nsq源码阅读 nsqlookupd源码三 tcp.go tcp_server.go

来源：互联网发布：大数据改变教育编辑：程序博客网时间：2024/05/16 15:58

nsqlookupd.go中对TCP的处理代码为

protocol.TCPServer(tcpListener, tcpServer, l.opts.Logger)

用户监听处理nsqd发送的信息

TCPServer在internal/protocol/tcp_server.go中定义：

package protocolimport ("fmt""net""runtime""strings""github.com/nsqio/nsq/internal/app")type TCPHandler interface {Handle(net.Conn)}//启动TCP服务，接受客户端连接，并注册处理方法func TCPServer(listener net.Listener, handler TCPHandler, l app.Logger) {l.Output(2, fmt.Sprintf("TCP: listening on %s", listener.Addr()))for {clientConn, err := listener.Accept()//针对不同的错误级别，采用不同的处理方式if err != nil {if nerr, ok := err.(net.Error); ok && nerr.Temporary() {l.Output(2, fmt.Sprintf("NOTICE: temporary Accept() failure - %s", err))runtime.Gosched()continue}// there's no direct way to detect this error because it is not exposedif !strings.Contains(err.Error(), "use of closed network connection") {l.Output(2, fmt.Sprintf("ERROR: listener.Accept() - %s", err))}break}//golang接口的应用go handler.Handle(clientConn)}l.Output(2, fmt.Sprintf("TCP: closing %s", listener.Addr()))}

protocol.tcpServer()的第二个参数，是一个tcpServer实例，在文件nsqlookupd/tcp.go中定义，改实例实现了internal/protocol/tcp_server.go中的TCPHandler接口，

tcp.go:

package nsqlookupdimport ("io""net""github.com/nsqio/nsq/internal/protocol")type tcpServer struct {ctx *Context}func (p *tcpServer) Handle(clientConn net.Conn) {p.ctx.nsqlookupd.logf("TCP: new client(%s)", clientConn.RemoteAddr())// The client should initialize itself by sending a 4 byte sequence indicating// the version of the protocol that it intends to communicate, this will allow us// to gracefully upgrade the protocol away from text/line oriented to whatever...//客户端初始化自己时，需要发送一个4字节序列数据指明它想使用的协议版本buf := make([]byte, 4)//读取协议内容//函数原型// func ReadFull(r Reader, buf []byte) (n int, err error)//把对象 r 中的数据读出来，然后存入一个缓冲区 buf 中_, err := io.ReadFull(clientConn, buf)if err != nil {p.ctx.nsqlookupd.logf("ERROR: failed to read protocol version - %s", err)return}//将读取到的字节流转换成stringprotocolMagic := string(buf)p.ctx.nsqlookupd.logf("CLIENT(%s): desired protocol magic '%s'",clientConn.RemoteAddr(), protocolMagic)//internal/protocol/protocol.go中定义了Protocol接口//接口中方法原型 IOLoop(conn net.Conn) errorvar prot protocol.Protocolswitch protocolMagic {case "  V1"://当前只支持"  V1"协议(前面两个空格，所以共4个字节)//协议在nsqlookupd/lookup_protocol_v1.go中定义//创建LookupProtocolV1实例//LookupProtocolV1实现了Protocol接口prot = &LookupProtocolV1{ctx: p.ctx}default://如果不是"  V1"协议，则断开链接，打印错误信息，返回protocol.SendResponse(clientConn, []byte("E_BAD_PROTOCOL"))clientConn.Close()p.ctx.nsqlookupd.logf("ERROR: client(%s) bad protocol magic '%s'",clientConn.RemoteAddr(), protocolMagic)return}//如果是"  V1"协议，则调用LookupProtocolV1的IOLoop方法err = prot.IOLoop(clientConn)if err != nil {p.ctx.nsqlookupd.logf("ERROR: client(%s) - %s", clientConn.RemoteAddr(), err)return}}

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