Reduce scanning effort

internal/model/model.go

@@ -1227,13 +1227,14 @@ func (m *Model) internalScanFolderSubs(folder string, subs []string) error {
 nextSub:
 	for _, sub := range subs {
 		for sub != "" {
-			if _, ok = fs.Get(protocol.LocalDeviceID, sub); ok {
+			parent := filepath.Dir(sub)
+			if parent == "." || parent == string(filepath.Separator) {
+				parent = ""
+			}
+			if _, ok = fs.Get(protocol.LocalDeviceID, parent); ok {
 				break
 			}
-			sub = filepath.Dir(sub)
-			if sub == "." || sub == string(filepath.Separator) {
-				sub = ""
-			}
+			sub = parent
 		}
 		for _, us := range unifySubs {
 			if strings.HasPrefix(sub, us) {

internal/rc/rc.go

@@ -17,9 +17,11 @@ import (
 	"io/ioutil"
 	"log"
 	"net/http"
+	"net/url"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strconv"
 	stdsync "sync"
 	"time"
 
@@ -233,6 +235,21 @@ func (p *Process) RescanDelay(folder string, delaySeconds int) error {
 	return err
 }
 
+func (p *Process) RescanSub(folder string, sub string, delaySeconds int) error {
+	return p.RescanSubs(folder, []string{sub}, delaySeconds)
+}
+
+func (p *Process) RescanSubs(folder string, subs []string, delaySeconds int) error {
+	data := url.Values{}
+	data.Set("folder", folder)
+	for _, sub := range subs {
+		data.Add("sub", sub)
+	}
+	data.Set("next", strconv.Itoa(delaySeconds))
+	_, err := p.Post("/rest/db/scan?"+data.Encode(), nil)
+	return err
+}
+
 func (p *Process) ConfigInSync() (bool, error) {
 	bs, err := p.Get("/rest/system/config/insync")
 	if err != nil {