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本文次要钻研一下nacos-coredns-plugin的ServerManager

ServerManager

nacos-coredns-plugin/nacos/server_manager.go

type ServerManager struct {    serverList      []string    lastRefreshTime int64    cursor          int}// get nacos ip list from address by envfunc (manager *ServerManager) RefreshServerListIfNeed() []string {    if CurrentMillis()-manager.lastRefreshTime < 60*1000 && len(manager.serverList) > 0 {        return manager.serverList    }    nacosServerList := os.Getenv("nacos_server_list")    var list []string    list = strings.Split(nacosServerList, ",")    var servers []string    for _, line := range list {        if line != "" {            servers = append(servers, strings.TrimSpace(line))        }    }    if len(servers) > 0 {        if !reflect.DeepEqual(manager.serverList, servers) {            NacosClientLogger.Info("server list is updated, old: ", manager.serverList, ", new: ", servers)        }        manager.serverList = servers        manager.lastRefreshTime = CurrentMillis()    }    return manager.serverList}func (manager *ServerManager) NextServer() string {    manager.RefreshServerListIfNeed()    if len(manager.serverList) == 0 {        panic("no nacos server avialible.")    }    return manager.serverList[rand.Intn(len(manager.serverList))]}func (manager *ServerManager) SetServers(servers []string) {    manager.serverList = servers}func (manager *ServerManager) GetServerList() []string {    return manager.serverList}
ServerManager定义了serverList、lastRefreshTime、cursor属性；它提供了RefreshServerListIfNeed、NextServer、SetServers、GetServerList办法；其中NextServer会先执行RefreshServerListIfNeed在返回随机的server；RefreshServerListIfNeed办法会依据lastRefreshTime来判断是否须要refresh，若要refresh则从新通过os.Getenv("nacos_server_list")获取server列表，而后更新lastRefreshTime

实例

nacos-coredns-plugin/nacos/server_manager_test.go

func TestServerManager_NextServer(t *testing.T) {    os.Setenv("nacos_server_list", "2.2.2.2,3.3.3.3")    sm := ServerManager{}    sm.RefreshServerListIfNeed()    ip := sm.NextServer()    if strings.Compare(ip, "2.2.2.2") == 0 ||        strings.Compare(ip, "3.3.3.3") == 0 {        t.Log("ServerManager.NextServer test is passed.")    }}func TestServerManager_RefreshServerListIfNeed(t *testing.T) {    os.Setenv("nacos_server_list", "2.2.2.2,3.3.3.3")    sm := ServerManager{}    sm.RefreshServerListIfNeed()    if len(sm.serverList) == 2 {        t.Log("ServerManager.RefreshServerListIfNeed test is passed.")    }}

小结

nacos-coredns-plugin的ServerManager定义了serverList、lastRefreshTime、cursor属性；它提供了RefreshServerListIfNeed、NextServer、SetServers、GetServerList办法。

doc

  • nacos-coredns-plugin