routing: return *unifiedPolicyEdge in getPolicy

We encapsulate the capacity inside a unifiedPolicyEdge for later usage.
The meaning of "policy" has changed now, which will be refactored in the
next commmit.

routing/pathfind.go

@@ -628,7 +628,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 	// satisfy our specific requirements.
 	processEdge := func(fromVertex route.Vertex,
 		fromFeatures *lnwire.FeatureVector,
-		edge *channeldb.CachedEdgePolicy, toNodeDist *nodeWithDist) {
+		edge *unifiedPolicyEdge, toNodeDist *nodeWithDist) {
 
 		edgesExpanded++
 
@@ -666,8 +666,8 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 		var fee lnwire.MilliSatoshi
 		var timeLockDelta uint16
 		if fromVertex != source {
-			fee = edge.ComputeFee(amountToSend)
-			timeLockDelta = edge.TimeLockDelta
+			fee = edge.policy.ComputeFee(amountToSend)
+			timeLockDelta = edge.policy.TimeLockDelta
 		}
 
 		incomingCltv := toNodeDist.incomingCltv + int32(timeLockDelta)
@@ -744,9 +744,9 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 
 		// Every edge should have a positive time lock delta. If we
 		// encounter a zero delta, log a warning line.
-		if edge.TimeLockDelta == 0 {
+		if edge.policy.TimeLockDelta == 0 {
 			log.Warnf("Channel %v has zero cltv delta",
-				edge.ChannelID)
+				edge.policy.ChannelID)
 		}
 
 		// Calculate the total routing info size if this hop were to be
@@ -767,7 +767,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 				LegacyPayload: !supportsTlv,
 			}
 
-			payloadSize = hop.PayloadSize(edge.ChannelID)
+			payloadSize = hop.PayloadSize(edge.policy.ChannelID)
 		}
 
 		routingInfoSize := toNodeDist.routingInfoSize + payloadSize
@@ -788,7 +788,7 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
 			amountToReceive: amountToReceive,
 			incomingCltv:    incomingCltv,
 			probability:     probability,
-			nextHop:         edge,
+			nextHop:         edge.policy,
 			routingInfoSize: routingInfoSize,
 		}
 		distance[fromVertex] = withDist

routing/router.go

@@ -2837,10 +2837,11 @@ func (r *ChannelRouter) BuildRoute(amt *lnwire.MilliSatoshi,
 
 		// Add fee for this hop.
 		if !localChan {
-			runningAmt += policy.ComputeFee(runningAmt)
+			runningAmt += policy.policy.ComputeFee(runningAmt)
 		}
 
-		log.Tracef("Select channel %v at position %v", policy.ChannelID, i)
+		log.Tracef("Select channel %v at position %v",
+			policy.policy.ChannelID, i)
 
 		edges[i] = unifiedPolicy
 	}
@@ -2862,12 +2863,12 @@ func (r *ChannelRouter) BuildRoute(amt *lnwire.MilliSatoshi,
 
 		if i > 0 {
 			// Decrease the amount to send while going forward.
-			receiverAmt -= policy.ComputeFeeFromIncoming(
+			receiverAmt -= policy.policy.ComputeFeeFromIncoming(
 				receiverAmt,
 			)
 		}
 
-		pathEdges = append(pathEdges, policy)
+		pathEdges = append(pathEdges, policy.policy)
 	}
 
 	// Build and return the final route.

routing/unified_policies.go

@@ -133,7 +133,7 @@ type unifiedPolicy struct {
 // specific amount to send. It differentiates between local and network
 // channels.
 func (u *unifiedPolicy) getPolicy(amt lnwire.MilliSatoshi,
-	bandwidthHints bandwidthHints) *channeldb.CachedEdgePolicy {
+	bandwidthHints bandwidthHints) *unifiedPolicyEdge {
 
 	if u.localChan {
 		return u.getPolicyLocal(amt, bandwidthHints)
@@ -145,10 +145,10 @@ func (u *unifiedPolicy) getPolicy(amt lnwire.MilliSatoshi,
 // getPolicyLocal returns the optimal policy to use for this local connection
 // given a specific amount to send.
 func (u *unifiedPolicy) getPolicyLocal(amt lnwire.MilliSatoshi,
-	bandwidthHints bandwidthHints) *channeldb.CachedEdgePolicy {
+	bandwidthHints bandwidthHints) *unifiedPolicyEdge {
 
 	var (
-		bestPolicy   *channeldb.CachedEdgePolicy
+		bestPolicy   *unifiedPolicyEdge
 		maxBandwidth lnwire.MilliSatoshi
 	)
 
@@ -192,7 +192,7 @@ func (u *unifiedPolicy) getPolicyLocal(amt lnwire.MilliSatoshi,
 		maxBandwidth = bandwidth
 
 		// Update best policy.
-		bestPolicy = edge.policy
+		bestPolicy = &unifiedPolicyEdge{policy: edge.policy}
 	}
 
 	return bestPolicy
@@ -202,7 +202,7 @@ func (u *unifiedPolicy) getPolicyLocal(amt lnwire.MilliSatoshi,
 // a specific amount to send. The goal is to return a policy that maximizes the
 // probability of a successful forward in a non-strict forwarding context.
 func (u *unifiedPolicy) getPolicyNetwork(
-	amt lnwire.MilliSatoshi) *channeldb.CachedEdgePolicy {
+	amt lnwire.MilliSatoshi) *unifiedPolicyEdge {
 
 	var (
 		bestPolicy  *channeldb.CachedEdgePolicy
@@ -255,8 +255,9 @@ func (u *unifiedPolicy) getPolicyNetwork(
 	// get forwarded. Because we penalize pair-wise, there won't be a second
 	// chance for this node pair. But this is all only needed for nodes that
 	// have distinct policies for channels to the same peer.
-	modifiedPolicy := *bestPolicy
-	modifiedPolicy.TimeLockDelta = maxTimelock
+	policyCopy := *bestPolicy
+	modifiedPolicy := unifiedPolicyEdge{policy: &policyCopy}
+	modifiedPolicy.policy.TimeLockDelta = maxTimelock
 
 	return &modifiedPolicy
 }

routing/unified_policies_test.go

@@ -39,12 +39,14 @@ func TestUnifiedPolicies(t *testing.T) {
 	u.addPolicy(fromNode, &p1, 7)
 	u.addPolicy(fromNode, &p2, 7)
 
-	checkPolicy := func(policy *channeldb.CachedEdgePolicy,
+	checkPolicy := func(unifiedPolicy *unifiedPolicyEdge,
 		feeBase lnwire.MilliSatoshi, feeRate lnwire.MilliSatoshi,
 		timeLockDelta uint16) {
 
 		t.Helper()
 
+		policy := unifiedPolicy.policy
+
 		if policy.FeeBaseMSat != feeBase {
 			t.Fatalf("expected fee base %v, got %v",
 				feeBase, policy.FeeBaseMSat)