服务端

建立服务器连接套接字

server.initServer
在这里插入图片描述
这个方法分别创建了ipv4/v6二个套接字,且设置套接字为非阻塞,并存储fds中
listenToPort

int listenToPort(int port, int *fds, int *count) {
    int j;

    /* Force binding of 0.0.0.0 if no bind address is specified, always
     * entering the loop if j == 0. */
    if (server.bindaddr_count == 0) server.bindaddr[0] = NULL;
    for (j = 0; j < server.bindaddr_count || j == 0; j++) {
        if (server.bindaddr[j] == NULL) {
            int unsupported = 0;
            /* Bind * for both IPv6 and IPv4, we enter here only if
             * server.bindaddr_count == 0. */
            //创建并绑定监听连接的fd,并记录到fds
            fds[*count] = anetTcp6Server(server.neterr,port,NULL,
                server.tcp_backlog);
            //若创建成功
            if (fds[*count] != ANET_ERR) {
                //将fd设置非阻塞
                anetNonBlock(NULL,fds[*count]);
                (*count)++;
            } else if (errno == EAFNOSUPPORT) {
                unsupported++;
                serverLog(LL_WARNING,"Not listening to IPv6: unsupported");
            }

            if (*count == 1 || unsupported) {
                /* Bind the IPv4 address as well. */
                //绑定ipv4
                fds[*count] = anetTcpServer(server.neterr,port,NULL,
                    server.tcp_backlog);
                if (fds[*count] != ANET_ERR) {
                    //将fd设置非阻塞
                    anetNonBlock(NULL,fds[*count]);
                    (*count)++;
                } else if (errno == EAFNOSUPPORT) {
                    unsupported++;
                    serverLog(LL_WARNING,"Not listening to IPv4: unsupported");
                }
            }
            /* Exit the loop if we were able to bind * on IPv4 and IPv6,
             * otherwise fds[*count] will be ANET_ERR and we'll print an
             * error and return to the caller with an error. */
            if (*count + unsupported == 2) break;
        } else if (strchr(server.bindaddr[j],':')) {
            /* Bind IPv6 address. */
            fds[*count] = anetTcp6Server(server.neterr,port,server.bindaddr[j],
                server.tcp_backlog);
        } else {
            /* Bind IPv4 address. */
            fds[*count] = anetTcpServer(server.neterr,port,server.bindaddr[j],
                server.tcp_backlog);
        }
        if (fds[*count] == ANET_ERR) {
            serverLog(LL_WARNING,
                "Could not create server TCP listening socket %s:%d: %s",
                server.bindaddr[j] ? server.bindaddr[j] : "*",
                port, server.neterr);
                if (errno == ENOPROTOOPT     || errno == EPROTONOSUPPORT ||
                    errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
                    errno == EAFNOSUPPORT    || errno == EADDRNOTAVAIL)
                    continue;
            return C_ERR;
        }
        anetNonBlock(NULL,fds[*count]);
        (*count)++;
    }
    return C_OK;
}

创建并绑定监听套接字连接

int anetTcp6Server(char *err, int port, char *bindaddr, int backlog)
{
    return _anetTcpServer(err, port, bindaddr, AF_INET6, backlog);
}


/**
 * 创建并绑定监听套接字连接
 * @param err
 * @param port
 * @param bindaddr
 * @param af
 * @param backlog
 * @return 接收连接的fd
 */
static int _anetTcpServer(char *err, int port, char *bindaddr, int af, int backlog)
{
    int s = -1, rv;
    char _port[6];  /* strlen("65535") */
    struct addrinfo hints, *servinfo, *p;

    //将port按照%d格式,截取6个复制到port中
    snprintf(_port,6,"%d",port);
    //将hints置0
    memset(&hints,0,sizeof(hints));

    //设置ipv6地址协议
    hints.ai_family = af;
    //数据协议为流式协议
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_PASSIVE;    /* No effect if bindaddr != NULL */

    //处理名字到地址以及服务到端口这两种转换,返回一个addrinfo的结构指针,servinfo为传出参数
    if ((rv = getaddrinfo(bindaddr,_port,&hints,&servinfo)) != 0) {
        anetSetError(err, "%s", gai_strerror(rv));
        return ANET_ERR;
    }
    for (p = servinfo; p != NULL; p = p->ai_next) {
        //创建socket服务器套接字
        if ((s = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) == -1)
            continue;

        if (af == AF_INET6 && anetV6Only(err,s) == ANET_ERR) goto error;
        //设置端口复用
        if (anetSetReuseAddr(err,s) == ANET_ERR) goto error;
        //绑定并创建监听套接字
        if (anetListen(err,s,p->ai_addr,p->ai_addrlen,backlog) == ANET_ERR) s = ANET_ERR;
        goto end;
    }
    if (p == NULL) {
        anetSetError(err, "unable to bind socket, errno: %d", errno);
        goto error;
    }

error:
    if (s != -1) close(s);
    s = ANET_ERR;
end:
    freeaddrinfo(servinfo);
    return s;
}

设置端口复用

/**
 * 设置端口复用
 * @param err
 * @param fd
 * @return
 */
static int anetSetReuseAddr(char *err, int fd) {
    int yes = 1;
    /* Make sure connection-intensive things like the redis benchmark
     * will be able to close/open sockets a zillion of times */
    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) == -1) {
        anetSetError(err, "setsockopt SO_REUSEADDR: %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

绑定并创建监听套接字

/**
 * 绑定并创建监听套接字
 * @param err
 * @param s
 * @param sa
 * @param len
 * @param backlog
 * @return
 */
static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len, int backlog) {
    if (bind(s,sa,len) == -1) {
        anetSetError(err, "bind: %s", strerror(errno));
        close(s);
        return ANET_ERR;
    }

    if (listen(s, backlog) == -1) {
        anetSetError(err, "listen: %s", strerror(errno));
        close(s);
        return ANET_ERR;
    }
    return ANET_OK;
}

fd创建好后,会将fd设置非阻塞
anet.anetNonBlock

/**
 * 将fd设置非阻塞
 * @param err
 * @param fd
 * @return
 */
int anetNonBlock(char *err, int fd) {
    return anetSetBlock(err,fd,1);
}
/**
 * 设置fd是否非阻塞
 * @param err
 * @param fd
 * @return
 */
int anetSetBlock(char *err, int fd, int non_block) {
    int flags;

    /* Set the socket blocking (if non_block is zero) or non-blocking.
     * Note that fcntl(2) for F_GETFL and F_SETFL can't be
     * interrupted by a signal. */
    //获取fd属性信息
    if ((flags = fcntl(fd, F_GETFL)) == -1) {
        anetSetError(err, "fcntl(F_GETFL): %s", strerror(errno));
        return ANET_ERR;
    }

    if (non_block)
        flags |= O_NONBLOCK;
    else
        flags &= ~O_NONBLOCK;

    if (fcntl(fd, F_SETFL, flags) == -1) {
        anetSetError(err, "fcntl(F_SETFL,O_NONBLOCK): %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

紧接着就是创建ipv4的套接字,跟上述一样,只是绑定的ip协议不一样而已.还有一步是创建本地套接字,也跟上述一样.

设置监听文件事件,以及对应事件执行函数

socket创建好了,因为我在windows测试的,这里采用的是select模型,对应的需要为每个fd设置监听的事件,以及回调函数,select模型案例,大家可以参考我的这篇文章.点击这里
因为之前分别创建了ipv4/v6二个套接字文件描述符,所以这里会分别注册2次监听AE_READABLE,当事件到达执行acceptTcpHandler
server.initServer
在这里插入图片描述
ae.aeCreateFileEvent
这里需要注意的是
&eventLoop->events[fd]指向的数据全部都置0和NULL了

/*
 * 根据 mask 参数的值，监听 fd 文件的状态，
 * 当 fd 可用时，执行 proc 函数
 */
int aeCreateFileEvent(aeEventLoop *eventLoop, int fd, int mask,
        aeFileProc *proc, void *clientData)
{
    if (fd >= eventLoop->setsize) {
        errno = ERANGE;
        return AE_ERR;
    }
    // 取出文件事件结构
    aeFileEvent *fe = &eventLoop->events[fd];

    // 监听指定 fd 的指定事件
    if (aeApiAddEvent(eventLoop, fd, mask) == -1)
        return AE_ERR;
    // 设置监听的文件事件类型
    fe->mask |= mask;
    //设置监听事件触发时执行的处理器
    if (mask & AE_READABLE) fe->rfileProc = proc;
    if (mask & AE_WRITABLE) fe->wfileProc = proc;
    fe->clientData = clientData;
    //更新最大fd,主要用于后面遍历0~maxfd
    if (fd > eventLoop->maxfd)
        eventLoop->maxfd = fd;
    return AE_OK;
}

监听指定 fd 的指定事件

static int aeApiAddEvent(aeEventLoop *eventLoop, int fd, int mask) {
    aeApiState *state = eventLoop->apidata;

    if (mask & AE_READABLE) FD_SET(fd,&state->rfds);
    if (mask & AE_WRITABLE) FD_SET(fd,&state->wfds);
    return 0;
}

在这里需要注意这个aeApiState 结构,这个结构分别存储了读写文件描述符的监听集合,且_rfds和_wfds作为备份.

typedef struct aeApiState {
    fd_set rfds, wfds;
    /* We need to have a copy of the fd sets as it's not safe to reuse
     * FD sets after select(). */
    fd_set _rfds, _wfds;
} aeApiState;

接受客户端连接

ae.aeProcessEvents
在这里插入图片描述
ae_select

static int aeApiPoll(aeEventLoop *eventLoop, struct timeval *tvp) {
    aeApiState *state = eventLoop->apidata;
    int retval, j, numevents = 0;
    //分别备份,读写文件描述符的监听集合
    memcpy(&state->_rfds,&state->rfds,sizeof(fd_set));
    memcpy(&state->_wfds,&state->wfds,sizeof(fd_set));
    //这里就是熟悉的select了
    retval = select(eventLoop->maxfd+1,
                &state->_rfds,&state->_wfds,NULL,tvp);
    if (retval > 0) {
    //说明有事件发生.
        for (j = 0; j <= eventLoop->maxfd; j++) {
            int mask = 0;
            aeFileEvent *fe = &eventLoop->events[j];

            if (fe->mask == AE_NONE) continue;
            if (fe->mask & AE_READABLE && FD_ISSET(j,&state->_rfds))
                mask |= AE_READABLE;
            if (fe->mask & AE_WRITABLE && FD_ISSET(j,&state->_wfds))
                mask |= AE_WRITABLE;
            //将发生的事件的fd以及事件类型,记录就绪队列中
            eventLoop->fired[numevents].fd = j;
            eventLoop->fired[numevents].mask = mask;
            numevents++;
        }
    }
    return numevents;
}

处理客户端连接
ae.aeProcessEvents

  //处理事件到达
        for (j = 0; j < numevents; j++) {
            // 从已就绪数组中获取事件
            aeFileEvent *fe = &eventLoop->events[eventLoop->fired[j].fd];
            int mask = eventLoop->fired[j].mask;
            int fd = eventLoop->fired[j].fd;
            int fired = 0; 
            int invert = fe->mask & AE_BARRIER;

            //处理读事件
            if (!invert && fe->mask & mask & AE_READABLE) {
                //调用设置的回调函数
                fe->rfileProc(eventLoop,fd,fe->clientData,mask);
                //确保读写事件只能执行一次
                fired++;
                //再次获取fe,防止扩展大小,造成指针错误
                fe = &eventLoop->events[fd]; /* Refresh in case of resize. */
            }

            /* Fire the writable event. */
            //处理写事件
            if (fe->mask & mask & AE_WRITABLE) {
                if (!fired || fe->wfileProc != fe->rfileProc) {
                    fe->wfileProc(eventLoop,fd,fe->clientData,mask);
                    fired++;
                }
            }

            if (invert) {
                fe = &eventLoop->events[fd]; /* Refresh in case of resize. */
                if ((fe->mask & mask & AE_READABLE) &&
                    (!fired || fe->wfileProc != fe->rfileProc))
                {
                    fe->rfileProc(eventLoop,fd,fe->clientData,mask);
                    fired++;
                }
            }

            processed++;
        }
    }

执行处理连接的回调函数
networking

void acceptTcpHandler(aeEventLoop *el, int fd, void *privdata, int mask) {
    int cport, cfd, max = MAX_ACCEPTS_PER_CALL;
    char cip[NET_IP_STR_LEN];
    UNUSED(el);
    UNUSED(mask);
    UNUSED(privdata);

    while(max--) {
        //客户端连接
        cfd = anetTcpAccept(server.neterr, fd, cip, sizeof(cip), &cport);
        if (cfd == ANET_ERR) {
            if (errno != EWOULDBLOCK)
                serverLog(LL_WARNING,
                    "Accepting client connection: %s", server.neterr);
            return;
        }
        serverLog(LL_VERBOSE,"Accepted %s:%d", cip, cport);
        // 为客户端创建客户端状态（redisClient）
        acceptCommonHandler(connCreateAcceptedSocket(cfd),0,cip);        
    }
}

创建客户端连接文件描述符
anet

/**
 * 客户端连接,返回fd
 * @param err
 * @param s
 * @param ip
 * @param ip_len
 * @param port
 * @return
 */
int anetTcpAccept(char *err, int s, char *ip, size_t ip_len, int *port) {
    int fd;
    struct sockaddr_storage sa;
    socklen_t salen = sizeof(sa);
    if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == -1)
        return ANET_ERR;
    //分别对ipv4/6ip以及port校验处理
    if (sa.ss_family == AF_INET) {
        struct sockaddr_in *s = (struct sockaddr_in *)&sa;
        if (ip) inet_ntop(AF_INET,(void*)&(s->sin_addr),ip,ip_len);
        if (port) *port = ntohs(s->sin_port);
    } else {
        struct sockaddr_in6 *s = (struct sockaddr_in6 *)&sa;
        if (ip) inet_ntop(AF_INET6,(void*)&(s->sin6_addr),ip,ip_len);
        if (port) *port = ntohs(s->sin6_port);
    }
    return fd;
}

创建客户端
networking

static void acceptCommonHandler(connection *conn, int flags, char *ip) {
    client *c;    // 创建客户端
    char conninfo[100];
    UNUSED(ip);

    if (connGetState(conn) != CONN_STATE_ACCEPTING) {
        serverLog(LL_VERBOSE,
            "Accepted client connection in error state: %s (conn: %s)",
            connGetLastError(conn),
            connGetInfo(conn, conninfo, sizeof(conninfo)));
        connClose(conn);
        return;
    }

    /* Limit the number of connections we take at the same time.
     *
     * Admission control will happen before a client is created and connAccept()
     * called, because we don't want to even start transport-level negotiation
     * if rejected. */
    // 如果新添加的客户端令服务器的最大客户端数量达到了
    // 那么向新客户端写入错误信息，并关闭新客户端
    // 先创建客户端，再进行数量检查是为了方便地进行错误信息写入
    if (listLength(server.clients) + getClusterConnectionsCount()
        >= server.maxclients)
    {
        char *err;
        if (server.cluster_enabled)
            err = "-ERR max number of clients + cluster "
                  "connections reached\r\n";
        else
            err = "-ERR max number of clients reached\r\n";

        /* That's a best effort error message, don't check write errors.
         * Note that for TLS connections, no handshake was done yet so nothing
         * is written and the connection will just drop. */
        if (connWrite(conn,err,strlen(err)) == -1) {
            /* Nothing to do, Just to avoid the warning... */
        }
        // 更新拒绝连接数
        server.stat_rejected_conn++;
        //关闭客户端连接
        connClose(conn);
        return;
    }

    /* Create connection and client */
    //创建客户端连接
    if ((c = createClient(conn)) == NULL) {
        serverLog(LL_WARNING,
            "Error registering fd event for the new client: %s (conn: %s)",
            connGetLastError(conn),
            connGetInfo(conn, conninfo, sizeof(conninfo)));
        connClose(conn); /* May be already closed, just ignore errors */
        return;
    }

    /* Last chance to keep flags */
    // 设置 FLAG
    c->flags |= flags;

    /* Initiate accept.
     *
     * Note that connAccept() is free to do two things here:
     * 1. Call clientAcceptHandler() immediately;
     * 2. Schedule a future call to clientAcceptHandler().
     *
     * Because of that, we must do nothing else afterwards.
     */
    if (connAccept(conn, clientAcceptHandler) == C_ERR) {
        char conninfo[100];
        if (connGetState(conn) == CONN_STATE_ERROR)
            serverLog(LL_WARNING,
                    "Error accepting a client connection: %s (conn: %s)",
                    connGetLastError(conn), connGetInfo(conn, conninfo, sizeof(conninfo)));
        freeClient(connGetPrivateData(conn));
        return;
    }
}


client *createClient(connection *conn) {
    client *c = zmalloc(sizeof(client));

    /* passing NULL as conn it is possible to create a non connected client.
     * This is useful since all the commands needs to be executed
     * in the context of a client. When commands are executed in other
     * contexts (for instance a Lua script) we need a non connected client. */
    // 当 conn 不为 null 时，创建带网络连接的客户端
    // 如果 conn 为 null ，那么创建无网络连接的伪客户端
    // 因为 Redis 的命令必须在客户端的上下文中使用，所以在执行 Lua 环境中的命令时
    // 需要用到这种伪终端
    if (conn) {
        // 非阻塞
        connNonBlock(conn);
        // 禁用 Nagle 算法
        connEnableTcpNoDelay(conn);
        // 设置 keep alive
        if (server.tcpkeepalive)
            connKeepAlive(conn,server.tcpkeepalive);
        // 绑定读事件到事件 loop （开始接收命令请求）,以及设置回调函数readQueryFromClient
        connSetReadHandler(conn, readQueryFromClient);
        connSetPrivateData(conn, c);
    }
    // 初始化各个属性

    // 默认数据库
    selectDb(c,0);
    uint64_t client_id = ++server.next_client_id;
    c->id = client_id;
    c->resp = 2;
    c->conn = conn;
    // 名字
    c->name = NULL;
    // 回复缓冲区的偏移量
    c->bufpos = 0;
    c->qb_pos = 0;
    // 查询缓冲区
    c->querybuf = sdsempty();
    c->pending_querybuf = sdsempty();
    // 查询缓冲区峰值
    c->querybuf_peak = 0;
    c->reqtype = 0;
    c->argc = 0;
    c->argv = NULL;
    c->cmd = c->lastcmd = NULL;
    c->user = DefaultUser;
    c->multibulklen = 0;
    c->bulklen = -1;
    c->sentlen = 0;
    c->flags = 0;
    c->ctime = c->lastinteraction = server.unixtime;
    /* If the default user does not require authentication, the user is
     * directly authenticated. */
    c->authenticated = (c->user->flags & USER_FLAG_NOPASS) &&
                       !(c->user->flags & USER_FLAG_DISABLED);
    c->replstate = REPL_STATE_NONE;
    c->repl_put_online_on_ack = 0;
    c->reploff = 0;
    c->read_reploff = 0;
    c->repl_ack_off = 0;
    c->repl_ack_time = 0;
    c->slave_listening_port = 0;
    c->slave_ip[0] = '\0';
    c->slave_capa = SLAVE_CAPA_NONE;
    c->reply = listCreate();
    c->reply_bytes = 0;
    c->obuf_soft_limit_reached_time = 0;
    listSetFreeMethod(c->reply,freeClientReplyValue);
    listSetDupMethod(c->reply,dupClientReplyValue);
    c->btype = BLOCKED_NONE;
    c->bpop.timeout = 0;
    c->bpop.keys = dictCreate(&objectKeyHeapPointerValueDictType,NULL);
    c->bpop.target = NULL;
    c->bpop.xread_group = NULL;
    c->bpop.xread_consumer = NULL;
    c->bpop.xread_group_noack = 0;
    c->bpop.numreplicas = 0;
    c->bpop.reploffset = 0;
    c->woff = 0;
    c->watched_keys = listCreate();
    c->pubsub_channels = dictCreate(&objectKeyPointerValueDictType,NULL);
    c->pubsub_patterns = listCreate();
    c->peerid = NULL;
    c->client_list_node = NULL;
    c->client_tracking_redirection = 0;
    c->client_tracking_prefixes = NULL;
    c->client_cron_last_memory_usage = 0;
    c->client_cron_last_memory_type = CLIENT_TYPE_NORMAL;
    c->auth_callback = NULL;
    c->auth_callback_privdata = NULL;
    c->auth_module = NULL;
    listSetFreeMethod(c->pubsub_patterns,decrRefCountVoid);
    listSetMatchMethod(c->pubsub_patterns,listMatchObjects);
    if (conn) linkClient(c); //c添加到链表尾部
    initClientMultiState(c);

    // 返回客户端
    return c;
}

为新建立连接的fd,绑定监听读事件,以及事件处理函数.主要用于客户端与服务端的交互
connection

static inline int connSetReadHandler(connection *conn, ConnectionCallbackFunc func) {
    //设置读事件发生时,处理函数
    return conn->type->set_read_handler(conn, func);
}

也就是在这一步为客户端连接文件描述符监听读事件,以及设置了读事件到达时的回调函数.

static int connSocketSetReadHandler(connection *conn, ConnectionCallbackFunc func) {
    if (func == conn->read_handler) return C_OK;

    conn->read_handler = func;
    if (!conn->read_handler)
        aeDeleteFileEvent(server.el,conn->fd,AE_READABLE);
    else //注册监听读事件
        if (aeCreateFileEvent(server.el,conn->fd,
                    AE_READABLE,conn->type->ae_handler,conn) == AE_ERR) return C_ERR;
    return C_OK;
}