multi: let ForEachChannel be a method on ChannelGraph

Having a `ForEachChannel` method on the `LightningNode` struct itself
results in a `kvdb.Backend` object needing to be stored within the
LightningNode struct. In this commit, this method is replaced with a
`ForEachNodeChannel` method on the `ChannelGraph` struct will perform
the same function without needing the db pointer to be stored within the
LightningNode. This change, the LightningNode struct more closely
represents the schema on disk.

The existing `ForEachNodeChannel` method on `ChannelGraph` is renamed to
`ForEachNodeDirectedChannel`. It performs a slightly different function
since it's call-back operates on Cached policies.

rpcserver.go

@@ -6151,30 +6151,33 @@ func (r *rpcServer) GetNodeInfo(ctx context.Context,
 		channels      []*lnrpc.ChannelEdge
 	)
 
-	if err := node.ForEachChannel(nil, func(_ kvdb.RTx,
-		edge *channeldb.ChannelEdgeInfo,
-		c1, c2 *channeldb.ChannelEdgePolicy) error {
+	err = graph.ForEachNodeChannel(nil, node.PubKeyBytes,
+		func(_ kvdb.RTx, edge *channeldb.ChannelEdgeInfo,
+			c1, c2 *channeldb.ChannelEdgePolicy) error {
 
-		numChannels++
-		totalCapacity += edge.Capacity
+			numChannels++
+			totalCapacity += edge.Capacity
 
-		// Only populate the node's channels if the user requested them.
-		if in.IncludeChannels {
-			// Do not include unannounced channels - private
-			// channels or public channels whose authentication
-			// proof were not confirmed yet.
-			if edge.AuthProof == nil {
-				return nil
+			// Only populate the node's channels if the user
+			// requested them.
+			if in.IncludeChannels {
+				// Do not include unannounced channels - private
+				// channels or public channels whose
+				// authentication proof were not confirmed yet.
+				if edge.AuthProof == nil {
+					return nil
+				}
+
+				// Convert the database's edge format into the
+				// network/RPC edge format.
+				channelEdge := marshalDbEdge(edge, c1, c2)
+				channels = append(channels, channelEdge)
 			}
 
-			// Convert the database's edge format into the
-			// network/RPC edge format.
-			channelEdge := marshalDbEdge(edge, c1, c2)
-			channels = append(channels, channelEdge)
-		}
-
-		return nil
-	}); err != nil {
+			return nil
+		},
+	)
+	if err != nil {
 		return nil, err
 	}
 
@@ -6763,34 +6766,39 @@ func (r *rpcServer) FeeReport(ctx context.Context,
 	}
 
 	var feeReports []*lnrpc.ChannelFeeReport
-	err = selfNode.ForEachChannel(nil, func(_ kvdb.RTx, chanInfo *channeldb.ChannelEdgeInfo,
-		edgePolicy, _ *channeldb.ChannelEdgePolicy) error {
+	err = channelGraph.ForEachNodeChannel(nil, selfNode.PubKeyBytes,
+		func(_ kvdb.RTx, chanInfo *channeldb.ChannelEdgeInfo,
+			edgePolicy, _ *channeldb.ChannelEdgePolicy) error {
 
-		// Self node should always have policies for its channels.
-		if edgePolicy == nil {
-			return fmt.Errorf("no policy for outgoing channel %v ",
-				chanInfo.ChannelID)
-		}
+			// Self node should always have policies for its
+			// channels.
+			if edgePolicy == nil {
+				return fmt.Errorf("no policy for outgoing "+
+					"channel %v ", chanInfo.ChannelID)
+			}
 
-		// We'll compute the effective fee rate by converting from a
-		// fixed point fee rate to a floating point fee rate. The fee
-		// rate field in the database the amount of mSAT charged per
-		// 1mil mSAT sent, so will divide by this to get the proper fee
-		// rate.
-		feeRateFixedPoint := edgePolicy.FeeProportionalMillionths
-		feeRate := float64(feeRateFixedPoint) / feeBase
+			// We'll compute the effective fee rate by converting
+			// from a fixed point fee rate to a floating point fee
+			// rate. The fee rate field in the database the amount
+			// of mSAT charged per 1mil mSAT sent, so will divide by
+			// this to get the proper fee rate.
+			feeRateFixedPoint :=
+				edgePolicy.FeeProportionalMillionths
+			feeRate := float64(feeRateFixedPoint) / feeBase
 
-		// TODO(roasbeef): also add stats for revenue for each channel
-		feeReports = append(feeReports, &lnrpc.ChannelFeeReport{
-			ChanId:       chanInfo.ChannelID,
-			ChannelPoint: chanInfo.ChannelPoint.String(),
-			BaseFeeMsat:  int64(edgePolicy.FeeBaseMSat),
-			FeePerMil:    int64(feeRateFixedPoint),
-			FeeRate:      feeRate,
-		})
+			// TODO(roasbeef): also add stats for revenue for each
+			// channel
+			feeReports = append(feeReports, &lnrpc.ChannelFeeReport{
+				ChanId:       chanInfo.ChannelID,
+				ChannelPoint: chanInfo.ChannelPoint.String(),
+				BaseFeeMsat:  int64(edgePolicy.FeeBaseMSat),
+				FeePerMil:    int64(feeRateFixedPoint),
+				FeeRate:      feeRate,
+			})
 
-		return nil
-	})
+			return nil
+		},
+	)
 	if err != nil {
 		return nil, err
 	}