Unread counts fixes (#8254)

* Fixup `ALTER TABLE` database queries

Make the new columns nullable, because doing otherwise can wedge a
server with a big database, as setting a default value rewrites the
table.

* Switch back to using the notifications count in the push badge

Clients are likely to be confused if we send a push but the badge count
is the unread messages one, and not the notifications one.

* Changelog

changelog.d/8254.feature

@@ -0,0 +1 @@
+Add unread messages count to sync responses, as specified in [MSC2654](https://github.com/matrix-org/matrix-doc/pull/2654).

synapse/push/push_tools.py

@@ -36,7 +36,7 @@ async def get_badge_count(store, user_id):
             )
             # return one badge count per conversation, as count per
             # message is so noisy as to be almost useless
-            badge += 1 if notifs["unread_count"] else 0
+            badge += 1 if notifs["notify_count"] else 0
     return badge
 
 

synapse/storage/databases/main/schema/delta/58/15unread_count.sql

@@ -19,8 +19,8 @@
 
 -- Add columns to event_push_actions and event_push_actions_staging to track unread
 -- messages and calculate unread counts.
-ALTER TABLE event_push_actions_staging ADD COLUMN unread SMALLINT NOT NULL DEFAULT 0;
-ALTER TABLE event_push_actions ADD COLUMN unread SMALLINT NOT NULL DEFAULT 0;
+ALTER TABLE event_push_actions_staging ADD COLUMN unread SMALLINT;
+ALTER TABLE event_push_actions ADD COLUMN unread SMALLINT;
 
 -- Add column to event_push_summary
-ALTER TABLE event_push_summary ADD COLUMN unread_count BIGINT NOT NULL DEFAULT 0;
+ALTER TABLE event_push_summary ADD COLUMN unread_count BIGINT;