registry/base_registry.go - dubbo-go - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package registry

 import (
 	"context"
 	"fmt"
 	"net/url"
 	"os"
 	"strconv"
 	"strings"
 	"sync"
 	"time"
 )

 import (
 	gxnet "github.com/dubbogo/gost/net"
 	perrors "github.com/pkg/errors"
 )

 import (
 	"github.com/apache/dubbo-go/common"
 	"github.com/apache/dubbo-go/common/constant"
 	"github.com/apache/dubbo-go/common/logger"
 )

 const (
 	// RegistryConnDelay connection delay
 	RegistryConnDelay = 3
 	// MaxWaitInterval max wait interval
 	MaxWaitInterval = 3 * time.Second
 )

 var (
 	processID = ""
 	localIP   = ""
 )

 func init() {
 	processID = fmt.Sprintf("%d", os.Getpid())
 	localIP, _ = gxnet.GetLocalIP()
 }

 /*
  * -----------------------------------NOTICE---------------------------------------------
  * If there is no special case, you'd better inherit BaseRegistry and implement the
  * FacadeBasedRegistry interface instead of directly implementing the Registry interface.
  * --------------------------------------------------------------------------------------
  */

 /*
  * FacadeBasedRegistry interface is subclass of Registry, and it is designed for registry who want to inherit BaseRegistry.
  * You have to implement the interface to inherit BaseRegistry.
  */
 type FacadeBasedRegistry interface {
 	Registry

 	// CreatePath create the path in the registry
 	CreatePath(string) error
 	// DoRegister actually do the register job
 	DoRegister(string, string) error
 	// DoSubscribe actually subscribe the URL
 	DoSubscribe(conf *common.URL) (Listener, error)
 	// CloseAndNilClient close the client and then reset the client in registry to nil
 	// you should notice that this method will be invoked inside a lock.
 	// So you should implement this method as light weighted as you can.
 	CloseAndNilClient()
 	// CloseListener close listeners
 	CloseListener()
 	// InitListeners init listeners
 	InitListeners()
 }

 // BaseRegistry is a common logic abstract for registry. It implement Registry interface.
 type BaseRegistry struct {
 	context             context.Context
 	facadeBasedRegistry FacadeBasedRegistry
 	*common.URL
 	birth    int64          // time of file birth, seconds since Epoch; 0 if unknown
 	wg       sync.WaitGroup // wg+done for zk restart
 	done     chan struct{}
 	cltLock  sync.Mutex            //ctl lock is a lock for services map
 	services map[string]common.URL // service name + protocol -> service config, for store the service registered
 }

 // InitBaseRegistry for init some local variables and set BaseRegistry's subclass to it
 func (r *BaseRegistry) InitBaseRegistry(url *common.URL, facadeRegistry FacadeBasedRegistry) Registry {
 	r.URL = url
 	r.birth = time.Now().UnixNano()
 	r.done = make(chan struct{})
 	r.services = make(map[string]common.URL)
 	r.facadeBasedRegistry = facadeRegistry
 	return r
 }

 // GetUrl for get registry's url
 func (r *BaseRegistry) GetUrl() common.URL {
 	return *r.URL
 }

 // Destroy for graceful down
 func (r *BaseRegistry) Destroy() {
 	//first step close registry's all listeners
 	r.facadeBasedRegistry.CloseListener()
 	// then close r.done to notify other program who listen to it
 	close(r.done)
 	// wait waitgroup done (wait listeners outside close over)
 	r.wg.Wait()
 	//close registry client
 	r.closeRegisters()
 }

 // Register implement interface registry to register
 func (r *BaseRegistry) Register(conf common.URL) error {
 	var (
 		ok  bool
 		err error
 	)
 	role, _ := strconv.Atoi(r.URL.GetParam(constant.ROLE_KEY, ""))
 	// Check if the service has been registered
 	r.cltLock.Lock()
 	_, ok = r.services[conf.Key()]
 	r.cltLock.Unlock()
 	if ok {
 		return perrors.Errorf("Path{%s} has been registered", conf.Key())
 	}

 	err = r.register(conf)
 	if err != nil {
 		return perrors.WithMessagef(err, "register(conf:%+v)", conf)
 	}

 	r.cltLock.Lock()
 	r.services[conf.Key()] = conf
 	r.cltLock.Unlock()
 	logger.Debugf("(%sRegistry)Register(conf{%#v})", common.DubboRole[role], conf)

 	return nil
 }

 // service is for getting service path stored in url
 func (r *BaseRegistry) service(c common.URL) string {
 	return url.QueryEscape(c.Service())
 }

 // RestartCallBack for reregister when reconnect
 func (r *BaseRegistry) RestartCallBack() bool {

 	// copy r.services
 	services := make([]common.URL, 0, len(r.services))
 	for _, confIf := range r.services {
 		services = append(services, confIf)
 	}

 	flag := true
 	for _, confIf := range services {
 		err := r.register(confIf)
 		if err != nil {
 			logger.Errorf("(ZkProviderRegistry)register(conf{%#v}) = error{%#v}",
 				confIf, perrors.WithStack(err))
 			flag = false
 			break
 		}
 		logger.Infof("success to re-register service :%v", confIf.Key())
 	}
 	r.facadeBasedRegistry.InitListeners()

 	return flag
 }

 // register for register url to registry, include init params
 func (r *BaseRegistry) register(c common.URL) error {
 	var (
 		err error
 		//revision   string
 		params     url.Values
 		rawURL     string
 		encodedURL string
 		dubboPath  string
 		//conf       config.URL
 	)
 	params = url.Values{}

 	c.RangeParams(func(key, value string) bool {
 		params.Add(key, value)
 		return true
 	})

 	params.Add("pid", processID)
 	params.Add("ip", localIP)
 	//params.Add("timeout", fmt.Sprintf("%d", int64(r.Timeout)/1e6))

 	role, _ := strconv.Atoi(r.URL.GetParam(constant.ROLE_KEY, ""))
 	switch role {

 	case common.PROVIDER:
 		dubboPath, rawURL, err = r.providerRegistry(c, params)
 	case common.CONSUMER:
 		dubboPath, rawURL, err = r.consumerRegistry(c, params)
 	default:
 		return perrors.Errorf("@c{%v} type is not referencer or provider", c)
 	}
 	encodedURL = url.QueryEscape(rawURL)
 	dubboPath = strings.ReplaceAll(dubboPath, "$", "%24")
 	err = r.facadeBasedRegistry.DoRegister(dubboPath, encodedURL)

 	if err != nil {
 		return perrors.WithMessagef(err, "register Node(path:%s, url:%s)", dubboPath, rawURL)
 	}
 	return nil
 }

 // providerRegistry for provider role do
 func (r *BaseRegistry) providerRegistry(c common.URL, params url.Values) (string, string, error) {
 	var (
 		dubboPath string
 		rawURL    string
 		err       error
 	)
 	if c.Path == "" || len(c.Methods) == 0 {
 		return "", "", perrors.Errorf("conf{Path:%s, Methods:%s}", c.Path, c.Methods)
 	}
 	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), common.DubboNodes[common.PROVIDER])
 	func() {
 		r.cltLock.Lock()
 		defer r.cltLock.Unlock()
 		err = r.facadeBasedRegistry.CreatePath(dubboPath)
 	}()
 	if err != nil {
 		logger.Errorf("facadeBasedRegistry.CreatePath(path{%s}) = error{%#v}", dubboPath, perrors.WithStack(err))
 		return "", "", perrors.WithMessagef(err, "facadeBasedRegistry.CreatePath(path:%s)", dubboPath)
 	}
 	params.Add("anyhost", "true")

 	// Dubbo java consumer to start looking for the provider url,because the category does not match,
 	// the provider will not find, causing the consumer can not start, so we use consumers.
 	// DubboRole               = [...]string{"consumer", "", "", "provider"}
 	// params.Add("category", (RoleType(PROVIDER)).Role())
 	params.Add("category", (common.RoleType(common.PROVIDER)).String())
 	params.Add("dubbo", "dubbo-provider-golang-"+constant.Version)

 	params.Add("side", (common.RoleType(common.PROVIDER)).Role())

 	if len(c.Methods) == 0 {
 		params.Add("methods", strings.Join(c.Methods, ","))
 	}
 	logger.Debugf("provider url params:%#v", params)
 	var host string
 	if c.Ip == "" {
 		host = localIP
 	} else {
 		host = c.Ip
 	}
 	host += ":" + c.Port

 	rawURL = fmt.Sprintf("%s://%s%s?%s", c.Protocol, host, c.Path, params.Encode())
 	// Print your own registration service providers.
 	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), (common.RoleType(common.PROVIDER)).String())
 	logger.Debugf("provider path:%s, url:%s", dubboPath, rawURL)
 	return dubboPath, rawURL, nil
 }

 // consumerRegistry for consumer role do
 func (r *BaseRegistry) consumerRegistry(c common.URL, params url.Values) (string, string, error) {
 	var (
 		dubboPath string
 		rawURL    string
 		err       error
 	)
 	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), common.DubboNodes[common.CONSUMER])

 	func() {
 		r.cltLock.Lock()
 		defer r.cltLock.Unlock()
 		err = r.facadeBasedRegistry.CreatePath(dubboPath)

 	}()
 	if err != nil {
 		logger.Errorf("facadeBasedRegistry.CreatePath(path{%s}) = error{%v}", dubboPath, perrors.WithStack(err))
 		return "", "", perrors.WithStack(err)
 	}
 	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), common.DubboNodes[common.PROVIDER])

 	func() {
 		r.cltLock.Lock()
 		defer r.cltLock.Unlock()
 		err = r.facadeBasedRegistry.CreatePath(dubboPath)
 	}()

 	if err != nil {
 		logger.Errorf("facadeBasedRegistry.CreatePath(path{%s}) = error{%v}", dubboPath, perrors.WithStack(err))
 		return "", "", perrors.WithStack(err)
 	}

 	params.Add("protocol", c.Protocol)
 	params.Add("category", (common.RoleType(common.CONSUMER)).String())
 	params.Add("dubbo", "dubbogo-consumer-"+constant.Version)

 	rawURL = fmt.Sprintf("consumer://%s%s?%s", localIP, c.Path, params.Encode())
 	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), (common.RoleType(common.CONSUMER)).String())

 	logger.Debugf("consumer path:%s, url:%s", dubboPath, rawURL)
 	return dubboPath, rawURL, nil
 }

 // sleepWait...
 func sleepWait(n int) {
 	wait := time.Duration((n + 1) * 2e8)
 	if wait > MaxWaitInterval {
 		wait = MaxWaitInterval
 	}
 	time.Sleep(wait)
 }

 // Subscribe :subscribe from registry, event will notify by notifyListener
 func (r *BaseRegistry) Subscribe(url *common.URL, notifyListener NotifyListener) {
 	n := 0
 	for {
 		n++
 		if !r.IsAvailable() {
 			logger.Warnf("event listener game over.")
 			return
 		}

 		listener, err := r.facadeBasedRegistry.DoSubscribe(url)
 		if err != nil {
 			if !r.IsAvailable() {
 				logger.Warnf("event listener game over.")
 				return
 			}
 			logger.Warnf("getListener() = err:%v", perrors.WithStack(err))
 			time.Sleep(time.Duration(RegistryConnDelay) * time.Second)
 			continue
 		}

 		for {
 			if serviceEvent, err := listener.Next(); err != nil {
 				logger.Warnf("Selector.watch() = error{%v}", perrors.WithStack(err))
 				listener.Close()
 				break
 			} else {
 				logger.Infof("update begin, service event: %v", serviceEvent.String())
 				notifyListener.Notify(serviceEvent)
 			}

 		}
 		sleepWait(n)
 	}
 }

 // closeRegisters close and remove registry client and reset services map
 func (r *BaseRegistry) closeRegisters() {
 	logger.Infof("begin to close provider client")
 	r.cltLock.Lock()
 	defer r.cltLock.Unlock()
 	// Close and remove(set to nil) the registry client
 	r.facadeBasedRegistry.CloseAndNilClient()
 	// reset the services map
 	r.services = nil
 }

 // IsAvailable judge to is registry not closed by chan r.done
 func (r *BaseRegistry) IsAvailable() bool {
 	select {
 	case <-r.done:
 		return false
 	default:
 		return true
 	}
 }

 // WaitGroup open for outside add the waitgroup to add some logic before registry destroyed over(graceful down)
 func (r *BaseRegistry) WaitGroup() *sync.WaitGroup {
 	return &r.wg
 }

 // Done open for outside to listen the event of registry Destroy() called.
 func (r *BaseRegistry) Done() chan struct{} {
 	return r.done
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package registry

	import (
	"context"
	"fmt"
	"net/url"
	"os"
	"strconv"
	"strings"
	"sync"
	"time"
	)

	import (
	gxnet "github.com/dubbogo/gost/net"
	perrors "github.com/pkg/errors"
	)

	import (
	"github.com/apache/dubbo-go/common"
	"github.com/apache/dubbo-go/common/constant"
	"github.com/apache/dubbo-go/common/logger"
	)

	const (
	// RegistryConnDelay connection delay
	RegistryConnDelay = 3
	// MaxWaitInterval max wait interval
	MaxWaitInterval = 3 * time.Second
	)

	var (
	processID = ""
	localIP = ""
	)

	func init() {
	processID = fmt.Sprintf("%d", os.Getpid())
	localIP, _ = gxnet.GetLocalIP()
	}

	/*
	* -----------------------------------NOTICE---------------------------------------------
	* If there is no special case, you'd better inherit BaseRegistry and implement the
	* FacadeBasedRegistry interface instead of directly implementing the Registry interface.
	* --------------------------------------------------------------------------------------
	*/

	/*
	* FacadeBasedRegistry interface is subclass of Registry, and it is designed for registry who want to inherit BaseRegistry.
	* You have to implement the interface to inherit BaseRegistry.
	*/
	type FacadeBasedRegistry interface {
	Registry

	// CreatePath create the path in the registry
	CreatePath(string) error
	// DoRegister actually do the register job
	DoRegister(string, string) error
	// DoSubscribe actually subscribe the URL
	DoSubscribe(conf *common.URL) (Listener, error)
	// CloseAndNilClient close the client and then reset the client in registry to nil
	// you should notice that this method will be invoked inside a lock.
	// So you should implement this method as light weighted as you can.
	CloseAndNilClient()
	// CloseListener close listeners
	CloseListener()
	// InitListeners init listeners
	InitListeners()
	}

	// BaseRegistry is a common logic abstract for registry. It implement Registry interface.
	type BaseRegistry struct {
	context context.Context
	facadeBasedRegistry FacadeBasedRegistry
	*common.URL
	birth int64 // time of file birth, seconds since Epoch; 0 if unknown
	wg sync.WaitGroup // wg+done for zk restart
	done chan struct{}
	cltLock sync.Mutex //ctl lock is a lock for services map
	services map[string]common.URL // service name + protocol -> service config, for store the service registered
	}

	// InitBaseRegistry for init some local variables and set BaseRegistry's subclass to it
	func (r BaseRegistry) InitBaseRegistry(url common.URL, facadeRegistry FacadeBasedRegistry) Registry {
	r.URL = url
	r.birth = time.Now().UnixNano()
	r.done = make(chan struct{})
	r.services = make(map[string]common.URL)
	r.facadeBasedRegistry = facadeRegistry
	return r
	}

	// GetUrl for get registry's url
	func (r *BaseRegistry) GetUrl() common.URL {
	return *r.URL
	}

	// Destroy for graceful down
	func (r *BaseRegistry) Destroy() {
	//first step close registry's all listeners
	r.facadeBasedRegistry.CloseListener()
	// then close r.done to notify other program who listen to it
	close(r.done)
	// wait waitgroup done (wait listeners outside close over)
	r.wg.Wait()
	//close registry client
	r.closeRegisters()
	}

	// Register implement interface registry to register
	func (r *BaseRegistry) Register(conf common.URL) error {
	var (
	ok bool
	err error
	)
	role, _ := strconv.Atoi(r.URL.GetParam(constant.ROLE_KEY, ""))
	// Check if the service has been registered
	r.cltLock.Lock()
	_, ok = r.services[conf.Key()]
	r.cltLock.Unlock()
	if ok {
	return perrors.Errorf("Path{%s} has been registered", conf.Key())
	}

	err = r.register(conf)
	if err != nil {
	return perrors.WithMessagef(err, "register(conf:%+v)", conf)
	}

	r.cltLock.Lock()
	r.services[conf.Key()] = conf
	r.cltLock.Unlock()
	logger.Debugf("(%sRegistry)Register(conf{%#v})", common.DubboRole[role], conf)

	return nil
	}

	// service is for getting service path stored in url
	func (r *BaseRegistry) service(c common.URL) string {
	return url.QueryEscape(c.Service())
	}

	// RestartCallBack for reregister when reconnect
	func (r *BaseRegistry) RestartCallBack() bool {

	// copy r.services
	services := make([]common.URL, 0, len(r.services))
	for _, confIf := range r.services {
	services = append(services, confIf)
	}

	flag := true
	for _, confIf := range services {
	err := r.register(confIf)
	if err != nil {
	logger.Errorf("(ZkProviderRegistry)register(conf{%#v}) = error{%#v}",
	confIf, perrors.WithStack(err))
	flag = false
	break
	}
	logger.Infof("success to re-register service :%v", confIf.Key())
	}
	r.facadeBasedRegistry.InitListeners()

	return flag
	}

	// register for register url to registry, include init params
	func (r *BaseRegistry) register(c common.URL) error {
	var (
	err error
	//revision string
	params url.Values
	rawURL string
	encodedURL string
	dubboPath string
	//conf config.URL
	)
	params = url.Values{}

	c.RangeParams(func(key, value string) bool {
	params.Add(key, value)
	return true
	})

	params.Add("pid", processID)
	params.Add("ip", localIP)
	//params.Add("timeout", fmt.Sprintf("%d", int64(r.Timeout)/1e6))

	role, _ := strconv.Atoi(r.URL.GetParam(constant.ROLE_KEY, ""))
	switch role {

	case common.PROVIDER:
	dubboPath, rawURL, err = r.providerRegistry(c, params)
	case common.CONSUMER:
	dubboPath, rawURL, err = r.consumerRegistry(c, params)
	default:
	return perrors.Errorf("@c{%v} type is not referencer or provider", c)
	}
	encodedURL = url.QueryEscape(rawURL)
	dubboPath = strings.ReplaceAll(dubboPath, "$", "%24")
	err = r.facadeBasedRegistry.DoRegister(dubboPath, encodedURL)

	if err != nil {
	return perrors.WithMessagef(err, "register Node(path:%s, url:%s)", dubboPath, rawURL)
	}
	return nil
	}

	// providerRegistry for provider role do
	func (r *BaseRegistry) providerRegistry(c common.URL, params url.Values) (string, string, error) {
	var (
	dubboPath string
	rawURL string
	err error
	)
	if c.Path == "" \|\| len(c.Methods) == 0 {
	return "", "", perrors.Errorf("conf{Path:%s, Methods:%s}", c.Path, c.Methods)
	}
	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), common.DubboNodes[common.PROVIDER])
	func() {
	r.cltLock.Lock()
	defer r.cltLock.Unlock()
	err = r.facadeBasedRegistry.CreatePath(dubboPath)
	}()
	if err != nil {
	logger.Errorf("facadeBasedRegistry.CreatePath(path{%s}) = error{%#v}", dubboPath, perrors.WithStack(err))
	return "", "", perrors.WithMessagef(err, "facadeBasedRegistry.CreatePath(path:%s)", dubboPath)
	}
	params.Add("anyhost", "true")

	// Dubbo java consumer to start looking for the provider url,because the category does not match,
	// the provider will not find, causing the consumer can not start, so we use consumers.
	// DubboRole = [...]string{"consumer", "", "", "provider"}
	// params.Add("category", (RoleType(PROVIDER)).Role())
	params.Add("category", (common.RoleType(common.PROVIDER)).String())
	params.Add("dubbo", "dubbo-provider-golang-"+constant.Version)

	params.Add("side", (common.RoleType(common.PROVIDER)).Role())

	if len(c.Methods) == 0 {
	params.Add("methods", strings.Join(c.Methods, ","))
	}
	logger.Debugf("provider url params:%#v", params)
	var host string
	if c.Ip == "" {
	host = localIP
	} else {
	host = c.Ip
	}
	host += ":" + c.Port

	rawURL = fmt.Sprintf("%s://%s%s?%s", c.Protocol, host, c.Path, params.Encode())
	// Print your own registration service providers.
	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), (common.RoleType(common.PROVIDER)).String())
	logger.Debugf("provider path:%s, url:%s", dubboPath, rawURL)
	return dubboPath, rawURL, nil
	}

	// consumerRegistry for consumer role do
	func (r *BaseRegistry) consumerRegistry(c common.URL, params url.Values) (string, string, error) {
	var (
	dubboPath string
	rawURL string
	err error
	)
	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), common.DubboNodes[common.CONSUMER])

	func() {
	r.cltLock.Lock()
	defer r.cltLock.Unlock()
	err = r.facadeBasedRegistry.CreatePath(dubboPath)

	}()
	if err != nil {
	logger.Errorf("facadeBasedRegistry.CreatePath(path{%s}) = error{%v}", dubboPath, perrors.WithStack(err))
	return "", "", perrors.WithStack(err)
	}
	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), common.DubboNodes[common.PROVIDER])

	func() {
	r.cltLock.Lock()
	defer r.cltLock.Unlock()
	err = r.facadeBasedRegistry.CreatePath(dubboPath)
	}()

	if err != nil {
	logger.Errorf("facadeBasedRegistry.CreatePath(path{%s}) = error{%v}", dubboPath, perrors.WithStack(err))
	return "", "", perrors.WithStack(err)
	}

	params.Add("protocol", c.Protocol)
	params.Add("category", (common.RoleType(common.CONSUMER)).String())
	params.Add("dubbo", "dubbogo-consumer-"+constant.Version)

	rawURL = fmt.Sprintf("consumer://%s%s?%s", localIP, c.Path, params.Encode())
	dubboPath = fmt.Sprintf("/dubbo/%s/%s", r.service(c), (common.RoleType(common.CONSUMER)).String())

	logger.Debugf("consumer path:%s, url:%s", dubboPath, rawURL)
	return dubboPath, rawURL, nil
	}

	// sleepWait...
	func sleepWait(n int) {
	wait := time.Duration((n + 1) * 2e8)
	if wait > MaxWaitInterval {
	wait = MaxWaitInterval
	}
	time.Sleep(wait)
	}

	// Subscribe :subscribe from registry, event will notify by notifyListener
	func (r BaseRegistry) Subscribe(url common.URL, notifyListener NotifyListener) {
	n := 0
	for {
	n++
	if !r.IsAvailable() {
	logger.Warnf("event listener game over.")
	return
	}

	listener, err := r.facadeBasedRegistry.DoSubscribe(url)
	if err != nil {
	if !r.IsAvailable() {
	logger.Warnf("event listener game over.")
	return
	}
	logger.Warnf("getListener() = err:%v", perrors.WithStack(err))
	time.Sleep(time.Duration(RegistryConnDelay) * time.Second)
	continue
	}

	for {
	if serviceEvent, err := listener.Next(); err != nil {
	logger.Warnf("Selector.watch() = error{%v}", perrors.WithStack(err))
	listener.Close()
	break
	} else {
	logger.Infof("update begin, service event: %v", serviceEvent.String())
	notifyListener.Notify(serviceEvent)
	}

	}
	sleepWait(n)
	}
	}

	// closeRegisters close and remove registry client and reset services map
	func (r *BaseRegistry) closeRegisters() {
	logger.Infof("begin to close provider client")
	r.cltLock.Lock()
	defer r.cltLock.Unlock()
	// Close and remove(set to nil) the registry client
	r.facadeBasedRegistry.CloseAndNilClient()
	// reset the services map
	r.services = nil
	}

	// IsAvailable judge to is registry not closed by chan r.done
	func (r *BaseRegistry) IsAvailable() bool {
	select {
	case <-r.done:
	return false
	default:
	return true
	}
	}

	// WaitGroup open for outside add the waitgroup to add some logic before registry destroyed over(graceful down)
	func (r BaseRegistry) WaitGroup() sync.WaitGroup {
	return &r.wg
	}

	// Done open for outside to listen the event of registry Destroy() called.
	func (r *BaseRegistry) Done() chan struct{} {
	return r.done
	}