生成全局唯一ID

//获取全局唯一ID
//server_id为服务的id,因当同一个服务部署在多个服务器上时，需要区别
unsigned long long GetUniqueID(unsigned int server_id)
{
    static unsigned long long seq_id = 0;
    unsigned long long seq = seq_msg_id++ ;
    seq = (seq<<8);
    seq = (seq>>8);
    unsigned long long tag = ((unsigned long long)server_id<<56);
    seq = (seq | tag) ;
    return seq ;
}

/**
 获取全局唯一ID,且ID为奇数
 */
unsigned long long GetOddID(unsigned int server_id)
{
    unsigned long long id = GetUniqueID(server_id);
    while (true)
    {
        if ((id & 0x01) == 0x01)
        {
            return id;
        }
        else
        {
            id = GetUniqueID(server_id);
        }
    }
}

//利用MD5库提供的64位哈希函数，来将字符串生成相应的hash值
//从而可得到经md5转化后的报文摘要

//数据库的UUID