接收发缓存区处理

/* With multiplexing we need to take per-client state.
 * Clients are taken in a linked list. */
typedef struct client {
    // ... 其他无关字段略 ...
    sds querybuf;           /* Buffer we use to accumulate client queries. */
    // ... 其他无关字段略 ...
    int argc;               /* Num of arguments of current command. */
    robj **argv;