func createListener(url url.URL) (net.Listener, error) {
	l, err := net.Listen("tcp", url.Host)
	if err != nil {
		return nil, err
	}
	l, err = transport.NewKeepAliveListener(l, url.Scheme, &tls.Config{})
	if err != nil {
		return nil, err
	}
	return l, nil
}

func createListenersOrPanic(urls types.URLs) (listeners []net.Listener) {
	for _, url := range urls {
		l, err := net.Listen("tcp", url.Host)
		if err != nil {
			panic(err)
		}

		l, err = transport.NewKeepAliveListener(l, url.Scheme, &tls.Config{})
		if err != nil {
			panic(err)
		}

		listeners = append(listeners, l)
	}
	return listeners
}

// newSecuredLocalListener opens a port localhost using any port
// with SSL enable
func newSecuredLocalListener(t *testing.T, certFile, keyFile, caFile string) net.Listener {
	var l net.Listener
	l, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	tlsInfo := transport.TLSInfo{
		CertFile: certFile,
		KeyFile:  keyFile,
		CAFile:   caFile,
	}
	l, err = transport.NewKeepAliveListener(l, "https", tlsInfo)
	if err != nil {
		t.Fatal(err)
	}
	return l
}

// newSecuredLocalListener opens a port localhost using any port
// with SSL enable
func newSecuredLocalListener(t *testing.T, certFile, keyFile, caFile string) net.Listener {
	var l net.Listener
	l, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	tlsInfo := transport.TLSInfo{
		CertFile: certFile,
		KeyFile:  keyFile,
		CAFile:   caFile,
	}
	tlscfg, err := tlsInfo.ServerConfig()
	if err != nil {
		t.Fatalf("unexpected serverConfig error: %v", err)
	}
	l, err = transport.NewKeepAliveListener(l, "https", tlscfg)
	if err != nil {
		t.Fatal(err)
	}
	return l
}

func startClientListeners(cfg *Config) (sctxs map[string]*serveCtx, err error) {
	if cfg.ClientAutoTLS && cfg.ClientTLSInfo.Empty() {
		chosts := make([]string, len(cfg.LCUrls))
		for i, u := range cfg.LCUrls {
			chosts[i] = u.Host
		}
		cfg.ClientTLSInfo, err = transport.SelfCert(path.Join(cfg.Dir, "fixtures/client"), chosts)
		if err != nil {
			plog.Fatalf("could not get certs (%v)", err)
		}
	} else if cfg.ClientAutoTLS {
		plog.Warningf("ignoring client auto TLS since certs given")
	}

	sctxs = make(map[string]*serveCtx)
	for _, u := range cfg.LCUrls {
		sctx := newServeCtx()

		if u.Scheme == "http" || u.Scheme == "unix" {
			if !cfg.ClientTLSInfo.Empty() {
				plog.Warningf("The scheme of client url %s is HTTP while peer key/cert files are presented. Ignored key/cert files.", u.String())
			}
			if cfg.ClientTLSInfo.ClientCertAuth {
				plog.Warningf("The scheme of client url %s is HTTP while client cert auth (--client-cert-auth) is enabled. Ignored client cert auth for this url.", u.String())
			}
		}
		if (u.Scheme == "https" || u.Scheme == "unixs") && cfg.ClientTLSInfo.Empty() {
			return nil, fmt.Errorf("TLS key/cert (--cert-file, --key-file) must be provided for client url %s with HTTPs scheme", u.String())
		}

		proto := "tcp"
		if u.Scheme == "unix" || u.Scheme == "unixs" {
			proto = "unix"
		}

		sctx.secure = u.Scheme == "https" || u.Scheme == "unixs"
		sctx.insecure = !sctx.secure
		if oldctx := sctxs[u.Host]; oldctx != nil {
			oldctx.secure = oldctx.secure || sctx.secure
			oldctx.insecure = oldctx.insecure || sctx.insecure
			continue
		}

		if sctx.l, err = net.Listen(proto, u.Host); err != nil {
			return nil, err
		}

		if fdLimit, fderr := runtimeutil.FDLimit(); fderr == nil {
			if fdLimit <= reservedInternalFDNum {
				plog.Fatalf("file descriptor limit[%d] of etcd process is too low, and should be set higher than %d to ensure internal usage", fdLimit, reservedInternalFDNum)
			}
			sctx.l = transport.LimitListener(sctx.l, int(fdLimit-reservedInternalFDNum))
		}

		if proto == "tcp" {
			if sctx.l, err = transport.NewKeepAliveListener(sctx.l, "tcp", nil); err != nil {
				return nil, err
			}
		}

		plog.Info("listening for client requests on ", u.Host)
		defer func() {
			if err != nil {
				sctx.l.Close()
				plog.Info("stopping listening for client requests on ", u.Host)
			}
		}()
		sctx.userHandlers = cfg.UserHandlers
		sctxs[u.Host] = sctx
	}
	return sctxs, nil
}

// startEtcd launches the etcd server and HTTP handlers for client/server communication.
func startEtcd(cfg *config) (<-chan struct{}, error) {
	initialPeers, token, err := setupCluster(cfg)
	if err != nil {
		return nil, fmt.Errorf("error setting up initial cluster: %v", err)
	}

	pt, err := transport.NewTimeoutTransport(cfg.peerTLSInfo, time.Second, rafthttp.ConnReadTimeout, rafthttp.ConnWriteTimeout)
	if err != nil {
		return nil, err
	}

	if !cfg.peerTLSInfo.Empty() {
		glog.V(2).Infof("etcd: peerTLS: %s", cfg.peerTLSInfo)
	}
	plns := make([]net.Listener, 0)
	for _, u := range cfg.lpurls {
		var l net.Listener
		l, err = transport.NewTimeoutListener(u.Host, u.Scheme, cfg.peerTLSInfo, rafthttp.ConnReadTimeout, rafthttp.ConnWriteTimeout)
		if err != nil {
			return nil, err
		}

		urlStr := u.String()
		glog.V(2).Info("etcd: listening for peers on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				glog.V(2).Info("etcd: stopping listening for peers on ", urlStr)
			}
		}()
		plns = append(plns, l)
	}

	if !cfg.clientTLSInfo.Empty() {
		glog.V(2).Infof("etcd: clientTLS: %s", cfg.clientTLSInfo)
	}
	clns := make([]net.Listener, 0)
	for _, u := range cfg.lcurls {
		l, err := net.Listen("tcp", u.Host)
		if err != nil {
			return nil, err
		}
		l, err = transport.NewKeepAliveListener(l, u.Scheme, cfg.clientTLSInfo)
		if err != nil {
			return nil, err
		}

		urlStr := u.String()
		glog.V(2).Info("etcd: listening for client requests on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				glog.V(2).Info("etcd: stopping listening for client requests on ", urlStr)
			}
		}()
		clns = append(clns, l)
	}

	srvcfg := &etcdserver.ServerConfig{
		Name:                cfg.name,
		ClientURLs:          cfg.acurls,
		PeerURLs:            cfg.apurls,
		DataDir:             cfg.dir,
		SnapCount:           cfg.snapCount,
		MaxSnapFiles:        cfg.maxSnapFiles,
		InitialPeerURLsMap:  initialPeers,
		InitialClusterToken: token,
		MaxWALFiles:         cfg.maxWalFiles,
		NewCluster:          true,
		ForceNewCluster:     false,
		Transport:           pt,
		TickMs:              cfg.TickMs,
		ElectionTicks:       cfg.electionTicks(),
	}
	var s *etcdserver.EtcdServer
	s, err = etcdserver.NewServer(srvcfg)
	if err != nil {
		return nil, err
	}
	osutil.HandleInterrupts()
	s.Start()
	osutil.RegisterInterruptHandler(s.Stop)

	ch := etcdhttp.NewClientHandler(s, srvcfg.ReqTimeout())
	ph := etcdhttp.NewPeerHandler(s.Cluster(), s.RaftHandler())
	// Start the peer server in a goroutine
	for _, l := range plns {
		go func(l net.Listener) {
			glog.Fatal(serveHTTP(l, ph, 5*time.Minute))
		}(l)
	}
	// Start a client server goroutine for each listen address
	for _, l := range clns {
		go func(l net.Listener) {
			// read timeout does not work with http close notify
			// TODO: https://github.com/golang/go/issues/9524
			glog.Fatal(serveHTTP(l, ch, 0))
		}(l)
	}
//.........这里部分代码省略.........

// startEtcd launches the etcd server and HTTP handlers for client/server communication.
func startEtcd(cfg *config) (<-chan struct{}, error) {
	urlsmap, token, err := getPeerURLsMapAndToken(cfg, "etcd")
	if err != nil {
		return nil, fmt.Errorf("error setting up initial cluster: %v", err)
	}

	pt, err := transport.NewTimeoutTransport(cfg.peerTLSInfo, peerDialTimeout(cfg.ElectionMs), rafthttp.ConnReadTimeout, rafthttp.ConnWriteTimeout)
	if err != nil {
		return nil, err
	}

	if !cfg.peerTLSInfo.Empty() {
		plog.Infof("peerTLS: %s", cfg.peerTLSInfo)
	}
	plns := make([]net.Listener, 0)
	for _, u := range cfg.lpurls {
		if u.Scheme == "http" && !cfg.peerTLSInfo.Empty() {
			plog.Warningf("The scheme of peer url %s is http while peer key/cert files are presented. Ignored peer key/cert files.", u.String())
		}
		var l net.Listener
		l, err = transport.NewTimeoutListener(u.Host, u.Scheme, cfg.peerTLSInfo, rafthttp.ConnReadTimeout, rafthttp.ConnWriteTimeout)
		if err != nil {
			return nil, err
		}

		urlStr := u.String()
		plog.Info("listening for peers on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				plog.Info("stopping listening for peers on ", urlStr)
			}
		}()
		plns = append(plns, l)
	}

	if !cfg.clientTLSInfo.Empty() {
		plog.Infof("clientTLS: %s", cfg.clientTLSInfo)
	}
	clns := make([]net.Listener, 0)
	for _, u := range cfg.lcurls {
		if u.Scheme == "http" && !cfg.clientTLSInfo.Empty() {
			plog.Warningf("The scheme of client url %s is http while client key/cert files are presented. Ignored client key/cert files.", u.String())
		}
		var l net.Listener
		l, err = transport.NewKeepAliveListener(u.Host, u.Scheme, cfg.clientTLSInfo)
		if err != nil {
			return nil, err
		}
		if fdLimit, err := runtimeutil.FDLimit(); err == nil {
			if fdLimit <= reservedInternalFDNum {
				plog.Fatalf("file descriptor limit[%d] of etcd process is too low, and should be set higher than %d to ensure internal usage", fdLimit, reservedInternalFDNum)
			}
			l = netutil.LimitListener(l, int(fdLimit-reservedInternalFDNum))
		}

		urlStr := u.String()
		plog.Info("listening for client requests on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				plog.Info("stopping listening for client requests on ", urlStr)
			}
		}()
		clns = append(clns, l)
	}

	var v3l net.Listener
	if cfg.v3demo {
		v3l, err = net.Listen("tcp", cfg.gRPCAddr)
		if err != nil {
			plog.Fatal(err)
		}
		plog.Infof("listening for client rpc on %s", cfg.gRPCAddr)
	}

	srvcfg := &etcdserver.ServerConfig{
		Name:                cfg.name,
		ClientURLs:          cfg.acurls,
		PeerURLs:            cfg.apurls,
		DataDir:             cfg.dir,
		DedicatedWALDir:     cfg.walDir,
		SnapCount:           cfg.snapCount,
		MaxSnapFiles:        cfg.maxSnapFiles,
		MaxWALFiles:         cfg.maxWalFiles,
		InitialPeerURLsMap:  urlsmap,
		InitialClusterToken: token,
		DiscoveryURL:        cfg.durl,
		DiscoveryProxy:      cfg.dproxy,
		NewCluster:          cfg.isNewCluster(),
		ForceNewCluster:     cfg.forceNewCluster,
		Transport:           pt,
		TickMs:              cfg.TickMs,
		ElectionTicks:       cfg.electionTicks(),
		V3demo:              cfg.v3demo,
		StrictReconfigCheck: cfg.strictReconfigCheck,
	}
	var s *etcdserver.EtcdServer
	s, err = etcdserver.NewServer(srvcfg)
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		ctx := &serveCtx{host: u.Host}

		if u.Scheme == "https" {
			ctx.secure = true
		} else {
			ctx.insecure = true
		}

		if sctxs[u.Host] != nil {
			if ctx.secure {
				sctxs[u.Host].secure = true
			}
			if ctx.insecure {
				sctxs[u.Host].insecure = true
			}
			continue
		}

		var l net.Listener

		l, err = net.Listen("tcp", u.Host)
		if err != nil {
			return nil, err
		}

		var fdLimit uint64
		if fdLimit, err = runtimeutil.FDLimit(); err == nil {
			if fdLimit <= reservedInternalFDNum {
				plog.Fatalf("file descriptor limit[%d] of etcd process is too low, and should be set higher than %d to ensure internal usage", fdLimit, reservedInternalFDNum)
			}
			l = transport.LimitListener(l, int(fdLimit-reservedInternalFDNum))
		}

		l, err = transport.NewKeepAliveListener(l, "tcp", nil)
		ctx.l = l
		if err != nil {
			return nil, err
		}

		plog.Info("listening for client requests on ", u.Host)
		defer func() {
			if err != nil {
				l.Close()
				plog.Info("stopping listening for client requests on ", u.Host)
			}
		}()
		sctxs[u.Host] = ctx
	}

	srvcfg := &etcdserver.ServerConfig{
		Name:                    cfg.name,
		ClientURLs:              cfg.acurls,
		PeerURLs:                cfg.apurls,
		DataDir:                 cfg.dir,
		DedicatedWALDir:         cfg.walDir,
		SnapCount:               cfg.snapCount,
		MaxSnapFiles:            cfg.maxSnapFiles,
		MaxWALFiles:             cfg.maxWalFiles,
		InitialPeerURLsMap:      urlsmap,
		InitialClusterToken:     token,
		DiscoveryURL:            cfg.durl,
		DiscoveryProxy:          cfg.dproxy,
		NewCluster:              cfg.isNewCluster(),
		ForceNewCluster:         cfg.forceNewCluster,
		PeerTLSInfo:             cfg.peerTLSInfo,
		TickMs:                  cfg.TickMs,

// startEtcd launches the etcd server and HTTP handlers for client/server communication.
func startEtcd(cfg *config) (<-chan struct{}, error) {
	urlsmap, token, err := getPeerURLsMapAndToken(cfg)
	if err != nil {
		return nil, fmt.Errorf("error setting up initial cluster: %v", err)
	}

	pt, err := transport.NewTimeoutTransport(cfg.peerTLSInfo, rafthttp.DialTimeout, rafthttp.ConnReadTimeout, rafthttp.ConnWriteTimeout)
	if err != nil {
		return nil, err
	}

	if !cfg.peerTLSInfo.Empty() {
		plog.Infof("peerTLS: %s", cfg.peerTLSInfo)
	}
	plns := make([]net.Listener, 0)
	for _, u := range cfg.lpurls {
		var l net.Listener
		l, err = transport.NewTimeoutListener(u.Host, u.Scheme, cfg.peerTLSInfo, rafthttp.ConnReadTimeout, rafthttp.ConnWriteTimeout)
		if err != nil {
			return nil, err
		}

		urlStr := u.String()
		plog.Info("listening for peers on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				plog.Info("stopping listening for peers on ", urlStr)
			}
		}()
		plns = append(plns, l)
	}

	if !cfg.clientTLSInfo.Empty() {
		plog.Infof("clientTLS: %s", cfg.clientTLSInfo)
	}
	clns := make([]net.Listener, 0)
	for _, u := range cfg.lcurls {
		var l net.Listener
		l, err = transport.NewKeepAliveListener(u.Host, u.Scheme, cfg.clientTLSInfo)
		if err != nil {
			return nil, err
		}

		urlStr := u.String()
		plog.Info("listening for client requests on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				plog.Info("stopping listening for client requests on ", urlStr)
			}
		}()
		clns = append(clns, l)
	}

	srvcfg := &etcdserver.ServerConfig{
		Name:                cfg.name,
		ClientURLs:          cfg.acurls,
		PeerURLs:            cfg.apurls,
		DataDir:             cfg.dir,
		SnapCount:           cfg.snapCount,
		MaxSnapFiles:        cfg.maxSnapFiles,
		MaxWALFiles:         cfg.maxWalFiles,
		InitialPeerURLsMap:  urlsmap,
		InitialClusterToken: token,
		DiscoveryURL:        cfg.durl,
		DiscoveryProxy:      cfg.dproxy,
		NewCluster:          cfg.isNewCluster(),
		ForceNewCluster:     cfg.forceNewCluster,
		Transport:           pt,
		TickMs:              cfg.TickMs,
		ElectionTicks:       cfg.electionTicks(),
	}
	var s *etcdserver.EtcdServer
	s, err = etcdserver.NewServer(srvcfg)
	if err != nil {
		return nil, err
	}
	s.Start()
	osutil.RegisterInterruptHandler(s.Stop)

	if cfg.corsInfo.String() != "" {
		plog.Infof("cors = %s", cfg.corsInfo)
	}
	ch := &cors.CORSHandler{
		Handler: etcdhttp.NewClientHandler(s),
		Info:    cfg.corsInfo,
	}
	ph := etcdhttp.NewPeerHandler(s.Cluster(), s.RaftHandler())
	// Start the peer server in a goroutine
	for _, l := range plns {
		go func(l net.Listener) {
			plog.Fatal(serveHTTP(l, ph, 5*time.Minute))
		}(l)
	}
	// Start a client server goroutine for each listen address
	for _, l := range clns {
		go func(l net.Listener) {
			// read timeout does not work with http close notify
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		ctx := &serveCtx{host: u.Host}

		if u.Scheme == "https" {
			ctx.secure = true
		} else {
			ctx.insecure = true
		}

		if sctxs[u.Host] != nil {
			if ctx.secure {
				sctxs[u.Host].secure = true
			}
			if ctx.insecure {
				sctxs[u.Host].insecure = true
			}
			continue
		}

		var l net.Listener

		l, err = net.Listen("tcp", u.Host)
		if err != nil {
			return nil, err
		}

		var fdLimit uint64
		if fdLimit, err = runtimeutil.FDLimit(); err == nil {
			if fdLimit <= reservedInternalFDNum {
				plog.Fatalf("file descriptor limit[%d] of etcd process is too low, and should be set higher than %d to ensure internal usage", fdLimit, reservedInternalFDNum)
			}
			l = transport.LimitListener(l, int(fdLimit-reservedInternalFDNum))
		}

		l, err = transport.NewKeepAliveListener(l, "tcp", nil)
		ctx.l = l
		if err != nil {
			return nil, err
		}

		plog.Info("listening for client requests on ", u.Host)
		defer func() {
			if err != nil {
				l.Close()
				plog.Info("stopping listening for client requests on ", u.Host)
			}
		}()
		sctxs[u.Host] = ctx
	}

	//载入服务器相关配置
	srvcfg := &etcdserver.ServerConfig{
		Name:                    cfg.name,            //etcd服务名
		ClientURLs:              cfg.acurls,          //其他etcd监听型号地址(一般为其他主机或其他端口) (同步与交互etcd信息)
		PeerURLs:                cfg.apurls,          //监听信号地址(本机端口) (同步与交互etcd信息)
		DataDir:                 cfg.dir,             //数据通信保存位置 (默认产生的文件夹 member/snap member/wal)
		DedicatedWALDir:         cfg.walDir,          //ETCD将写WAL文件到walDir而不是DATADIR。这允许使用一个专用磁盘 并有助于避免记录和其它IO操作之间io的竞争。 默认为空 写入DataDir
		SnapCount:               cfg.snapCount,       //提交的事务数来触发快照到磁盘 默认为10000
		MaxSnapFiles:            cfg.maxSnapFiles,    //快照文件保留最大数量（0为无限制）默认值：5 windows为:0
		MaxWALFiles:             cfg.maxWalFiles,     //wal文件保留最大数量（0为无限制）默认值：5 windows为:0
		InitialPeerURLsMap:      urlsmap,             //其他etcd监听型号地址
		InitialClusterToken:     token,               //通信认证用
		DiscoveryURL:            cfg.durl,            //动态发现协议的url
		DiscoveryProxy:          cfg.dproxy,          //动态发现协议(HTTP代理)
		NewCluster:              cfg.isNewCluster(),  //是否为新建集群
		ForceNewCluster:         cfg.forceNewCluster, //--???--
		PeerTLSInfo:             cfg.peerTLSInfo,     //加密文本传输协议基本信息

func startGRPCProxy(cmd *cobra.Command, args []string) {
	l, err := net.Listen("tcp", grpcProxyListenAddr)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	if l, err = transport.NewKeepAliveListener(l, "tcp", nil); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	plog.Infof("listening for grpc-proxy client requests on %s", grpcProxyListenAddr)
	defer func() {
		l.Close()
		plog.Infof("stopping listening for grpc-proxy client requests on %s", grpcProxyListenAddr)
	}()
	m := cmux.New(l)

	cfg, err := newClientCfg()
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

	client, err := clientv3.New(*cfg)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

	kvp := grpcproxy.NewKvProxy(client)
	watchp := grpcproxy.NewWatchProxy(client)
	clusterp := grpcproxy.NewClusterProxy(client)
	leasep := grpcproxy.NewLeaseProxy(client)
	mainp := grpcproxy.NewMaintenanceProxy(client)
	authp := grpcproxy.NewAuthProxy(client)

	server := grpc.NewServer(
		grpc.StreamInterceptor(grpc_prometheus.StreamServerInterceptor),
		grpc.UnaryInterceptor(grpc_prometheus.UnaryServerInterceptor),
	)
	pb.RegisterKVServer(server, kvp)
	pb.RegisterWatchServer(server, watchp)
	pb.RegisterClusterServer(server, clusterp)
	pb.RegisterLeaseServer(server, leasep)
	pb.RegisterMaintenanceServer(server, mainp)
	pb.RegisterAuthServer(server, authp)

	errc := make(chan error)

	grpcl := m.Match(cmux.HTTP2())
	go func() { errc <- server.Serve(grpcl) }()

	httpmux := http.NewServeMux()
	httpmux.HandleFunc("/", http.NotFound)
	httpmux.Handle("/metrics", prometheus.Handler())
	srvhttp := &http.Server{
		Handler: httpmux,
	}

	var httpl net.Listener
	if cfg.TLS != nil {
		srvhttp.TLSConfig = cfg.TLS
		httpl = tls.NewListener(m.Match(cmux.Any()), cfg.TLS)
	} else {
		httpl = m.Match(cmux.HTTP1())
	}
	go func() { errc <- srvhttp.Serve(httpl) }()

	go func() { errc <- m.Serve() }()

	fmt.Fprintln(os.Stderr, <-errc)
	os.Exit(1)
}

// startEtcd launches the etcd server and HTTP handlers for client/server communication.
func startEtcd(cfg *config) (<-chan struct{}, error) {
	cls, err := setupCluster(cfg)
	if err != nil {
		return nil, fmt.Errorf("error setting up initial cluster: %v", err)
	}

	if cfg.dir == "" {
		cfg.dir = fmt.Sprintf("%v.etcd", cfg.name)
		log.Printf("no data-dir provided, using default data-dir ./%s", cfg.dir)
	}
	if err := makeMemberDir(cfg.dir); err != nil {
		return nil, fmt.Errorf("cannot use /member sub-directory: %v", err)
	}
	membdir := path.Join(cfg.dir, "member")
	if err := fileutil.IsDirWriteable(membdir); err != nil {
		return nil, fmt.Errorf("cannot write to data directory: %v", err)
	}

	pt, err := transport.NewTimeoutTransport(cfg.peerTLSInfo, rafthttp.ConnReadTimeout, rafthttp.ConnWriteTimeout)
	if err != nil {
		return nil, err
	}

	if !cfg.peerTLSInfo.Empty() {
		log.Printf("etcd: peerTLS: %s", cfg.peerTLSInfo)
	}
	plns := make([]net.Listener, 0)
	for _, u := range cfg.lpurls {
		var l net.Listener
		l, err = transport.NewTimeoutListener(u.Host, u.Scheme, cfg.peerTLSInfo, rafthttp.ConnReadTimeout, rafthttp.ConnWriteTimeout)
		if err != nil {
			return nil, err
		}

		urlStr := u.String()
		log.Print("etcd: listening for peers on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				log.Print("etcd: stopping listening for peers on ", urlStr)
			}
		}()
		plns = append(plns, l)
	}

	if !cfg.clientTLSInfo.Empty() {
		log.Printf("etcd: clientTLS: %s", cfg.clientTLSInfo)
	}
	clns := make([]net.Listener, 0)
	for _, u := range cfg.lcurls {
		var l net.Listener
		l, err = transport.NewKeepAliveListener(u.Host, u.Scheme, cfg.clientTLSInfo)
		if err != nil {
			return nil, err
		}

		urlStr := u.String()
		log.Print("etcd: listening for client requests on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				log.Print("etcd: stopping listening for client requests on ", urlStr)
			}
		}()
		clns = append(clns, l)
	}

	srvcfg := &etcdserver.ServerConfig{
		Name:            cfg.name,
		ClientURLs:      cfg.acurls,
		PeerURLs:        cfg.apurls,
		DataDir:         membdir,
		SnapCount:       cfg.snapCount,
		MaxSnapFiles:    cfg.maxSnapFiles,
		MaxWALFiles:     cfg.maxWalFiles,
		Cluster:         cls,
		DiscoveryURL:    cfg.durl,
		DiscoveryProxy:  cfg.dproxy,
		NewCluster:      cfg.isNewCluster(),
		ForceNewCluster: cfg.forceNewCluster,
		Transport:       pt,
		TickMs:          cfg.TickMs,
		ElectionTicks:   cfg.electionTicks(),
	}
	var s *etcdserver.EtcdServer
	s, err = etcdserver.NewServer(srvcfg)
	if err != nil {
		return nil, err
	}
	s.Start()

	if cfg.corsInfo.String() != "" {
		log.Printf("etcd: cors = %s", cfg.corsInfo)
	}
	ch := &cors.CORSHandler{
		Handler: etcdhttp.NewClientHandler(s),
		Info:    cfg.corsInfo,
	}
	ph := etcdhttp.NewPeerHandler(s.Cluster, s.RaftHandler())
//.........这里部分代码省略.........

// startEtcd launches the etcd server and HTTP handlers for client/server communication.
func startEtcd(cfg *config) (<-chan struct{}, error) {
	urlsmap, token, err := getPeerURLsMapAndToken(cfg, "etcd")
	if err != nil {
		return nil, fmt.Errorf("error setting up initial cluster: %v", err)
	}

	if cfg.peerAutoTLS && cfg.peerTLSInfo.Empty() {
		phosts := make([]string, 0)
		for _, u := range cfg.lpurls {
			phosts = append(phosts, u.Host)
		}
		cfg.peerTLSInfo, err = transport.SelfCert(cfg.dir, phosts)
		if err != nil {
			plog.Fatalf("could not get certs (%v)", err)
		}
	} else if cfg.peerAutoTLS {
		plog.Warningf("ignoring peer auto TLS since certs given")
	}

	if !cfg.peerTLSInfo.Empty() {
		plog.Infof("peerTLS: %s", cfg.peerTLSInfo)
	}

	plns := make([]net.Listener, 0)
	for _, u := range cfg.lpurls {
		if u.Scheme == "http" && !cfg.peerTLSInfo.Empty() {
			plog.Warningf("The scheme of peer url %s is http while peer key/cert files are presented. Ignored peer key/cert files.", u.String())
		}
		var l net.Listener
		l, err = rafthttp.NewListener(u, cfg.peerTLSInfo)
		if err != nil {
			return nil, err
		}

		urlStr := u.String()
		plog.Info("listening for peers on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				plog.Info("stopping listening for peers on ", urlStr)
			}
		}()
		plns = append(plns, l)
	}

	if !cfg.clientTLSInfo.Empty() {
		plog.Infof("clientTLS: %s", cfg.clientTLSInfo)
	}
	clns := make([]net.Listener, 0)
	for _, u := range cfg.lcurls {
		if u.Scheme == "http" && !cfg.clientTLSInfo.Empty() {
			plog.Warningf("The scheme of client url %s is http while client key/cert files are presented. Ignored client key/cert files.", u.String())
		}
		var l net.Listener
		l, err = net.Listen("tcp", u.Host)
		if err != nil {
			return nil, err
		}

		if fdLimit, err := runtimeutil.FDLimit(); err == nil {
			if fdLimit <= reservedInternalFDNum {
				plog.Fatalf("file descriptor limit[%d] of etcd process is too low, and should be set higher than %d to ensure internal usage", fdLimit, reservedInternalFDNum)
			}
			l = transport.LimitListener(l, int(fdLimit-reservedInternalFDNum))
		}

		// Do not wrap around this listener if TLS Info is set.
		// HTTPS server expects TLS Conn created by TLSListener.
		l, err = transport.NewKeepAliveListener(l, u.Scheme, cfg.clientTLSInfo)
		if err != nil {
			return nil, err
		}

		urlStr := u.String()
		plog.Info("listening for client requests on ", urlStr)
		defer func() {
			if err != nil {
				l.Close()
				plog.Info("stopping listening for client requests on ", urlStr)
			}
		}()
		clns = append(clns, l)
	}

	srvcfg := &etcdserver.ServerConfig{
		Name:                    cfg.name,
		ClientURLs:              cfg.acurls,
		PeerURLs:                cfg.apurls,
		DataDir:                 cfg.dir,
		DedicatedWALDir:         cfg.walDir,
		SnapCount:               cfg.snapCount,
		MaxSnapFiles:            cfg.maxSnapFiles,
		MaxWALFiles:             cfg.maxWalFiles,
		InitialPeerURLsMap:      urlsmap,
		InitialClusterToken:     token,
		DiscoveryURL:            cfg.durl,
		DiscoveryProxy:          cfg.dproxy,
		NewCluster:              cfg.isNewCluster(),
		ForceNewCluster:         cfg.forceNewCluster,
//.........这里部分代码省略.........