = room_state_events[membership_event_id]
 
@@ -402,7 +406,7 @@ class EventCreationHandler:
         self.auth = hs.get_auth()
         self._event_auth_handler = hs.get_event_auth_handler()
         self.store = hs.get_datastores().main
-        self.storage = hs.get_storage()
+        self._storage_controllers = hs.get_storage_controllers()
         self.state = hs.get_state_handler()
         self.clock = hs.get_clock()
         self.validator = EventValidator()
@@ -1032,7 +1036,7 @@ class EventCreationHandler:
         # after it is created
         if builder.internal_metadata.outlier:
             event.internal_metadata.outlier = True
-            context = EventContext.for_outlier(self.storage)
+            context = EventContext.for_outlier(self._storage_controllers)
         elif (
             event.type == EventTypes.MSC2716_INSERTION
             and state_event_ids
@@ -1445,7 +1449,7 @@ class EventCreationHandler:
         """
         extra_users = extra_users or []
 
-        assert self.storage.persistence is not None
+        assert self._storage_controllers.persistence is not None
         assert self._events_shard_config.should_handle(
             self._instance_name, event.room_id
         )
@@ -1679,7 +1683,7 @@ class EventCreationHandler:
             event,
             event_pos,
             max_stream_token,
-        ) = await self.storage.persistence.persist_event(
+        ) = await self._storage_controllers.persistence.persist_event(
             event, context=context, backfilled=backfilled
         )
 
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index 35afe6b855..6262a35822 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -129,8 +129,8 @@ class PaginationHandler:
         self.hs = hs
         self.auth = hs.get_auth()
         self.store = hs.get_datastores().main
-        self.storage = hs.get_storage()
-        self.state_storage = self.storage.state
+        self._storage_controllers = hs.get_storage_controllers()
+        self._state_storage_controller = self._storage_controllers.state
         self.clock = hs.get_clock()
         self._server_name = hs.hostname
         self._room_shutdown_handler = hs.get_room_shutdown_handler()
@@ -352,7 +352,7 @@ class PaginationHandler:
         self._purges_in_progress_by_room.add(room_id)
         try:
             async with self.pagination_lock.write(room_id):
-                await self.storage.purge_events.purge_history(
+                await self._storage_controllers.purge_events.purge_history(
                     room_id, token, delete_local_events
                 )
             logger.info("[purge] complete")
@@ -414,7 +414,7 @@ class PaginationHandler:
                 if joined:
                     raise SynapseError(400, "Users are still joined to this room")
 
-            await self.storage.purge_events.purge_room(room_id)
+            await self._storage_controllers.purge_events.purge_room(room_id)
 
     async def get_messages(
         self,
@@ -529,7 +529,10 @@ class PaginationHandler:
             events = await event_filter.filter(events)
 
         events = await filter_events_for_client(
-            self.storage, user_id, events, is_peeking=(member_event_id is None)
+            self._storage_controllers,
+            user_id,
+            events,
+            is_peeking=(member_event_id is None),
         )
 
         # if after the filter applied there are no more events
@@ -550,7 +553,7 @@ class PaginationHandler:
                 (EventTypes.Member, event.sender) for event in events
             )
 
-            state_ids = await self.state_storage.get_state_ids_for_event(
+            state_ids = await self._state_storage_controller.get_state_ids_for_event(
                 events[0].event_id, state_filter=state_filter
             )
 
@@ -664,7 +667,7 @@ class PaginationHandler:
                                 400, "Users are still joined to this room"
                             )
 
-                    await self.storage.purge_events.purge_room(room_id)
+                    await self._storage_controllers.purge_events.purge_room(room_id)
 
             logger.info("complete")
             self._delete_by_id[delete_id].status = DeleteStatus.STATUS_COMPLETE
diff --git a/synapse/handlers/relations.py b/synapse/handlers/relations.py
index ab7e54857d..9a1cc11bb3 100644
--- a/synapse/handlers/relations.py
+++ b/synapse/handlers/relations.py
@@ -69,7 +69,7 @@ class BundledAggregations:
 class RelationsHandler:
     def __init__(self, hs: "HomeServer"):
         self._main_store = hs.get_datastores().main
-        self._storage = hs.get_storage()
+        self._storage_controllers = hs.get_storage_controllers()
         self._auth = hs.get_auth()
         self._clock = hs.get_clock()
         self._event_handler = hs.get_event_handler()
@@ -143,7 +143,10 @@ class RelationsHandler:
         )
 
         events = await filter_events_for_client(
-            self._storage, user_id, events, is_peeking=(member_event_id is None)
+            self._storage_controllers,
+            user_id,
+            events,
+            is_peeking=(member_event_id is None),
         )
 
         now = self._clock.time_msec()
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index e2775b34f1..5c91d33f58 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -1192,8 +1192,8 @@ class RoomContextHandler:
         self.hs = hs
         self.auth = hs.get_auth()
         self.store = hs.get_datastores().main
-        self.storage = hs.get_storage()
-        self.state_storage = self.storage.state
+        self._storage_controllers = hs.get_storage_controllers()
+        self._state_storage_controller = self._storage_controllers.state
         self._relations_handler = hs.get_relations_handler()
 
     async def get_event_context(
@@ -1236,7 +1236,10 @@ class RoomContextHandler:
             if use_admin_priviledge:
                 return events
             return await filter_events_for_client(
-                self.storage, user.to_string(), events, is_peeking=is_peeking
+                self._storage_controllers,
+                user.to_string(),
+                events,
+                is_peeking=is_peeking,
             )
 
         event = await self.store.get_event(
@@ -1293,7 +1296,7 @@ class RoomContextHandler:
         # first? Shouldn't we be consistent with /sync?
         # https://github.com/matrix-org/matrix-doc/issues/687
 
-        state = await self.state_storage.get_state_for_events(
+        state = await self._state_storage_controller.get_state_for_events(
             [last_event_id], state_filter=state_filter
         )
 
diff --git a/synapse/handlers/room_batch.py b/synapse/handlers/room_batch.py
index 7ce32f2e9c..1414e575d6 100644
--- a/synapse/handlers/room_batch.py
+++ b/synapse/handlers/room_batch.py
@@ -17,7 +17,7 @@ class RoomBatchHandler:
     def __init__(self, hs: "HomeServer"):
         self.hs = hs
         self.store = hs.get_datastores().main
-        self.state_storage = hs.get_storage().state
+        self._state_storage_controller = hs.get_storage_controllers().state
         self.event_creation_handler = hs.get_event_creation_handler()
         self.room_member_handler = hs.get_room_member_handler()
         self.auth = hs.get_auth()
@@ -141,7 +141,7 @@ class RoomBatchHandler:
         ) = await self.store.get_max_depth_of(event_ids)
         # mapping from (type, state_key) -> state_event_id
         assert most_recent_event_id is not None
-        prev_state_map = await self.state_storage.get_state_ids_for_event(
+        prev_state_map = await self._state_storage_controller.get_state_ids_for_event(
             most_recent_event_id
         )
         # List of state event ID's
diff --git a/synapse/handlers/search.py b/synapse/handlers/search.py
index e02c915248..659f99f7e2 100644
--- a/synapse/handlers/search.py
+++ b/synapse/handlers/search.py
@@ -55,8 +55,8 @@ class SearchHandler:
         self.hs = hs
         self._event_serializer = hs.get_event_client_serializer()
         self._relations_handler = hs.get_relations_handler()
-        self.storage = hs.get_storage()
-        self.state_storage = self.storage.state
+        self._storage_controllers = hs.get_storage_controllers()
+        self._state_storage_controller = self._storage_controllers.state
         self.auth = hs.get_auth()
 
     async def get_old_rooms_from_upgraded_room(self, room_id: str) -> Iterable[str]:
@@ -460,7 +460,7 @@ class SearchHandler:
         filtered_events = await search_filter.filter([r["event"] for r in results])
 
         events = await filter_events_for_client(
-            self.storage, user.to_string(), filtered_events
+            self._storage_controllers, user.to_string(), filtered_events
         )
 
         events.sort(key=lambda e: -rank_map[e.event_id])
@@ -559,7 +559,7 @@ class SearchHandler:
             filtered_events = await search_filter.filter([r["event"] for r in results])
 
             events = await filter_events_for_client(
-                self.storage, user.to_string(), filtered_events
+                self._storage_controllers, user.to_string(), filtered_events
             )
 
             room_events.extend(events)
@@ -644,11 +644,11 @@ class SearchHandler:
             )
 
             events_before = await filter_events_for_client(
-                self.storage, user.to_string(), res.events_before
+                self._storage_controllers, user.to_string(), res.events_before
             )
 
             events_after = await filter_events_for_client(
-                self.storage, user.to_string(), res.events_after
+                self._storage_controllers, user.to_string(), res.events_after
             )
 
             context: JsonDict = {
@@ -677,7 +677,7 @@ class SearchHandler:
                     [(EventTypes.Member, sender) for sender in senders]
                 )
 
-                state = await self.state_storage.get_state_for_event(
+                state = await self._state_storage_controller.get_state_for_event(
                     last_event_id, state_filter
                 )
 
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index c5c538e0c3..b5859dcb28 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -238,8 +238,8 @@ class SyncHandler:
         self.clock = hs.get_clock()
         self.state = hs.get_state_handler()
         self.auth = hs.get_auth()
-        self.storage = hs.get_storage()
-        self.state_storage = self.storage.state
+        self._storage_controllers = hs.get_storage_controllers()
+        self._state_storage_controller = self._storage_controllers.state
 
         # TODO: flush cache entries on subsequent sync request.
         #    Once we get the next /sync request (ie, one with the same access token
@@ -512,7 +512,7 @@ class SyncHandler:
                     current_state_ids = frozenset(current_state_ids_map.values())
 
                 recents = await filter_events_for_client(
-                    self.storage,
+                    self._storage_controllers,
                     sync_config.user.to_string(),
                     recents,
                     always_include_ids=current_state_ids,
@@ -580,7 +580,7 @@ class SyncHandler:
                     current_state_ids = frozenset(current_state_ids_map.values())
 
                 loaded_recents = await filter_events_for_client(
-                    self.storage,
+                    self._storage_controllers,
                     sync_config.user.to_string(),
                     loaded_recents,
                     always_include_ids=current_state_ids,
@@ -630,7 +630,7 @@ class SyncHandler:
             event: event of interest
             state_filter: The state filter used to fetch state from the database.
         """
-        state_ids = await self.state_storage.get_state_ids_for_event(
+        state_ids = await self._state_storage_controller.get_state_ids_for_event(
             event.event_id, state_filter=state_filter or StateFilter.all()
         )
         if event.is_state():
@@ -710,7 +710,7 @@ class SyncHandler:
             return None
 
         last_event = last_events[-1]
-        state_ids = await self.state_storage.get_state_ids_for_event(
+        state_ids = await self._state_storage_controller.get_state_ids_for_event(
             last_event.event_id,
             state_filter=StateFilter.from_types(
                 [(EventTypes.Name, ""), (EventTypes.CanonicalAlias, "")]
@@ -889,13 +889,15 @@ class SyncHandler:
             if full_state:
                 if batch:
                     current_state_ids = (
-                        await self.state_storage.get_state_ids_for_event(
+                        await self._state_storage_controller.get_state_ids_for_event(
                             batch.events[-1].event_id, state_filter=state_filter
                         )
                     )
 
-                    state_ids = await self.state_storage.get_state_ids_for_event(
-                        batch.events[0].event_id, state_filter=state_filter
+                    state_ids = (
+                        await self._state_storage_controller.get_state_ids_for_event(
+                            batch.events[0].event_id, state_filter=state_filter
+                        )
                     )
 
                 else:
@@ -915,7 +917,7 @@ class SyncHandler:
             elif batch.limited:
                 if batch:
                     state_at_timeline_start = (
-                        await self.state_storage.get_state_ids_for_event(
+                        await self._state_storage_controller.get_state_ids_for_event(
                             batch.events[0].event_id, state_filter=state_filter
                         )
                     )
@@ -950,7 +952,7 @@ class SyncHandler:
 
                 if batch:
                     current_state_ids = (
-                        await self.state_storage.get_state_ids_for_event(
+                        await self._state_storage_controller.get_state_ids_for_event(
                             batch.events[-1].event_id, state_filter=state_filter
                         )
                     )
@@ -982,7 +984,7 @@ class SyncHandler:
                         # So we fish out all the member events corresponding to the
                         # timeline here, and then dedupe any redundant ones below.
 
-                        state_ids = await self.state_storage.get_state_ids_for_event(
+                        state_ids = await self._state_storage_controller.get_state_ids_for_event(
                             batch.events[0].event_id,
                             # we only want members!
                             state_filter=StateFilter.from_types(
diff --git a/synapse/notifier.py b/synapse/notifier.py
index c2b66eec62..1100434b3f 100644
--- a/synapse/notifier.py
+++ b/synapse/notifier.py
@@ -221,7 +221,7 @@ class Notifier:
         self.room_to_user_streams: Dict[str, Set[_NotifierUserStream]] = {}
 
         self.hs = hs
-        self.storage = hs.get_storage()
+        self._storage_controllers = hs.get_storage_controllers()
         self.event_sources = hs.get_event_sources()
         self.store = hs.get_datastores().main
         self.pending_new_room_events: List[_PendingRoomEventEntry] = []
@@ -623,7 +623,7 @@ class Notifier:
 
                 if name == "room":
                     new_events = await filter_events_for_client(
-                        self.storage,
+                        self._storage_controllers,
                         user.to_string(),
                         new_events,
                         is_peeking=is_peeking,
diff --git a/synapse/push/httppusher.py b/synapse/push/httppusher.py
index d5603596c0..e96fb45e9f 100644
--- a/synapse/push/httppusher.py
+++ b/synapse/push/httppusher.py
@@ -65,7 +65,7 @@ class HttpPusher(Pusher):
 
     def __init__(self, hs: "HomeServer", pusher_config: PusherConfig):
         super().__init__(hs, pusher_config)
-        self.storage = self.hs.get_storage()
+        self._storage_controllers = self.hs.get_storage_controllers()
         self.app_display_name = pusher_config.app_display_name
         self.device_display_name = pusher_config.device_display_name
         self.pushkey_ts = pusher_config.ts
@@ -343,7 +343,9 @@ class HttpPusher(Pusher):
             }
             return d
 
-        ctx = await push_tools.get_context_for_event(self.storage, event, self.user_id)
+        ctx = await push_tools.get_context_for_event(
+            self._storage_controllers, event, self.user_id
+        )
 
         d = {
             "notification": {
diff --git a/synapse/push/mailer.py b/synapse/push/mailer.py
index 84124af965..63aefd07f5 100644
--- a/synapse/push/mailer.py
+++ b/synapse/push/mailer.py
@@ -114,10 +114,10 @@ class Mailer:
 
         self.send_email_handler = hs.get_send_email_handler()
         self.store = self.hs.get_datastores().main
-        self.state_storage = self.hs.get_storage().state
+        self._state_storage_controller = self.hs.get_storage_controllers().state
         self.macaroon_gen = self.hs.get_macaroon_generator()
         self.state_handler = self.hs.get_state_handler()
-        self.storage = hs.get_storage()
+        self._storage_controllers = hs.get_storage_controllers()
         self.app_name = app_name
         self.email_subjects: EmailSubjectConfig = hs.config.email.email_subjects
 
@@ -456,7 +456,7 @@ class Mailer:
         }
 
         the_events = await filter_events_for_client(
-            self.storage, user_id, results.events_before
+            self._storage_controllers, user_id, results.events_before
         )
         the_events.append(notif_event)
 
@@ -494,7 +494,7 @@ class Mailer:
             )
         else:
             # Attempt to check the historical state for the room.
-            historical_state = await self.state_storage.get_state_for_event(
+            historical_state = await self._state_storage_controller.get_state_for_event(
                 event.event_id, StateFilter.from_types((type_state_key,))
             )
             sender_state_event = historical_state.get(type_state_key)
@@ -767,8 +767,10 @@ class Mailer:
                 member_event_ids.append(sender_state_event_id)
             else:
                 # Attempt to check the historical state for the room.
-                historical_state = await self.state_storage.get_state_for_event(
-                    event_id, StateFilter.from_types((type_state_key,))
+                historical_state = (
+                    await self._state_storage_controller.get_state_for_event(
+                        event_id, StateFilter.from_types((type_state_key,))
+                    )
                 )
                 sender_state_event = historical_state.get(type_state_key)
                 if sender_state_event:
diff --git a/synapse/push/push_tools.py b/synapse/push/push_tools.py
index a1bf5b20dd..8397229ccb 100644
--- a/synapse/push/push_tools.py
+++ b/synapse/push/push_tools.py
@@ -16,7 +16,7 @@ from typing import Dict
 from synapse.api.constants import ReceiptTypes
 from synapse.events import EventBase
 from synapse.push.presentable_names import calculate_room_name, name_from_member_event
-from synapse.storage import Storage
+from synapse.storage.controllers import StorageControllers
 from synapse.storage.databases.main import DataStore
 
 
@@ -52,7 +52,7 @@ async def get_badge_count(store: DataStore, user_id: str, group_by_room: bool) -
 
 
 async def get_context_for_event(
-    storage: Storage, ev: EventBase, user_id: str
+    storage: StorageControllers, ev: EventBase, user_id: str
 ) -> Dict[str, str]:
     ctx = {}
 
diff --git a/synapse/replication/http/federation.py b/synapse/replication/http/federation.py
index 3e7300b4a1..eed29cd597 100644
--- a/synapse/replication/http/federation.py
+++ b/synapse/replication/http/federation.py
@@ -69,7 +69,7 @@ class ReplicationFederationSendEventsRestServlet(ReplicationEndpoint):
         super().__init__(hs)
 
         self.store = hs.get_datastores().main
-        self.storage = hs.get_storage()
+        self._storage_controllers = hs.get_storage_controllers()
         self.clock = hs.get_clock()
         self.federation_event_handler = hs.get_federation_event_handler()
 
@@ -133,7 +133,7 @@ class ReplicationFederationSendEventsRestServlet(ReplicationEndpoint):
                 event.internal_metadata.outlier = event_payload["outlier"]
 
                 context = EventContext.deserialize(
-                    self.storage, event_payload["context"]
+                    self._storage_controllers, event_payload["context"]
                 )
 
                 event_and_contexts.append((event, context))
diff --git a/synapse/replication/http/send_event.py b/synapse/replication/http/send_event.py
index ce78176836..c2b2588ea5 100644
--- a/synapse/replication/http/send_event.py
+++ b/synapse/replication/http/send_event.py
@@ -70,7 +70,7 @@ class ReplicationSendEventRestServlet(ReplicationEndpoint):
 
         self.event_creation_handler = hs.get_event_creation_handler()
         self.store = hs.get_datastores().main
-        self.storage = hs.get_storage()
+        self._storage_controllers = hs.get_storage_controllers()
         self.clock = hs.get_clock()
 
     @staticmethod
@@ -127,7 +127,9 @@ class ReplicationSendEventRestServlet(ReplicationEndpoint):
             event.internal_metadata.outlier = content["outlier"]
 
             requester = Requester.deserialize(self.store, content["requester"])
-            context = EventContext.deserialize(self.storage, content["context"])
+            context = EventContext.deserialize(
+                self._storage_controllers, content["context"]
+            )
 
             ratelimit = content["ratelimit"]
             extra_users = [UserID.from_string(u) for u in content["extra_users"]]
diff --git a/synapse/server.py b/synapse/server.py
index 3fd23aaf52..a66ec228db 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -123,7 +123,8 @@ from synapse.server_notices.worker_server_notices_sender import (
     WorkerServerNoticesSender,
 )
 from synapse.state import StateHandler, StateResolutionHandler
-from synapse.storage import Databases, Storage
+from synapse.storage import Databases
+from synapse.storage.controllers import StorageControllers
 from synapse.streams.events import EventSources
 from synapse.types import DomainSpecificString, ISynapseReactor
 from synapse.util import Clock
@@ -729,8 +730,8 @@ class HomeServer(metaclass=abc.ABCMeta):
         return PasswordPolicyHandler(self)
 
     @cache_in_self
-    def get_storage(self) -> Storage:
-        return Storage(self, self.get_datastores())
+    def get_storage_controllers(self) -> StorageControllers:
+        return StorageControllers(self, self.get_datastores())
 
     @cache_in_self
     def get_replication_streamer(self) -> ReplicationStreamer:
diff --git a/synapse/state/__init__.py b/synapse/state/__init__.py
index 9c9d946f38..bf09f5128a 100644
--- a/synapse/state/__init__.py
+++ b/synapse/state/__init__.py
@@ -127,10 +127,10 @@ class StateHandler:
     def __init__(self, hs: "HomeServer"):
         self.clock = hs.get_clock()
         self.store = hs.get_datastores().main
-        self.state_storage = hs.get_storage().state
+        self._state_storage_controller = hs.get_storage_controllers().state
         self.hs = hs
         self._state_resolution_handler = hs.get_state_resolution_handler()
-        self._storage = hs.get_storage()
+        self._storage_controllers = hs.get_storage_controllers()
 
     @overload
     async def get_current_state(
@@ -337,12 +337,14 @@ class StateHandler:
         #
 
         if not state_group_before_event:
-            state_group_before_event = await self.state_storage.store_state_group(
-                event.event_id,
-                event.room_id,
-                prev_group=state_group_before_event_prev_group,
-                delta_ids=deltas_to_state_group_before_event,
-                current_state_ids=state_ids_before_event,
+            state_group_before_event = (
+                await self._state_storage_controller.store_state_group(
+                    event.event_id,
+                    event.room_id,
+                    prev_group=state_group_before_event_prev_group,
+                    delta_ids=deltas_to_state_group_before_event,
+                    current_state_ids=state_ids_before_event,
+                )
             )
 
             # Assign the new state group to the cached state entry.
@@ -359,7 +361,7 @@ class StateHandler:
 
         if not event.is_state():
             return EventContext.with_state(
-                storage=self._storage,
+                storage=self._storage_controllers,
                 state_group_before_event=state_group_before_event,
                 state_group=state_group_before_event,
                 state_delta_due_to_event={},
@@ -382,16 +384,18 @@ class StateHandler:
         state_ids_after_event[key] = event.event_id
         delta_ids = {key: event.event_id}
 
-        state_group_after_event = await self.state_storage.store_state_group(
-            event.event_id,
-            event.room_id,
-            prev_group=state_group_before_event,
-            delta_ids=delta_ids,
-            current_state_ids=state_ids_after_event,
+        state_group_after_event = (
+            await self._state_storage_controller.store_state_group(
+                event.event_id,
+                event.room_id,
+                prev_group=state_group_before_event,
+                delta_ids=delta_ids,
+                current_state_ids=state_ids_after_event,
+            )
         )
 
         return EventContext.with_state(
-            storage=self._storage,
+            storage=self._storage_controllers,
             state_group=state_group_after_event,
             state_group_before_event=state_group_before_event,
             state_delta_due_to_event=delta_ids,
@@ -416,7 +420,9 @@ class StateHandler:
         """
         logger.debug("resolve_state_groups event_ids %s", event_ids)
 
-        state_groups = await self.state_storage.get_state_group_for_events(event_ids)
+        state_groups = await self._state_storage_controller.get_state_group_for_events(
+            event_ids
+        )
 
         state_group_ids = state_groups.values()
 
@@ -424,8 +430,13 @@ class StateHandler:
         state_group_ids_set = set(state_group_ids)
         if len(state_group_ids_set) == 1:
             (state_group_id,) = state_group_ids_set
-            state = await self.state_storage.get_state_for_groups(state_group_ids_set)
-            prev_group, delta_ids = await self.state_storage.get_state_group_delta(
+            state = await self._state_storage_controller.get_state_for_groups(
+                state_group_ids_set
+            )
+            (
+                prev_group,
+                delta_ids,
+            ) = await self._state_storage_controller.get_state_group_delta(
                 state_group_id
             )
             return _StateCacheEntry(
@@ -439,7 +450,7 @@ class StateHandler:
 
         room_version = await self.store.get_room_version_id(room_id)
 
-        state_to_resolve = await self.state_storage.get_state_for_groups(
+        state_to_resolve = await self._state_storage_controller.get_state_for_groups(
             state_group_ids_set
         )
 
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index 105e4e1fec..bac21ecf9c 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -18,41 +18,20 @@ The storage layer is split up into multiple parts to allow Synapse to run
 against different configurations of databases (e.g. single or multiple
 databases). The `DatabasePool` class represents connections to a single physical
 database. The `databases` are classes that talk directly to a `DatabasePool`
-instance and have associated schemas, background updates, etc. On top of those
-there are classes that provide high level interfaces that combine calls to
-multiple `databases`.
+instance and have associated schemas, background updates, etc.
+
+On top of the databases are the StorageControllers, located in the
+`synapse.storage.controllers` module. These classes provide high level
+interfaces that combine calls to multiple `databases`. They are bundled into the
+`StorageControllers` singleton for ease of use, and exposed via
+`HomeServer.get_storage_controllers()`.
 
 There are also schemas that get applied to every database, regardless of the
 data stores associated with them (e.g. the schema version tables), which are
 stored in `synapse.storage.schema`.
 """
-from typing import TYPE_CHECKING
 
 from synapse.storage.databases import Databases
 from synapse.storage.databases.main import DataStore
-from synapse.storage.persist_events import EventsPersistenceStorage
-from synapse.storage.purge_events import PurgeEventsStorage
-from synapse.storage.state import StateGroupStorage
-
-if TYPE_CHECKING:
-    from synapse.server import HomeServer
-
 
 __all__ = ["Databases", "DataStore"]
-
-
-class Storage:
-    """The high level interfaces for talking to various storage layers."""
-
-    def __init__(self, hs: "HomeServer", stores: Databases):
-        # We include the main data store here mainly so that we don't have to
-        # rewrite all the existing code to split it into high vs low level
-        # interfaces.
-        self.main = stores.main
-
-        self.purge_events = PurgeEventsStorage(hs, stores)
-        self.state = StateGroupStorage(hs, stores)
-
-        self.persistence = None
-        if stores.persist_events:
-            self.persistence = EventsPersistenceStorage(hs, stores)
diff --git a/synapse/storage/controllers/__init__.py b/synapse/storage/controllers/__init__.py
new file mode 100644
index 0000000000..992261d07b
--- /dev/null
+++ b/synapse/storage/controllers/__init__.py
@@ -0,0 +1,46 @@
+# Copyright 2022 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import TYPE_CHECKING
+
+from synapse.storage.controllers.persist_events import (
+    EventsPersistenceStorageController,
+)
+from synapse.storage.controllers.purge_events import PurgeEventsStorageController
+from synapse.storage.controllers.state import StateGroupStorageController
+from synapse.storage.databases import Databases
+from synapse.storage.databases.main import DataStore
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
+
+__all__ = ["Databases", "DataStore"]
+
+
+class StorageControllers:
+    """The high level interfaces for talking to various storage controller layers."""
+
+    def __init__(self, hs: "HomeServer", stores: Databases):
+        # We include the main data store here mainly so that we don't have to
+        # rewrite all the existing code to split it into high vs low level
+        # interfaces.
+        self.main = stores.main
+
+        self.purge_events = PurgeEventsStorageController(hs, stores)
+        self.state = StateGroupStorageController(hs, stores)
+
+        self.persistence = None
+        if stores.persist_events:
+            self.persistence = EventsPersistenceStorageController(hs, stores)
diff --git a/synapse/storage/persist_events.py b/synapse/storage/controllers/persist_events.py
index a21dea91c8..ef8c135b12 100644
--- a/synapse/storage/persist_events.py
+++ b/synapse/storage/controllers/persist_events.py
@@ -272,7 +272,7 @@ class _EventPeristenceQueue(Generic[_PersistResult]):
             pass
 
 
-class EventsPersistenceStorage:
+class EventsPersistenceStorageController:
     """High level interface for handling persisting newly received events.
 
     Takes care of batching up events by room, and calculating the necessary
diff --git a/synapse/storage/purge_events.py b/synapse/storage/controllers/purge_events.py
index 30669beb7c..9ca50d6a09 100644
--- a/synapse/storage/purge_events.py
+++ b/synapse/storage/controllers/purge_events.py
@@ -24,7 +24,7 @@ if TYPE_CHECKING:
 logger = logging.getLogger(__name__)
 
 
-class PurgeEventsStorage:
+class PurgeEventsStorageController:
     """High level interface for purging rooms and event history."""
 
     def __init__(self, hs: "HomeServer", stores: Databases):
diff --git a/synapse/storage/controllers/state.py b/synapse/storage/controllers/state.py
new file mode 100644
index 0000000000..0f09953086
--- /dev/null
+++ b/synapse/storage/controllers/state.py
@@ -0,0 +1,351 @@
+# Copyright 2022 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import logging
+from typing import (
+    TYPE_CHECKING,
+    Awaitable,
+    Collection,
+    Dict,
+    Iterable,
+    List,
+    Mapping,
+    Optional,
+    Tuple,
+)
+
+from synapse.events import EventBase
+from synapse.storage.state import StateFilter
+from synapse.storage.util.partial_state_events_tracker import PartialStateEventsTracker
+from synapse.types import MutableStateMap, StateMap
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+    from synapse.storage.databases import Databases
+
+logger = logging.getLogger(__name__)
+
+
+class StateGroupStorageController:
+    """High level interface to fetching state for event."""
+
+    def __init__(self, hs: "HomeServer", stores: "Databases"):
+        self._is_mine_id = hs.is_mine_id
+        self.stores = stores
+        self._partial_state_events_tracker = PartialStateEventsTracker(stores.main)
+
+    def notify_event_un_partial_stated(self, event_id: str) -> None:
+        self._partial_state_events_tracker.notify_un_partial_stated(event_id)
+
+    async def get_state_group_delta(
+        self, state_group: int
+    ) -> Tuple[Optional[int], Optional[StateMap[str]]]:
+        """Given a state group try to return a previous group and a delta between
+        the old and the new.
+
+        Args:
+            state_group: The state group used to retrieve state deltas.
+
+        Returns:
+            A tuple of the previous group and a state map of the event IDs which
+            make up the delta between the old and new state groups.
+        """
+
+        state_group_delta = await self.stores.state.get_state_group_delta(state_group)
+        return state_group_delta.prev_group, state_group_delta.delta_ids
+
+    async def get_state_groups_ids(
+        self, _room_id: str, event_ids: Collection[str]
+    ) -> Dict[int, MutableStateMap[str]]:
+        """Get the event IDs of all the state for the state groups for the given events
+
+        Args:
+            _room_id: id of the room for these events
+            event_ids: ids of the events
+
+        Returns:
+            dict of state_group_id -> (dict of (type, state_key) -> event id)
+
+        Raises:
+            RuntimeError if we don't have a state group for one or more of the events
+               (ie they are outliers or unknown)
+        """
+        if not event_ids:
+            return {}
+
+        event_to_groups = await self.get_state_group_for_events(event_ids)
+
+        groups = set(event_to_groups.values())
+        group_to_state = await self.stores.state._get_state_for_groups(groups)
+
+        return group_to_state
+
+    async def get_state_ids_for_group(
+        self, state_group: int, state_filter: Optional[StateFilter] = None
+    ) -> StateMap[str]:
+        """Get the event IDs of all the state in the given state group
+
+        Args:
+            state_group: A state group for which we want to get the state IDs.
+            state_filter: specifies the type of state event to fetch from DB, example: EventTypes.JoinRules
+
+        Returns:
+            Resolves to a map of (type, state_key) -> event_id
+        """
+        group_to_state = await self.get_state_for_groups((state_group,), state_filter)
+
+        return group_to_state[state_group]
+
+    async def get_state_groups(
+        self, room_id: str, event_ids: Collection[str]
+    ) -> Dict[int, List[EventBase]]:
+        """Get the state groups for the given list of event_ids
+
+        Args:
+            room_id: ID of the room for these events.
+            event_ids: The event IDs to retrieve state for.
+
+        Returns:
+            dict of state_group_id -> list of state events.
+        """
+        if not event_ids:
+            return {}
+
+        group_to_ids = await self.get_state_groups_ids(room_id, event_ids)
+
+        state_event_map = await self.stores.main.get_events(
+            [
+                ev_id
+                for group_ids in group_to_ids.values()
+                for ev_id in group_ids.values()
+            ],
+            get_prev_content=False,
+        )
+
+        return {
+            group: [
+                state_event_map[v]
+                for v in event_id_map.values()
+                if v in state_event_map
+            ]
+            for group, event_id_map in group_to_ids.items()
+        }
+
+    def _get_state_groups_from_groups(
+        self, groups: List[int], state_filter: StateFilter
+    ) -> Awaitable[Dict[int, StateMap[str]]]:
+        """Returns the state groups for a given set of groups, filtering on
+        types of state events.
+
+        Args:
+            groups: list of state group IDs to query
+            state_filter: The state filter used to fetch state
+                from the database.
+
+        Returns:
+            Dict of state group to state map.
+        """
+
+        return self.stores.state._get_state_groups_from_groups(groups, state_filter)
+
+    async def get_state_for_events(
+        self, event_ids: Collection[str], state_filter: Optional[StateFilter] = None
+    ) -> Dict[str, StateMap[EventBase]]:
+        """Given a list of event_ids and type tuples, return a list of state
+        dicts for each event.
+
+        Args:
+            event_ids: The events to fetch the state of.
+            state_filter: The state filter used to fetch state.
+
+        Returns:
+            A dict of (event_id) -> (type, state_key) -> [state_events]
+
+        Raises:
+            RuntimeError if we don't have a state group for one or more of the events
+               (ie they are outliers or unknown)
+        """
+        await_full_state = True
+        if state_filter and not state_filter.must_await_full_state(self._is_mine_id):
+            await_full_state = False
+
+        event_to_groups = await self.get_state_group_for_events(
+            event_ids, await_full_state=await_full_state
+        )
+
+        groups = set(event_to_groups.values())
+        group_to_state = await self.stores.state._get_state_for_groups(
+            groups, state_filter or StateFilter.all()
+        )
+
+        state_event_map = await self.stores.main.get_events(
+            [ev_id for sd in group_to_state.values() for ev_id in sd.values()],
+            get_prev_content=False,
+        )
+
+        event_to_state = {
+            event_id: {
+                k: state_event_map[v]
+                for k, v in group_to_state[group].items()
+                if v in state_event_map
+            }
+            for event_id, group in event_to_groups.items()
+        }
+
+        return {event: event_to_state[event] for event in event_ids}
+
+    async def get_state_ids_for_events(
+        self,
+        event_ids: Collection[str],
+        state_filter: Optional[StateFilter] = None,
+    ) -> Dict[str, StateMap[str]]:
+        """
+        Get the state dicts corresponding to a list of events, containing the event_ids
+        of the state events (as opposed to the events themselves)
+
+        Args:
+            event_ids: events whose state should be returned
+            state_filter: The state filter used to fetch state from the database.
+
+        Returns:
+            A dict from event_id -> (type, state_key) -> event_id
+
+        Raises:
+            RuntimeError if we don't have a state group for one or more of the events
+                (ie they are outliers or unknown)
+        """
+        await_full_state = True
+        if state_filter and not state_filter.must_await_full_state(self._is_mine_id):
+            await_full_state = False
+
+        event_to_groups = await self.get_state_group_for_events(
+            event_ids, await_full_state=await_full_state
+        )
+
+        groups = set(event_to_groups.values())
+        group_to_state = await self.stores.state._get_state_for_groups(
+            groups, state_filter or StateFilter.all()
+        )
+
+        event_to_state = {
+            event_id: group_to_state[group]
+            for event_id, group in event_to_groups.items()
+        }
+
+        return {event: event_to_state[event] for event in event_ids}
+
+    async def get_state_for_event(
+        self, event_id: str, state_filter: Optional[StateFilter] = None
+    ) -> StateMap[EventBase]:
+        """
+        Get the state dict corresponding to a particular event
+
+        Args:
+            event_id: event whose state should be returned
+            state_filter: The state filter used to fetch state from the database.
+
+        Returns:
+            A dict from (type, state_key) -> state_event
+
+        Raises:
+            RuntimeError if we don't have a state group for the event (ie it is an
+                outlier or is unknown)
+        """
+        state_map = await self.get_state_for_events(
+            [event_id], state_filter or StateFilter.all()
+        )
+        return state_map[event_id]
+
+    async def get_state_ids_for_event(
+        self, event_id: str, state_filter: Optional[StateFilter] = None
+    ) -> StateMap[str]:
+        """
+        Get the state dict corresponding to a particular event
+
+        Args:
+            event_id: event whose state should be returned
+            state_filter: The state filter used to fetch state from the database.
+
+        Returns:
+            A dict from (type, state_key) -> state_event_id
+
+        Raises:
+            RuntimeError if we don't have a state group for the event (ie it is an
+                outlier or is unknown)
+        """
+        state_map = await self.get_state_ids_for_events(
+            [event_id], state_filter or StateFilter.all()
+        )
+        return state_map[event_id]
+
+    def get_state_for_groups(
+        self, groups: Iterable[int], state_filter: Optional[StateFilter] = None
+    ) -> Awaitable[Dict[int, MutableStateMap[str]]]:
+        """Gets the state at each of a list of state groups, optionally
+        filtering by type/state_key
+
+        Args:
+            groups: list of state groups for which we want to get the state.
+            state_filter: The state filter used to fetch state.
+                from the database.
+
+        Returns:
+            Dict of state group to state map.
+        """
+        return self.stores.state._get_state_for_groups(
+            groups, state_filter or StateFilter.all()
+        )
+
+    async def get_state_group_for_events(
+        self,
+        event_ids: Collection[str],
+        await_full_state: bool = True,
+    ) -> Mapping[str, int]:
+        """Returns mapping event_id -> state_group
+
+        Args:
+            event_ids: events to get state groups for
+            await_full_state: if true, will block if we do not yet have complete
+               state at these events.
+        """
+        if await_full_state:
+            await self._partial_state_events_tracker.await_full_state(event_ids)
+
+        return await self.stores.main._get_state_group_for_events(event_ids)
+
+    async def store_state_group(
+        self,
+        event_id: str,
+        room_id: str,
+        prev_group: Optional[int],
+        delta_ids: Optional[StateMap[str]],
+        current_state_ids: StateMap[str],
+    ) -> int:
+        """Store a new set of state, returning a newly assigned state group.
+
+        Args:
+            event_id: The event ID for which the state was calculated.
+            room_id: ID of the room for which the state was calculated.
+            prev_group: A previous state group for the room, optional.
+            delta_ids: The delta between state at `prev_group` and
+                `current_state_ids`, if `prev_group` was given. Same format as
+                `current_state_ids`.
+            current_state_ids: The state to store. Map of (type, state_key)
+                to event_id.
+
+        Returns:
+            The state group ID
+        """
+        return await self.stores.state.store_state_group(
+            event_id, room_id, prev_group, delta_ids, current_state_ids
+        )
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index ab630953ac..96aaffb53c 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -15,7 +15,6 @@
 import logging
 from typing import (
     TYPE_CHECKING,
-    Awaitable,
     Callable,
     Collection,
     Dict,
@@ -32,15 +31,11 @@ import attr
 from frozendict import frozendict
 
 from synapse.api.constants import EventTypes
-from synapse.events import EventBase
-from synapse.storage.util.partial_state_events_tracker import PartialStateEventsTracker
 from synapse.types import MutableStateMap, StateKey, StateMap
 
 if TYPE_CHECKING:
     from typing import FrozenSet  # noqa: used within quoted type hint; flake8 sad
 
-    from synapse.server import HomeServer
-    from synapse.storage.databases import Databases
 
 logger = logging.getLogger(__name__)
 
@@ -578,318 +573,3 @@ _ALL_NON_MEMBER_STATE_FILTER = StateFilter(
     types=frozendict({EventTypes.Member: frozenset()}), include_others=True
 )
 _NONE_STATE_FILTER = StateFilter(types=frozendict(), include_others=False)
-
-
-class StateGroupStorage:
-    """High level interface to fetching state for event."""
-
-    def __init__(self, hs: "HomeServer", stores: "Databases"):
-        self._is_mine_id = hs.is_mine_id
-        self.stores = stores
-        self._partial_state_events_tracker = PartialStateEventsTracker(stores.main)
-
-    def notify_event_un_partial_stated(self, event_id: str) -> None:
-        self._partial_state_events_tracker.notify_un_partial_stated(event_id)
-
-    async def get_state_group_delta(
-        self, state_group: int
-    ) -> Tuple[Optional[int], Optional[StateMap[str]]]:
-        """Given a state group try to return a previous group and a delta between
-        the old and the new.
-
-        Args:
-            state_group: The state group used to retrieve state deltas.
-
-        Returns:
-            A tuple of the previous group and a state map of the event IDs which
-            make up the delta between the old and new state groups.
-        """
-
-        state_group_delta = await self.stores.state.get_state_group_delta(state_group)
-        return state_group_delta.prev_group, state_group_delta.delta_ids
-
-    async def get_state_groups_ids(
-        self, _room_id: str, event_ids: Collection[str]
-    ) -> Dict[int, MutableStateMap[str]]:
-        """Get the event IDs of all the state for the state groups for the given events
-
-        Args:
-            _room_id: id of the room for these events
-            event_ids: ids of the events
-
-        Returns:
-            dict of state_group_id -> (dict of (type, state_key) -> event id)
-
-        Raises:
-            RuntimeError if we don't have a state group for one or more of the events
-               (ie they are outliers or unknown)
-        """
-        if not event_ids:
-            return {}
-
-        event_to_groups = await self.get_state_group_for_events(event_ids)
-
-        groups = set(event_to_groups.values())
-        group_to_state = await self.stores.state._get_state_for_groups(groups)
-
-        return group_to_state
-
-    async def get_state_ids_for_group(
-        self, state_group: int, state_filter: Optional[StateFilter] = None
-    ) -> StateMap[str]:
-        """Get the event IDs of all the state in the given state group
-
-        Args:
-            state_group: A state group for which we want to get the state IDs.
-            state_filter: specifies the type of state event to fetch from DB, example: EventTypes.JoinRules
-
-        Returns:
-            Resolves to a map of (type, state_key) -> event_id
-        """
-        group_to_state = await self.get_state_for_groups((state_group,), state_filter)
-
-        return group_to_state[state_group]
-
-    async def get_state_groups(
-        self, room_id: str, event_ids: Collection[str]
-    ) -> Dict[int, List[EventBase]]:
-        """Get the state groups for the given list of event_ids
-
-        Args:
-            room_id: ID of the room for these events.
-            event_ids: The event IDs to retrieve state for.
-
-        Returns:
-            dict of state_group_id -> list of state events.
-        """
-        if not event_ids:
-            return {}
-
-        group_to_ids = await self.get_state_groups_ids(room_id, event_ids)
-
-        state_event_map = await self.stores.main.get_events(
-            [
-                ev_id
-                for group_ids in group_to_ids.values()
-                for ev_id in group_ids.values()
-            ],
-            get_prev_content=False,
-        )
-
-        return {
-            group: [
-                state_event_map[v]
-                for v in event_id_map.values()
-                if v in state_event_map
-            ]
-            for group, event_id_map in group_to_ids.items()
-        }
-
-    def _get_state_groups_from_groups(
-        self, groups: List[int], state_filter: StateFilter
-    ) -> Awaitable[Dict[int, StateMap[str]]]:
-        """Returns the state groups for a given set of groups, filtering on
-        types of state events.
-
-        Args:
-            groups: list of state group IDs to query
-            state_filter: The state filter used to fetch state
-                from the database.
-
-        Returns:
-            Dict of state group to state map.
-        """
-
-        return self.stores.state._get_state_groups_from_groups(groups, state_filter)
-
-    async def get_state_for_events(
-        self, event_ids: Collection[str], state_filter: Optional[StateFilter] = None
-    ) -> Dict[str, StateMap[EventBase]]:
-        """Given a list of event_ids and type tuples, return a list of state
-        dicts for each event.
-
-        Args:
-            event_ids: The events to fetch the state of.
-            state_filter: The state filter used to fetch state.
-
-        Returns:
-            A dict of (event_id) -> (type, state_key) -> [state_events]
-
-        Raises:
-            RuntimeError if we don't have a state group for one or more of the events
-               (ie they are outliers or unknown)
-        """
-        await_full_state = True
-        if state_filter and not state_filter.must_await_full_state(self._is_mine_id):
-            await_full_state = False
-
-        event_to_groups = await self.get_state_group_for_events(
-            event_ids, await_full_state=await_full_state
-        )
-
-        groups = set(event_to_groups.values())
-        group_to_state = await self.stores.state._get_state_for_groups(
-            groups, state_filter or StateFilter.all()
-        )
-
-        state_event_map = await self.stores.main.get_events(
-            [ev_id for sd in group_to_state.values() for ev_id in sd.values()],
-            get_prev_content=False,
-        )
-
-        event_to_state = {
-            event_id: {
-                k: state_event_map[v]
-                for k, v in group_to_state[group].items()
-                if v in state_event_map
-            }
-            for event_id, group in event_to_groups.items()
-        }
-
-        return {event: event_to_state[event] for event in event_ids}
-
-    async def get_state_ids_for_events(
-        self,
-        event_ids: Collection[str],
-        state_filter: Optional[StateFilter] = None,
-    ) -> Dict[str, StateMap[str]]:
-        """
-        Get the state dicts corresponding to a list of events, containing the event_ids
-        of the state events (as opposed to the events themselves)
-
-        Args:
-            event_ids: events whose state should be returned
-            state_filter: The state filter used to fetch state from the database.
-
-        Returns:
-            A dict from event_id -> (type, state_key) -> event_id
-
-        Raises:
-            RuntimeError if we don't have a state group for one or more of the events
-                (ie they are outliers or unknown)
-        """
-        await_full_state = True
-        if state_filter and not state_filter.must_await_full_state(self._is_mine_id):
-            await_full_state = False
-
-        event_to_groups = await self.get_state_group_for_events(
-            event_ids, await_full_state=await_full_state
-        )
-
-        groups = set(event_to_groups.values())
-        group_to_state = await self.stores.state._get_state_for_groups(
-            groups, state_filter or StateFilter.all()
-        )
-
-        event_to_state = {
-            event_id: group_to_state[group]
-            for event_id, group in event_to_groups.items()
-        }
-
-        return {event: event_to_state[event] for event in event_ids}
-
-    async def get_state_for_event(
-        self, event_id: str, state_filter: Optional[StateFilter] = None
-    ) -> StateMap[EventBase]:
-        """
-        Get the state dict corresponding to a particular event
-
-        Args:
-            event_id: event whose state should be returned
-            state_filter: The state filter used to fetch state from the database.
-
-        Returns:
-            A dict from (type, state_key) -> state_event
-
-        Raises:
-            RuntimeError if we don't have a state group for the event (ie it is an
-                outlier or is unknown)
-        """
-        state_map = await self.get_state_for_events(
-            [event_id], state_filter or StateFilter.all()
-        )
-        return state_map[event_id]
-
-    async def get_state_ids_for_event(
-        self, event_id: str, state_filter: Optional[StateFilter] = None
-    ) -> StateMap[str]:
-        """
-        Get the state dict corresponding to a particular event
-
-        Args:
-            event_id: event whose state should be returned
-            state_filter: The state filter used to fetch state from the database.
-
-        Returns:
-            A dict from (type, state_key) -> state_event_id
-
-        Raises:
-            RuntimeError if we don't have a state group for the event (ie it is an
-                outlier or is unknown)
-        """
-        state_map = await self.get_state_ids_for_events(
-            [event_id], state_filter or StateFilter.all()
-        )
-        return state_map[event_id]
-
-    def get_state_for_groups(
-        self, groups: Iterable[int], state_filter: Optional[StateFilter] = None
-    ) -> Awaitable[Dict[int, MutableStateMap[str]]]:
-        """Gets the state at each of a list of state groups, optionally
-        filtering by type/state_key
-
-        Args:
-            groups: list of state groups for which we want to get the state.
-            state_filter: The state filter used to fetch state.
-                from the database.
-
-        Returns:
-            Dict of state group to state map.
-        """
-        return self.stores.state._get_state_for_groups(
-            groups, state_filter or StateFilter.all()
-        )
-
-    async def get_state_group_for_events(
-        self,
-        event_ids: Collection[str],
-        await_full_state: bool = True,
-    ) -> Mapping[str, int]:
-        """Returns mapping event_id -> state_group
-
-        Args:
-            event_ids: events to get state groups for
-            await_full_state: if true, will block if we do not yet have complete
-               state at these events.
-        """
-        if await_full_state:
-            await self._partial_state_events_tracker.await_full_state(event_ids)
-
-        return await self.stores.main._get_state_group_for_events(event_ids)
-
-    async def store_state_group(
-        self,
-        event_id: str,
-        room_id: str,
-        prev_group: Optional[int],
-        delta_ids: Optional[StateMap[str]],
-        current_state_ids: StateMap[str],
-    ) -> int:
-        """Store a new set of state, returning a newly assigned state group.
-
-        Args:
-            event_id: The event ID for which the state was calculated.
-            room_id: ID of the room for which the state was calculated.
-            prev_group: A previous state group for the room, optional.
-            delta_ids: The delta between state at `prev_group` and
-                `current_state_ids`, if `prev_group` was given. Same format as
-                `current_state_ids`.
-            current_state_ids: The state to store. Map of (type, state_key)
-                to event_id.
-
-        Returns:
-            The state group ID
-        """
-        return await self.stores.state.store_state_group(
-            event_id, room_id, prev_group, delta_ids, current_state_ids
-        )
diff --git a/synapse/visibility.py b/synapse/visibility.py
index da4af02796..97548c14e3 100644
--- a/synapse/visibility.py
+++ b/synapse/visibility.py
@@ -20,7 +20,7 @@ from typing_extensions import Final
 from synapse.api.constants import EventTypes, HistoryVisibility, Membership
 from synapse.events import EventBase
 from synapse.events.utils import prune_event
-from synapse.storage import Storage
+from synapse.storage.controllers import StorageControllers
 from synapse.storage.state import StateFilter
 from synapse.types import RetentionPolicy, StateMap, get_domain_from_id
 
@@ -47,7 +47,7 @@ _HISTORY_VIS_KEY: Final[Tuple[str, str]] = (EventTypes.RoomHistoryVisibility, ""
 
 
 async def filter_events_for_client(
-    storage: Storage,
+    storage: StorageControllers,
     user_id: str,
     events: List[EventBase],
     is_peeking: bool = False,
@@ -268,7 +268,7 @@ async def filter_events_for_client(
 
 
 async def filter_events_for_server(
-    storage: Storage,
+    storage: StorageControllers,
     server_name: str,
     events: List[EventBase],
     redact: bool = True,
@@ -360,7 +360,7 @@ async def filter_events_for_server(
 
 
 async def _event_to_history_vis(
-    storage: Storage, events: Collection[EventBase]
+    storage: StorageControllers, events: Collection[EventBase]
 ) -> Dict[str, str]:
     """Get the history visibility at each of the given events
 
@@ -407,7 +407,7 @@ async def _event_to_history_vis(
 
 
 async def _event_to_memberships(
-    storage: Storage, events: Collection[EventBase], server_name: str
+    storage: StorageControllers, events: Collection[EventBase], server_name: str
 ) -> Dict[str, StateMap[EventBase]]:
     """Get the remote membership list at each of the given events