add Cleanup function to close open inotify watches

bug: 101635

tail.go

@@ -305,3 +305,9 @@ func (tail *Tail) sendLine(line []byte) bool {
 
 	return true
 }
+
+// Cleanup removes open inotify watchers, because the Linux kernel does do so
+// upon process exit.
+func Cleanup() {
+	watch.Cleanup()
+}

tail_test.go

@@ -38,6 +38,7 @@ func TestMustExist(t *testing.T) {
 		t.Error("MustExist:true on an existing file is violated")
 	}
 	tail.Stop()
+	Cleanup()
 }
 
 func TestStop(t *testing.T) {
@@ -48,6 +49,7 @@ func TestStop(t *testing.T) {
 	if tail.Stop() != nil {
 		t.Error("Should be stoped successfully")
 	}
+	Cleanup()
 }
 
 func TestMaxLineSize(_t *testing.T) {
@@ -61,6 +63,7 @@ func TestMaxLineSize(_t *testing.T) {
 	<-time.After(100 * time.Millisecond)
 	t.RemoveFile("test.txt")
 	tail.Stop()
+	Cleanup()
 }
 
 func TestLocationFull(_t *testing.T) {
@@ -74,6 +77,7 @@ func TestLocationFull(_t *testing.T) {
 	<-time.After(100 * time.Millisecond)
 	t.RemoveFile("test.txt")
 	tail.Stop()
+	Cleanup()
 }
 
 func TestLocationFullDontFollow(_t *testing.T) {
@@ -88,6 +92,7 @@ func TestLocationFullDontFollow(_t *testing.T) {
 	<-time.After(100 * time.Millisecond)
 
 	tail.Stop()
+	Cleanup()
 }
 
 func TestLocationEnd(_t *testing.T) {
@@ -104,6 +109,7 @@ func TestLocationEnd(_t *testing.T) {
 	<-time.After(100 * time.Millisecond)
 	t.RemoveFile("test.txt")
 	tail.Stop()
+	Cleanup()
 }
 
 func TestLocationMiddle(_t *testing.T) {
@@ -121,6 +127,7 @@ func TestLocationMiddle(_t *testing.T) {
 	<-time.After(100 * time.Millisecond)
 	t.RemoveFile("test.txt")
 	tail.Stop()
+	Cleanup()
 }
 
 func _TestReOpen(_t *testing.T, poll bool) {
@@ -160,6 +167,7 @@ func _TestReOpen(_t *testing.T, poll bool) {
 	// the reading of data written above. Timings can vary based on
 	// test environment.
 	// tail.Stop()
+	Cleanup()
 }
 
 // The use of polling file watcher could affect file rotation
@@ -202,6 +210,7 @@ func _TestReSeek(_t *testing.T, poll bool) {
 	// the reading of data written above. Timings can vary based on
 	// test environment.
 	// tail.Stop()
+	Cleanup()
 }
 
 // The use of polling file watcher could affect file rotation
@@ -233,6 +242,7 @@ func TestRateLimiting(_t *testing.T) {
 	<-time.After(100 * time.Millisecond)
 	t.RemoveFile("test.txt")
 	tail.Stop()
+	Cleanup()
 }
 
 func TestTell(_t *testing.T) {
@@ -266,6 +276,7 @@ func TestTell(_t *testing.T) {
 	}
 	t.RemoveFile("test.txt")
 	tail.Done()
+	Cleanup()
 }
 
 // Test library

watch/inotify.go

@@ -7,9 +7,12 @@ import (
 	"github.com/howeyc/fsnotify"
 	"launchpad.net/tomb"
 	"os"
+"fmt"
 	"path/filepath"
 )
 
+var inotifyTracker *InotifyTracker
+
 // InotifyFileWatcher uses inotify to monitor file changes.
 type InotifyFileWatcher struct {
 	Filename string
@@ -22,11 +25,11 @@ func NewInotifyFileWatcher(filename string) *InotifyFileWatcher {
 }
 
 func (fw *InotifyFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
-	w, err := fsnotify.NewWatcher()
+	w, err := inotifyTracker.NewWatcher()
 	if err != nil {
 		return err
 	}
-	defer w.Close()
+	defer inotifyTracker.CloseWatcher(w)
 
 	dirname := filepath.Dir(fw.Filename)
 
@@ -35,7 +38,6 @@ func (fw *InotifyFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
 	if err != nil {
 		return err
 	}
-	defer w.RemoveWatch(filepath.Dir(fw.Filename))
 
 	// Do a real check now as the file might have been created before
 	// calling `WatchFlags` above.
@@ -46,8 +48,10 @@ func (fw *InotifyFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
 
 	for {
 		select {
-		case evt := <-w.Event:
-			if evt.Name == fw.Filename {
+		case evt, ok := <-w.Event:
+			if !ok {
+				return fmt.Errorf("inotify watcher has been closed")
+			}else if evt.Name == fw.Filename {
 				return nil
 			}
 		case <-t.Dying():
@@ -60,7 +64,7 @@ func (fw *InotifyFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
 func (fw *InotifyFileWatcher) ChangeEvents(t *tomb.Tomb, fi os.FileInfo) *FileChanges {
 	changes := NewFileChanges()
 
-	w, err := fsnotify.NewWatcher()
+	w, err := inotifyTracker.NewWatcher()
 	if err != nil {
 		util.Fatal("Error creating fsnotify watcher: %v", err)
 	}
@@ -72,17 +76,20 @@ func (fw *InotifyFileWatcher) ChangeEvents(t *tomb.Tomb, fi os.FileInfo) *FileCh
 	fw.Size = fi.Size()
 
 	go func() {
-		defer w.Close()
-		defer w.RemoveWatch(fw.Filename)
+		defer inotifyTracker.CloseWatcher(w)
 		defer changes.Close()
 
 		for {
 			prevSize := fw.Size
 
 			var evt *fsnotify.FileEvent
+			var ok bool
 
 			select {
-			case evt = <-w.Event:
+			case evt, ok = <-w.Event:
+				if !ok {
+					return
+				}
 			case <-t.Dying():
 				return
 			}
@@ -119,3 +126,11 @@ func (fw *InotifyFileWatcher) ChangeEvents(t *tomb.Tomb, fi os.FileInfo) *FileCh
 
 	return changes
 }
+
+func Cleanup() {
+	inotifyTracker.CloseAll()
+}
+
+func init() {
+	inotifyTracker = NewInotifyTracker()
+}

watch/inotify_tracker.go

@@ -0,0 +1,49 @@
+package watch
+
+import (
+	"github.com/howeyc/fsnotify"
+	"log"
+	"sync"
+)
+
+type InotifyTracker struct {
+	mux      sync.Mutex
+	watchers map[*fsnotify.Watcher]bool
+}
+
+func NewInotifyTracker() *InotifyTracker {
+	t := new(InotifyTracker)
+	t.watchers = make(map[*fsnotify.Watcher]bool)
+	return t
+}
+
+func (t *InotifyTracker) NewWatcher() (*fsnotify.Watcher, error) {
+	t.mux.Lock()
+	defer t.mux.Unlock()
+	w, err := fsnotify.NewWatcher()
+	if err == nil {
+		t.watchers[w] = true
+	}
+	return w, err
+}
+
+func (t *InotifyTracker) CloseWatcher(w *fsnotify.Watcher) (err error) {
+	t.mux.Lock()
+	defer t.mux.Unlock()
+	if _, ok := t.watchers[w]; ok {
+		err = w.Close()
+		delete(t.watchers, w)
+	}
+	return
+}
+
+func (t *InotifyTracker) CloseAll() {
+	t.mux.Lock()
+	defer t.mux.Unlock()
+	for w, _ := range t.watchers {
+		if err := w.Close(); err != nil {
+			log.Printf("Error closing watcher: %v", err)
+		}
+		delete(t.watchers, w)
+	}
+}