reduce channel monitor log verbosity (#241)

* refactor: reduce channel monitor log verbosity

* refactor: debug -> info

channelmonitor/channelmonitor.go

@@ -160,7 +160,7 @@ type monitoredChannel struct {
 	chid                    datatransfer.ChannelID
 	cfg                     *Config
 	unsub                   datatransfer.Unsubscribe
-	restartChannelDebounced func()
+	restartChannelDebounced func(error)
 	onShutdown              func(datatransfer.ChannelID)
 	shutdownLk              sync.Mutex
 
@@ -187,8 +187,33 @@ func newMonitoredChannel(
 		cfg:        cfg,
 		onShutdown: onShutdown,
 	}
+
+	// "debounce" calls to restart channel, ie if there are multiple calls in a
+	// short space of time, only send a message to restart the channel once
+	var lk sync.Mutex
+	var lastErr error
 	debouncer := debounce.New(cfg.RestartDebounce)
-	mpc.restartChannelDebounced = func() { debouncer(mpc.restartChannel) }
+	mpc.restartChannelDebounced = func(err error) {
+		// Log the error at debug level
+		log.Debug(err.Error())
+
+		// Save the last error passed to restartChannelDebounced
+		lk.Lock()
+		lastErr = err
+		lk.Unlock()
+
+		debouncer(func() {
+			// Log only the last error passed to restartChannelDebounced at warning level
+			lk.Lock()
+			log.Warnf("%s", lastErr)
+			lk.Unlock()
+
+			// Restart the channel
+			mpc.restartChannel()
+		})
+	}
+
+	// Start monitoring the channel
 	mpc.start()
 	return mpc
 }
@@ -247,13 +272,13 @@ func (mc *monitoredChannel) start() {
 		case datatransfer.SendDataError:
 			// If the transport layer reports an error sending data over the wire,
 			// attempt to restart the channel
-			log.Warnf("%s: data transfer transport send error, restarting data transfer", mc.chid)
-			go mc.restartChannelDebounced()
+			err := xerrors.Errorf("%s: data transfer transport send error, restarting data transfer", mc.chid)
+			go mc.restartChannelDebounced(err)
 		case datatransfer.ReceiveDataError:
 			// If the transport layer reports an error receiving data over the wire,
 			// attempt to restart the channel
-			log.Warnf("%s: data transfer transport receive error, restarting data transfer", mc.chid)
-			go mc.restartChannelDebounced()
+			err := xerrors.Errorf("%s: data transfer transport receive error, restarting data transfer", mc.chid)
+			go mc.restartChannelDebounced(err)
 		case datatransfer.FinishTransfer:
 			// The channel initiator has finished sending / receiving all data.
 			// Watch to make sure that the responder sends a message to acknowledge
@@ -355,7 +380,7 @@ func (mc *monitoredChannel) restartChannel() {
 
 	// Check if channel is already being restarted
 	if !restartedAt.IsZero() {
-		log.Infof("%s: restart called but already restarting channel, "+
+		log.Debugf("%s: restart called but already restarting channel, "+
 			"waiting to restart again (since %s; restart backoff is %s)",
 			mc.chid, time.Since(restartedAt), mc.cfg.RestartBackoff)
 		return
@@ -397,7 +422,7 @@ func (mc *monitoredChannel) restartChannel() {
 		}
 
 		// There was a restart queued, restart again
-		log.Infof("%s: restart was queued - restarting again", mc.chid)
+		log.Debugf("%s: restart was queued - restarting again", mc.chid)
 	}
 }
 
@@ -416,7 +441,7 @@ func (mc *monitoredChannel) doRestartChannel() error {
 	}
 
 	// Send the restart message
-	log.Infof("%s: restarting (%d consecutive restarts)", mc.chid, restartCount)
+	log.Debugf("%s: restarting (%d consecutive restarts)", mc.chid, restartCount)
 	err := mc.sendRestartMessage(restartCount)
 	if err != nil {
 		log.Warnf("%s: restart failed, trying again: %s", mc.chid, err)
@@ -433,17 +458,17 @@ func (mc *monitoredChannel) sendRestartMessage(restartCount int) error {
 	// Note that at the networking layer there is logic to retry if a network
 	// connection cannot be established, so this may take some time.
 	p := mc.chid.OtherParty(mc.mgr.PeerID())
-	log.Infof("%s: re-establishing connection to %s", mc.chid, p)
+	log.Debugf("%s: re-establishing connection to %s", mc.chid, p)
 	start := time.Now()
 	err := mc.mgr.ConnectTo(mc.ctx, p)
 	if err != nil {
 		return xerrors.Errorf("%s: failed to reconnect to peer %s after %s: %w",
 			mc.chid, p, time.Since(start), err)
 	}
-	log.Infof("%s: re-established connection to %s in %s", mc.chid, p, time.Since(start))
+	log.Debugf("%s: re-established connection to %s in %s", mc.chid, p, time.Since(start))
 
 	// Send a restart message for the channel
-	log.Infof("%s: sending restart message to %s (%d consecutive restarts)", mc.chid, p, restartCount)
+	log.Debugf("%s: sending restart message to %s (%d consecutive restarts)", mc.chid, p, restartCount)
 	err = mc.mgr.RestartDataTransferChannel(mc.ctx, mc.chid)
 	if err != nil {
 		return xerrors.Errorf("%s: failed to send restart message to %s: %w", mc.chid, p, err)
@@ -453,11 +478,11 @@ func (mc *monitoredChannel) sendRestartMessage(restartCount int) error {
 	// If a restart backoff is configured, backoff after a restart before
 	// attempting another.
 	if mc.cfg.RestartBackoff > 0 {
-		log.Infof("%s: backing off %s before allowing any other restarts",
+		log.Debugf("%s: backing off %s before allowing any other restarts",
 			mc.chid, mc.cfg.RestartBackoff)
 		select {
 		case <-time.After(mc.cfg.RestartBackoff):
-			log.Infof("%s: restart back-off of %s complete", mc.chid, mc.cfg.RestartBackoff)
+			log.Debugf("%s: restart back-off of %s complete", mc.chid, mc.cfg.RestartBackoff)
 		case <-mc.ctx.Done():
 			return nil
 		}

impl/events.go

@@ -233,12 +233,12 @@ func (m *manager) OnRequestDisconnected(chid datatransfer.ChannelID, err error)
 }
 
 func (m *manager) OnSendDataError(chid datatransfer.ChannelID, err error) error {
-	log.Warnf("channel %+v had transport send error: %s", chid, err)
+	log.Debugf("channel %+v had transport send error: %s", chid, err)
 	return m.channels.SendDataError(chid, err)
 }
 
 func (m *manager) OnReceiveDataError(chid datatransfer.ChannelID, err error) error {
-	log.Warnf("channel %+v had transport receive error: %s", chid, err)
+	log.Debugf("channel %+v had transport receive error: %s", chid, err)
 	return m.channels.ReceiveDataError(chid, err)
 }