Moved InotifyTracker initialization to constructor function

watch/inotify.go

@@ -28,11 +28,11 @@ func (fw *InotifyFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
 	dirname := filepath.Dir(fw.Filename)
 
 	// Watch for new files to be created in the parent directory.
-	err := shared.WatchFlags(dirname, fsnotify.FSN_CREATE)
+	err := WatchFlags(dirname, fsnotify.FSN_CREATE)
 	if err != nil {
 		return err
 	}
-	defer shared.RemoveWatch(dirname)
+	defer RemoveWatch(dirname)
 
 	// Do a real check now as the file might have been created before
 	// calling `WatchFlags` above.
@@ -41,7 +41,7 @@ func (fw *InotifyFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
 		return err
 	}
 
-	events := shared.Events(fw.Filename)
+	events := Events(fw.Filename)
 
 	for {
 		select {
@@ -61,7 +61,7 @@ func (fw *InotifyFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
 func (fw *InotifyFileWatcher) ChangeEvents(t *tomb.Tomb, fi os.FileInfo) *FileChanges {
 	changes := NewFileChanges()
 
-	err := shared.Watch(fw.Filename)
+	err := Watch(fw.Filename)
 	if err != nil {
 		go changes.NotifyDeleted()
 	}
@@ -69,10 +69,10 @@ func (fw *InotifyFileWatcher) ChangeEvents(t *tomb.Tomb, fi os.FileInfo) *FileCh
 	fw.Size = fi.Size()
 
 	go func() {
-		defer shared.RemoveWatch(fw.Filename)
+		defer RemoveWatch(fw.Filename)
 		defer changes.Close()
 
-		events := shared.Events(fw.Filename)
+		events := Events(fw.Filename)
 
 		for {
 			prevSize := fw.Size

watch/inotify_tracker.go

@@ -30,6 +30,11 @@ type watchInfo struct {
 
 var (
 	// globally shared InotifyTracker; ensures only one fsnotify.Watcher is used
+	shared *InotifyTracker
+
+	// these are used to ensure the shared InotifyTracker is run exactly once
+	once  = sync.Once{}
+	goRun = func() {
 		shared = &InotifyTracker{
 			mux:    sync.Mutex{},
 			chans:  make(map[string]chan *fsnotify.FileEvent),
@@ -38,10 +43,6 @@ var (
 			remove: make(chan string),
 			error:  make(chan error),
 		}
-
-	// these are used to ensure the shared InotifyTracker is run exactly once
-	once  = &sync.Once{}
-	goRun = func() {
 		go shared.run()
 	}
 
@@ -50,13 +51,13 @@ var (
 
 // WatchFlags signals the run goroutine to begin watching the input filename using
 // using all flags.
-func (shared *InotifyTracker) Watch(fname string) error {
+func Watch(fname string) error {
-	return shared.WatchFlags(fname, fsnotify.FSN_ALL)
+	return WatchFlags(fname, fsnotify.FSN_ALL)
 }
 
 // WatchFlags signals the run goroutine to begin watching the input filename using
 // using the input flags.
-func (shared *InotifyTracker) WatchFlags(fname string, flags uint32) error {
+func WatchFlags(fname string, flags uint32) error {
 	// start running the shared InotifyTracker if not already running
 	once.Do(goRun)
 
@@ -68,7 +69,7 @@ func (shared *InotifyTracker) WatchFlags(fname string, flags uint32) error {
 }
 
 // RemoveWatch signals the run goroutine to remove the watch for the input filename
-func (shared *InotifyTracker) RemoveWatch(fname string) {
+func RemoveWatch(fname string) {
 	// start running the shared InotifyTracker if not already running
 	once.Do(goRun)
 
@@ -86,17 +87,16 @@ func (shared *InotifyTracker) RemoveWatch(fname string) {
 // Events returns a channel to which FileEvents corresponding to the input filename
 // will be sent. This channel will be closed when removeWatch is called on this
 // filename.
-func (shared *InotifyTracker) Events(fname string) chan *fsnotify.FileEvent {
+func Events(fname string) chan *fsnotify.FileEvent {
 	shared.mux.Lock()
 	defer shared.mux.Unlock()
 
 	return shared.chans[fname]
 }
 
-// Cleanup removes the watch for the input filename and closes the shared Watcher
+// Cleanup removes the watch for the input filename if necessary.
-// if there are no more targets.
 func Cleanup(fname string) {
-	shared.RemoveWatch(fname)
+	RemoveWatch(fname)
 }
 
 // watchFlags calls fsnotify.WatchFlags for the input filename and flags, creating