/sync: Handle missing state events and return events in the correct order
MODIFY
src/github.com/matrix-org/dendrite/syncserver/storage/output_room_events_table.go
src/github.com/matrix-org/dendrite/syncserver/storage/output_room_events_table.go
@@ -146,19 +146,15 @@ func (s *outputRoomEventsStatements) StateBetween(txn *sql.Tx, oldPos, newPos ty
eventIDToEvent[ev.EventID()] = ev
}
- stateBetween, missingEvents := mapEventIDsToEvents(eventIDToEvent, stateNeeded)
-
- if len(missingEvents) > 0 {
- return nil, fmt.Errorf("error StateBetween: TODO missing events")
- }
- return stateBetween, nil
+ return s.fetchStateEvents(txn, stateNeeded, eventIDToEvent)
}
-// convert the set of event IDs into a set of events. Mark any which are missing.
-func mapEventIDsToEvents(eventIDToEvent map[string]gomatrixserverlib.Event, stateNeeded map[string]map[string]bool) (map[string][]gomatrixserverlib.Event, map[string][]string) {
+// fetchStateEvents converts the set of event IDs into a set of events. It will fetch any which are missing from the database.
+// Returns a map of room ID to list of events.
+func (s *outputRoomEventsStatements) fetchStateEvents(txn *sql.Tx, roomIDToEventIDSet map[string]map[string]bool, eventIDToEvent map[string]gomatrixserverlib.Event) (map[string][]gomatrixserverlib.Event, error) {
stateBetween := make(map[string][]gomatrixserverlib.Event)
missingEvents := make(map[string][]string)
- for roomID, ids := range stateNeeded {
+ for roomID, ids := range roomIDToEventIDSet {
events := stateBetween[roomID]
for id, need := range ids {
if !need {
@@ -175,7 +171,25 @@ func mapEventIDsToEvents(eventIDToEvent map[string]gomatrixserverlib.Event, stat
}
stateBetween[roomID] = events
}
- return stateBetween, missingEvents
+
+ if len(missingEvents) > 0 {
+ // This happens when add_state_ids has an event ID which is not in the provided range.
+ // We need to explicitly fetch them.
+ allMissingEventIDs := []string{}
+ for _, missingEvIDs := range missingEvents {
+ allMissingEventIDs = append(allMissingEventIDs, missingEvIDs...)
+ }
+ evs, err := s.Events(txn, allMissingEventIDs)
+ if err != nil {
+ return nil, err
+ }
+ // we know we got them all otherwise an error would've been returned, so just loop the events
+ for _, ev := range evs {
+ roomID := ev.RoomID()
+ stateBetween[roomID] = append(stateBetween[roomID], ev)
+ }
+ }
+ return stateBetween, nil
}
// MaxID returns the ID of the last inserted event in this table. 'txn' is optional. If it is not supplied,
@@ -210,7 +224,13 @@ func (s *outputRoomEventsStatements) RecentEventsInRoom(txn *sql.Tx, roomID stri
return nil, err
}
defer rows.Close()
- return rowsToEvents(rows)
+ events, err := rowsToEvents(rows)
+ if err != nil {
+ return nil, err
+ }
+ // reverse the order because [0] is the newest event due to the ORDER BY in SQL-land. The reverse order makes [0] the oldest event,
+ // which is correct for /sync responses.
+ return reverseEvents(events), nil
}
// Events returns the events for the given event IDs. Returns an error if any one of the event IDs given are missing
@@ -248,3 +268,10 @@ func rowsToEvents(rows *sql.Rows) ([]gomatrixserverlib.Event, error) {
}
return result, nil
}
+
+func reverseEvents(input []gomatrixserverlib.Event) (output []gomatrixserverlib.Event) {
+ for i := len(input) - 1; i >= 0; i-- {
+ output = append(output, input[i])
+ }
+ return
+}

/sync: Handle missing state events and return events in the correct order (#72)