breacharbiter: at startup, watch pending closed channels to mark as fully closed

This commit adds a start up check to the breachArbiter: it will now
watch all channels which are in the “pending closed” state, to ensure
that state of the database is up to date at all times. Once any of the
closing transactions for these channels have been confirmed, then they
will properly be marked as such within the database.

breacharbiter.go

@@ -120,6 +120,51 @@ func (b *breachArbiter) Start() error {
 	b.wg.Add(1)
 	go b.contractObserver(channelsToWatch)
 
+	// Additionally, we'll also want to retrieve any pending close or force
+	// close transactions to we can properly mark them as resolved in the
+	// database.
+	pendingCloseChans, err := b.db.FetchClosedChannels(true)
+	if err != nil {
+		brarLog.Errorf("unable to fetch closing channels: %v", err)
+		return err
+	}
+	for _, pendingClose := range pendingCloseChans {
+		// If this channel was force closed, and we have a non-zero
+		// balance, then the utxoNursery is currently watching over it.
+		// As a result we don't need to watch over it.
+		if pendingClose.CloseType == channeldb.ForceClose &&
+			pendingClose.OurBalance != 0 {
+			continue
+		}
+
+		brarLog.Infof("Watching for the closure of ChannelPoint(%v)",
+			pendingClose.ChanPoint)
+
+		chanPoint := &pendingClose.ChanPoint
+		closeTXID := &pendingClose.ClosingTXID
+		confNtfn, err := b.notifier.RegisterConfirmationsNtfn(closeTXID, 1)
+		if err != nil {
+			return err
+		}
+
+		go func() {
+			// In the case that the ChainNotifier is shutting down,
+			// all subscriber notification channels will be closed,
+			// generating a nil receive.
+			confInfo, ok := <-confNtfn.Confirmed
+			if !ok {
+				return
+			}
+
+			brarLog.Infof("ChannelPoint(%v) is fully closed, "+
+				"at height: %v", chanPoint, confInfo.BlockHeight)
+
+			if err := b.db.MarkChanFullyClosed(chanPoint); err != nil {
+				brarLog.Errorf("unable to mark chan as closed: %v", err)
+			}
+		}()
+	}
+
 	return nil
 }