lib/model, lib/config: Refactor folder health/error handling (fixes #4445, fixes #4451)

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4455
LGTM: AudriusButkevicius, calmh

lib/model/rwfolder.go

@@ -165,7 +165,7 @@ func (f *sendReceiveFolder) Serve() {
 	var prevIgnoreHash string
 
 	if f.FSWatcherEnabled {
-		f.startWatcher()
+		f.startWatch()
 	}
 
 	for {
@@ -178,12 +178,6 @@ func (f *sendReceiveFolder) Serve() {
 			f.pullTimer.Reset(0)
 			l.Debugln(f, "remote index updated, rescheduling pull")
 
-		case <-f.ignoresUpdated:
-			if f.FSWatcherEnabled {
-				f.restartWatcher()
-			}
-			f.IndexUpdated()
-
 		case <-f.pullTimer.C:
 			select {
 			case <-f.initialScanFinished:
@@ -214,8 +208,8 @@ func (f *sendReceiveFolder) Serve() {
 				continue
 			}
 
-			if err := f.model.CheckFolderHealth(f.folderID); err != nil {
-				l.Infoln("Skipping pull of", f.Description(), "due to folder error:", err)
+			if err := f.CheckHealth(); err != nil {
+				l.Debugln("Skipping pull of", f.Description(), "due to folder error:", err)
 				f.pullTimer.Reset(f.sleep)
 				continue
 			}
@@ -292,6 +286,9 @@ func (f *sendReceiveFolder) Serve() {
 		case fsEvents := <-f.watchChan:
 			l.Debugln(f, "filesystem notification rescan")
 			f.scanSubdirs(fsEvents)
+
+		case <-f.restartWatchChan:
+			f.restartWatch()
 		}
 	}
 }
@@ -1696,6 +1693,11 @@ func (f *sendReceiveFolder) currentErrors() []fileError {
 	return errors
 }
 
+func (f *sendReceiveFolder) IgnoresUpdated() {
+	f.folder.IgnoresUpdated()
+	f.IndexUpdated()
+}
+
 // A []fileError is sent as part of an event and will be JSON serialized.
 type fileError struct {
 	Path string `json:"path"`