Easy refactors of the user directory

synapse/handlers/state_deltas.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import logging
+from enum import Enum, auto
 from typing import TYPE_CHECKING, Optional
 
 if TYPE_CHECKING:
@@ -21,6 +22,12 @@
 logger = logging.getLogger(__name__)
 
 
+class MatchChange(Enum):
+    no_change = auto()
+    now_true = auto()
+    now_false = auto()
+
+
 class StateDeltasHandler:
     def __init__(self, hs: "HomeServer"):
         self.store = hs.get_datastore()
@@ -31,18 +38,12 @@ async def _get_key_change(
         event_id: Optional[str],
         key_name: str,
         public_value: str,
-    ) -> Optional[bool]:
+    ) -> MatchChange:
         """Given two events check if the `key_name` field in content changed
         from not matching `public_value` to doing so.
 
         For example, check if `history_visibility` (`key_name`) changed from
         `shared` to `world_readable` (`public_value`).
-
-        Returns:
-            None if the field in the events either both match `public_value`
-            or if neither do, i.e. there has been no change.
-            True if it didn't match `public_value` but now does
-            False if it did match `public_value` but now doesn't
         """
         prev_event = None
         event = None
@@ -54,7 +55,7 @@ async def _get_key_change(
 
         if not event and not prev_event:
             logger.debug("Neither event exists: %r %r", prev_event_id, event_id)
-            return None
+            return MatchChange.no_change
 
         prev_value = None
         value = None
@@ -68,8 +69,8 @@ async def _get_key_change(
         logger.debug("prev_value: %r -> value: %r", prev_value, value)
 
         if value == public_value and prev_value != public_value:
-            return True
+            return MatchChange.now_true
         elif value != public_value and prev_value == public_value:
-            return False
+            return MatchChange.now_false
         else:
-            return None
+            return MatchChange.no_change

synapse/handlers/user_directory.py

@@ -17,7 +17,7 @@
 
 import synapse.metrics
 from synapse.api.constants import EventTypes, HistoryVisibility, JoinRules, Membership
-from synapse.handlers.state_deltas import StateDeltasHandler
+from synapse.handlers.state_deltas import MatchChange, StateDeltasHandler
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage.roommember import ProfileInfo
 from synapse.types import JsonDict
@@ -208,7 +208,7 @@ async def _handle_deltas(self, deltas: List[Dict[str, Any]]) -> None:
                     public_value=Membership.JOIN,
                 )
 
-                if change is False:
+                if change is MatchChange.now_false:
                     # Need to check if the server left the room entirely, if so
                     # we might need to remove all the users in that room
                     is_in_room = await self.store.is_host_joined(
@@ -231,14 +231,14 @@ async def _handle_deltas(self, deltas: List[Dict[str, Any]]) -> None:
 
                 is_support = await self.store.is_support_user(state_key)
                 if not is_support:
-                    if change is None:
+                    if change is MatchChange.no_change:
                         # Handle any profile changes
                         await self._handle_profile_change(
                             state_key, room_id, prev_event_id, event_id
                         )
                         continue
 
-                    if change:  # The user joined
+                    if change is MatchChange.now_true:  # The user joined
                         event = await self.store.get_event(event_id, allow_none=True)
                         # It isn't expected for this event to not exist, but we
                         # don't want the entire background process to break.
@@ -275,14 +275,14 @@ async def _handle_room_publicity_change(
         logger.debug("Handling change for %s: %s", typ, room_id)
 
         if typ == EventTypes.RoomHistoryVisibility:
-            change = await self._get_key_change(
+            publicness = await self._get_key_change(
                 prev_event_id,
                 event_id,
                 key_name="history_visibility",
                 public_value=HistoryVisibility.WORLD_READABLE,
             )
         elif typ == EventTypes.JoinRules:
-            change = await self._get_key_change(
+            publicness = await self._get_key_change(
                 prev_event_id,
                 event_id,
                 key_name="join_rule",
@@ -292,7 +292,7 @@ async def _handle_room_publicity_change(
             raise Exception("Invalid event type")
         # If change is None, no change. True => become world_readable/public,
         # False => was world_readable/public
-        if change is None:
+        if publicness is MatchChange.no_change:
             logger.debug("No change")
             return
 
@@ -302,13 +302,13 @@ async def _handle_room_publicity_change(
             room_id
         )
 
-        logger.debug("Change: %r, is_public: %r", change, is_public)
+        logger.debug("Change: %r, publicness: %r", publicness, is_public)
 
-        if change and not is_public:
+        if publicness is MatchChange.now_true and not is_public:
             # If we became world readable but room isn't currently public then
             # we ignore the change
             return
-        elif not change and is_public:
+        elif publicness is MatchChange.now_false and is_public:
             # If we stopped being world readable but are still public,
             # ignore the change
             return