avoid spamming trigger and event channels while draining

internal/fswatcher/fswatcher.go

@@ -25,6 +25,7 @@ type FSWatcher struct {
 	w           Walker
 	maxWatchers int
 	eventSize   int
+	drain       bool
 }
 
 func NewFSWatcher() *FSWatcher {
@@ -33,9 +34,14 @@ func NewFSWatcher() *FSWatcher {
 		w:           walker.NewWalker(),
 		maxWatchers: inotify.MaxWatchers,
 		eventSize:   inotify.EventSize,
+		drain:       true,
 	}
 }
 
+func (fs *FSWatcher) Enable() {
+	fs.drain = false
+}
+
 func (fs *FSWatcher) Close() {
 	fs.i.Close()
 }
@@ -116,6 +122,10 @@ func (fs *FSWatcher) observe(triggerCh chan struct{}, dataCh chan []byte, errCh
 
 	for {
 		n, err := fs.i.Read(buf)
+		if fs.drain {
+			continue
+		}
+
 		triggerCh <- struct{}{}
 		if err != nil {
 			errCh <- fmt.Errorf("reading inotify buffer: %v", err)

internal/pspy/pspy.go

@@ -24,6 +24,7 @@ type Logger interface {
 type FSWatcher interface {
 	Init(rdirs, dirs []string) (chan error, chan struct{})
 	Run() (chan struct{}, chan string, chan error)
+	Enable()
 }
 
 type PSScanner interface {
@@ -110,7 +111,7 @@ func startFSW(fsw FSWatcher, logger Logger, drainFor time.Duration, sigCh <-chan
 
 	// ignore all file system events created on startup
 	logger.Infof("Draining file system events due to startup...")
-	ok = drainEventsFor(triggerCh, fsEventCh, drainFor, sigCh)
+	ok = drainEventsFor(triggerCh, fsEventCh, drainFor, sigCh, fsw)
 	logger.Infof("done")
 	return
 }
@@ -137,14 +138,13 @@ func logErrors(errCh chan error, logger Logger) {
 	}
 }
 
-func drainEventsFor(triggerCh chan struct{}, eventCh chan string, d time.Duration, sigCh <-chan os.Signal) bool {
+func drainEventsFor(triggerCh chan struct{}, eventCh chan string, d time.Duration, sigCh <-chan os.Signal, fsw FSWatcher) bool {
 	for {
 		select {
 		case <-sigCh:
 			return false
-		case <-triggerCh:
-		case <-eventCh:
 		case <-time.After(d):
+			fsw.Enable()
 			return true
 		}
 	}

internal/pspy/pspy_test.go

@@ -68,8 +68,6 @@ func TestStartFSW(t *testing.T) {
 	sigCh := make(chan os.Signal)
 
 	go func() {
-		fsw.runTriggerCh <- struct{}{} // trigger sent while draining
-		fsw.runEventCh <- "event sent while draining"
 		fsw.runErrCh <- errors.New("error sent while draining")
 		<-time.After(drainFor) // ensure draining is over
 		fsw.runTriggerCh <- struct{}{}
@@ -294,6 +292,10 @@ func (fsw *mockFSWatcher) Run() (chan struct{}, chan string, chan error) {
 	return fsw.runTriggerCh, fsw.runEventCh, fsw.runErrCh
 }
 
+func (fsw *mockFSWatcher) Enable() {
+	return
+}
+
 // PSScanner
 
 type mockPSScanner struct {