nsq源码阅读 nsqlookupd源码四 lookup_protocol_v1.go

阅读nsqlookupd/tcp.go源码时，有一段代码：

err = prot.IOLoop(clientConn)

对TCP数据处理的核心逻辑，对应的代码就是nsqlookupd/lookup_protocol_v1.go，现在来阅读这里的代码：

package nsqlookupdimport ("bufio""encoding/binary""encoding/json""fmt""io""log""net""os""strings""sync/atomic""time""github.com/nsqio/nsq/internal/protocol""github.com/nsqio/nsq/internal/version")type LookupProtocolV1 struct {ctx *Context}//实现internal/protocol/protocol.go中Protocol接口的IOLoop方法func (p *LookupProtocolV1) IOLoop(conn net.Conn) error {var err errorvar line string//新建客户端实例, NewClientV1在nsqlookupd/client_v1.go文件中定义client := NewClientV1(conn)reader := bufio.NewReader(client)for {//方法原型 func (b *Reader) ReadString(delim byte) (line string, err error)//参数delim，传入定界符，这里表示读取一行数据line, err = reader.ReadString('\n')if err != nil {break}//去除两边的空格line = strings.TrimSpace(line)//使用空格分割数据//函数原型 func Split(s, sep string) []stringparams := strings.Split(line, " ")var response []byte//调用LookupProtocolV1的Exec()方法//查看Exec()方法源码可知，params第一个元素是动作的类型，共四种PING IDENTIFY REGISTER UNREGISTER//当客户端初始化完后，首先发送IDENTIFY操作，辨认身份，再发送REGISTER 注册一个Registration category:client key: subkey://如果客户端新增一个topic，发送REGISTER，注册这个topic//如果客户端删除一个topic，发送UNREGISTER，注销即删除这个注册信息//TODO 客户端新增或删除channel时，是否调用REGISTER UNREGISTER操作，待确认//客户端每15秒发送一个PING操作response, err = p.Exec(client, reader, params)if err != nil {ctx := ""if parentErr := err.(protocol.ChildErr).Parent(); parentErr != nil {ctx = " - " + parentErr.Error()}p.ctx.nsqlookupd.logf("ERROR: [%s] - %s%s", client, err, ctx)//将错误信息发送给客户端_, sendErr := protocol.SendResponse(client, []byte(err.Error()))if sendErr != nil {p.ctx.nsqlookupd.logf("ERROR: [%s] - %s%s", client, sendErr, ctx)break}// errors of type FatalClientErr should forceably close the connectionif _, ok := err.(*protocol.FatalClientErr); ok {break}continue}//Exec()方法返回了响应数据，将响应数据发送给客户端if response != nil {_, err = protocol.SendResponse(client, response)if err != nil {break}}}//如果上面的循环终止了(程序退出或致命错误)，关闭客户端连接，并删除客户端的所有注册信息conn.Close()p.ctx.nsqlookupd.logf("CLIENT(%s): closing", client)if client.peerInfo != nil {registrations := p.ctx.nsqlookupd.DB.LookupRegistrations(client.peerInfo.id)for _, r := range registrations {if removed, _ := p.ctx.nsqlookupd.DB.RemoveProducer(r, client.peerInfo.id); removed {p.ctx.nsqlookupd.logf("DB: client(%s) UNREGISTER category:%s key:%s subkey:%s",client, r.Category, r.Key, r.SubKey)}}}return err}func (p *LookupProtocolV1) Exec(client *ClientV1, reader *bufio.Reader, params []string) ([]byte, error) {switch params[0] {case "PING":return p.PING(client, params)case "IDENTIFY":return p.IDENTIFY(client, reader, params[1:])case "REGISTER":return p.REGISTER(client, reader, params[1:])case "UNREGISTER":return p.UNREGISTER(client, reader, params[1:])}return nil, protocol.NewFatalClientErr(nil, "E_INVALID", fmt.Sprintf("invalid command %s", params[0]))}func getTopicChan(command string, params []string) (string, string, error) {if len(params) == 0 {return "", "", protocol.NewFatalClientErr(nil, "E_INVALID", fmt.Sprintf("%s insufficient number of params", command))}topicName := params[0]var channelName stringif len(params) >= 2 {channelName = params[1]}if !protocol.IsValidTopicName(topicName) {return "", "", protocol.NewFatalClientErr(nil, "E_BAD_TOPIC", fmt.Sprintf("%s topic name '%s' is not valid", command, topicName))}if channelName != "" && !protocol.IsValidChannelName(channelName) {return "", "", protocol.NewFatalClientErr(nil, "E_BAD_CHANNEL", fmt.Sprintf("%s channel name '%s' is not valid", command, channelName))}return topicName, channelName, nil}//client新建topic时，执行REGISTER操作，注册信息//TODO client新建channel时，是否执行REGISTER，待确认func (p *LookupProtocolV1) REGISTER(client *ClientV1, reader *bufio.Reader, params []string) ([]byte, error) {//必须先执行IDENTIFY操作if client.peerInfo == nil {return nil, protocol.NewFatalClientErr(nil, "E_INVALID", "client must IDENTIFY")}//获取topic名称和channel名称//猜测REGISTER时，client发送的消息为 "REGISTER topicName channelName"topic, channel, err := getTopicChan("REGISTER", params)if err != nil {return nil, err}//注册信息到RegistrationDBif channel != "" {key := Registration{"channel", topic, channel}if p.ctx.nsqlookupd.DB.AddProducer(key, &Producer{peerInfo: client.peerInfo}) {p.ctx.nsqlookupd.logf("DB: client(%s) REGISTER category:%s key:%s subkey:%s",client, "channel", topic, channel)}}key := Registration{"topic", topic, ""}if p.ctx.nsqlookupd.DB.AddProducer(key, &Producer{peerInfo: client.peerInfo}) {p.ctx.nsqlookupd.logf("DB: client(%s) REGISTER category:%s key:%s subkey:%s",client, "topic", topic, "")}return []byte("OK"), nil}//注销func (p *LookupProtocolV1) UNREGISTER(client *ClientV1, reader *bufio.Reader, params []string) ([]byte, error) {if client.peerInfo == nil {return nil, protocol.NewFatalClientErr(nil, "E_INVALID", "client must IDENTIFY")}topic, channel, err := getTopicChan("UNREGISTER", params)if err != nil {return nil, err}if channel != "" {key := Registration{"channel", topic, channel}removed, left := p.ctx.nsqlookupd.DB.RemoveProducer(key, client.peerInfo.id)if removed {p.ctx.nsqlookupd.logf("DB: client(%s) UNREGISTER category:%s key:%s subkey:%s",client, "channel", topic, channel)}// for ephemeral channels, remove the channel as well if it has no producersif left == 0 && strings.HasSuffix(channel, "#ephemeral") {p.ctx.nsqlookupd.DB.RemoveRegistration(key)}} else {// no channel was specified so this is a topic unregistration// remove all of the channel registrations...// normally this shouldn't happen which is why we print a warning message// if anything is actually removedregistrations := p.ctx.nsqlookupd.DB.FindRegistrations("channel", topic, "*")for _, r := range registrations {if removed, _ := p.ctx.nsqlookupd.DB.RemoveProducer(r, client.peerInfo.id); removed {p.ctx.nsqlookupd.logf("WARNING: client(%s) unexpected UNREGISTER category:%s key:%s subkey:%s",client, "channel", topic, r.SubKey)}}key := Registration{"topic", topic, ""}if removed, _ := p.ctx.nsqlookupd.DB.RemoveProducer(key, client.peerInfo.id); removed {p.ctx.nsqlookupd.logf("DB: client(%s) UNREGISTER category:%s key:%s subkey:%s",client, "topic", topic, "")}}return []byte("OK"), nil}//客户端初始化后，先进行IDENTIFY操作，验证身份，初始化peerInfo//IDENTIFY操作在四个操作中最先执行，且只执行一次func (p *LookupProtocolV1) IDENTIFY(client *ClientV1, reader *bufio.Reader, params []string) ([]byte, error) {var err error//已经验证过身份了if client.peerInfo != nil {return nil, protocol.NewFatalClientErr(err, "E_INVALID", "cannot IDENTIFY again")}//读取数据body的长度到bodyLen变量中var bodyLen int32err = binary.Read(reader, binary.BigEndian, &bodyLen)if err != nil {return nil, protocol.NewFatalClientErr(err, "E_BAD_BODY", "IDENTIFY failed to read body size")}body := make([]byte, bodyLen)//读取bodyLen长度的数据_, err = io.ReadFull(reader, body)if err != nil {return nil, protocol.NewFatalClientErr(err, "E_BAD_BODY", "IDENTIFY failed to read body")}// body is a json structure with producer information//将客户端的地址作为peerInfo的唯一标识符peerInfo := PeerInfo{id: client.RemoteAddr().String()}//将json格式的数据解析到peerInfoerr = json.Unmarshal(body, &peerInfo)if err != nil {return nil, protocol.NewFatalClientErr(err, "E_BAD_BODY", "IDENTIFY failed to decode JSON body")}peerInfo.RemoteAddress = client.RemoteAddr().String()// require all fields//验证数据完整性if peerInfo.BroadcastAddress == "" || peerInfo.TCPPort == 0 || peerInfo.HTTPPort == 0 || peerInfo.Version == "" {return nil, protocol.NewFatalClientErr(nil, "E_BAD_BODY", "IDENTIFY missing fields")}//修改peerInfo的lastUpdate为当前时间，不理解为什么这样做//老版本是这样做的 peerInfo.lastUpdate = time.Now().UnixNano()//atomic.StoreInt64() 赋予变量新值，而不管它原来是什么值。atomic.StoreInt64(&peerInfo.lastUpdate, time.Now().UnixNano())p.ctx.nsqlookupd.logf("CLIENT(%s): IDENTIFY Address:%s TCP:%d HTTP:%d Version:%s",client, peerInfo.BroadcastAddress, peerInfo.TCPPort, peerInfo.HTTPPort, peerInfo.Version)//将当前client注册到RegistrationDB里，Registration的Category是"client"， Key和SubKey都为空client.peerInfo = &peerInfoif p.ctx.nsqlookupd.DB.AddProducer(Registration{"client", "", ""}, &Producer{peerInfo: client.peerInfo}) {p.ctx.nsqlookupd.logf("DB: client(%s) REGISTER category:%s key:%s subkey:%s", client, "client", "", "")}// build a response//构建一个响应数据给clientdata := make(map[string]interface{})//nsqlookupd监听的TCP端口data["tcp_port"] = p.ctx.nsqlookupd.RealTCPAddr().Port//nsqlookupd监听的HTTP端口data["http_port"] = p.ctx.nsqlookupd.RealHTTPAddr().Port//当前版本data["version"] = version.Binaryhostname, err := os.Hostname()if err != nil {log.Fatalf("ERROR: unable to get hostname %s", err)}//nsqlookupd的广播地址data["broadcast_address"] = p.ctx.nsqlookupd.opts.BroadcastAddress//hostnamedata["hostname"] = hostname//转化为jsonresponse, err := json.Marshal(data)if err != nil {p.ctx.nsqlookupd.logf("ERROR: marshaling %v", data)return []byte("OK"), nil}return response, nil}func (p *LookupProtocolV1) PING(client *ClientV1, params []string) ([]byte, error) {if client.peerInfo != nil {// we could get a PING before other commands on the same client connectioncur := time.Unix(0, atomic.LoadInt64(&client.peerInfo.lastUpdate))now := time.Now()p.ctx.nsqlookupd.logf("CLIENT(%s): pinged (last ping %s)", client.peerInfo.id,now.Sub(cur))//赋予变量新值，而不管它原来是什么值。//函数原型：//atomic.StoreUint32(addr *uint32, val uint32)//atomic.StoreUint64(addr *uint64, val uint64)//atomic.StoreInt32(addr *int32, val int32)//atomic.StoreInt64(addr *int64, val int64)//atomic.StoreUintptr(addr *uintptr, val uintptr)//atomic.StorePointer(addr *unsafe.Pointer, val unsafe.Pointer)atomic.StoreInt64(&client.peerInfo.lastUpdate, now.UnixNano())}return []byte("OK"), nil}

REGISTER和UNREGISTER操作时，对于channel的新增和删除是否触发这俩操作，不是很清楚，先放一放。