Add refreshable file data-source implementation (#86)

ext/datasource/datasource.go

@@ -22,3 +22,39 @@ type DataSource interface {
 	// Close the data source.
 	io.Closer
 }
+
+type Base struct {
+	handlers []PropertyHandler
+}
+
+func (b *Base) Handlers() []PropertyHandler {
+	return b.handlers
+}
+
+// return idx if existed, else return -1
+func (b *Base) indexOfHandler(h PropertyHandler) int {
+	for idx, handler := range b.handlers {
+		if handler == h {
+			return idx
+		}
+	}
+	return -1
+}
+
+func (b *Base) AddPropertyHandler(h PropertyHandler) {
+	if h == nil || b.indexOfHandler(h) >= 0 {
+		return
+	}
+	b.handlers = append(b.handlers, h)
+}
+
+func (b *Base) RemovePropertyHandler(h PropertyHandler) {
+	if h == nil {
+		return
+	}
+	idx := b.indexOfHandler(h)
+	if idx < 0 {
+		return
+	}
+	b.handlers = append(b.handlers[:idx], b.handlers[idx+1:]...)
+}

ext/datasource/datasource_test.go

@@ -0,0 +1,64 @@
+package datasource
+
+import (
+	"github.com/stretchr/testify/assert"
+	"reflect"
+	"testing"
+)
+
+func TestBase_AddPropertyHandler(t *testing.T) {
+	t.Run("AddPropertyHandler_nil", func(t *testing.T) {
+		b := &Base{
+			handlers: make([]PropertyHandler, 0),
+		}
+		b.AddPropertyHandler(nil)
+		assert.True(t, len(b.handlers) == 0, "Fail to execute the case TestBase_AddPropertyHandler.")
+	})
+
+	t.Run("AddPropertyHandler_Normal", func(t *testing.T) {
+		b := &Base{
+			handlers: make([]PropertyHandler, 0),
+		}
+		h := &DefaultPropertyHandler{}
+		b.AddPropertyHandler(h)
+		assert.True(t, len(b.handlers) == 1 && reflect.DeepEqual(b.handlers[0], h), "Fail to execute the case TestBase_AddPropertyHandler.")
+	})
+}
+
+func TestBase_RemovePropertyHandler(t *testing.T) {
+	t.Run("TestBase_RemovePropertyHandler_nil", func(t *testing.T) {
+		b := &Base{
+			handlers: make([]PropertyHandler, 0),
+		}
+		h1 := &DefaultPropertyHandler{}
+		b.handlers = append(b.handlers, h1)
+		b.RemovePropertyHandler(nil)
+		assert.True(t, len(b.handlers) == 1, "The case TestBase_RemovePropertyHandler execute failed.")
+	})
+
+	t.Run("TestBase_RemovePropertyHandler", func(t *testing.T) {
+		b := &Base{
+			handlers: make([]PropertyHandler, 0),
+		}
+		h1 := &DefaultPropertyHandler{}
+		b.handlers = append(b.handlers, h1)
+		b.RemovePropertyHandler(h1)
+		assert.True(t, len(b.handlers) == 0, "The case TestBase_RemovePropertyHandler execute failed.")
+	})
+}
+
+func TestBase_indexOfHandler(t *testing.T) {
+	t.Run("TestBase_indexOfHandler", func(t *testing.T) {
+		b := &Base{
+			handlers: make([]PropertyHandler, 0),
+		}
+		h1 := &DefaultPropertyHandler{}
+		b.handlers = append(b.handlers, h1)
+		h2 := &DefaultPropertyHandler{}
+		b.handlers = append(b.handlers, h2)
+		h3 := &DefaultPropertyHandler{}
+		b.handlers = append(b.handlers, h3)
+
+		assert.True(t, b.indexOfHandler(h2) == 1, "Fail to execute the case TestBase_indexOfHandler.")
+	})
+}

ext/datasource/file/refreshable_file.go

@@ -0,0 +1,119 @@
+package file
+
+import (
+	"github.com/alibaba/sentinel-golang/ext/datasource"
+	"github.com/alibaba/sentinel-golang/logging"
+	"github.com/alibaba/sentinel-golang/util"
+	"github.com/fsnotify/fsnotify"
+	"github.com/pkg/errors"
+	"io/ioutil"
+	"os"
+)
+
+var (
+	logger = logging.GetDefaultLogger()
+)
+
+type RefreshableFileDataSource struct {
+	datasource.Base
+	sourceFilePath string
+	isInitialized  util.AtomicBool
+	closeChan      chan struct{}
+	watcher        *fsnotify.Watcher
+}
+
+func NewFileDataSource(sourceFilePath string, handlers ...datasource.PropertyHandler) *RefreshableFileDataSource {
+	var ds = &RefreshableFileDataSource{
+		sourceFilePath: sourceFilePath,
+		closeChan:      make(chan struct{}),
+	}
+	for _, h := range handlers {
+		ds.AddPropertyHandler(h)
+	}
+	return ds
+}
+
+func (s *RefreshableFileDataSource) ReadSource() ([]byte, error) {
+	f, err := os.Open(s.sourceFilePath)
+	if err != nil {
+		return nil, errors.Errorf("RefreshableFileDataSource fail to open the property file, err: %+v.", err)
+	}
+	defer f.Close()
+
+	src, err := ioutil.ReadAll(f)
+	if err != nil {
+		return nil, errors.Errorf("RefreshableFileDataSource fail to read file, err: %+v.", err)
+	}
+	return src, nil
+}
+
+func (s *RefreshableFileDataSource) Initialize() error {
+	if !s.isInitialized.CompareAndSet(false, true) {
+		return nil
+	}
+
+	err := s.doReadAndUpdate()
+	if err != nil {
+		logger.Errorf("Fail to execute doReadAndUpdate, err: %+v", err)
+	}
+
+	w, err := fsnotify.NewWatcher()
+	if err != nil {
+		return errors.Errorf("Fail to new a watcher instance of fsnotify, err: %+v", err)
+	}
+	err = w.Add(s.sourceFilePath)
+	if err != nil {
+		return errors.Errorf("Fail add a watcher on file[%s], err: %+v", s.sourceFilePath, err)
+	}
+	s.watcher = w
+
+	go util.RunWithRecover(func() {
+		defer s.watcher.Close()
+		for {
+			select {
+			case ev := <-s.watcher.Events:
+				if ev.Op&fsnotify.Write == fsnotify.Write {
+					err := s.doReadAndUpdate()
+					if err != nil {
+						logger.Errorf("Fail to execute doReadAndUpdate, err: %+v", err)
+					}
+				}
+
+				if ev.Op&fsnotify.Remove == fsnotify.Remove || ev.Op&fsnotify.Rename == fsnotify.Rename {
+					logger.Errorf("The file source[%s] was removed or renamed.", s.sourceFilePath)
+					for _, h := range s.Handlers() {
+						err := h.Handle(nil)
+						if err != nil {
+							logger.Errorf("RefreshableFileDataSource fail to publish property, err: %+v.", err)
+						}
+					}
+				}
+			case err := <-s.watcher.Errors:
+				logger.Errorf("Watch err on file[%s], err: %+v", s.sourceFilePath, err)
+			case <-s.closeChan:
+				return
+			}
+		}
+	}, logger)
+	return nil
+}
+
+func (s *RefreshableFileDataSource) doReadAndUpdate() error {
+	src, err := s.ReadSource()
+	if err != nil {
+		return errors.Errorf("Fail to read source, err: %+v", err)
+	}
+	for _, h := range s.Handlers() {
+		err := h.Handle(src)
+		if err != nil {
+			return errors.Errorf("RefreshableFileDataSource fail to publish property, err: %+v.", err)
+		}
+	}
+	return nil
+}
+
+func (s *RefreshableFileDataSource) Close() error {
+	s.closeChan <- struct{}{}
+	logger.Infof("The RefreshableFileDataSource for [%s] had been closed.", s.sourceFilePath)
+	return nil
+}