Пример #1
0
SqlitePage::BlockAreas SqlitePage::freeBlocks()
{
    BlockAreas freeBlockAreaList;
    
    CellList cellList = this->cellList(); // FIXIT
    if (cellList.empty()) {
        return freeBlockAreaList;
    }
    
    BlockArea firstBlock;
    PageHeader header = pageHeader();
    // FIXIT: 8 is not good
    firstBlock.begin = header.numOfCells * 2 + 8;
    firstBlock.end = cellList[cellList.size() - 1].offset - 1;
    freeBlockAreaList.push_back(firstBlock);
    
    if (cellList.size() > 1) {
        // Cell List 是自底向上增长的，所以这里使用反向迭代器遍历
        CellList::reverse_iterator rpos;
        for (rpos =  cellList.rbegin();
             rpos != cellList.rend(); ++rpos) {
            BlockArea block;
            block.begin = rpos->offset;
            block.end = rpos->offset + rpos->length;
            CellList::reverse_iterator tmp_rpos = rpos + 1;
            if (block.end < tmp_rpos->offset - kMinFreeBlockSize &&
                block.end < page_.size() - kMinFreeBlockSize) {
                freeBlockAreaList.push_back(block);
            }
        }
    }
    return freeBlockAreaList;
}