htlcswitch/link: reusable BatchTicker

This commit modifies the default BatchTicker
implementation such that it will generate a
new ticker with each call to Start(). This
allows us to create a new ticker after
releasing an old one due to the batch
being empty.

htlcswitch/link.go

@@ -107,22 +107,29 @@ type Ticker interface {
 
 // BatchTicker implements the Ticker interface, and wraps a time.Ticker.
 type BatchTicker struct {
+	duration time.Duration
 	ticker   *time.Ticker
 }
 
 // NewBatchTicker returns a new BatchTicker that wraps the passed time.Ticker.
-func NewBatchTicker(t *time.Ticker) *BatchTicker {
-	return &BatchTicker{t}
+func NewBatchTicker(d time.Duration) *BatchTicker {
+	return &BatchTicker{
+		duration: d,
+	}
 }
 
 // Start returns the tick channel for the underlying time.Ticker.
 func (t *BatchTicker) Start() <-chan time.Time {
+	t.ticker = time.NewTicker(t.duration)
 	return t.ticker.C
 }
 
 // Stop stops the underlying time.Ticker.
 func (t *BatchTicker) Stop() {
+	if t.ticker != nil {
 		t.ticker.Stop()
+		t.ticker = nil
+	}
 }
 
 // ChannelLinkConfig defines the configuration for the channel link. ALL
@@ -794,6 +801,7 @@ func (l *channelLink) fwdPkgGarbager() {
 // NOTE: This MUST be run as a goroutine.
 func (l *channelLink) htlcManager() {
 	defer func() {
+		l.cfg.BatchTicker.Stop()
 		l.wg.Done()
 		log.Infof("ChannelLink(%v) has exited", l)
 	}()
@@ -843,9 +851,6 @@ func (l *channelLink) htlcManager() {
 	l.wg.Add(1)
 	go l.fwdPkgGarbager()
 
-	batchTick := l.cfg.BatchTicker.Start()
-	defer l.cfg.BatchTicker.Stop()
-
 	// We'll only need the batch ticker if we have outgoing updates that are
 	// not covered by our last signature. This value will be nil unless a
 	// downstream packet forces the batchCounter to be positive. After the
@@ -938,6 +943,7 @@ out:
 			// here. We also disable the batch ticker from waking up
 			// the htlcManager while the batch is empty.
 			if l.batchCounter == 0 {
+				l.cfg.BatchTicker.Stop()
 				maybeBatchTick = nil
 				continue
 			}
@@ -967,8 +973,8 @@ out:
 			// If the downstream packet resulted in a non-empty
 			// batch, reinstate the batch ticker so that it can be
 			// cleared.
-			if l.batchCounter > 0 {
-				maybeBatchTick = batchTick
+			if l.batchCounter > 0 && maybeBatchTick == nil {
+				maybeBatchTick = l.cfg.BatchTicker.Start()
 			}
 
 		// A message from the switch was just received. This indicates
@@ -996,8 +1002,8 @@ out:
 			// If the downstream packet resulted in a non-empty
 			// batch, reinstate the batch ticker so that it can be
 			// cleared.
-			if l.batchCounter > 0 {
-				maybeBatchTick = batchTick
+			if l.batchCounter > 0 && maybeBatchTick == nil {
+				maybeBatchTick = l.cfg.BatchTicker.Start()
 			}
 
 		// A message from the connected peer was just received. This