Track notification counts per thread (implement MSC3773). (#13776)

When retrieving counts of notifications segment the results based on the
thread ID, but choose whether to return them as individual threads or as
a single summed field by letting the client opt-in via a sync flag.

The summarization code is also updated to be per thread, instead of per
room.

2 files changed, 13 insertions, 0 deletions

diff --git a/synapse/api/constants.py b/synapse/api/constants.py

index c031903b1a..44c5ffc6a5 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -31,6 +31,9 @@ MAX_ALIAS_LENGTH = 255
 # the maximum length for a user id is 255 characters
 MAX_USERID_LENGTH = 255
 
+# Constant value used for the pseudo-thread which is the main timeline.
+MAIN_TIMELINE: Final = "main"
+
 
 class Membership:
 
diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py

index f7f46f8d80..c6e44dcf82 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -84,6 +84,7 @@ ROOM_EVENT_FILTER_SCHEMA = {
         "contains_url": {"type": "boolean"},
         "lazy_load_members": {"type": "boolean"},
         "include_redundant_members": {"type": "boolean"},
+        "org.matrix.msc3773.unread_thread_notifications": {"type": "boolean"},
         # Include or exclude events with the provided labels.
         # cf https://github.com/matrix-org/matrix-doc/pull/2326
         "org.matrix.labels": {"type": "array", "items": {"type": "string"}},
@@ -240,6 +241,9 @@ class FilterCollection:
     def include_redundant_members(self) -> bool:
         return self._room_state_filter.include_redundant_members
 
+    def unread_thread_notifications(self) -> bool:
+        return self._room_timeline_filter.unread_thread_notifications
+
     async def filter_presence(
         self, events: Iterable[UserPresenceState]
     ) -> List[UserPresenceState]:
@@ -304,6 +308,12 @@ class Filter:
         self.include_redundant_members = filter_json.get(
             "include_redundant_members", False
         )
+        if hs.config.experimental.msc3773_enabled:
+            self.unread_thread_notifications: bool = filter_json.get(
+                "org.matrix.msc3773.unread_thread_notifications", False
+            )
+        else:
+            self.unread_thread_notifications = False
 
         self.types = filter_json.get("types", None)
         self.not_types = filter_json.get("not_types", [])