Serialize scans and pulls (fixes #1391)

internal/model/model.go

@@ -55,6 +55,7 @@ type service interface {
 	BringToFront(string)
 	DelayScan(d time.Duration)
 	IndexUpdated() // Remote index was updated notification
+	Scan(subs []string) error
 
 	setState(state folderState)
 	setError(err error)
@@ -1226,6 +1227,21 @@ func (m *Model) ScanFolder(folder string) error {
 }
 
 func (m *Model) ScanFolderSubs(folder string, subs []string) error {
+	m.fmut.Lock()
+	runner, ok := m.folderRunners[folder]
+	m.fmut.Unlock()
+
+	// Folders are added to folderRunners only when they are started. We can't
+	// scan them before they have started, so that's what we need to check for
+	// here.
+	if !ok {
+		return errors.New("no such folder")
+	}
+
+	return runner.Scan(subs)
+}
+
+func (m *Model) internalScanFolderSubs(folder string, subs []string) error {
 	for i, sub := range subs {
 		sub = osutil.NativeFilename(sub)
 		if p := filepath.Clean(filepath.Join(folder, sub)); !strings.HasPrefix(p, folder) {

internal/model/rofolder.go

@@ -22,9 +22,15 @@ type roFolder struct {
 	timer     *time.Timer
 	model     *Model
 	stop      chan struct{}
+	scanNow   chan rescanRequest
 	delayScan chan time.Duration
 }
 
+type rescanRequest struct {
+	subs []string
+	err  chan error
+}
+
 func newROFolder(model *Model, folder string, interval time.Duration) *roFolder {
 	return &roFolder{
 		stateTracker: stateTracker{
@@ -36,6 +42,7 @@ func newROFolder(model *Model, folder string, interval time.Duration) *roFolder
 		timer:     time.NewTimer(time.Millisecond),
 		model:     model,
 		stop:      make(chan struct{}),
+		scanNow:   make(chan rescanRequest),
 		delayScan: make(chan time.Duration),
 	}
 }
@@ -76,7 +83,7 @@ func (s *roFolder) Serve() {
 				l.Debugln(s, "rescan")
 			}
 
-			if err := s.model.ScanFolder(s.folder); err != nil {
+			if err := s.model.internalScanFolderSubs(s.folder, nil); err != nil {
 				// Potentially sets the error twice, once in the scanner just
 				// by doing a check, and once here, if the error returned is
 				// the same one as returned by CheckFolderHealth, though
@@ -92,11 +99,34 @@ func (s *roFolder) Serve() {
 			}
 
 			if s.intv == 0 {
-				return
+				continue
 			}
 
 			reschedule()
 
+		case req := <-s.scanNow:
+			if err := s.model.CheckFolderHealth(s.folder); err != nil {
+				l.Infoln("Skipping folder", s.folder, "scan due to folder error:", err)
+				req.err <- err
+				continue
+			}
+
+			if debug {
+				l.Debugln(s, "forced rescan")
+			}
+
+			if err := s.model.internalScanFolderSubs(s.folder, req.subs); err != nil {
+				// Potentially sets the error twice, once in the scanner just
+				// by doing a check, and once here, if the error returned is
+				// the same one as returned by CheckFolderHealth, though
+				// duplicate set is handled by setError.
+				s.setError(err)
+				req.err <- err
+				continue
+			}
+
+			req.err <- nil
+
 		case next := <-s.delayScan:
 			s.timer.Reset(next)
 		}
@@ -110,6 +140,15 @@ func (s *roFolder) Stop() {
 func (s *roFolder) IndexUpdated() {
 }
 
+func (s *roFolder) Scan(subs []string) error {
+	req := rescanRequest{
+		subs: subs,
+		err:  make(chan error),
+	}
+	s.scanNow <- req
+	return <-req.err
+}
+
 func (s *roFolder) String() string {
 	return fmt.Sprintf("roFolder/%s@%p", s.folder, s)
 }

internal/model/rwfolder.go

@@ -32,7 +32,7 @@ import (
 const (
 	pauseIntv     = 60 * time.Second
 	nextPullIntv  = 10 * time.Second
-	shortPullIntv = 5 * time.Second
+	shortPullIntv = time.Second
 )
 
 // A pullBlockState is passed to the puller routine for each block that needs
@@ -90,6 +90,7 @@ type rwFolder struct {
 	scanTimer   *time.Timer
 	pullTimer   *time.Timer
 	delayScan   chan time.Duration
+	scanNow     chan rescanRequest
 	remoteIndex chan struct{} // An index update was received, we should re-evaluate needs
 }
 
@@ -118,6 +119,7 @@ func newRWFolder(m *Model, shortID uint64, cfg config.FolderConfiguration) *rwFo
 		pullTimer:   time.NewTimer(shortPullIntv),
 		scanTimer:   time.NewTimer(time.Millisecond), // The first scan should be done immediately.
 		delayScan:   make(chan time.Duration),
+		scanNow:     make(chan rescanRequest),
 		remoteIndex: make(chan struct{}, 1), // This needs to be 1-buffered so that we queue a notification if we're busy doing a pull when it comes.
 	}
 }
@@ -278,7 +280,7 @@ func (p *rwFolder) Serve() {
 				l.Debugln(p, "rescan")
 			}
 
-			if err := p.model.ScanFolder(p.folder); err != nil {
+			if err := p.model.internalScanFolderSubs(p.folder, nil); err != nil {
 				// Potentially sets the error twice, once in the scanner just
 				// by doing a check, and once here, if the error returned is
 				// the same one as returned by CheckFolderHealth, though
@@ -296,6 +298,29 @@ func (p *rwFolder) Serve() {
 				initialScanCompleted = true
 			}
 
+		case req := <-p.scanNow:
+			if err := p.model.CheckFolderHealth(p.folder); err != nil {
+				l.Infoln("Skipping folder", p.folder, "scan due to folder error:", err)
+				req.err <- err
+				continue
+			}
+
+			if debug {
+				l.Debugln(p, "forced rescan")
+			}
+
+			if err := p.model.internalScanFolderSubs(p.folder, req.subs); err != nil {
+				// Potentially sets the error twice, once in the scanner just
+				// by doing a check, and once here, if the error returned is
+				// the same one as returned by CheckFolderHealth, though
+				// duplicate set is handled by setError.
+				p.setError(err)
+				req.err <- err
+				continue
+			}
+
+			req.err <- nil
+
 		case next := <-p.delayScan:
 			p.scanTimer.Reset(next)
 		}
@@ -317,6 +342,15 @@ func (p *rwFolder) IndexUpdated() {
 	}
 }
 
+func (p *rwFolder) Scan(subs []string) error {
+	req := rescanRequest{
+		subs: subs,
+		err:  make(chan error),
+	}
+	p.scanNow <- req
+	return <-req.err
+}
+
 func (p *rwFolder) String() string {
 	return fmt.Sprintf("rwFolder/%s@%p", p.folder, p)
 }