From 8e1087d1cdcbb21b495cffa74ac0afc6c2ffa533 Mon Sep 17 00:00:00 2001
From: "Johan T. Halseth" <johanth@gmail.com>
Date: Mon, 10 May 2021 10:06:23 +0200
Subject: [PATCH] lwallet: only count public channels towards our reserved
 value

Since private channels (most likely) won't be used for routing other
than as last hop, they bear a smaller risk that we must quickly force
close them in order to resolve a HTLC up/downstream.

In the case where it actually has to be force to resolve a payment (if
it is the first/last hop on a routed payment), we can assume that the
router will have UTXOs available from the reserved value from the
incoming public channel.
---
 lnwallet/wallet.go | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/lnwallet/wallet.go b/lnwallet/wallet.go
index dc6d6838..c61cf8b3 100644
--- a/lnwallet/wallet.go
+++ b/lnwallet/wallet.go
@@ -604,9 +604,11 @@ func (l *LightningWallet) PsbtFundingVerify(pendingChanID [32]byte,
 	// If this commit type is an anchor channel we add that to our counter,
 	// but only if we are contributing funds to the channel. This is done
 	// to still allow incoming channels even though we have no UTXOs
-	// available, as in bootstrapping phases.
+	// available, as in bootstrapping phases. We only count public
+	// channels.
+	isPublic := pendingReservation.partialState.ChannelFlags&lnwire.FFAnnounceChannel != 0
 	if pendingReservation.partialState.ChanType.HasAnchors() &&
-		intent.LocalFundingAmt() > 0 {
+		intent.LocalFundingAmt() > 0 && isPublic {
 		numAnchors++
 	}
 
@@ -819,9 +821,11 @@ func (l *LightningWallet) handleFundingReserveRequest(req *InitFundingReserveMsg
 	// If this commit type is an anchor channel we add that to our counter,
 	// but only if we are contributing funds to the channel. This is done
 	// to still allow incoming channels even though we have no UTXOs
-	// available, as in bootstrapping phases.
+	// available, as in bootstrapping phases. We only count public
+	// channels.
+	isPublic := req.Flags&lnwire.FFAnnounceChannel != 0
 	if req.CommitType == CommitmentTypeAnchorsZeroFeeHtlcTx &&
-		fundingIntent.LocalFundingAmt() > 0 {
+		fundingIntent.LocalFundingAmt() > 0 && isPublic {
 		numAnchors++
 	}
 
@@ -888,8 +892,8 @@ func (l *LightningWallet) handleFundingReserveRequest(req *InitFundingReserveMsg
 	req.err <- nil
 }
 
-// currentNumAnchorChans returns the current number of anchor channels the
-// wallet should be ready to fee bump if needed.
+// currentNumAnchorChans returns the current number of non-private anchor
+// channels the wallet should be ready to fee bump if needed.
 func (l *LightningWallet) currentNumAnchorChans() (int, error) {
 	// Count all anchor channels that are open or pending
 	// open, or waiting close.
@@ -899,10 +903,22 @@ func (l *LightningWallet) currentNumAnchorChans() (int, error) {
 	}
 
 	var numAnchors int
-	for _, c := range chans {
+	cntChannel := func(c *channeldb.OpenChannel) {
+		// We skip private channels, as we assume they won't be used
+		// for routing.
+		if c.ChannelFlags&lnwire.FFAnnounceChannel == 0 {
+			return
+		}
+
+		// Count anchor channels.
 		if c.ChanType.HasAnchors() {
 			numAnchors++
 		}
+
+	}
+
+	for _, c := range chans {
+		cntChannel(c)
 	}
 
 	// We also count pending close channels.
@@ -925,9 +941,7 @@ func (l *LightningWallet) currentNumAnchorChans() (int, error) {
 			continue
 		}
 
-		if c.ChanType.HasAnchors() {
-			numAnchors++
-		}
+		cntChannel(c)
 	}
 
 	return numAnchors, nil