lib/model, lib/versioner: Drive version cleanup from scanner (fixes #6313) (#6693)

This change adds a separate config for the cleanup interval, and runs that cleanup from the main folder loop.

lib/versioner/trashcan.go

@@ -12,11 +12,8 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/thejerf/suture"
-
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/fs"
-	"github.com/syncthing/syncthing/lib/util"
 )
 
 func init() {
@@ -25,7 +22,6 @@ func init() {
 }
 
 type trashcan struct {
-	suture.Service
 	folderFs        fs.Filesystem
 	versionsFs      fs.Filesystem
 	cleanoutDays    int
@@ -42,7 +38,6 @@ func newTrashcan(cfg config.FolderConfiguration) Versioner {
 		cleanoutDays:    cleanoutDays,
 		copyRangeMethod: cfg.CopyRangeMethod,
 	}
-	s.Service = util.AsService(s.serve, s.String())
 
 	l.Debugf("instantiated %#v", s)
 	return s
@@ -56,37 +51,16 @@ func (t *trashcan) Archive(filePath string) error {
 	})
 }
 
-func (t *trashcan) serve(ctx context.Context) {
-	l.Debugln(t, "starting")
-	defer l.Debugln(t, "stopping")
-
-	// Do the first cleanup one minute after startup.
-	timer := time.NewTimer(time.Minute)
-	defer timer.Stop()
-
-	for {
-		select {
-		case <-ctx.Done():
-			return
-
-		case <-timer.C:
-			if t.cleanoutDays > 0 {
-				if err := t.cleanoutArchive(); err != nil {
-					l.Infoln("Cleaning trashcan:", err)
-				}
-			}
-
-			// Cleanups once a day should be enough.
-			timer.Reset(24 * time.Hour)
-		}
-	}
-}
-
 func (t *trashcan) String() string {
 	return fmt.Sprintf("trashcan@%p", t)
 }
 
-func (t *trashcan) cleanoutArchive() error {
+func (t *trashcan) Clean(ctx context.Context) error {
+	if t.cleanoutDays <= 0 {
+		// no cleanout requested
+		return nil
+	}
+
 	if _, err := t.versionsFs.Lstat("."); fs.IsNotExist(err) {
 		return nil
 	}
@@ -98,6 +72,11 @@ func (t *trashcan) cleanoutArchive() error {
 		if err != nil {
 			return err
 		}
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+		}
 
 		if info.IsDir() && !info.IsSymlink() {
 			dirTracker.addDir(path)