下面我们紧接着研究客户与服务器交互的readQueryFromClient函数。

    redisClient *c = (redisClient*) privdata;

 //指向之前设置的对象指针       int nread;  int readlen;  //REDIS_IOBUF_LEN         size_t qblen;  //指示之前已经读的数据    //设置几个变量  

 

    REDIS_NOTUSED(el);      REDIS_NOTUSED(mask);  //没有任何意义

    server.current_client = c;

 //存储当前的对象         readlen = REDIS_IOBUF_LEN;

//每次想读的数据长度

      /* If this is a multi bulk request, and we are processing a bulk reply      * that is large enough, try to maximize the probability that the query      * buffer contains exactly the SDS string representing the object, even      * at the risk of requiring more read(2) calls. This way the function      * processMultiBulkBuffer() can avoid copying buffers to create the      * Redis Object representing the argument. */      //自定义检查点: 1 2 3      //自定义检查点: 1 2 3      //自定义检查点: 1 2 3

 

         if (c->reqtype == REDIS_REQ_MULTIBULK   && c->multibulklen   && c->bulklen != -1         && c->bulklen >= REDIS_MBULK_BIG_ARG         )     {         int remaining = (unsigned)(c->bulklen+2)-sdslen(c->querybuf);

        if (remaining < readlen) readlen = remaining;

    }  //不需要执行  

    qblen = sdslen(c->querybuf);

//之前缓冲区里已经存在的数据的长度

        if (c->querybuf_peak < qblen)   c->querybuf_peak = qblen;  //不需要执行  //自定义检查点: 1 2 3           c->querybuf = sdsMakeRoomFor(c->querybuf, readlen);

//保证有足够的空间

        nread = read(fd, c->querybuf+qblen, readlen); //开始读取数据

 if (nread == -1)

 {         if (errno == EAGAIN)   {             nread = 0;         }   else   {             redisLog(REDIS_VERBOSE, "Reading from client: %s",strerror(errno));             freeClient(c);             return;         }     }  else if (nread == 0)  {         redisLog(REDIS_VERBOSE, "Client closed connection");         freeClient(c);         return;     }

//对读取操作的返回状态进行判断。

困了，睡觉！！！