channeldb+routing: add tx parameter

Adds an optional tx parameter to ForAllOutgoingChannels and FetchChannel
so that data can be queried within the context of an existing database
transaction.

routing/localchans/manager.go

@@ -8,6 +8,7 @@ import (
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/discovery"
 	"github.com/lightningnetwork/lnd/htlcswitch"
+	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/routing"
 )
@@ -27,12 +28,14 @@ type Manager struct {
 
 	// ForAllOutgoingChannels is required to iterate over all our local
 	// channels.
-	ForAllOutgoingChannels func(cb func(*channeldb.ChannelEdgeInfo,
+	ForAllOutgoingChannels func(cb func(kvdb.RTx,
+		*channeldb.ChannelEdgeInfo,
 		*channeldb.ChannelEdgePolicy) error) error
 
-	// FetchChannel is used to query local channel parameters.
-	FetchChannel func(chanPoint wire.OutPoint) (*channeldb.OpenChannel,
-		error)
+	// FetchChannel is used to query local channel parameters. Optionally an
+	// existing db tx can be supplied.
+	FetchChannel func(tx kvdb.RTx, chanPoint wire.OutPoint) (
+		*channeldb.OpenChannel, error)
 
 	// policyUpdateLock ensures that the database and the link do not fall
 	// out of sync if there are concurrent fee update calls. Without it,
@@ -66,6 +69,7 @@ func (r *Manager) UpdatePolicy(newSchema routing.ChannelPolicy,
 	// If we have a filter then we'll only collected those channels,
 	// otherwise we'll collect them all.
 	err := r.ForAllOutgoingChannels(func(
+		tx kvdb.RTx,
 		info *channeldb.ChannelEdgeInfo,
 		edge *channeldb.ChannelEdgePolicy) error {
 
@@ -197,7 +201,7 @@ func (r *Manager) updateEdge(chanPoint wire.OutPoint,
 func (r *Manager) getHtlcAmtLimits(chanPoint wire.OutPoint) (
 	lnwire.MilliSatoshi, lnwire.MilliSatoshi, error) {
 
-	ch, err := r.FetchChannel(chanPoint)
+	ch, err := r.FetchChannel(nil, chanPoint)
 	if err != nil {
 		return 0, 0, err
 	}

routing/localchans/manager_test.go

@@ -3,6 +3,7 @@ package localchans
 import (
 	"testing"
 
+	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lnwire"
 
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
@@ -88,10 +89,12 @@ func TestManager(t *testing.T) {
 		return nil
 	}
 
-	forAllOutgoingChannels := func(cb func(*channeldb.ChannelEdgeInfo,
+	forAllOutgoingChannels := func(cb func(kvdb.RTx,
+		*channeldb.ChannelEdgeInfo,
 		*channeldb.ChannelEdgePolicy) error) error {
 
 		return cb(
+			nil,
 			&channeldb.ChannelEdgeInfo{
 				Capacity:     chanCap,
 				ChannelPoint: chanPoint,
@@ -100,8 +103,8 @@ func TestManager(t *testing.T) {
 		)
 	}
 
-	fetchChannel := func(chanPoint wire.OutPoint) (*channeldb.OpenChannel,
-		error) {
+	fetchChannel := func(tx kvdb.RTx, chanPoint wire.OutPoint) (
+		*channeldb.OpenChannel, error) {
 
 		constraints := channeldb.ChannelConstraints{
 			MaxPendingAmount: maxPendingAmount,

routing/router.go

@@ -137,7 +137,8 @@ type ChannelGraphSource interface {
 	// ForAllOutgoingChannels is used to iterate over all channels
 	// emanating from the "source" node which is the center of the
 	// star-graph.
-	ForAllOutgoingChannels(cb func(c *channeldb.ChannelEdgeInfo,
+	ForAllOutgoingChannels(cb func(tx kvdb.RTx,
+		c *channeldb.ChannelEdgeInfo,
 		e *channeldb.ChannelEdgePolicy) error) error
 
 	// CurrentBlockHeight returns the block height from POV of the router
@@ -2426,17 +2427,18 @@ func (r *ChannelRouter) ForEachNode(cb func(*channeldb.LightningNode) error) err
 // the router.
 //
 // NOTE: This method is part of the ChannelGraphSource interface.
-func (r *ChannelRouter) ForAllOutgoingChannels(cb func(*channeldb.ChannelEdgeInfo,
-	*channeldb.ChannelEdgePolicy) error) error {
+func (r *ChannelRouter) ForAllOutgoingChannels(cb func(kvdb.RTx,
+	*channeldb.ChannelEdgeInfo, *channeldb.ChannelEdgePolicy) error) error {
 
-	return r.selfNode.ForEachChannel(nil, func(_ kvdb.RTx, c *channeldb.ChannelEdgeInfo,
+	return r.selfNode.ForEachChannel(nil, func(tx kvdb.RTx,
+		c *channeldb.ChannelEdgeInfo,
 		e, _ *channeldb.ChannelEdgePolicy) error {
 
 		if e == nil {
 			return fmt.Errorf("channel from self node has no policy")
 		}
 
-		return cb(c, e)
+		return cb(tx, c, e)
 	})
 }