Wait for lazy join to complete when getting current state (#12872)

9 files changed, 207 insertions, 39 deletions

diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 8df80664a2..57bd74700e 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -77,7 +77,7 @@ class SQLBaseStore(metaclass=ABCMeta):
 
         # Purge other caches based on room state.
         self._attempt_to_invalidate_cache("get_room_summary", (room_id,))
-        self._attempt_to_invalidate_cache("get_current_state_ids", (room_id,))
+        self._attempt_to_invalidate_cache("get_partial_current_state_ids", (room_id,))
 
     def _attempt_to_invalidate_cache(
         self, cache_name: str, key: Optional[Collection[Any]]
diff --git a/synapse/storage/controllers/__init__.py b/synapse/storage/controllers/__init__.py
index 992261d07b..55649719f6 100644
--- a/synapse/storage/controllers/__init__.py
+++ b/synapse/storage/controllers/__init__.py
@@ -18,7 +18,7 @@ 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.controllers.state import StateStorageController
 from synapse.storage.databases import Databases
 from synapse.storage.databases.main import DataStore
 
@@ -39,7 +39,7 @@ class StorageControllers:
         self.main = stores.main
 
         self.purge_events = PurgeEventsStorageController(hs, stores)
-        self.state = StateGroupStorageController(hs, stores)
+        self.state = StateStorageController(hs, stores)
 
         self.persistence = None
         if stores.persist_events:
diff --git a/synapse/storage/controllers/persist_events.py b/synapse/storage/controllers/persist_events.py
index ef8c135b12..4caaa81808 100644
--- a/synapse/storage/controllers/persist_events.py
+++ b/synapse/storage/controllers/persist_events.py
@@ -994,7 +994,7 @@ class EventsPersistenceStorageController:
 
         Assumes that we are only persisting events for one room at a time.
         """
-        existing_state = await self.main_store.get_current_state_ids(room_id)
+        existing_state = await self.main_store.get_partial_current_state_ids(room_id)
 
         to_delete = [key for key in existing_state if key not in current_state]
 
@@ -1083,7 +1083,7 @@ class EventsPersistenceStorageController:
         # The server will leave the room, so we go and find out which remote
         # users will still be joined when we leave.
         if current_state is None:
-            current_state = await self.main_store.get_current_state_ids(room_id)
+            current_state = await self.main_store.get_partial_current_state_ids(room_id)
             current_state = dict(current_state)
             for key in delta.to_delete:
                 current_state.pop(key, None)
diff --git a/synapse/storage/controllers/state.py b/synapse/storage/controllers/state.py
index 0f09953086..9952b00493 100644
--- a/synapse/storage/controllers/state.py
+++ b/synapse/storage/controllers/state.py
@@ -14,7 +14,9 @@
 import logging
 from typing import (
     TYPE_CHECKING,
+    Any,
     Awaitable,
+    Callable,
     Collection,
     Dict,
     Iterable,
@@ -24,9 +26,13 @@ from typing import (
     Tuple,
 )
 
+from synapse.api.constants import EventTypes
 from synapse.events import EventBase
 from synapse.storage.state import StateFilter
-from synapse.storage.util.partial_state_events_tracker import PartialStateEventsTracker
+from synapse.storage.util.partial_state_events_tracker import (
+    PartialCurrentStateTracker,
+    PartialStateEventsTracker,
+)
 from synapse.types import MutableStateMap, StateMap
 
 if TYPE_CHECKING:
@@ -36,17 +42,27 @@ if TYPE_CHECKING:
 logger = logging.getLogger(__name__)
 
 
-class StateGroupStorageController:
-    """High level interface to fetching state for event."""
+class StateStorageController:
+    """High level interface to fetching state for an event, or the current state
+    in a room.
+    """
 
     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)
+        self._partial_state_room_tracker = PartialCurrentStateTracker(stores.main)
 
     def notify_event_un_partial_stated(self, event_id: str) -> None:
         self._partial_state_events_tracker.notify_un_partial_stated(event_id)
 
+    def notify_room_un_partial_stated(self, room_id: str) -> None:
+        """Notify that the room no longer has any partial state.
+
+        Must be called after `DataStore.clear_partial_state_room`
+        """
+        self._partial_state_room_tracker.notify_un_partial_stated(room_id)
+
     async def get_state_group_delta(
         self, state_group: int
     ) -> Tuple[Optional[int], Optional[StateMap[str]]]:
@@ -349,3 +365,93 @@ class StateGroupStorageController:
         return await self.stores.state.store_state_group(
             event_id, room_id, prev_group, delta_ids, current_state_ids
         )
+
+    async def get_current_state_ids(
+        self,
+        room_id: str,
+        state_filter: Optional[StateFilter] = None,
+        on_invalidate: Optional[Callable[[], None]] = None,
+    ) -> StateMap[str]:
+        """Get the current state event ids for a room based on the
+        current_state_events table.
+
+        If a state filter is given (that is not `StateFilter.all()`) the query
+        result is *not* cached.
+
+        Args:
+            room_id: The room to get the state IDs of. state_filter: The state
+            filter used to fetch state from the
+                database.
+            on_invalidate: Callback for when the `get_current_state_ids` cache
+                for the room gets invalidated.
+
+        Returns:
+            The current state of the room.
+        """
+        if not state_filter or state_filter.must_await_full_state(self._is_mine_id):
+            await self._partial_state_room_tracker.await_full_state(room_id)
+
+        if state_filter and not state_filter.is_full():
+            return await self.stores.main.get_partial_filtered_current_state_ids(
+                room_id, state_filter
+            )
+        else:
+            return await self.stores.main.get_partial_current_state_ids(
+                room_id, on_invalidate=on_invalidate
+            )
+
+    async def get_canonical_alias_for_room(self, room_id: str) -> Optional[str]:
+        """Get canonical alias for room, if any
+
+        Args:
+            room_id: The room ID
+
+        Returns:
+            The canonical alias, if any
+        """
+
+        state = await self.get_current_state_ids(
+            room_id, StateFilter.from_types([(EventTypes.CanonicalAlias, "")])
+        )
+
+        event_id = state.get((EventTypes.CanonicalAlias, ""))
+        if not event_id:
+            return None
+
+        event = await self.stores.main.get_event(event_id, allow_none=True)
+        if not event:
+            return None
+
+        return event.content.get("canonical_alias")
+
+    async def get_current_state_deltas(
+        self, prev_stream_id: int, max_stream_id: int
+    ) -> Tuple[int, List[Dict[str, Any]]]:
+        """Fetch a list of room state changes since the given stream id
+
+        Each entry in the result contains the following fields:
+            - stream_id (int)
+            - room_id (str)
+            - type (str): event type
+            - state_key (str):
+            - event_id (str|None): new event_id for this state key. None if the
+                state has been deleted.
+            - prev_event_id (str|None): previous event_id for this state key. None
+                if it's new state.
+
+        Args:
+            prev_stream_id: point to get changes since (exclusive)
+            max_stream_id: the point that we know has been correctly persisted
+               - ie, an upper limit to return changes from.
+
+        Returns:
+            A tuple consisting of:
+               - the stream id which these results go up to
+               - list of current_state_delta_stream rows. If it is empty, we are
+                 up to date.
+        """
+        # FIXME(faster_joins): what do we do here?
+
+        return await self.stores.main.get_partial_current_state_deltas(
+            prev_stream_id, max_stream_id
+        )
diff --git a/synapse/storage/databases/main/room.py b/synapse/storage/databases/main/room.py
index cfd8ce1624..68d4fc2e64 100644
--- a/synapse/storage/databases/main/room.py
+++ b/synapse/storage/databases/main/room.py
@@ -1139,6 +1139,24 @@ class RoomWorkerStore(CacheInvalidationWorkerStore):
             keyvalues={"room_id": room_id},
         )
 
+    async def is_partial_state_room(self, room_id: str) -> bool:
+        """Checks if this room has partial state.
+
+        Returns true if this is a "partial-state" room, which means that the state
+        at events in the room, and `current_state_events`, may not yet be
+        complete.
+        """
+
+        entry = await self.db_pool.simple_select_one_onecol(
+            table="partial_state_rooms",
+            keyvalues={"room_id": room_id},
+            retcol="room_id",
+            allow_none=True,
+            desc="is_partial_state_room",
+        )
+
+        return entry is not None
+
 
 class _BackgroundUpdates:
     REMOVE_TOMESTONED_ROOMS_BG_UPDATE = "remove_tombstoned_rooms_from_directory"
diff --git a/synapse/storage/databases/main/state.py b/synapse/storage/databases/main/state.py
index 3f2be3854b..bdd00273cd 100644
--- a/synapse/storage/databases/main/state.py
+++ b/synapse/storage/databases/main/state.py
@@ -242,7 +242,7 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
         Raises:
             NotFoundError if the room is unknown
         """
-        state_ids = await self.get_current_state_ids(room_id)
+        state_ids = await self.get_partial_current_state_ids(room_id)
 
         if not state_ids:
             raise NotFoundError(f"Current state for room {room_id} is empty")
@@ -258,10 +258,12 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
         return create_event
 
     @cached(max_entries=100000, iterable=True)
-    async def get_current_state_ids(self, room_id: str) -> StateMap[str]:
+    async def get_partial_current_state_ids(self, room_id: str) -> StateMap[str]:
         """Get the current state event ids for a room based on the
         current_state_events table.
 
+        This may be the partial state if we're lazy joining the room.
+
         Args:
             room_id: The room to get the state IDs of.
 
@@ -280,17 +282,19 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
             return {(intern_string(r[0]), intern_string(r[1])): r[2] for r in txn}
 
         return await self.db_pool.runInteraction(
-            "get_current_state_ids", _get_current_state_ids_txn
+            "get_partial_current_state_ids", _get_current_state_ids_txn
         )
 
     # FIXME: how should this be cached?
-    async def get_filtered_current_state_ids(
+    async def get_partial_filtered_current_state_ids(
         self, room_id: str, state_filter: Optional[StateFilter] = None
     ) -> StateMap[str]:
         """Get the current state event of a given type for a room based on the
         current_state_events table.  This may not be as up-to-date as the result
         of doing a fresh state resolution as per state_handler.get_current_state
 
+        This may be the partial state if we're lazy joining the room.
+
         Args:
             room_id
             state_filter: The state filter used to fetch state
@@ -306,7 +310,7 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
 
         if not where_clause:
             # We delegate to the cached version
-            return await self.get_current_state_ids(room_id)
+            return await self.get_partial_current_state_ids(room_id)
 
         def _get_filtered_current_state_ids_txn(
             txn: LoggingTransaction,
@@ -334,30 +338,6 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
             "get_filtered_current_state_ids", _get_filtered_current_state_ids_txn
         )
 
-    async def get_canonical_alias_for_room(self, room_id: str) -> Optional[str]:
-        """Get canonical alias for room, if any
-
-        Args:
-            room_id: The room ID
-
-        Returns:
-            The canonical alias, if any
-        """
-
-        state = await self.get_filtered_current_state_ids(
-            room_id, StateFilter.from_types([(EventTypes.CanonicalAlias, "")])
-        )
-
-        event_id = state.get((EventTypes.CanonicalAlias, ""))
-        if not event_id:
-            return None
-
-        event = await self.get_event(event_id, allow_none=True)
-        if not event:
-            return None
-
-        return event.content.get("canonical_alias")
-
     @cached(max_entries=50000)
     async def _get_state_group_for_event(self, event_id: str) -> Optional[int]:
         return await self.db_pool.simple_select_one_onecol(
diff --git a/synapse/storage/databases/main/state_deltas.py b/synapse/storage/databases/main/state_deltas.py
index 188afec332..445213e12a 100644
--- a/synapse/storage/databases/main/state_deltas.py
+++ b/synapse/storage/databases/main/state_deltas.py
@@ -27,7 +27,7 @@ class StateDeltasStore(SQLBaseStore):
     # attribute. TODO: can we get static analysis to enforce this?
     _curr_state_delta_stream_cache: StreamChangeCache
 
-    async def get_current_state_deltas(
+    async def get_partial_current_state_deltas(
         self, prev_stream_id: int, max_stream_id: int
     ) -> Tuple[int, List[Dict[str, Any]]]:
         """Fetch a list of room state changes since the given stream id
@@ -42,6 +42,8 @@ class StateDeltasStore(SQLBaseStore):
             - prev_event_id (str|None): previous event_id for this state key. None
                 if it's new state.
 
+        This may be the partial state if we're lazy joining the room.
+
         Args:
             prev_stream_id: point to get changes since (exclusive)
             max_stream_id: the point that we know has been correctly persisted
diff --git a/synapse/storage/databases/main/user_directory.py b/synapse/storage/databases/main/user_directory.py
index 2282242e9d..ddb25b5cea 100644
--- a/synapse/storage/databases/main/user_directory.py
+++ b/synapse/storage/databases/main/user_directory.py
@@ -441,7 +441,9 @@ class UserDirectoryBackgroundUpdateStore(StateDeltasStore):
             (EventTypes.RoomHistoryVisibility, ""),
         )
 
-        current_state_ids = await self.get_filtered_current_state_ids(  # type: ignore[attr-defined]
+        # Getting the partial state is fine, as we're not looking at membership
+        # events.
+        current_state_ids = await self.get_partial_filtered_current_state_ids(  # type: ignore[attr-defined]
             room_id, StateFilter.from_types(types_to_filter)
         )
 
diff --git a/synapse/storage/util/partial_state_events_tracker.py b/synapse/storage/util/partial_state_events_tracker.py
index a61a951ef0..211437cfaa 100644
--- a/synapse/storage/util/partial_state_events_tracker.py
+++ b/synapse/storage/util/partial_state_events_tracker.py
@@ -21,6 +21,7 @@ from twisted.internet.defer import Deferred
 
 from synapse.logging.context import PreserveLoggingContext, make_deferred_yieldable
 from synapse.storage.databases.main.events_worker import EventsWorkerStore
+from synapse.storage.databases.main.room import RoomWorkerStore
 from synapse.util import unwrapFirstError
 
 logger = logging.getLogger(__name__)
@@ -118,3 +119,62 @@ class PartialStateEventsTracker:
                     observer_set.discard(observer)
                     if not observer_set:
                         del self._observers[event_id]
+
+
+class PartialCurrentStateTracker:
+    """Keeps track of which rooms have partial state, after partial-state joins"""
+
+    def __init__(self, store: RoomWorkerStore):
+        self._store = store
+
+        # a map from room id to a set of Deferreds which are waiting for that room to be
+        # un-partial-stated.
+        self._observers: Dict[str, Set[Deferred[None]]] = defaultdict(set)
+
+    def notify_un_partial_stated(self, room_id: str) -> None:
+        """Notify that we now have full current state for a given room
+
+        Unblocks any callers to await_full_state() for that room.
+
+        Args:
+            room_id: the room that now has full current state.
+        """
+        observers = self._observers.pop(room_id, None)
+        if not observers:
+            return
+        logger.info(
+            "Notifying %i things waiting for un-partial-stating of room %s",
+            len(observers),
+            room_id,
+        )
+        with PreserveLoggingContext():
+            for o in observers:
+                o.callback(None)
+
+    async def await_full_state(self, room_id: str) -> None:
+        # We add the deferred immediately so that the DB call to check for
+        # partial state doesn't race when we unpartial the room.
+        d: Deferred[None] = Deferred()
+        self._observers.setdefault(room_id, set()).add(d)
+
+        try:
+            # Check if the room has partial current state or not.
+            has_partial_state = await self._store.is_partial_state_room(room_id)
+            if not has_partial_state:
+                return
+
+            logger.info(
+                "Awaiting un-partial-stating of room %s",
+                room_id,
+            )
+
+            await make_deferred_yieldable(d)
+
+            logger.info("Room has un-partial-stated")
+        finally:
+            # Remove the added observer, and remove the room entry if its empty.
+            ds = self._observers.get(room_id)
+            if ds is not None:
+                ds.discard(d)
+                if not ds:
+                    self._observers.pop(room_id, None)