C++从零开始区块链：区块链业务模块之主链同步

同样是采用一个简单，但效率低下的方案，遍历自己的链和其他节点的链，谁的长谁的就是主链。
然后将自己的链和主链进行比较，将自己的链上的区块挂在主链上，挂的同时验证一下自己的区块是否已经存在于主链上，如果存在就跳过。

void BlockChain::MergeBlockChain(const std::string &json)
{
    std::list<Block> lst_block = GetBlockListFromJson(json);
    lst_block.pop_front();

    if (lst_block.size() > m_lst_block.size())
    {
        std::list<Block>::iterator it;

        pthread_mutex_lock(&m_mutexBlock);

        for (it = m_lst_block.begin(); it != m_lst_block.end(); ++it)
        {
            Block block = lst_block.back();
            if(it->proof <= block.proof)
                continue;
            std::string strJson = GetJsonFromBlock(block);
            std::string strHash = Cryptography::GetHash(strJson.c_str(), strJson.length());

            it->index = block.index + 1;
            it->previous_hash = strHash;
            lst_block.push_back(*it);
        }

        m_lst_block = lst_block;

        pthread_mutex_unlock(&m_mutexBlock);
    }
    else
    {
        std::list<Block>::iterator it;
        for (it = lst_block.begin(); it != lst_block.end(); ++it)
        {
            pthread_mutex_lock(&m_mutexBlock);

            Block block = m_lst_block.back();
            if (it->proof <= block.proof)
            {
                pthread_mutex_unlock(&m_mutexBlock);
                continue;
            }
            std::string strJson = GetJsonFromBlock(block);
            std::string strHash = Cryptography::GetHash(strJson.c_str(), strJson.length());

            it->index = block.index + 1;
            it->previous_hash = strHash;
            m_lst_block.push_back(*it);

            pthread_mutex_unlock(&m_mutexBlock);
        }
    }
}