void setGarbageLeftPage(long left) {
        Debug.$assert1.t(isMine() && isGarbagePage() && left > 0 && left <= MAX_VALID_PAGE_ADDR && left != _page
                && _alloc + GARBAGE_BLOCK_SIZE <= _bufferSize && _alloc >= _keyBlockEnd);
        putLong(_alloc + GARBAGE_BLOCK_LEFT_PAGE, left);
        bumpGeneration();
    }