[GitHub] [dubbo-go] DogBaoBao opened a new pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

DogBaoBao opened a new pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732


   <!--  Thanks for sending a pull request! 
   -->
   
   **What this PR does**:
   The implementation of ServiceDiscovery based on file system.
   
   **Which issue(s) this PR fixes**:
   <!--
   *Automatically closes linked issue when PR is merged.
   Usage: `Fixes #<issue number>`, or `Fixes (paste link of issue)`.
   _If PR is about `failing-tests or flakes`, please post the related issues/tests in a comment and do not use `Fixes`_*
   -->
   Fixes #426
   
   **Special notes for your reviewer**:
   
   **Does this PR introduce a user-facing change?**:
   <!--
   If no, just write "NONE" in the release-note block below.
   If yes, a release note is required:
   Enter your extended release note in the block below. If the PR requires additional action from users switching to the new release, include the string "action required".
   -->
   ```release-note
   
   ```


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[GitHub] [dubbo-go] zouyx commented on a change in pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

zouyx commented on a change in pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732#discussion_r484622036



##########
File path: config_center/file/listener.go
##########
@@ -0,0 +1,155 @@
+/*
+ * 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 file
+
+import (
+	"io/ioutil"
+	"sync"
+)
+
+import (
+	"github.com/fsnotify/fsnotify"
+)
+
+import (
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/remoting"
+)
+
+// CacheListener is file watcher
+type CacheListener struct {
+	watch        *fsnotify.Watcher
+	keyListeners sync.Map
+	rootPath     string
+}
+
+// NewCacheListener creates a new CacheListener
+func NewCacheListener(rootPath string) *CacheListener {
+	cl := &CacheListener{rootPath: rootPath}
+	// start watcher
+	watch, err := fsnotify.NewWatcher()
+	if err != nil {
+		logger.Errorf("file : listen config fail, error:%v ", err)
+	}
+	go func() {
+		for {
+			select {
+			case event := <-watch.Events:
+				key := event.Name
+				logger.Debugf("watcher %s, event %v", cl.rootPath, event)
+				if event.Op&fsnotify.Write == fsnotify.Write {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeUpdate)
+					}
+				}
+				if event.Op&fsnotify.Create == fsnotify.Create {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeAdd)
+					}
+				}
+				if event.Op&fsnotify.Remove == fsnotify.Remove {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						removeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeDel)
+					}
+				}
+			case err := <-watch.Errors:
+				// err may be nil, ignore
+				if err != nil {
+					logger.Warnf("file : listen watch fail:%+v", err)
+				}
+			}
+		}
+	}()
+	cl.watch = watch
+
+	extension.AddCustomShutdownCallback(func() {
+		cl.watch.Close()
+	})
+
+	return cl
+}
+
+func removeCallback(lmap map[config_center.ConfigurationListener]struct{}, key string, event remoting.EventType) {
+	if len(lmap) == 0 {
+		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)

Review comment:
       ```suggestion
   		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)
   		return
   ```
   
   Should return directly here

##########
File path: config_center/file/listener.go
##########
@@ -0,0 +1,155 @@
+/*
+ * 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 file
+
+import (
+	"io/ioutil"
+	"sync"
+)
+
+import (
+	"github.com/fsnotify/fsnotify"
+)
+
+import (
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/remoting"
+)
+
+// CacheListener is file watcher
+type CacheListener struct {
+	watch        *fsnotify.Watcher
+	keyListeners sync.Map
+	rootPath     string
+}
+
+// NewCacheListener creates a new CacheListener
+func NewCacheListener(rootPath string) *CacheListener {
+	cl := &CacheListener{rootPath: rootPath}
+	// start watcher
+	watch, err := fsnotify.NewWatcher()
+	if err != nil {
+		logger.Errorf("file : listen config fail, error:%v ", err)
+	}
+	go func() {
+		for {
+			select {
+			case event := <-watch.Events:
+				key := event.Name
+				logger.Debugf("watcher %s, event %v", cl.rootPath, event)
+				if event.Op&fsnotify.Write == fsnotify.Write {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeUpdate)
+					}
+				}
+				if event.Op&fsnotify.Create == fsnotify.Create {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeAdd)
+					}
+				}
+				if event.Op&fsnotify.Remove == fsnotify.Remove {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						removeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeDel)
+					}
+				}
+			case err := <-watch.Errors:
+				// err may be nil, ignore
+				if err != nil {
+					logger.Warnf("file : listen watch fail:%+v", err)
+				}
+			}
+		}
+	}()
+	cl.watch = watch
+
+	extension.AddCustomShutdownCallback(func() {
+		cl.watch.Close()
+	})
+
+	return cl
+}
+
+func removeCallback(lmap map[config_center.ConfigurationListener]struct{}, key string, event remoting.EventType) {
+	if len(lmap) == 0 {
+		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)
+	}
+	for l := range lmap {
+		callback(l, key, "", event)
+	}
+}
+
+func dataChangeCallback(lmap map[config_center.ConfigurationListener]struct{}, key string, event remoting.EventType) {
+	if len(lmap) == 0 {
+		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)

Review comment:
       As above?

##########
File path: config_center/file/listener.go
##########
@@ -0,0 +1,155 @@
+/*
+ * 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 file
+
+import (
+	"io/ioutil"
+	"sync"
+)
+
+import (
+	"github.com/fsnotify/fsnotify"
+)
+
+import (
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/remoting"
+)
+
+// CacheListener is file watcher
+type CacheListener struct {
+	watch        *fsnotify.Watcher
+	keyListeners sync.Map
+	rootPath     string
+}
+
+// NewCacheListener creates a new CacheListener
+func NewCacheListener(rootPath string) *CacheListener {
+	cl := &CacheListener{rootPath: rootPath}
+	// start watcher
+	watch, err := fsnotify.NewWatcher()
+	if err != nil {
+		logger.Errorf("file : listen config fail, error:%v ", err)
+	}
+	go func() {
+		for {
+			select {
+			case event := <-watch.Events:
+				key := event.Name
+				logger.Debugf("watcher %s, event %v", cl.rootPath, event)
+				if event.Op&fsnotify.Write == fsnotify.Write {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeUpdate)
+					}
+				}
+				if event.Op&fsnotify.Create == fsnotify.Create {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeAdd)
+					}
+				}
+				if event.Op&fsnotify.Remove == fsnotify.Remove {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						removeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeDel)
+					}
+				}
+			case err := <-watch.Errors:
+				// err may be nil, ignore
+				if err != nil {
+					logger.Warnf("file : listen watch fail:%+v", err)
+				}
+			}
+		}
+	}()
+	cl.watch = watch
+
+	extension.AddCustomShutdownCallback(func() {
+		cl.watch.Close()
+	})
+
+	return cl
+}
+
+func removeCallback(lmap map[config_center.ConfigurationListener]struct{}, key string, event remoting.EventType) {
+	if len(lmap) == 0 {
+		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)
+	}
+	for l := range lmap {
+		callback(l, key, "", event)
+	}
+}
+
+func dataChangeCallback(lmap map[config_center.ConfigurationListener]struct{}, key string, event remoting.EventType) {
+	if len(lmap) == 0 {
+		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)
+	}
+	c := getFileContent(key)
+	for l := range lmap {
+		callback(l, key, c, event)
+	}
+}
+
+func callback(listener config_center.ConfigurationListener, path, data string, event remoting.EventType) {
+	listener.Process(&config_center.ConfigChangeEvent{Key: path, Value: data, ConfigType: event})
+}
+
+// Close will remove key listener and close watcher
+func (cl *CacheListener) Close() error {
+	cl.keyListeners.Range(func(key, value interface{}) bool {
+		cl.keyListeners.Delete(key)
+		return true
+	})
+	return cl.watch.Close()
+}
+
+// AddListener will add a listener if loaded
+// if you watcher a file or directory not exist, will error with no such file or directory
+func (cl *CacheListener) AddListener(key string, listener config_center.ConfigurationListener) {
+	// reference from https://stackoverflow.com/questions/34018908/golang-why-dont-we-have-a-set-datastructure
+	// make a map[your type]struct{} like set in java
+	listeners, loaded := cl.keyListeners.LoadOrStore(key, map[config_center.ConfigurationListener]struct{}{listener: {}})
+	if loaded {
+		listeners.(map[config_center.ConfigurationListener]struct{})[listener] = struct{}{}
+		cl.keyListeners.Store(key, listeners)
+	} else {
+		if err := cl.watch.Add(key); err != nil {
+			logger.Errorf("watcher add path:%s err:%v", key, err)
+		}
+	}
+}
+
+// RemoveListener will delete a listener if loaded
+func (cl *CacheListener) RemoveListener(key string, listener config_center.ConfigurationListener) {
+	listeners, loaded := cl.keyListeners.Load(key)
+	if loaded {
+		delete(listeners.(map[config_center.ConfigurationListener]struct{}), listener)
+		if err := cl.watch.Remove(key); err != nil {
+			logger.Errorf("watcher remove path:%s err:%v", key, err)
+		}
+	}

Review comment:
       ```suggestion
   	if !loaded {
   		return
   	}
   	delete(listeners.(map[config_center.ConfigurationListener]struct{}), listener)
   		if err := cl.watch.Remove(key); err != nil {
   			logger.Errorf("watcher remove path:%s err:%v", key, err)
   		}
   ```

##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,291 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	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/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+var (
+	// 16 would be enough. We won't use concurrentMap because in most cases, there are not race condition
+	instanceMap = make(map[string]registry.ServiceDiscovery, 16)
+	initLock    sync.Mutex
+)
+
+// init will put the service discovery into extension
+func init() {
+	extension.SetServiceDiscovery(constant.FILE_KEY, newFileSystemServiceDiscovery)
+}
+
+// fileServiceDiscovery is the implementation of service discovery based on file.
+type fileSystemServiceDiscovery struct {
+	dynamicConfiguration file.FileSystemDynamicConfiguration
+	rootPath             string
+	fileMap              map[string]string
+}
+
+func newFileSystemServiceDiscovery(name string) (registry.ServiceDiscovery, error) {
+	instance, ok := instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	initLock.Lock()
+	defer initLock.Unlock()
+
+	// double check
+	instance, ok = instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	sdc, ok := config.GetBaseConfig().GetServiceDiscoveries(name)
+	if !ok || sdc.Protocol != constant.FILE_KEY {
+		return nil, perrors.New("could not init the instance because the config is invalid")
+	}
+
+	if rp, err := file.Home(); err != nil {
+		return nil, perrors.WithStack(err)
+	} else {
+		fdcf := extension.GetConfigCenterFactory(constant.FILE_KEY)
+		p := path.Join(rp, ".dubbo", "registry")
+		url, _ := common.NewURL("")
+		url.AddParamAvoidNil(file.CONFIG_CENTER_DIR_PARAM_NAME, p)
+		if c, err := fdcf.GetDynamicConfiguration(&url); err != nil {
+			return nil, perrors.New("could not find the config for name: " + name)
+		} else {
+			sd := &fileSystemServiceDiscovery{
+				dynamicConfiguration: *c.(*file.FileSystemDynamicConfiguration),
+				rootPath:             p,
+				fileMap:              make(map[string]string),
+			}
+
+			extension.AddCustomShutdownCallback(func() {
+				sd.Destroy()
+			})
+
+			for _, v := range sd.GetServices().Values() {
+				for _, i := range sd.GetInstances(v.(string)) {
+					// like java do nothing
+					l := &RegistryConfigurationListener{}
+					sd.dynamicConfiguration.AddListener(getServiceInstanceId(i), l, config_center.WithGroup(getServiceName(i)))
+				}
+			}
+
+			return sd, nil
+		}
+	}
+}
+
+// nolint
+func (fssd *fileSystemServiceDiscovery) String() string {
+	return fmt.Sprintf("file-system-service-discovery")
+}
+
+// Destroy will destroy the service discovery.
+// If the discovery cannot be destroy, it will return an error.
+func (fssd *fileSystemServiceDiscovery) Destroy() error {
+	fssd.dynamicConfiguration.Close()
+
+	for _, f := range fssd.fileMap {
+		fssd.releaseAndRemoveRegistrationFiles(f)
+	}
+
+	return nil
+}
+
+// nolint
+func (fssd *fileSystemServiceDiscovery) releaseAndRemoveRegistrationFiles(file string) {
+	os.RemoveAll(file)
+}
+
+// ----------------- registration ----------------
+
+// Register will register an instance of ServiceInstance to registry
+func (fssd *fileSystemServiceDiscovery) Register(instance registry.ServiceInstance) error {
+	id := getServiceInstanceId(instance)
+	sn := getServiceName(instance)
+	if c, err := getContent(instance); err != nil {
+		return err
+	} else {
+		if err := fssd.dynamicConfiguration.PublishConfig(id, sn, c); err != nil {
+			return perrors.WithStack(err)
+		} else {
+			fssd.fileMap[id] = fssd.dynamicConfiguration.GetPath(id, sn)
+		}
+	}

Review comment:
       ```suggestion
   	} 
   	if err := fssd.dynamicConfiguration.PublishConfig(id, sn, c); err != nil {
   		return perrors.WithStack(err)
   	}
   	fssd.fileMap[id] = fssd.dynamicConfiguration.GetPath(id, sn)
   		
   ```

##########
File path: config_center/file/listener.go
##########
@@ -0,0 +1,155 @@
+/*
+ * 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 file
+
+import (
+	"io/ioutil"
+	"sync"
+)
+
+import (
+	"github.com/fsnotify/fsnotify"
+)
+
+import (
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/remoting"
+)
+
+// CacheListener is file watcher
+type CacheListener struct {
+	watch        *fsnotify.Watcher
+	keyListeners sync.Map
+	rootPath     string
+}
+
+// NewCacheListener creates a new CacheListener
+func NewCacheListener(rootPath string) *CacheListener {
+	cl := &CacheListener{rootPath: rootPath}
+	// start watcher
+	watch, err := fsnotify.NewWatcher()
+	if err != nil {
+		logger.Errorf("file : listen config fail, error:%v ", err)
+	}
+	go func() {
+		for {
+			select {
+			case event := <-watch.Events:
+				key := event.Name
+				logger.Debugf("watcher %s, event %v", cl.rootPath, event)
+				if event.Op&fsnotify.Write == fsnotify.Write {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeUpdate)
+					}
+				}
+				if event.Op&fsnotify.Create == fsnotify.Create {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeAdd)
+					}
+				}
+				if event.Op&fsnotify.Remove == fsnotify.Remove {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						removeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeDel)
+					}
+				}
+			case err := <-watch.Errors:
+				// err may be nil, ignore
+				if err != nil {
+					logger.Warnf("file : listen watch fail:%+v", err)
+				}
+			}
+		}
+	}()
+	cl.watch = watch
+
+	extension.AddCustomShutdownCallback(func() {
+		cl.watch.Close()
+	})
+
+	return cl
+}
+
+func removeCallback(lmap map[config_center.ConfigurationListener]struct{}, key string, event remoting.EventType) {
+	if len(lmap) == 0 {
+		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)
+	}
+	for l := range lmap {
+		callback(l, key, "", event)
+	}
+}
+
+func dataChangeCallback(lmap map[config_center.ConfigurationListener]struct{}, key string, event remoting.EventType) {
+	if len(lmap) == 0 {
+		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)
+	}
+	c := getFileContent(key)
+	for l := range lmap {
+		callback(l, key, c, event)
+	}
+}
+
+func callback(listener config_center.ConfigurationListener, path, data string, event remoting.EventType) {
+	listener.Process(&config_center.ConfigChangeEvent{Key: path, Value: data, ConfigType: event})
+}
+
+// Close will remove key listener and close watcher
+func (cl *CacheListener) Close() error {
+	cl.keyListeners.Range(func(key, value interface{}) bool {
+		cl.keyListeners.Delete(key)
+		return true
+	})
+	return cl.watch.Close()
+}
+
+// AddListener will add a listener if loaded
+// if you watcher a file or directory not exist, will error with no such file or directory
+func (cl *CacheListener) AddListener(key string, listener config_center.ConfigurationListener) {
+	// reference from https://stackoverflow.com/questions/34018908/golang-why-dont-we-have-a-set-datastructure
+	// make a map[your type]struct{} like set in java
+	listeners, loaded := cl.keyListeners.LoadOrStore(key, map[config_center.ConfigurationListener]struct{}{listener: {}})
+	if loaded {
+		listeners.(map[config_center.ConfigurationListener]struct{})[listener] = struct{}{}
+		cl.keyListeners.Store(key, listeners)
+	} else {
+		if err := cl.watch.Add(key); err != nil {
+			logger.Errorf("watcher add path:%s err:%v", key, err)
+		}
+	}

Review comment:
       ```suggestion
   	if loaded {
   		listeners.(map[config_center.ConfigurationListener]struct{})[listener] = struct{}{}
   		cl.keyListeners.Store(key, listeners)
   		return
   	} 
   		if err := cl.watch.Add(key); err != nil {
   			logger.Errorf("watcher add path:%s err:%v", key, err)
   		}
   	
   ```

##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,291 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	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/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+var (
+	// 16 would be enough. We won't use concurrentMap because in most cases, there are not race condition
+	instanceMap = make(map[string]registry.ServiceDiscovery, 16)
+	initLock    sync.Mutex
+)
+
+// init will put the service discovery into extension
+func init() {
+	extension.SetServiceDiscovery(constant.FILE_KEY, newFileSystemServiceDiscovery)
+}
+
+// fileServiceDiscovery is the implementation of service discovery based on file.
+type fileSystemServiceDiscovery struct {
+	dynamicConfiguration file.FileSystemDynamicConfiguration
+	rootPath             string
+	fileMap              map[string]string
+}
+
+func newFileSystemServiceDiscovery(name string) (registry.ServiceDiscovery, error) {
+	instance, ok := instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	initLock.Lock()
+	defer initLock.Unlock()
+
+	// double check
+	instance, ok = instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	sdc, ok := config.GetBaseConfig().GetServiceDiscoveries(name)
+	if !ok || sdc.Protocol != constant.FILE_KEY {
+		return nil, perrors.New("could not init the instance because the config is invalid")
+	}
+
+	if rp, err := file.Home(); err != nil {
+		return nil, perrors.WithStack(err)
+	} else {
+		fdcf := extension.GetConfigCenterFactory(constant.FILE_KEY)
+		p := path.Join(rp, ".dubbo", "registry")

Review comment:
       ```suggestion
   		p := path.Join(rp, ".dubbo",constant.REGISTRY_KEY)
   ```

##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,291 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	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/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+var (
+	// 16 would be enough. We won't use concurrentMap because in most cases, there are not race condition
+	instanceMap = make(map[string]registry.ServiceDiscovery, 16)
+	initLock    sync.Mutex
+)
+
+// init will put the service discovery into extension
+func init() {
+	extension.SetServiceDiscovery(constant.FILE_KEY, newFileSystemServiceDiscovery)
+}
+
+// fileServiceDiscovery is the implementation of service discovery based on file.
+type fileSystemServiceDiscovery struct {
+	dynamicConfiguration file.FileSystemDynamicConfiguration
+	rootPath             string
+	fileMap              map[string]string
+}
+
+func newFileSystemServiceDiscovery(name string) (registry.ServiceDiscovery, error) {
+	instance, ok := instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	initLock.Lock()
+	defer initLock.Unlock()
+
+	// double check
+	instance, ok = instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	sdc, ok := config.GetBaseConfig().GetServiceDiscoveries(name)
+	if !ok || sdc.Protocol != constant.FILE_KEY {
+		return nil, perrors.New("could not init the instance because the config is invalid")
+	}
+
+	if rp, err := file.Home(); err != nil {
+		return nil, perrors.WithStack(err)
+	} else {
+		fdcf := extension.GetConfigCenterFactory(constant.FILE_KEY)
+		p := path.Join(rp, ".dubbo", "registry")
+		url, _ := common.NewURL("")
+		url.AddParamAvoidNil(file.CONFIG_CENTER_DIR_PARAM_NAME, p)
+		if c, err := fdcf.GetDynamicConfiguration(&url); err != nil {
+			return nil, perrors.New("could not find the config for name: " + name)
+		} else {
+			sd := &fileSystemServiceDiscovery{
+				dynamicConfiguration: *c.(*file.FileSystemDynamicConfiguration),
+				rootPath:             p,
+				fileMap:              make(map[string]string),
+			}
+
+			extension.AddCustomShutdownCallback(func() {
+				sd.Destroy()
+			})
+
+			for _, v := range sd.GetServices().Values() {
+				for _, i := range sd.GetInstances(v.(string)) {
+					// like java do nothing
+					l := &RegistryConfigurationListener{}
+					sd.dynamicConfiguration.AddListener(getServiceInstanceId(i), l, config_center.WithGroup(getServiceName(i)))
+				}
+			}
+
+			return sd, nil
+		}

Review comment:
       ```suggestion
   		} 
   			sd := &fileSystemServiceDiscovery{
   				dynamicConfiguration: *c.(*file.FileSystemDynamicConfiguration),
   				rootPath:             p,
   				fileMap:              make(map[string]string),
   			}
   
   			extension.AddCustomShutdownCallback(func() {
   				sd.Destroy()
   			})
   
   			for _, v := range sd.GetServices().Values() {
   				for _, i := range sd.GetInstances(v.(string)) {
   					// like java do nothing
   					l := &RegistryConfigurationListener{}
   					sd.dynamicConfiguration.AddListener(getServiceInstanceId(i), l, config_center.WithGroup(getServiceName(i)))
   				}
   			}
   
   			return sd, nil
   		
   ```

##########
File path: config_center/file/listener.go
##########
@@ -0,0 +1,155 @@
+/*
+ * 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 file
+
+import (
+	"io/ioutil"
+	"sync"
+)
+
+import (
+	"github.com/fsnotify/fsnotify"
+)
+
+import (
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/remoting"
+)
+
+// CacheListener is file watcher
+type CacheListener struct {
+	watch        *fsnotify.Watcher
+	keyListeners sync.Map
+	rootPath     string
+}
+
+// NewCacheListener creates a new CacheListener
+func NewCacheListener(rootPath string) *CacheListener {
+	cl := &CacheListener{rootPath: rootPath}
+	// start watcher
+	watch, err := fsnotify.NewWatcher()
+	if err != nil {
+		logger.Errorf("file : listen config fail, error:%v ", err)
+	}
+	go func() {
+		for {
+			select {
+			case event := <-watch.Events:
+				key := event.Name
+				logger.Debugf("watcher %s, event %v", cl.rootPath, event)
+				if event.Op&fsnotify.Write == fsnotify.Write {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeUpdate)
+					}
+				}
+				if event.Op&fsnotify.Create == fsnotify.Create {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						dataChangeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeAdd)
+					}
+				}
+				if event.Op&fsnotify.Remove == fsnotify.Remove {
+					if l, ok := cl.keyListeners.Load(key); ok {
+						removeCallback(l.(map[config_center.ConfigurationListener]struct{}), key, remoting.EventTypeDel)
+					}
+				}
+			case err := <-watch.Errors:
+				// err may be nil, ignore
+				if err != nil {
+					logger.Warnf("file : listen watch fail:%+v", err)
+				}
+			}
+		}
+	}()
+	cl.watch = watch
+
+	extension.AddCustomShutdownCallback(func() {
+		cl.watch.Close()
+	})
+
+	return cl
+}
+
+func removeCallback(lmap map[config_center.ConfigurationListener]struct{}, key string, event remoting.EventType) {
+	if len(lmap) == 0 {
+		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)
+	}
+	for l := range lmap {
+		callback(l, key, "", event)
+	}
+}
+
+func dataChangeCallback(lmap map[config_center.ConfigurationListener]struct{}, key string, event remoting.EventType) {
+	if len(lmap) == 0 {
+		logger.Warnf("file watch callback but configuration listener is empty, key:%s, event:%v", key, event)
+	}
+	c := getFileContent(key)
+	for l := range lmap {
+		callback(l, key, c, event)
+	}
+}
+
+func callback(listener config_center.ConfigurationListener, path, data string, event remoting.EventType) {
+	listener.Process(&config_center.ConfigChangeEvent{Key: path, Value: data, ConfigType: event})
+}
+
+// Close will remove key listener and close watcher
+func (cl *CacheListener) Close() error {
+	cl.keyListeners.Range(func(key, value interface{}) bool {
+		cl.keyListeners.Delete(key)
+		return true
+	})
+	return cl.watch.Close()
+}
+
+// AddListener will add a listener if loaded
+// if you watcher a file or directory not exist, will error with no such file or directory
+func (cl *CacheListener) AddListener(key string, listener config_center.ConfigurationListener) {
+	// reference from https://stackoverflow.com/questions/34018908/golang-why-dont-we-have-a-set-datastructure
+	// make a map[your type]struct{} like set in java
+	listeners, loaded := cl.keyListeners.LoadOrStore(key, map[config_center.ConfigurationListener]struct{}{listener: {}})
+	if loaded {
+		listeners.(map[config_center.ConfigurationListener]struct{})[listener] = struct{}{}
+		cl.keyListeners.Store(key, listeners)
+	} else {
+		if err := cl.watch.Add(key); err != nil {
+			logger.Errorf("watcher add path:%s err:%v", key, err)
+		}
+	}
+}
+
+// RemoveListener will delete a listener if loaded
+func (cl *CacheListener) RemoveListener(key string, listener config_center.ConfigurationListener) {
+	listeners, loaded := cl.keyListeners.Load(key)
+	if loaded {
+		delete(listeners.(map[config_center.ConfigurationListener]struct{}), listener)
+		if err := cl.watch.Remove(key); err != nil {
+			logger.Errorf("watcher remove path:%s err:%v", key, err)
+		}
+	}
+}
+
+func getFileContent(path string) string {
+	if c, err := ioutil.ReadFile(path); err != nil {
+		logger.Errorf("read file path:%s err:%v", path, err)
+		return ""
+	} else {
+		return string(c)
+	}

Review comment:
       ```suggestion
   	} 
   	return string(c)
   	
   ```

##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,291 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	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/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+var (
+	// 16 would be enough. We won't use concurrentMap because in most cases, there are not race condition
+	instanceMap = make(map[string]registry.ServiceDiscovery, 16)
+	initLock    sync.Mutex
+)
+
+// init will put the service discovery into extension
+func init() {
+	extension.SetServiceDiscovery(constant.FILE_KEY, newFileSystemServiceDiscovery)
+}
+
+// fileServiceDiscovery is the implementation of service discovery based on file.
+type fileSystemServiceDiscovery struct {
+	dynamicConfiguration file.FileSystemDynamicConfiguration
+	rootPath             string
+	fileMap              map[string]string
+}
+
+func newFileSystemServiceDiscovery(name string) (registry.ServiceDiscovery, error) {
+	instance, ok := instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	initLock.Lock()
+	defer initLock.Unlock()
+
+	// double check
+	instance, ok = instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	sdc, ok := config.GetBaseConfig().GetServiceDiscoveries(name)
+	if !ok || sdc.Protocol != constant.FILE_KEY {
+		return nil, perrors.New("could not init the instance because the config is invalid")
+	}
+
+	if rp, err := file.Home(); err != nil {
+		return nil, perrors.WithStack(err)
+	} else {
+		fdcf := extension.GetConfigCenterFactory(constant.FILE_KEY)
+		p := path.Join(rp, ".dubbo", "registry")
+		url, _ := common.NewURL("")
+		url.AddParamAvoidNil(file.CONFIG_CENTER_DIR_PARAM_NAME, p)
+		if c, err := fdcf.GetDynamicConfiguration(&url); err != nil {
+			return nil, perrors.New("could not find the config for name: " + name)
+		} else {
+			sd := &fileSystemServiceDiscovery{
+				dynamicConfiguration: *c.(*file.FileSystemDynamicConfiguration),
+				rootPath:             p,
+				fileMap:              make(map[string]string),
+			}
+
+			extension.AddCustomShutdownCallback(func() {
+				sd.Destroy()
+			})
+
+			for _, v := range sd.GetServices().Values() {
+				for _, i := range sd.GetInstances(v.(string)) {
+					// like java do nothing
+					l := &RegistryConfigurationListener{}
+					sd.dynamicConfiguration.AddListener(getServiceInstanceId(i), l, config_center.WithGroup(getServiceName(i)))
+				}
+			}
+
+			return sd, nil
+		}
+	}
+}
+
+// nolint
+func (fssd *fileSystemServiceDiscovery) String() string {
+	return fmt.Sprintf("file-system-service-discovery")
+}
+
+// Destroy will destroy the service discovery.
+// If the discovery cannot be destroy, it will return an error.
+func (fssd *fileSystemServiceDiscovery) Destroy() error {
+	fssd.dynamicConfiguration.Close()
+
+	for _, f := range fssd.fileMap {
+		fssd.releaseAndRemoveRegistrationFiles(f)
+	}
+
+	return nil
+}
+
+// nolint
+func (fssd *fileSystemServiceDiscovery) releaseAndRemoveRegistrationFiles(file string) {
+	os.RemoveAll(file)
+}
+
+// ----------------- registration ----------------
+
+// Register will register an instance of ServiceInstance to registry
+func (fssd *fileSystemServiceDiscovery) Register(instance registry.ServiceInstance) error {
+	id := getServiceInstanceId(instance)
+	sn := getServiceName(instance)
+	if c, err := getContent(instance); err != nil {
+		return err
+	} else {
+		if err := fssd.dynamicConfiguration.PublishConfig(id, sn, c); err != nil {
+			return perrors.WithStack(err)
+		} else {
+			fssd.fileMap[id] = fssd.dynamicConfiguration.GetPath(id, sn)
+		}
+	}
+
+	return nil
+}
+
+// nolint
+func getServiceInstanceId(si registry.ServiceInstance) string {
+	if si.GetId() == "" {
+		return si.GetHost() + "." + strconv.Itoa(si.GetPort())
+	}
+
+	return si.GetId()
+}
+
+// nolint
+func getServiceName(si registry.ServiceInstance) string {
+	return si.GetServiceName()
+}
+
+// getContent json string
+func getContent(si registry.ServiceInstance) (string, error) {
+	if bytes, err := json.Marshal(si); err != nil {
+		return "", err
+	} else {
+		return string(bytes), nil
+	}

Review comment:
       ```suggestion
   	} 
   	return string(bytes), nil
   	
   ```

##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,291 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	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/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+var (
+	// 16 would be enough. We won't use concurrentMap because in most cases, there are not race condition
+	instanceMap = make(map[string]registry.ServiceDiscovery, 16)
+	initLock    sync.Mutex
+)
+
+// init will put the service discovery into extension
+func init() {
+	extension.SetServiceDiscovery(constant.FILE_KEY, newFileSystemServiceDiscovery)
+}
+
+// fileServiceDiscovery is the implementation of service discovery based on file.
+type fileSystemServiceDiscovery struct {
+	dynamicConfiguration file.FileSystemDynamicConfiguration
+	rootPath             string
+	fileMap              map[string]string
+}
+
+func newFileSystemServiceDiscovery(name string) (registry.ServiceDiscovery, error) {
+	instance, ok := instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	initLock.Lock()
+	defer initLock.Unlock()
+
+	// double check
+	instance, ok = instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	sdc, ok := config.GetBaseConfig().GetServiceDiscoveries(name)
+	if !ok || sdc.Protocol != constant.FILE_KEY {
+		return nil, perrors.New("could not init the instance because the config is invalid")
+	}
+
+	if rp, err := file.Home(); err != nil {
+		return nil, perrors.WithStack(err)
+	} else {
+		fdcf := extension.GetConfigCenterFactory(constant.FILE_KEY)
+		p := path.Join(rp, ".dubbo", "registry")
+		url, _ := common.NewURL("")
+		url.AddParamAvoidNil(file.CONFIG_CENTER_DIR_PARAM_NAME, p)
+		if c, err := fdcf.GetDynamicConfiguration(&url); err != nil {
+			return nil, perrors.New("could not find the config for name: " + name)
+		} else {
+			sd := &fileSystemServiceDiscovery{
+				dynamicConfiguration: *c.(*file.FileSystemDynamicConfiguration),
+				rootPath:             p,
+				fileMap:              make(map[string]string),
+			}
+
+			extension.AddCustomShutdownCallback(func() {
+				sd.Destroy()
+			})
+
+			for _, v := range sd.GetServices().Values() {
+				for _, i := range sd.GetInstances(v.(string)) {
+					// like java do nothing
+					l := &RegistryConfigurationListener{}
+					sd.dynamicConfiguration.AddListener(getServiceInstanceId(i), l, config_center.WithGroup(getServiceName(i)))
+				}
+			}
+
+			return sd, nil
+		}
+	}
+}
+
+// nolint
+func (fssd *fileSystemServiceDiscovery) String() string {
+	return fmt.Sprintf("file-system-service-discovery")
+}
+
+// Destroy will destroy the service discovery.
+// If the discovery cannot be destroy, it will return an error.
+func (fssd *fileSystemServiceDiscovery) Destroy() error {
+	fssd.dynamicConfiguration.Close()
+
+	for _, f := range fssd.fileMap {
+		fssd.releaseAndRemoveRegistrationFiles(f)
+	}
+
+	return nil
+}
+
+// nolint
+func (fssd *fileSystemServiceDiscovery) releaseAndRemoveRegistrationFiles(file string) {
+	os.RemoveAll(file)
+}
+
+// ----------------- registration ----------------
+
+// Register will register an instance of ServiceInstance to registry
+func (fssd *fileSystemServiceDiscovery) Register(instance registry.ServiceInstance) error {
+	id := getServiceInstanceId(instance)
+	sn := getServiceName(instance)
+	if c, err := getContent(instance); err != nil {
+		return err
+	} else {
+		if err := fssd.dynamicConfiguration.PublishConfig(id, sn, c); err != nil {
+			return perrors.WithStack(err)
+		} else {
+			fssd.fileMap[id] = fssd.dynamicConfiguration.GetPath(id, sn)
+		}
+	}
+
+	return nil
+}
+
+// nolint
+func getServiceInstanceId(si registry.ServiceInstance) string {
+	if si.GetId() == "" {
+		return si.GetHost() + "." + strconv.Itoa(si.GetPort())
+	}
+
+	return si.GetId()
+}
+
+// nolint
+func getServiceName(si registry.ServiceInstance) string {
+	return si.GetServiceName()
+}
+
+// getContent json string
+func getContent(si registry.ServiceInstance) (string, error) {
+	if bytes, err := json.Marshal(si); err != nil {
+		return "", err
+	} else {
+		return string(bytes), nil
+	}
+}
+
+// Update will update the data of the instance in registry
+func (fssd *fileSystemServiceDiscovery) Update(instance registry.ServiceInstance) error {
+	return fssd.Register(instance)
+}
+
+// Unregister will unregister this instance from registry
+func (fssd *fileSystemServiceDiscovery) Unregister(instance registry.ServiceInstance) error {
+	id := getServiceInstanceId(instance)
+	sn := getServiceName(instance)
+	if err := fssd.dynamicConfiguration.RemoveConfig(id, sn); err != nil {
+		return err
+	} else {
+		delete(fssd.fileMap, instance.GetId())
+		return nil
+	}
+}
+
+// ----------------- discovery -------------------
+// GetDefaultPageSize will return the default page size
+func (fssd *fileSystemServiceDiscovery) GetDefaultPageSize() int {
+	return 100
+}
+
+// GetServices will return the all service names.
+func (fssd *fileSystemServiceDiscovery) GetServices() *gxset.HashSet {
+	r := gxset.NewSet()
+	// dynamicConfiguration root path is the actual root path
+	fileInfo, _ := ioutil.ReadDir(fssd.dynamicConfiguration.RootPath())
+
+	for _, file := range fileInfo {
+		if file.IsDir() {
+			r.Add(file.Name())
+		}
+	}
+
+	return r
+}
+
+// GetInstances will return all service instances with serviceName
+func (fssd *fileSystemServiceDiscovery) GetInstances(serviceName string) []registry.ServiceInstance {
+	if set, err := fssd.dynamicConfiguration.GetConfigKeysByGroup(serviceName); err != nil {
+		logger.Errorf("[FileServiceDiscovery] Could not query the instances for service{%s}, error = err{%v} ",
+			serviceName, err)
+
+		return make([]registry.ServiceInstance, 0, 0)
+	} else {

Review comment:
       remove else - -

##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,291 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	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/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+var (
+	// 16 would be enough. We won't use concurrentMap because in most cases, there are not race condition
+	instanceMap = make(map[string]registry.ServiceDiscovery, 16)
+	initLock    sync.Mutex
+)
+
+// init will put the service discovery into extension
+func init() {
+	extension.SetServiceDiscovery(constant.FILE_KEY, newFileSystemServiceDiscovery)
+}
+
+// fileServiceDiscovery is the implementation of service discovery based on file.
+type fileSystemServiceDiscovery struct {
+	dynamicConfiguration file.FileSystemDynamicConfiguration
+	rootPath             string
+	fileMap              map[string]string
+}
+
+func newFileSystemServiceDiscovery(name string) (registry.ServiceDiscovery, error) {
+	instance, ok := instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	initLock.Lock()
+	defer initLock.Unlock()
+
+	// double check
+	instance, ok = instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	sdc, ok := config.GetBaseConfig().GetServiceDiscoveries(name)
+	if !ok || sdc.Protocol != constant.FILE_KEY {
+		return nil, perrors.New("could not init the instance because the config is invalid")
+	}
+
+	if rp, err := file.Home(); err != nil {
+		return nil, perrors.WithStack(err)
+	} else {
+		fdcf := extension.GetConfigCenterFactory(constant.FILE_KEY)
+		p := path.Join(rp, ".dubbo", "registry")
+		url, _ := common.NewURL("")
+		url.AddParamAvoidNil(file.CONFIG_CENTER_DIR_PARAM_NAME, p)
+		if c, err := fdcf.GetDynamicConfiguration(&url); err != nil {
+			return nil, perrors.New("could not find the config for name: " + name)
+		} else {
+			sd := &fileSystemServiceDiscovery{
+				dynamicConfiguration: *c.(*file.FileSystemDynamicConfiguration),
+				rootPath:             p,
+				fileMap:              make(map[string]string),
+			}
+
+			extension.AddCustomShutdownCallback(func() {
+				sd.Destroy()
+			})
+
+			for _, v := range sd.GetServices().Values() {
+				for _, i := range sd.GetInstances(v.(string)) {
+					// like java do nothing
+					l := &RegistryConfigurationListener{}
+					sd.dynamicConfiguration.AddListener(getServiceInstanceId(i), l, config_center.WithGroup(getServiceName(i)))
+				}
+			}
+
+			return sd, nil
+		}
+	}
+}
+
+// nolint
+func (fssd *fileSystemServiceDiscovery) String() string {
+	return fmt.Sprintf("file-system-service-discovery")
+}
+
+// Destroy will destroy the service discovery.
+// If the discovery cannot be destroy, it will return an error.
+func (fssd *fileSystemServiceDiscovery) Destroy() error {
+	fssd.dynamicConfiguration.Close()
+
+	for _, f := range fssd.fileMap {
+		fssd.releaseAndRemoveRegistrationFiles(f)
+	}
+
+	return nil
+}
+
+// nolint
+func (fssd *fileSystemServiceDiscovery) releaseAndRemoveRegistrationFiles(file string) {
+	os.RemoveAll(file)
+}
+
+// ----------------- registration ----------------
+
+// Register will register an instance of ServiceInstance to registry
+func (fssd *fileSystemServiceDiscovery) Register(instance registry.ServiceInstance) error {
+	id := getServiceInstanceId(instance)
+	sn := getServiceName(instance)
+	if c, err := getContent(instance); err != nil {
+		return err
+	} else {
+		if err := fssd.dynamicConfiguration.PublishConfig(id, sn, c); err != nil {
+			return perrors.WithStack(err)
+		} else {
+			fssd.fileMap[id] = fssd.dynamicConfiguration.GetPath(id, sn)
+		}
+	}
+
+	return nil
+}
+
+// nolint
+func getServiceInstanceId(si registry.ServiceInstance) string {
+	if si.GetId() == "" {
+		return si.GetHost() + "." + strconv.Itoa(si.GetPort())
+	}
+
+	return si.GetId()
+}
+
+// nolint
+func getServiceName(si registry.ServiceInstance) string {
+	return si.GetServiceName()
+}
+
+// getContent json string
+func getContent(si registry.ServiceInstance) (string, error) {
+	if bytes, err := json.Marshal(si); err != nil {
+		return "", err
+	} else {
+		return string(bytes), nil
+	}
+}
+
+// Update will update the data of the instance in registry
+func (fssd *fileSystemServiceDiscovery) Update(instance registry.ServiceInstance) error {
+	return fssd.Register(instance)
+}
+
+// Unregister will unregister this instance from registry
+func (fssd *fileSystemServiceDiscovery) Unregister(instance registry.ServiceInstance) error {
+	id := getServiceInstanceId(instance)
+	sn := getServiceName(instance)
+	if err := fssd.dynamicConfiguration.RemoveConfig(id, sn); err != nil {
+		return err
+	} else {
+		delete(fssd.fileMap, instance.GetId())
+		return nil
+	}

Review comment:
       ```suggestion
   	} 
   		delete(fssd.fileMap, instance.GetId())
   		return nil
   	
   ```




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[GitHub] [dubbo-go] DogBaoBao commented on pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

DogBaoBao commented on pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732#issuecomment-683836982


   Not finished, I'm working on it.


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[GitHub] [dubbo-go] DogBaoBao commented on a change in pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

DogBaoBao commented on a change in pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732#discussion_r485545761



##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,291 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	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/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+var (
+	// 16 would be enough. We won't use concurrentMap because in most cases, there are not race condition
+	instanceMap = make(map[string]registry.ServiceDiscovery, 16)
+	initLock    sync.Mutex
+)
+
+// init will put the service discovery into extension
+func init() {
+	extension.SetServiceDiscovery(constant.FILE_KEY, newFileSystemServiceDiscovery)
+}
+
+// fileServiceDiscovery is the implementation of service discovery based on file.
+type fileSystemServiceDiscovery struct {
+	dynamicConfiguration file.FileSystemDynamicConfiguration
+	rootPath             string
+	fileMap              map[string]string
+}
+
+func newFileSystemServiceDiscovery(name string) (registry.ServiceDiscovery, error) {
+	instance, ok := instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	initLock.Lock()
+	defer initLock.Unlock()
+
+	// double check
+	instance, ok = instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	sdc, ok := config.GetBaseConfig().GetServiceDiscoveries(name)
+	if !ok || sdc.Protocol != constant.FILE_KEY {
+		return nil, perrors.New("could not init the instance because the config is invalid")
+	}
+
+	if rp, err := file.Home(); err != nil {
+		return nil, perrors.WithStack(err)
+	} else {
+		fdcf := extension.GetConfigCenterFactory(constant.FILE_KEY)
+		p := path.Join(rp, ".dubbo", "registry")

Review comment:
       this may not the registry meaning the registry




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[GitHub] [dubbo-go] AlexStocks merged pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

AlexStocks merged pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732


   


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[GitHub] [dubbo-go] AlexStocks merged pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

AlexStocks merged pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732






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[GitHub] [dubbo-go] zouyx commented on a change in pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

zouyx commented on a change in pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732#discussion_r484283770



##########
File path: common/constant/key.go
##########
@@ -169,6 +169,10 @@ const (
 	NACOS_USERNAME               = "username"
 )
 
+const (
+	FILE_KEY = "file"

Review comment:
       file_discovery_service_key？

##########
File path: config_center/file/impl.go
##########
@@ -0,0 +1,304 @@
+/*
+ * 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 file
+
+import (
+	"bytes"
+	"errors"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"os/user"
+	"path"
+	"path/filepath"
+	"runtime"
+	"strings"
+)
+
+import (

Review comment:
       second block is 3rd-party pkg，third block is internal pkg

##########
File path: config_center/dynamic_configuration.go
##########
@@ -57,6 +57,8 @@ type DynamicConfiguration interface {
 
 	// PublishConfig will publish the config with the (key, group, value) pair
 	PublishConfig(string, string, string) error
+	// PublishConfig will remove the config white the (key, group) pair

Review comment:
       comment is wrong

##########
File path: config_center/file/listener.go
##########
@@ -0,0 +1,150 @@
+/*
+ * 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 file
+
+import (
+	"io/ioutil"
+	"sync"
+)
+
+import (
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/remoting"
+)
+
+import (

Review comment:
       sort this block

##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,291 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	"github.com/apache/dubbo-go/common"
+	"github.com/apache/dubbo-go/common/constant"
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"

Review comment:
       sort block

##########
File path: registry/file/service_discovery_test.go
##########
@@ -0,0 +1,89 @@
+/*
+ * 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 file
+
+import (
+	"math/rand"
+	"strconv"
+	"testing"
+	"time"
+)
+
+import (
+	"github.com/apache/dubbo-go/common/constant"
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/registry"
+)
+
+import (

Review comment:
       sort block




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[GitHub] [dubbo-go] zouyx commented on a change in pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

zouyx commented on a change in pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732#discussion_r486095803



##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,306 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	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/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+var (
+	// 16 would be enough. We won't use concurrentMap because in most cases, there are not race condition
+	instanceMap = make(map[string]registry.ServiceDiscovery, 16)
+	initLock    sync.Mutex
+)
+
+// init will put the service discovery into extension
+func init() {
+	extension.SetServiceDiscovery(constant.FILE_KEY, newFileSystemServiceDiscovery)
+}
+
+// fileServiceDiscovery is the implementation of service discovery based on file.
+type fileSystemServiceDiscovery struct {
+	dynamicConfiguration file.FileSystemDynamicConfiguration
+	rootPath             string
+	fileMap              map[string]string
+}
+
+func newFileSystemServiceDiscovery(name string) (registry.ServiceDiscovery, error) {
+	instance, ok := instanceMap[name]

Review comment:
       where do you set instance into  instanceMap? do i miss something?

##########
File path: config_center/file/impl.go
##########
@@ -0,0 +1,310 @@
+/*
+ * 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 file
+
+import (
+	"bytes"
+	"errors"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"os/user"
+	"path"
+	"path/filepath"
+	"runtime"
+	"strings"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	perrors "github.com/pkg/errors"
+)
+
+import (
+	"github.com/apache/dubbo-go/common"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/parser"
+)
+
+const (
+	PARAM_NAME_PREFIX                 = "dubbo.config-center."
+	CONFIG_CENTER_DIR_PARAM_NAME      = PARAM_NAME_PREFIX + "dir"
+	CONFIG_CENTER_ENCODING_PARAM_NAME = PARAM_NAME_PREFIX + "encoding"
+	DEFAULT_CONFIG_CENTER_ENCODING    = "UTF-8"
+)
+
+// FileSystemDynamicConfiguration
+type FileSystemDynamicConfiguration struct {
+	config_center.BaseDynamicConfiguration
+	url           *common.URL
+	rootPath      string
+	encoding      string
+	cacheListener *CacheListener
+	parser        parser.ConfigurationParser
+}
+
+func newFileSystemDynamicConfiguration(url *common.URL) (*FileSystemDynamicConfiguration, error) {
+	encode := url.GetParam(CONFIG_CENTER_ENCODING_PARAM_NAME, DEFAULT_CONFIG_CENTER_ENCODING)
+
+	root := url.GetParam(CONFIG_CENTER_DIR_PARAM_NAME, "")
+	var c *FileSystemDynamicConfiguration
+	if _, err := os.Stat(root); err != nil {
+		// not exist, use default, /XXX/xx/.dubbo/config-center
+		if rp, err := Home(); err != nil {
+			return nil, perrors.WithStack(err)
+		} else {
+			root = path.Join(rp, ".dubbo", "config-center")
+		}
+	}
+
+	if _, err := os.Stat(root); err != nil {
+		// it must be dir, if not exist, will create
+		if err = createDir(root); err != nil {
+			return nil, perrors.WithStack(err)
+		}
+	}
+
+	c = &FileSystemDynamicConfiguration{
+		url:      url,
+		rootPath: root,
+		encoding: encode,
+	}
+
+	c.cacheListener = NewCacheListener(c.rootPath)
+
+	return c, nil
+}
+
+// RootPath get root path
+func (fsdc *FileSystemDynamicConfiguration) RootPath() string {
+	return fsdc.rootPath
+}
+
+// Parser Get Parser
+func (fsdc *FileSystemDynamicConfiguration) Parser() parser.ConfigurationParser {
+	return fsdc.parser
+}
+
+// SetParser Set Parser
+func (fsdc *FileSystemDynamicConfiguration) SetParser(p parser.ConfigurationParser) {
+	fsdc.parser = p
+}
+
+// AddListener Add listener
+func (fsdc *FileSystemDynamicConfiguration) AddListener(key string, listener config_center.ConfigurationListener,
+	opts ...config_center.Option) {
+	tmpOpts := &config_center.Options{}
+	for _, opt := range opts {
+		opt(tmpOpts)
+	}
+
+	path := fsdc.GetPath(key, tmpOpts.Group)
+
+	fsdc.cacheListener.AddListener(path, listener)
+}
+
+// RemoveListener Remove listener
+func (fsdc *FileSystemDynamicConfiguration) RemoveListener(key string, listener config_center.ConfigurationListener,
+	opts ...config_center.Option) {
+	tmpOpts := &config_center.Options{}
+	for _, opt := range opts {
+		opt(tmpOpts)
+	}
+
+	path := fsdc.GetPath(key, tmpOpts.Group)
+
+	fsdc.cacheListener.RemoveListener(path, listener)
+}
+
+// GetProperties get properties file
+func (fsdc *FileSystemDynamicConfiguration) GetProperties(key string, opts ...config_center.Option) (string, error) {
+	tmpOpts := &config_center.Options{}
+	for _, opt := range opts {
+		opt(tmpOpts)
+	}
+
+	path := fsdc.GetPath(key, tmpOpts.Group)
+	file, err := ioutil.ReadFile(path)
+	if err != nil {
+		return "", perrors.WithStack(err)
+	}
+
+	return string(file), nil
+}
+
+// GetRule get Router rule properties file
+func (fsdc *FileSystemDynamicConfiguration) GetRule(key string, opts ...config_center.Option) (string, error) {
+	return fsdc.GetProperties(key, opts...)
+}
+
+// GetInternalProperty get value by key in Default properties file(dubbo.properties)
+func (fsdc *FileSystemDynamicConfiguration) GetInternalProperty(key string, opts ...config_center.Option) (string,
+	error) {
+	return fsdc.GetProperties(key, opts...)
+}
+
+// PublishConfig will publish the config with the (key, group, value) pair
+func (fsdc *FileSystemDynamicConfiguration) PublishConfig(key string, group string, value string) error {
+	path := fsdc.GetPath(key, group)
+	return fsdc.write2File(path, value)
+}
+
+// GetConfigKeysByGroup will return all keys with the group
+func (fsdc *FileSystemDynamicConfiguration) GetConfigKeysByGroup(group string) (*gxset.HashSet, error) {
+	path := fsdc.GetPath("", group)
+	r := gxset.NewSet()
+
+	fileInfo, _ := ioutil.ReadDir(path)
+
+	for _, file := range fileInfo {
+		// list file
+		if !file.IsDir() {
+			r.Add(file.Name())
+		}

Review comment:
       ```suggestion
   		if file.IsDir() {
   			continue
   		}
   		r.Add(file.Name())
   ```

##########
File path: registry/file/service_discovery.go
##########
@@ -0,0 +1,306 @@
+/*
+ * 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 file
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	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/extension"
+	"github.com/apache/dubbo-go/common/logger"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/file"
+	"github.com/apache/dubbo-go/registry"
+)
+
+var (
+	// 16 would be enough. We won't use concurrentMap because in most cases, there are not race condition
+	instanceMap = make(map[string]registry.ServiceDiscovery, 16)
+	initLock    sync.Mutex
+)
+
+// init will put the service discovery into extension
+func init() {
+	extension.SetServiceDiscovery(constant.FILE_KEY, newFileSystemServiceDiscovery)
+}
+
+// fileServiceDiscovery is the implementation of service discovery based on file.
+type fileSystemServiceDiscovery struct {
+	dynamicConfiguration file.FileSystemDynamicConfiguration
+	rootPath             string
+	fileMap              map[string]string
+}
+
+func newFileSystemServiceDiscovery(name string) (registry.ServiceDiscovery, error) {
+	instance, ok := instanceMap[name]
+	if ok {
+		return instance, nil
+	}
+
+	initLock.Lock()
+	defer initLock.Unlock()

Review comment:
       This lock is too long, i suggest unlock it after set into instanceMap .




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[GitHub] [dubbo-go] AlexStocks commented on a change in pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

AlexStocks commented on a change in pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732#discussion_r484648533



##########
File path: config_center/file/factory.go
##########
@@ -0,0 +1,42 @@
+/*
+ * 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 file
+
+import (
+	"github.com/apache/dubbo-go/common"
+	"github.com/apache/dubbo-go/common/constant"
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/config_center"
+	"github.com/apache/dubbo-go/config_center/parser"
+)
+
+func init() {
+	extension.SetConfigCenterFactory(constant.FILE_KEY, func() config_center.DynamicConfigurationFactory { return &fileDynamicConfigurationFactory{} })

Review comment:
       代码太长了，拆分成多行吧。




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[GitHub] [dubbo-go] DogBaoBao commented on a change in pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

DogBaoBao commented on a change in pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732#discussion_r484457075



##########
File path: common/constant/key.go
##########
@@ -169,6 +169,10 @@ const (
 	NACOS_USERNAME               = "username"
 )
 
+const (
+	FILE_KEY = "file"

Review comment:
       yes，the key from java:
   
   ```
   file=org.apache.dubbo.registry.client.FileSystemServiceDiscovery
   ```
   




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[GitHub] [dubbo-go] AlexStocks merged pull request #732: Ftr: File system service discovery

[GitBox <gi...@apache.org>]

AlexStocks merged pull request #732:
URL: https://github.com/apache/dubbo-go/pull/732






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