add stop channel for each announcer

t.go

@@ -266,10 +266,10 @@ func (t *Torrent) AddTrackers(announceList [][]string) {
 	t.addTrackers(announceList)
 }
 
-func (t *Torrent) ClearTrackers() {
+func (t *Torrent) ModifyTrackers(announceList [][]string) {
 	t.cl.lock()
 	defer t.cl.unlock()
-	t.clearTrackers()
+	t.modifyTrackers(announceList)
 }
 
 func (t *Torrent) Piece(i pieceIndex) *Piece {

torrent.go

@@ -1708,8 +1708,12 @@ func (t *Torrent) addTrackers(announceList [][]string) {
 	t.updateWantPeersEvent()
 }
 
-func (t *Torrent) clearTrackers() {
+func (t *Torrent) modifyTrackers(announceList [][]string) {
+	for _, v := range t.trackerAnnouncers {
+		v.Stop()
+	}
 	clear(t.metainfo.AnnounceList)
+	t.addTrackers(announceList)
 }
 
 // Don't call this before the info is available.
@@ -1963,6 +1967,7 @@ func (t *Torrent) startScrapingTrackerWithInfohash(u *url.URL, urlStr string, sh
 			u:               *u,
 			t:               t,
 			lookupTrackerIp: t.cl.config.LookupTrackerIp,
+			stopCh:          make(chan struct{}),
 		}
 		go newAnnouncer.Run()
 		return newAnnouncer

tracker_scraper.go

@@ -23,11 +23,15 @@ type trackerScraper struct {
 	t               *Torrent
 	lastAnnounce    trackerAnnounceResult
 	lookupTrackerIp func(*url.URL) ([]net.IP, error)
+
+	stopCh chan struct{}
 }
 
 type torrentTrackerAnnouncer interface {
 	statusLine() string
 	URL() *url.URL
+
+	Stop()
 }
 
 func (me trackerScraper) URL() *url.URL {
@@ -202,6 +206,10 @@ func (me *trackerScraper) canIgnoreInterval(notify *<-chan struct{}) bool {
 	}
 }
 
+func (me *trackerScraper) Stop() {
+	close(me.stopCh)
+}
+
 func (me *trackerScraper) Run() {
 	defer me.announceStopped()
 
@@ -252,6 +260,8 @@ func (me *trackerScraper) Run() {
 		}
 
 		select {
+		case <-me.stopCh:
+			return
 		case <-me.t.closed.Done():
 			return
 		case <-reconsider:

wstracker.go

@@ -31,6 +31,9 @@ func (me websocketTrackerStatus) URL() *url.URL {
 	return &me.url
 }
 
+func (me websocketTrackerStatus) Stop() {
+}
+
 type refCountedWebtorrentTrackerClient struct {
 	webtorrent.TrackerClient
 	refCount int