loopin: no timeout tx if invoice was paid

This action is not needed, since the swap is complete.
Wait until the timeout anyway to be able to push the key on every block.

Author: starius

loopin.go

@@ -854,9 +854,11 @@ func getTxFee(tx *wire.MsgTx, fee chainfee.SatPerKVByte) btcutil.Amount {
 	return fee.FeeForVSize(lntypes.VByte(vsize))
 }
 
-// waitForSwapComplete waits until a spending tx of the htlc gets confirmed and
-// the swap invoice is either settled or canceled. If the htlc times out, the
-// timeout tx will be published.
+// waitForSwapComplete waits until a spending tx of the HTLC gets confirmed and
+// the swap invoice is either settled or canceled. If the HTLC times out and the
+// invoice is still not paid, the timeout tx will be published. If the HTLC
+// times out and the invoice is paid, the function stops waiting and returns
+// clearly.
 func (s *loopInSwap) waitForSwapComplete(ctx context.Context,
 	htlcOutpoint *wire.OutPoint, htlcValue btcutil.Amount) error {
 
@@ -882,8 +884,14 @@ func (s *loopInSwap) waitForSwapComplete(ctx context.Context,
 	}
 
 	// publishTxOnTimeout publishes the timeout tx if the contract has
-	// expired.
+	// expired and invoice has not been settled.
 	publishTxOnTimeout := func() (btcutil.Amount, error) {
+		// Don't publish the timeout tx if we are not waiting for funds
+		// from HTLC, e.g. if the invoice was settled.
+		if s.state != loopdb.StateHtlcPublished {
+			return 0, nil
+		}
+
 		if s.height >= s.LoopInContract.CltvExpiry {
 			return s.publishTimeoutTx(ctx, htlcOutpoint, htlcValue)
 		}
@@ -902,7 +910,18 @@ func (s *loopInSwap) waitForSwapComplete(ctx context.Context,
 	htlcSpend := false
 	invoiceFinalized := false
 	htlcKeyRevealed := false
-	for !htlcSpend || !invoiceFinalized {
+	for {
+		// Check stop conditions.
+		if htlcSpend {
+			break
+		}
+		if s.state == loopdb.StateInvoiceSettled {
+			if s.height >= s.LoopInContract.CltvExpiry {
+				s.setState(loopdb.StateSuccess)
+				break
+			}
+		}
+
 		select {
 		// If the client requested the swap to be abandoned, we override
 		// the status in the database.