discovery+peer: add logs to reveal shutdown flow

Also adds a `TODO` for checking the err chan.

discovery/gossiper.go

@@ -658,6 +658,7 @@ func (d *AuthenticatedGossiper) Stop() error {
 
 func (d *AuthenticatedGossiper) stop() {
 	log.Info("Authenticated Gossiper is stopping")
+	defer log.Info("Authenticated Gossiper stopped")
 
 	d.blockEpochs.Cancel()
 

discovery/reliable_sender.go

@@ -84,6 +84,9 @@ func (s *reliableSender) Start() error {
 // Stop halts the reliable sender from sending messages to peers.
 func (s *reliableSender) Stop() {
 	s.stop.Do(func() {
+		log.Debugf("reliableSender is stopping")
+		defer log.Debugf("reliableSender stopped")
+
 		close(s.quit)
 		s.wg.Wait()
 	})

discovery/sync_manager.go

@@ -183,6 +183,9 @@ func (m *SyncManager) Start() {
 // Stop stops the SyncManager from performing its duties.
 func (m *SyncManager) Stop() {
 	m.stop.Do(func() {
+		log.Debugf("SyncManager is stopping")
+		defer log.Debugf("SyncManager stopped")
+
 		close(m.quit)
 		m.wg.Wait()
 

discovery/syncer.go

@@ -450,6 +450,9 @@ func (g *GossipSyncer) Start() {
 // exited.
 func (g *GossipSyncer) Stop() {
 	g.stopped.Do(func() {
+		log.Debugf("Stopping GossipSyncer(%x)", g.cfg.peerPub[:])
+		defer log.Debugf("GossipSyncer(%x) stopped", g.cfg.peerPub[:])
+
 		close(g.quit)
 		g.wg.Wait()
 	})