class CassandraSieveQuotaDAO {

    public Mono<Long> spaceUsedBy(Username username) {
        return cassandraAsyncExecutor.executeSingleRowOptional(
            selectSpaceUsedByUserStatement.bind()
                .setString(CassandraSieveSpaceTable.USER_NAME, username.asString()))
            .map(optional -> optional.map(row -> row.getLong(CassandraSieveSpaceTable.SPACE_USED))
                .orElse(0L));
    }

    @Inject public  CassandraSieveQuotaDAO(Session session);

}