From c3d5204f09a5f4159c0c03c12f3e52a59765cd73 Mon Sep 17 00:00:00 2001
From: Wilmer Paulino <wilmer.paulino@gmail.com>
Date: Thu, 6 Dec 2018 21:13:56 -0800
Subject: [PATCH] chainntnfs/txnotifier: refactor ProcessRelevantSpendTx to
 detect script spends

In this commit, we refactor the TxNotifier's ProcessRelevantSpendTx to
also detect script spends. This can easily be done as the transaction
filtering logic was refactored into its own method in a previous commit.
---
 chainntnfs/txnotifier.go | 49 +++++++++++++++++++---------------------
 1 file changed, 23 insertions(+), 26 deletions(-)

diff --git a/chainntnfs/txnotifier.go b/chainntnfs/txnotifier.go
index da70a607..2d772e28 100644
--- a/chainntnfs/txnotifier.go
+++ b/chainntnfs/txnotifier.go
@@ -870,9 +870,11 @@ func (n *TxNotifier) CancelSpend(spendRequest SpendRequest, spendID uint64) {
 
 // ProcessRelevantSpendTx processes a transaction provided externally. This will
 // check whether the transaction is relevant to the notifier if it spends any
-// outputs for which we currently have registered notifications for. If it is
-// relevant, spend notifications will be dispatched to the caller.
-func (n *TxNotifier) ProcessRelevantSpendTx(tx *wire.MsgTx, txHeight int32) error {
+// outpoints/output scripts for which we currently have registered notifications
+// for. If it is relevant, spend notifications will be dispatched to the caller.
+func (n *TxNotifier) ProcessRelevantSpendTx(tx *btcutil.Tx,
+	blockHeight uint32) error {
+
 	select {
 	case <-n.quit:
 		return ErrTxNotifierExiting
@@ -884,31 +886,26 @@ func (n *TxNotifier) ProcessRelevantSpendTx(tx *wire.MsgTx, txHeight int32) erro
 	n.Lock()
 	defer n.Unlock()
 
-	// Grab the set of active registered outpoints to determine if the
-	// transaction spends any of them.
-	spendNtfns := n.spendNotifications
+	// We'll use a channel to coalesce all the spend requests that this
+	// transaction fulfills.
+	type spend struct {
+		request *SpendRequest
+		details *SpendDetail
+	}
 
-	// We'll check if this transaction spends an output that has an existing
-	// spend notification for it.
-	for i, txIn := range tx.TxIn {
-		// If this input doesn't spend an existing registered outpoint,
-		// we'll go on to the next.
-		prevOut := txIn.PreviousOutPoint
-		if _, ok := spendNtfns[prevOut]; !ok {
-			continue
-		}
+	// We'll set up the onSpend filter callback to gather all the fulfilled
+	// spends requests within this transaction.
+	var spends []spend
+	onSpend := func(request SpendRequest, details *SpendDetail) {
+		spends = append(spends, spend{&request, details})
+	}
+	n.filterTx(tx, nil, blockHeight, nil, onSpend)
 
-		// Otherwise, we'll create a spend summary and send off the
-		// details to the notification subscribers.
-		txHash := tx.TxHash()
-		details := &SpendDetail{
-			SpentOutPoint:     &prevOut,
-			SpenderTxHash:     &txHash,
-			SpendingTx:        tx,
-			SpenderInputIndex: uint32(i),
-			SpendingHeight:    txHeight,
-		}
-		if err := n.updateSpendDetails(prevOut, details); err != nil {
+	// After the transaction has been filtered, we can finally dispatch
+	// notifications for each request.
+	for _, spend := range spends {
+		err := n.updateSpendDetails(*spend.request, spend.details)
+		if err != nil {
 			return err
 		}
 	}