c++知识点

string redis_cmd = "GET " + redis_key;
result = _rd_client.exec_command(redis_cmd.c_str());

//exec_command定义
redisReply* redis_client::exec_command(const char *cmd) {
    return exec_command_with_args(cmd);
}

const int TIME_WAIT = 100000; //100 ms
string redis_cmd = "GET " + redis_key;
UB_LOG_TRACE("read output redis command: %s", redis_cmd.c_str());

    for (unsigned int i = 1; i <= pay_define::MAX_RETRY_TIMES; i++) 
    {    
        try  
        {    
            redisReply* result = NULL;
            result = _rd_client.exec_command(redis_cmd.c_str());
            if (!result) 
            {    
                UB_LOG_WARNING("get output from redis result is null");
                usleep(TIME_WAIT);
                continue;    
            }    

            if (result->type != REDIS_REPLY_STRING) 
            {    
                if (result->type == REDIS_REPLY_ERROR)
                {    
                    UB_LOG_WARNING("get output from redis result error");
                }    
                else if (result->type == REDIS_REPLY_NIL) 
                {    
                    UB_LOG_WARNING("get output from redis result is empty");
                }    

                freeReplyObject(result);
                usleep(TIME_WAIT);
                continue;
            }    

            //copy redis value to out_pack                                                                                                                                   
            mc_pack_t * pOutput = const_cast<yapserver::mc_pack_writer&>(out_pack);
            memcpy((void*)pOutput, result->str, result->len);