Faster joins: omit partial rooms from eager syncs until the resync completes (#14870)

* Allow `AbstractSet` in `StrCollection`

Or else frozensets are excluded. This will be useful in an upcoming
commit where I plan to change a function that accepts `List[str]` to
accept `StrCollection` instead.

* `rooms_to_exclude` -> `rooms_to_exclude_globally`

I am about to make use of this exclusion mechanism to exclude rooms for
a specific user and a specific sync. This rename helps to clarify the
distinction between the global config and the rooms to exclude for a
specific sync.

* Better function names for internal sync methods

* Track a list of excluded rooms on SyncResultBuilder

I plan to feed a list of partially stated rooms for this sync to ignore

* Exclude partial state rooms during eager sync

using the mechanism established in the previous commit

* Track un-partial-state stream in sync tokens

So that we can work out which rooms have become fully-stated during a
given sync period.

* Fix mutation of `@cached` return value

This was fouling up a complement test added alongside this PR.
Excluding a room would mean the set of forgotten rooms in the cache
would be extended. This means that room could be erroneously considered
forgotten in the future.

Introduced in #12310, Synapse 1.57.0. I don't think this had any
user-visible side effects (until now).

* SyncResultBuilder: track rooms to force as newly joined

Similar plan as before. We've omitted rooms from certain sync responses;
now we establish the mechanism to reintroduce them into future syncs.

* Read new field, to present rooms as newly joined

* Force un-partial-stated rooms to be newly-joined

for eager incremental syncs only, provided they're still fully stated

* Notify user stream listeners to wake up long polling syncs

* Changelog

* Typo fix

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>

* Unnecessary list cast

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>

* Rephrase comment

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>

* Another comment

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>

* Fixup merge(?)

* Poke notifier when receiving un-partial-stated msg over replication

* Fixup merge whoops

Thanks MV :)

Co-authored-by: Mathieu Velen <mathieuv@matrix.org>

Co-authored-by: Mathieu Velten <mathieuv@matrix.org>
Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/synapse/notifier.py b/synapse/notifier.py
index 28f0d4a25a..2b0e52f23c 100644
--- a/synapse/notifier.py
+++ b/synapse/notifier.py
@@ -314,6 +314,32 @@ class Notifier:
             event_entries.append((entry, event.event_id))
         await self.notify_new_room_events(event_entries, max_room_stream_token)
 
+    async def on_un_partial_stated_room(
+        self,
+        room_id: str,
+        new_token: int,
+    ) -> None:
+        """Used by the resync background processes to wake up all listeners
+        of this room when it is un-partial-stated.
+
+        It will also notify replication listeners of the change in stream.
+        """
+
+        # Wake up all related user stream notifiers
+        user_streams = self.room_to_user_streams.get(room_id, set())
+        time_now_ms = self.clock.time_msec()
+        for user_stream in user_streams:
+            try:
+                user_stream.notify(
+                    StreamKeyType.UN_PARTIAL_STATED_ROOMS, new_token, time_now_ms
+                )
+            except Exception:
+                logger.exception("Failed to notify listener")
+
+        # Poke the replication so that other workers also see the write to
+        # the un-partial-stated rooms stream.
+        self.notify_replication()
+
     async def notify_new_room_events(
         self,
         event_entries: List[Tuple[_PendingRoomEventEntry, str]],