Prevent memory leak from reoccurring when presence is disabled.

synapse/handlers/presence.py

@@ -659,27 +659,28 @@ def __init__(self, hs: "HomeServer"):
         )
 
         now = self.clock.time_msec()
-        for state in self.user_to_current_state.values():
-            self.wheel_timer.insert(
-                now=now, obj=state.user_id, then=state.last_active_ts + IDLE_TIMER
-            )
-            self.wheel_timer.insert(
-                now=now,
-                obj=state.user_id,
-                then=state.last_user_sync_ts + SYNC_ONLINE_TIMEOUT,
-            )
-            if self.is_mine_id(state.user_id):
+        if self._presence_enabled:
+            for state in self.user_to_current_state.values():
                 self.wheel_timer.insert(
-                    now=now,
-                    obj=state.user_id,
-                    then=state.last_federation_update_ts + FEDERATION_PING_INTERVAL,
+                    now=now, obj=state.user_id, then=state.last_active_ts + IDLE_TIMER
                 )
-            else:
                 self.wheel_timer.insert(
                     now=now,
                     obj=state.user_id,
-                    then=state.last_federation_update_ts + FEDERATION_TIMEOUT,
+                    then=state.last_user_sync_ts + SYNC_ONLINE_TIMEOUT,
                 )
+                if self.is_mine_id(state.user_id):
+                    self.wheel_timer.insert(
+                        now=now,
+                        obj=state.user_id,
+                        then=state.last_federation_update_ts + FEDERATION_PING_INTERVAL,
+                    )
+                else:
+                    self.wheel_timer.insert(
+                        now=now,
+                        obj=state.user_id,
+                        then=state.last_federation_update_ts + FEDERATION_TIMEOUT,
+                    )
 
         # Set of users who have presence in the `user_to_current_state` that
         # have not yet been persisted
@@ -804,6 +805,13 @@ async def _update_states(
                 This is currently used to bump the max presence stream ID without changing any
                 user's presence (see PresenceHandler.add_users_to_send_full_presence_to).
         """
+        if not self._presence_enabled:
+            # We shouldn't get here if presence is disabled, but we check anyway
+            # to ensure that we don't a) send out presence federation and b)
+            # don't add things to the wheel timer that will never be handled.
+            logger.warning("Tried to update presence states when presence is disabled")
+            return
+
         now = self.clock.time_msec()
 
         with Measure(self.clock, "presence_update_states"):
@@ -1229,6 +1237,10 @@ async def set_state(
         ):
             raise SynapseError(400, "Invalid presence state")
 
+        # If presence is disabled, no-op
+        if not self.hs.config.server.use_presence:
+            return
+
         user_id = target_user.to_string()
 
         prev_state = await self.current_state_for_user(user_id)