redis源码解析之redis事件

源码分析：
networking.c/acceptTcpHandler函数是Redis的连接应答处理器，这个处理器用于对连接服务器监听套接字的客户端进行应答
对于socket.h/accpet的包装

当Redis服务器进行初始化的时候，程序会将连接应答处理器和服务器监听套接字的AE_READABLE事件关联起来，当socket.h/connect
函数连接服务器套接字的时候，会产生AE_READABLE事件，引发连接应答处理器执行，并且执行相应的套接字应答事件
源码中是，redis.c/initServer

/* Create an event handler for accepting new connections in TCP and Unix
     * domain sockets. */
for (j = 0; j < server.ipfd_count; j++) {
    if (aeCreateFileEvent(server.el, server.ipfd[j], AE_READABLE,
        acceptTcpHandler,NULL) == AE_ERR)
        {
            redisPanic(
                "Unrecoverable error creating server.ipfd file event.");
        }
}

命令请求处理器，networking.c/readQueryFromClient函数是Redis的命令请求处理器，这个处理器负责从套接字中读入客户端发送
的请求内容

redisClient *createClient(int fd){

    
    if (fd != -1) {
        anetNonBlock(NULL,fd);
        anetEnableTcpNoDelay(NULL,fd);
        if (server.tcpkeepalive)
            anetKeepAlive(NULL,fd,server.tcpkeepalive);
        if (aeCreateFileEvent(server.el,fd,AE_READABLE,
            readQueryFromClient, c) == AE_ERR)
        {
            close(fd);
            zfree(c);
            return NULL;
        }
    }
}

命令回复处理器，networking.c/sendReplyToClient函数是Redis的命令回复处理器，这个处理器负责将服务器执行命令后的数据返回给客户端
int prepareClientToWrite(redisClient *c) {
    /* If it's the Lua client we always return ok without installing any
     * handler since there is no socket at all. */
    if (c->flags & REDIS_LUA_CLIENT) return REDIS_OK;

    /* Masters don't receive replies, unless REDIS_MASTER_FORCE_REPLY flag
     * is set. */
    if ((c->flags & REDIS_MASTER) &&
        !(c->flags & REDIS_MASTER_FORCE_REPLY)) return REDIS_ERR;

    if (c->fd <= 0) return REDIS_ERR; /* Fake client for AOF loading. */

    /* Only install the handler if not already installed and, in case of
     * slaves, if the client can actually receive writes. */
    if (c->bufpos == 0 && listLength(c->reply) == 0 &&
        (c->replstate == REDIS_REPL_NONE ||
         (c->replstate == REDIS_REPL_ONLINE && !c->repl_put_online_on_ack)))
    {
        /* Try to install the write handler. */
        if (aeCreateFileEvent(server.el, c->fd, AE_WRITABLE,
                sendReplyToClient, c) == AE_ERR)
        {
            freeClientAsync(c);
            return REDIS_ERR;
        }
    }

    /* Authorize the caller to queue in the output buffer of this client. */
    return REDIS_OK;
}

源码也是在redis.c/initServer函数中，初始化了时间事件
/* Create the serverCron() time event, that's our main way to process
     * background operations. */
if(aeCreateTimeEvent(server.el, 1, serverCron, NULL, NULL) == AE_ERR) {
    redisPanic("Can't create the serverCron time event.");
    exit(1);
}

aeProcessEvents中
/* Check time events */
if (flags & AE_TIME_EVENTS)
    processed += processTimeEvents(eventLoop);