数据库学习——关于redis的一点笔记

 下载 redis2.4.* 版本源码

 

A，注册一个命令

 

struct redisCommand {
    char *name;					//命令名称
    redisCommandProc *proc;		//命令调用函数
    int arity;					//命令参数个数
    int flags;					//如果标记为REDIS_CMD_DENYOOM,NULL，内存满后此命令不可执行，主要针对写数据库的命令
    /* Use a function to determine which keys need to be loaded
     * in the background prior to executing this command. Takes precedence
     * over vm_firstkey and others, ignored when NULL */
    redisVmPreloadProc *vm_preload_proc;
    /* What keys should be loaded in background when calling this command? */
    int vm_firstkey; /* The first argument that's a key (0 = no keys) */
    int vm_lastkey;  /* THe last argument that's a key */
    int vm_keystep;  /* The step between first and last key */
};

 

主要需要设置前面四个参数即可，后面的几个属性是关于开启vm的时候redis预读选项的配置，redis2.6以后由于废弃了vm特性，我也没看到这些参数有什么用。

 

redisCommandProc函数有一个参数redisClient *c

可以通过c->argv获取命令的参数列表

然后经过后台处理后，调用addReply函数给客户端响应消息

 

 

B，配置keepalive特性

 

tcp开启keepalive特性，redis封装了anetTcpKeepAlive函数，不过没有启用，不知道为什么

 

在network.c的createClient函数里面添加如下代码，设置keepalive的几个参数值

 

 

    anetNonBlock(NULL,fd);
    anetTcpNoDelay(NULL,fd);
    if(server.keepalive){
        anetTcpKeepAlive(NULL,fd);
        setsockopt(fd, SOL_TCP, TCP_KEEPIDLE, (void*)&server.keepidle , sizeof(server.keepidle ));
        setsockopt(fd, SOL_TCP, TCP_KEEPINTVL, (void *)&server.keepinterval , sizeof(server.keepinterval ));
        setsockopt(fd, SOL_TCP, TCP_KEEPCNT, (void *)&server.keepcount , sizeof(server.keepcount ));
    }

 

Redis 2.6.*里面是默认开启tcp keepalive的。