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本文主要研究一下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 env
func (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方法;其中NextServer会先执行RefreshServerListIfNeed在返回随机的server;RefreshServerListIfNeed方法会根据lastRefreshTime来判断是否需要refresh,若要refresh则重新通过os.Getenv("nacos_server_list")获取server列表,然后更新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方法。
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