lib/backup/fslocal: add FS.MustStop() method for stopping bandwidth limiter

app/vmbackup/main.go

@@ -90,6 +90,7 @@ func main() {
 	if err := a.Run(); err != nil {
 		logger.Fatalf("cannot create backup: %s", err)
 	}
+	srcFS.MustStop()
 }
 
 func usage() {

app/vmrestore/main.go

@@ -52,6 +52,7 @@ func main() {
 	if err := a.Run(); err != nil {
 		logger.Fatalf("cannot restore from backup: %s", err)
 	}
+	dstFS.MustStop()
 }
 
 func usage() {

lib/backup/fslocal/bandwidth_limiter.go

@@ -15,6 +15,9 @@ type bandwidthLimiter struct {
 
 	// quota for the current second
 	quota int
+
+	stopCh chan struct{}
+	wg     sync.WaitGroup
 }
 
 func newBandwidthLimiter(perSecondLimit int) *bandwidthLimiter {
@@ -25,10 +28,20 @@ func newBandwidthLimiter(perSecondLimit int) *bandwidthLimiter {
 	bl.perSecondLimit = perSecondLimit
 	var mu sync.Mutex
 	bl.c = sync.NewCond(&mu)
-	go bl.perSecondUpdater()
+	bl.stopCh = make(chan struct{})
+	bl.wg.Add(1)
+	go func() {
+		defer bl.wg.Done()
+		bl.perSecondUpdater()
+	}()
 	return &bl
 }
 
+func (bl *bandwidthLimiter) MustStop() {
+	close(bl.stopCh)
+	bl.wg.Wait()
+}
+
 func (bl *bandwidthLimiter) NewReadCloser(rc io.ReadCloser) *bandwidthLimitedReader {
 	return &bandwidthLimitedReader{
 		rc: rc,
@@ -83,7 +96,12 @@ func (blw *bandwidthLimitedWriter) Close() error {
 func (bl *bandwidthLimiter) perSecondUpdater() {
 	tc := time.NewTicker(time.Second)
 	c := bl.c
-	for range tc.C {
+	for {
+		select {
+		case <-tc.C:
+		case <-bl.stopCh:
+			return
+		}
 		c.L.Lock()
 		bl.quota = bl.perSecondLimit
 		c.Signal()

lib/backup/fslocal/fslocal.go

@@ -27,7 +27,9 @@ type FS struct {
 	bl *bandwidthLimiter
 }
 
-// Init initializes fs
+// Init initializes fs.
+//
+// The returned fs must be stopped when no long needed with MustStop call.
 func (fs *FS) Init() error {
 	if fs.MaxBytesPerSecond > 0 {
 		fs.bl = newBandwidthLimiter(fs.MaxBytesPerSecond)
@@ -35,6 +37,15 @@ func (fs *FS) Init() error {
 	return nil
 }
 
+// MustStop stops fs.
+func (fs *FS) MustStop() {
+	if fs.bl == nil {
+		return
+	}
+	fs.bl.MustStop()
+	fs.bl = nil
+}
+
 // String returns user-readable representation for the fs.
 func (fs *FS) String() string {
 	return fmt.Sprintf("fslocal %q", fs.Dir)