stop autofile and autogroup properly

NOTE: from the ticker#Stop documentation:

```
Stop does not close the channel, to prevent a read from the channel
succeeding incorrectly.
https://golang.org/src/time/tick.go?s=1318:1341#L35
```

Refs #2072

libs/autofile/autofile.go

@@ -35,18 +35,20 @@ const autoFileOpenDuration = 1000 * time.Millisecond
 // Automatically closes and re-opens file for writing.
 // This is useful for using a log file with the logrotate tool.
 type AutoFile struct {
-	ID     string
-	Path   string
-	ticker *time.Ticker
-	mtx    sync.Mutex
-	file   *os.File
+	ID            string
+	Path          string
+	ticker        *time.Ticker
+	tickerStopped chan struct{} // closed when ticker is stopped
+	mtx           sync.Mutex
+	file          *os.File
 }
 
 func OpenAutoFile(path string) (af *AutoFile, err error) {
 	af = &AutoFile{
-		ID:     cmn.RandStr(12) + ":" + path,
-		Path:   path,
-		ticker: time.NewTicker(autoFileOpenDuration),
+		ID:            cmn.RandStr(12) + ":" + path,
+		Path:          path,
+		ticker:        time.NewTicker(autoFileOpenDuration),
+		tickerStopped: make(chan struct{}),
 	}
 	if err = af.openFile(); err != nil {
 		return
@@ -58,18 +60,18 @@ func OpenAutoFile(path string) (af *AutoFile, err error) {
 
 func (af *AutoFile) Close() error {
 	af.ticker.Stop()
+	close(af.tickerStopped)
 	err := af.closeFile()
 	sighupWatchers.removeAutoFile(af)
 	return err
 }
 
 func (af *AutoFile) processTicks() {
-	for {
-		_, ok := <-af.ticker.C
-		if !ok {
-			return // Done.
-		}
+	select {
+	case <-af.ticker.C:
 		af.closeFile()
+	case <-af.tickerStopped:
+		return
 	}
 }
 

libs/autofile/group.go

@@ -199,21 +199,15 @@ func (g *Group) Flush() error {
 }
 
 func (g *Group) processTicks() {
-	for {
-		_, ok := <-g.ticker.C
-		if !ok {
-			return // Done.
-		}
+	select {
+	case <-g.ticker.C:
 		g.checkHeadSizeLimit()
 		g.checkTotalSizeLimit()
+	case <-g.Quit():
+		return
 	}
 }
 
-// NOTE: for testing
-func (g *Group) stopTicker() {
-	g.ticker.Stop()
-}
-
 // NOTE: this function is called manually in tests.
 func (g *Group) checkHeadSizeLimit() {
 	limit := g.HeadSizeLimit()

libs/autofile/group_test.go

@@ -26,7 +26,7 @@ func createTestGroup(t *testing.T, headSizeLimit int64) *Group {
 	g, err := OpenGroup(headPath)
 	require.NoError(t, err, "Error opening Group")
 	g.SetHeadSizeLimit(headSizeLimit)
-	g.stopTicker()
+	g.ticker.Stop()
 	require.NotEqual(t, nil, g, "Failed to create Group")
 	return g
 }