Use the ignored_users table to test event visibility & sync. (#12225)

Instead of fetching the raw account data and re-parsing it. The
ignored_users table is a denormalised version of the account data
for quick searching.

synapse/storage/databases/main/account_data.py

@@ -14,7 +14,17 @@
 # limitations under the License.
 
 import logging
-from typing import TYPE_CHECKING, Any, Dict, Iterable, List, Optional, Set, Tuple, cast
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Dict,
+    FrozenSet,
+    Iterable,
+    List,
+    Optional,
+    Tuple,
+    cast,
+)
 
 from synapse.api.constants import AccountDataTypes
 from synapse.replication.slave.storage._slaved_id_tracker import SlavedIdTracker
@@ -365,7 +375,7 @@ class AccountDataWorkerStore(PushRulesWorkerStore, CacheInvalidationWorkerStore)
         )
 
     @cached(max_entries=5000, iterable=True)
-    async def ignored_by(self, user_id: str) -> Set[str]:
+    async def ignored_by(self, user_id: str) -> FrozenSet[str]:
         """
         Get users which ignore the given user.
 
@@ -375,7 +385,7 @@ class AccountDataWorkerStore(PushRulesWorkerStore, CacheInvalidationWorkerStore)
         Return:
             The user IDs which ignore the given user.
         """
-        return set(
+        return frozenset(
             await self.db_pool.simple_select_onecol(
                 table="ignored_users",
                 keyvalues={"ignored_user_id": user_id},
@@ -384,6 +394,26 @@ class AccountDataWorkerStore(PushRulesWorkerStore, CacheInvalidationWorkerStore)
             )
         )
 
+    @cached(max_entries=5000, iterable=True)
+    async def ignored_users(self, user_id: str) -> FrozenSet[str]:
+        """
+        Get users which the given user ignores.
+
+        Params:
+            user_id: The user ID which is making the request.
+
+        Return:
+            The user IDs which are ignored by the given user.
+        """
+        return frozenset(
+            await self.db_pool.simple_select_onecol(
+                table="ignored_users",
+                keyvalues={"ignorer_user_id": user_id},
+                retcol="ignored_user_id",
+                desc="ignored_users",
+            )
+        )
+
     def process_replication_rows(
         self,
         stream_name: str,
@@ -529,6 +559,10 @@ class AccountDataWorkerStore(PushRulesWorkerStore, CacheInvalidationWorkerStore)
         else:
             currently_ignored_users = set()
 
+        # If the data has not changed, nothing to do.
+        if previously_ignored_users == currently_ignored_users:
+            return
+
         # Delete entries which are no longer ignored.
         self.db_pool.simple_delete_many_txn(
             txn,
@@ -551,6 +585,7 @@ class AccountDataWorkerStore(PushRulesWorkerStore, CacheInvalidationWorkerStore)
         # Invalidate the cache for any ignored users which were added or removed.
         for ignored_user_id in previously_ignored_users ^ currently_ignored_users:
             self._invalidate_cache_and_stream(txn, self.ignored_by, (ignored_user_id,))
+        self._invalidate_cache_and_stream(txn, self.ignored_users, (user_id,))
 
     async def purge_account_data_for_user(self, user_id: str) -> None:
         """