Preparatory work to fix the user directory assuming that any remote membership state events represent a profile change. [rei:userdirpriv] (#14755)

* Remove special-case method for new memberships only, use more generic method

* Only collect profiles from state events in public rooms

* Add a table to track stale remote user profiles

* Add store methods to set and delete rows in this new table

* Mark remote profiles as stale when a member state event comes in to a private room

* Newsfile

Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>

* Simplify by removing Optionality of `event_id`

* Replace names and avatars with None if they're set to dodgy things

I think this makes more sense anyway.

* Move schema delta to 74 (I missed the boat?)

* Turns out these can be None after all

---------

Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>

2 files changed, 79 insertions, 0 deletions

diff --git a/synapse/storage/databases/main/user_directory.py b/synapse/storage/databases/main/user_directory.py
index f16a509ac4..9cf01b7f36 100644
--- a/synapse/storage/databases/main/user_directory.py
+++ b/synapse/storage/databases/main/user_directory.py
@@ -54,6 +54,7 @@ from synapse.storage.databases.main.state_deltas import StateDeltasStore
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
 from synapse.types import (
     JsonDict,
+    UserID,
     UserProfile,
     get_domain_from_id,
     get_localpart_from_id,
@@ -473,11 +474,42 @@ class UserDirectoryBackgroundUpdateStore(StateDeltasStore):
 
         return False
 
+    async def set_remote_user_profile_in_user_dir_stale(
+        self, user_id: str, next_try_at_ms: int, retry_counter: int
+    ) -> None:
+        """
+        Marks a remote user as having a possibly-stale user directory profile.
+
+        Args:
+            user_id: the remote user who may have a stale profile on this server.
+            next_try_at_ms: timestamp in ms after which the user directory profile can be
+                refreshed.
+            retry_counter: number of failures in refreshing the profile so far. Used for
+                exponential backoff calculations.
+        """
+        assert not self.hs.is_mine_id(
+            user_id
+        ), "Can't mark a local user as a stale remote user."
+
+        server_name = UserID.from_string(user_id).domain
+
+        await self.db_pool.simple_upsert(
+            table="user_directory_stale_remote_users",
+            keyvalues={"user_id": user_id},
+            values={
+                "next_try_at_ts": next_try_at_ms,
+                "retry_counter": retry_counter,
+                "user_server_name": server_name,
+            },
+            desc="set_remote_user_profile_in_user_dir_stale",
+        )
+
     async def update_profile_in_user_dir(
         self, user_id: str, display_name: Optional[str], avatar_url: Optional[str]
     ) -> None:
         """
         Update or add a user's profile in the user directory.
+        If the user is remote, the profile will be marked as not stale.
         """
         # If the display name or avatar URL are unexpected types, replace with None.
         display_name = non_null_str_or_none(display_name)
@@ -491,6 +523,14 @@ class UserDirectoryBackgroundUpdateStore(StateDeltasStore):
                 values={"display_name": display_name, "avatar_url": avatar_url},
             )
 
+            if not self.hs.is_mine_id(user_id):
+                # Remote users: Make sure the profile is not marked as stale anymore.
+                self.db_pool.simple_delete_txn(
+                    txn,
+                    table="user_directory_stale_remote_users",
+                    keyvalues={"user_id": user_id},
+                )
+
             # The display name that goes into the database index.
             index_display_name = display_name
             if index_display_name is not None:
diff --git a/synapse/storage/schema/main/delta/74/01_user_directory_stale_remote_users.sql b/synapse/storage/schema/main/delta/74/01_user_directory_stale_remote_users.sql
new file mode 100644
index 0000000000..dcb38f3d7b
--- /dev/null
+++ b/synapse/storage/schema/main/delta/74/01_user_directory_stale_remote_users.sql
@@ -0,0 +1,39 @@
+/* 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.
+ */
+
+-- Table containing a list of remote users whose profiles may have changed
+-- since their last update in the user directory.
+CREATE TABLE user_directory_stale_remote_users (
+    -- The User ID of the remote user whose profile may be stale.
+    user_id TEXT NOT NULL PRIMARY KEY,
+
+    -- The server name of the user.
+    user_server_name TEXT NOT NULL,
+
+    -- The timestamp (in ms) after which we should next try to request the user's
+    -- latest profile.
+    next_try_at_ts BIGINT NOT NULL,
+
+    -- The number of retries so far.
+    -- 0 means we have not yet attempted to refresh the profile.
+    -- Used for calculating exponential backoff.
+    retry_counter INTEGER NOT NULL
+);
+
+-- Create an index so we can easily query upcoming servers to try.
+CREATE INDEX user_directory_stale_remote_users_next_try_idx ON user_directory_stale_remote_users(next_try_at_ts, user_server_name);
+
+-- Create an index so we can easily query upcoming users to try for a particular server.
+CREATE INDEX user_directory_stale_remote_users_next_try_by_server_idx ON user_directory_stale_remote_users(user_server_name, next_try_at_ts);