htlcswitch+peer: remove ShutdownIfChannelClean

htlcswitch/link.go

@@ -273,13 +273,6 @@ type ChannelLinkConfig struct {
 	GetAliases func(base lnwire.ShortChannelID) []lnwire.ShortChannelID
 }
 
-// shutdownReq contains an error channel that will be used by the channelLink
-// to send an error if shutdown failed. If shutdown succeeded, the channel will
-// be closed.
-type shutdownReq struct {
-	err chan error
-}
-
 // channelLink is the service which drives a channel's commitment update
 // state-machine. In the event that an HTLC needs to be propagated to another
 // link, the forward handler from config is used which sends HTLC to the
@@ -340,10 +333,6 @@ type channelLink struct {
 	// by the HTLC switch.
 	downstream chan *htlcPacket
 
-	// shutdownRequest is a channel that the channelLink will listen on to
-	// service shutdown requests from ShutdownIfChannelClean calls.
-	shutdownRequest chan *shutdownReq
-
 	// updateFeeTimer is the timer responsible for updating the link's
 	// commitment fee every time it fires.
 	updateFeeTimer *time.Timer
@@ -458,7 +447,6 @@ func NewChannelLink(cfg ChannelLinkConfig,
 		cfg:                 cfg,
 		channel:             channel,
 		shortChanID:         channel.ShortChanID(),
-		shutdownRequest:     make(chan *shutdownReq),
 		hodlMap:             make(map[models.CircuitKey]hodlHtlc),
 		hodlQueue:           queue.NewConcurrentQueue(10),
 		log:                 build.NewPrefixLog(logPrefix, log),
@@ -1446,24 +1434,6 @@ func (l *channelLink) htlcManager() {
 				)
 			}
 
-		case req := <-l.shutdownRequest:
-			// If the channel is clean, we send nil on the err chan
-			// and return to prevent the htlcManager goroutine from
-			// processing any more updates. The full link shutdown
-			// will be triggered by RemoveLink in the peer.
-			if l.channel.IsChannelClean() {
-				req.err <- nil
-				return
-			}
-
-			l.log.Infof("Channel is in an unclean state " +
-				"(lingering updates), graceful shutdown of " +
-				"channel link not possible")
-
-			// Otherwise, the channel has lingering updates, send
-			// an error and continue.
-			req.err <- ErrLinkFailedShutdown
-
 		case <-l.quit:
 			return
 		}
@@ -3020,29 +2990,6 @@ func (l *channelLink) HandleChannelUpdate(message lnwire.Message) {
 	l.mailBox.AddMessage(message)
 }
 
-// ShutdownIfChannelClean triggers a link shutdown if the channel is in a clean
-// state and errors if the channel has lingering updates.
-//
-// NOTE: Part of the ChannelUpdateHandler interface.
-func (l *channelLink) ShutdownIfChannelClean() error {
-	errChan := make(chan error, 1)
-
-	select {
-	case l.shutdownRequest <- &shutdownReq{
-		err: errChan,
-	}:
-	case <-l.quit:
-		return ErrLinkShuttingDown
-	}
-
-	select {
-	case err := <-errChan:
-		return err
-	case <-l.quit:
-		return ErrLinkShuttingDown
-	}
-}
-
 // updateChannelFee updates the commitment fee-per-kw on this channel by
 // committing to an update_fee message.
 func (l *channelLink) updateChannelFee(feePerKw chainfee.SatPerKWeight) error {