Introduce thread-safe PeerMap

http/announce_test.go

@@ -374,8 +374,8 @@ func loadPrivateTestData(tkr *tracker.Tracker) error {
 	torrent := &models.Torrent{
 		ID:       1,
 		Infohash: infoHash,
-		Seeders:  models.PeerMap{},
-		Leechers: models.PeerMap{},
+		Seeders:  models.NewPeerMap(),
+		Leechers: models.NewPeerMap(),
 	}
 
 	return conn.PutTorrent(torrent)

http/writer.go

@@ -111,8 +111,8 @@ func filesDict(torrents []*models.Torrent) bencode.Dict {
 
 func torrentDict(torrent *models.Torrent) bencode.Dict {
 	return bencode.Dict{
-		"complete":   len(torrent.Seeders),
-		"incomplete": len(torrent.Leechers),
+		"complete":   torrent.Seeders.Len(),
+		"incomplete": torrent.Leechers.Len(),
 		"downloaded": torrent.Snatches,
 	}
 }