presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/metadata/DatabaseShardManager.java/DatabaseShardManager/lockTable
class DatabaseShardManager:    private static void lockTable(Handle handle, long tableId)
    {
        if (handle.attach(MetadataDao.class).getLockedTableId(tableId) == null) {
            throw transactionConflict();
        }
    }