fix(config): fix file source watcher stop behavior when Stop is called (#2630)

Co-authored-by: Mohamed MHAMDI <mmhamdi@hubside.com>

config/source/file/watcher.go

@@ -13,8 +13,7 @@ import (
 type watcher struct {
 	f *file
 
-	fw   *fsnotify.Watcher
-	exit chan bool
+	fw *fsnotify.Watcher
 }
 
 func newWatcher(f *file) (source.Watcher, error) {
@@ -26,24 +25,21 @@ func newWatcher(f *file) (source.Watcher, error) {
 	fw.Add(f.path)
 
 	return &watcher{
-		f:    f,
-		fw:   fw,
-		exit: make(chan bool),
+		f:  f,
+		fw: fw,
 	}, nil
 }
 
 func (w *watcher) Next() (*source.ChangeSet, error) {
-	// is it closed?
-	select {
-	case <-w.exit:
-		return nil, source.ErrWatcherStopped
-	default:
-	}
-
 	// try get the event
 	select {
-	case event, _ := <-w.fw.Events:
-		if event.Op == fsnotify.Rename {
+	case event, ok := <-w.fw.Events:
+		// check if channel was closed (i.e. Watcher.Close() was called).
+		if !ok {
+			return nil, source.ErrWatcherStopped
+		}
+
+		if event.Has(fsnotify.Rename) {
 			// check existence of file, and add watch again
 			_, err := os.Stat(event.Name)
 			if err == nil || os.IsExist(err) {
@@ -55,11 +51,15 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 		if err != nil {
 			return nil, err
 		}
+
 		return c, nil
-	case err := <-w.fw.Errors:
+	case err, ok := <-w.fw.Errors:
+		// check if channel was closed (i.e. Watcher.Close() was called).
+		if !ok {
+			return nil, source.ErrWatcherStopped
+		}
+
 		return nil, err
-	case <-w.exit:
-		return nil, source.ErrWatcherStopped
 	}
 }
 

config/source/file/watcher_linux.go

@@ -13,8 +13,7 @@ import (
 type watcher struct {
 	f *file
 
-	fw   *fsnotify.Watcher
-	exit chan bool
+	fw *fsnotify.Watcher
 }
 
 func newWatcher(f *file) (source.Watcher, error) {
@@ -26,24 +25,21 @@ func newWatcher(f *file) (source.Watcher, error) {
 	fw.Add(f.path)
 
 	return &watcher{
-		f:    f,
-		fw:   fw,
-		exit: make(chan bool),
+		f:  f,
+		fw: fw,
 	}, nil
 }
 
 func (w *watcher) Next() (*source.ChangeSet, error) {
-	// is it closed?
-	select {
-	case <-w.exit:
-		return nil, source.ErrWatcherStopped
-	default:
-	}
-
 	// try get the event
 	select {
-	case event := <-w.fw.Events:
-		if event.Op == fsnotify.Rename {
+	case event, ok := <-w.fw.Events:
+		// check if channel was closed (i.e. Watcher.Close() was called).
+		if !ok {
+			return nil, source.ErrWatcherStopped
+		}
+
+		if event.Has(fsnotify.Rename) {
 			// check existence of file, and add watch again
 			_, err := os.Stat(event.Name)
 			if err == nil || os.IsExist(err) {
@@ -60,10 +56,13 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 		w.fw.Add(w.f.path)
 
 		return c, nil
-	case err := <-w.fw.Errors:
+	case err, ok := <-w.fw.Errors:
+		// check if channel was closed (i.e. Watcher.Close() was called).
+		if !ok {
+			return nil, source.ErrWatcherStopped
+		}
+
 		return nil, err
-	case <-w.exit:
-		return nil, source.ErrWatcherStopped
 	}
 }
 

config/source/file/watcher_test.go

@@ -0,0 +1,120 @@
+package file_test
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"go-micro.dev/v4/config/source"
+	"go-micro.dev/v4/config/source/file"
+)
+
+// createTestFile a local helper to creates a temporary file with the given data
+func createTestFile(data []byte) (*os.File, func(), string, error) {
+	path := filepath.Join(os.TempDir(), fmt.Sprintf("file.%d", time.Now().UnixNano()))
+	fh, err := os.Create(path)
+	if err != nil {
+		return nil, func() {}, "", err
+	}
+
+	_, err = fh.Write(data)
+	if err != nil {
+		return nil, func() {}, "", err
+	}
+
+	return fh, func() {
+		fh.Close()
+		os.Remove(path)
+	}, path, err
+}
+
+func TestWatcher(t *testing.T) {
+	data := []byte(`{"foo": "bar"}`)
+	fh, cleanup, path, err := createTestFile(data)
+	if err != nil {
+		t.Error(err)
+	}
+	defer cleanup()
+
+	f := file.NewSource(file.WithPath(path))
+	if err != nil {
+		t.Error(err)
+	}
+
+	// create a watcher
+	w, err := f.Watch()
+	if err != nil {
+		t.Error(err)
+	}
+
+	newdata := []byte(`{"foo": "baz"}`)
+
+	go func() {
+		sc, err := w.Next()
+		if err != nil {
+			t.Error(err)
+			return
+		}
+
+		if !bytes.Equal(sc.Data, newdata) {
+			t.Error("expected data to be different")
+		}
+	}()
+
+	// rewrite to the file to trigger a change
+	_, err = fh.WriteAt(newdata, 0)
+	if err != nil {
+		t.Error(err)
+	}
+
+	// wait for the underlying watcher to detect changes
+	time.Sleep(time.Second)
+}
+
+func TestWatcherStop(t *testing.T) {
+	data := []byte(`{"foo": "bar"}`)
+	_, cleanup, path, err := createTestFile(data)
+	if err != nil {
+		t.Error(err)
+	}
+	defer cleanup()
+
+	src := file.NewSource(file.WithPath(path))
+	if err != nil {
+		t.Error(err)
+	}
+
+	// create a watcher
+	w, err := src.Watch()
+	if err != nil {
+		t.Error(err)
+	}
+
+	defer func() {
+		var err error
+		c := make(chan struct{})
+		defer close(c)
+
+		go func() {
+			_, err = w.Next()
+			c <- struct{}{}
+		}()
+
+		select {
+		case <-time.After(2 * time.Second):
+			err = errors.New("timeout waiting for Watcher.Next() to return")
+		case <-c:
+		}
+
+		if !errors.Is(err, source.ErrWatcherStopped) {
+			t.Error(err)
+		}
+	}()
+
+	// stop the watcher
+	w.Stop()
+}

go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/bitly/go-simplejson v0.5.0
 	github.com/ef-ds/deque v1.0.4
 	github.com/evanphx/json-patch/v5 v5.5.0
-	github.com/fsnotify/fsnotify v1.4.9
+	github.com/fsnotify/fsnotify v1.6.0
 	github.com/fsouza/go-dockerclient v1.7.3
 	github.com/go-acme/lego/v4 v4.4.0
 	github.com/go-git/go-git/v5 v5.4.2

go.sum

@@ -339,6 +339,8 @@ github.com/frankban/quicktest v1.11.3/go.mod h1:wRf/ReqHper53s+kmmSZizM8NamnL3IM
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/fsnotify/fsnotify v1.4.9 h1:hsms1Qyu0jgnwNXIxa+/V/PDsU6CfLf6CNO8H7IWoS4=
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
+github.com/fsnotify/fsnotify v1.6.0 h1:n+5WquG0fcWoWp6xPWfHdbskMCQaFnG6PfBrh1Ky4HY=
+github.com/fsnotify/fsnotify v1.6.0/go.mod h1:sl3t1tCWJFWoRz9R8WJCbQihKKwmorjAbSClcnxKAGw=
 github.com/fsouza/go-dockerclient v1.7.3 h1:i6iMcktl688vsKUEExA6gU1UjPgIvmGtJeQ0mbuFqZo=
 github.com/fsouza/go-dockerclient v1.7.3/go.mod h1:8xfZB8o9SptLNJ13VoV5pMiRbZGWkU/Omu5VOu/KC9Y=
 github.com/fullsailor/pkcs7 v0.0.0-20190404230743-d7302db945fa/go.mod h1:KnogPXtdwXqoenmZCw6S+25EAm2MkxbG0deNDu4cbSA=
@@ -1147,6 +1149,7 @@ golang.org/x/sys v0.0.0-20211116061358-0a5406a5449c/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0 h1:MVltZSvRTcU2ljQOhs94SXPftV6DCNnZViHeQps87pQ=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201113234701-d7a72108b828/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=