1 files changed, 30 insertions, 0 deletions
diff --git a/syncapi/storage/postgres/current_room_state_table.go b/syncapi/storage/postgres/current_room_state_table.go
index 8ee387b3..c4667baf 100644
--- a/syncapi/storage/postgres/current_room_state_table.go
+++ b/syncapi/storage/postgres/current_room_state_table.go
@@ -107,6 +107,11 @@ const selectEventsWithEventIDsSQL = "" +
 	"SELECT event_id, added_at, headered_event_json, 0 AS session_id, false AS exclude_from_sync, '' AS transaction_id" +
 	" FROM syncapi_current_room_state WHERE event_id = ANY($1)"
 
+const selectSharedUsersSQL = "" +
+	"SELECT state_key FROM syncapi_current_room_state WHERE room_id = ANY(" +
+	"	SELECT room_id FROM syncapi_current_room_state WHERE state_key = $1 AND membership='join'" +
+	") AND state_key = ANY($2) AND membership='join';"
+
 type currentRoomStateStatements struct {
 	upsertRoomStateStmt                *sql.Stmt
 	deleteRoomStateByEventIDStmt       *sql.Stmt
@@ -118,6 +123,7 @@ type currentRoomStateStatements struct {
 	selectJoinedUsersInRoomStmt        *sql.Stmt
 	selectEventsWithEventIDsStmt       *sql.Stmt
 	selectStateEventStmt               *sql.Stmt
+	selectSharedUsersStmt              *sql.Stmt
 }
 
 func NewPostgresCurrentRoomStateTable(db *sql.DB) (tables.CurrentRoomState, error) {
@@ -156,6 +162,9 @@ func NewPostgresCurrentRoomStateTable(db *sql.DB) (tables.CurrentRoomState, erro
 	if s.selectStateEventStmt, err = db.Prepare(selectStateEventSQL); err != nil {
 		return nil, err
 	}
+	if s.selectSharedUsersStmt, err = db.Prepare(selectSharedUsersSQL); err != nil {
+		return nil, err
+	}
 	return s, nil
 }
 
@@ -379,3 +388,24 @@ func (s *currentRoomStateStatements) SelectStateEvent(
 	}
 	return &ev, err
 }
+
+func (s *currentRoomStateStatements) SelectSharedUsers(
+	ctx context.Context, txn *sql.Tx, userID string, otherUserIDs []string,
+) ([]string, error) {
+	stmt := sqlutil.TxStmt(txn, s.selectSharedUsersStmt)
+	rows, err := stmt.QueryContext(ctx, userID, otherUserIDs)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "selectSharedUsersStmt: rows.close() failed")
+
+	var stateKey string
+	result := make([]string, 0, len(otherUserIDs))
+	for rows.Next() {
+		if err := rows.Scan(&stateKey); err != nil {
+			return nil, err
+		}
+		result = append(result, stateKey)
+	}
+	return result, rows.Err()
+}