sytest: Make 'Inbound federation can backfill events' pass (#1051)

* sytest: Make 'Inbound federation can backfill events' pass

This breaks 'Outbound federation can backfill events' because now
we are returning the right number of events, which the previous
test was relying on.

Previously, /messages was backfilling the membership event, causing
the test to pass. Now we are no longer backfilling the membership
event due to the change in this commit, causing the test to fail.

The test should instead be returning the membership event locally
from synacpis database, but it doesn't do it fast enough, resulting
in a no-op /sync response with a next_batch=s0_0 which will never
pick up the local membership event when it rolls in. The test
does attempt to retry, but doesn't take the new next_batch=s1_0
resulting in it missing from the /messages response.

* Linting

1 files changed, 6 insertions, 5 deletions

diff --git a/syncapi/routing/messages.go b/syncapi/routing/messages.go
index 811188cc..88e16fe5 100644
--- a/syncapi/routing/messages.go
+++ b/syncapi/routing/messages.go
@@ -205,6 +205,7 @@ func (r *messagesReq) retrieveEvents() (
 	}
 
 	var events []gomatrixserverlib.HeaderedEvent
+	util.GetLogger(r.ctx).WithField("start", start).WithField("end", end).Infof("Fetched %d events locally", len(streamEvents))
 
 	// There can be two reasons for streamEvents to be empty: either we've
 	// reached the oldest event in the room (or the most recent one, depending
@@ -373,13 +374,13 @@ func (e eventsByDepth) Less(i, j int) bool {
 // event, or if there is no remote homeserver to contact.
 // Returns an error if there was an issue with retrieving the list of servers in
 // the room or sending the request.
-func (r *messagesReq) backfill(roomID string, fromEventIDs []string, limit int) ([]gomatrixserverlib.HeaderedEvent, error) {
+func (r *messagesReq) backfill(roomID string, backwardsExtremities map[string][]string, limit int) ([]gomatrixserverlib.HeaderedEvent, error) {
 	var res api.QueryBackfillResponse
 	err := r.rsAPI.QueryBackfill(context.Background(), &api.QueryBackfillRequest{
-		RoomID:            roomID,
-		EarliestEventsIDs: fromEventIDs,
-		Limit:             limit,
-		ServerName:        r.cfg.Matrix.ServerName,
+		RoomID:               roomID,
+		BackwardsExtremities: backwardsExtremities,
+		Limit:                limit,
+		ServerName:           r.cfg.Matrix.ServerName,
 	}, &res)
 	if err != nil {
 		return nil, fmt.Errorf("QueryBackfill failed: %w", err)