channeldb: add new methods to allow adding a new edge+policy w/ existing db transaction

channeldb/graph.go

@@ -483,11 +483,18 @@ func (c *ChannelGraph) deleteLightningNode(nodes *bbolt.Bucket,
 // the channel supports. The chanPoint and chanID are used to uniquely identify
 // the edge globally within the database.
 func (c *ChannelGraph) AddChannelEdge(edge *ChannelEdgeInfo) error {
+	return c.db.Update(func(tx *bbolt.Tx) error {
+		return c.addChannelEdge(tx, edge)
+	})
+}
+
+// addChannelEdge is the private form of AddChannelEdge that allows callers to
+// utilize an existing db transaction.
+func (c *ChannelGraph) addChannelEdge(tx *bbolt.Tx, edge *ChannelEdgeInfo) error {
 	// Construct the channel's primary key which is the 8-byte channel ID.
 	var chanKey [8]byte
 	binary.BigEndian.PutUint64(chanKey[:], edge.ChannelID)
 
-	return c.db.Update(func(tx *bbolt.Tx) error {
 	nodes, err := tx.CreateBucketIfNotExists(nodeBucket)
 	if err != nil {
 		return err
@@ -505,18 +512,16 @@ func (c *ChannelGraph) AddChannelEdge(edge *ChannelEdgeInfo) error {
 		return err
 	}
 
-		// First, attempt to check if this edge has already been
+	// First, attempt to check if this edge has already been created. If
-		// created. If so, then we can exit early as this method is
+	// so, then we can exit early as this method is meant to be idempotent.
-		// meant to be idempotent.
 	if edgeInfo := edgeIndex.Get(chanKey[:]); edgeInfo != nil {
 		return ErrEdgeAlreadyExist
 	}
 
-		// Before we insert the channel into the database, we'll ensure
+	// Before we insert the channel into the database, we'll ensure that
-		// that both nodes already exist in the channel graph. If
+	// both nodes already exist in the channel graph. If either node
-		// either node doesn't, then we'll insert a "shell" node that
+	// doesn't, then we'll insert a "shell" node that just includes its
-		// just includes its public key, so subsequent validation and
+	// public key, so subsequent validation and queries can work properly.
-		// queries can work properly.
 	_, node1Err := fetchLightningNode(nodes, edge.NodeKey1Bytes[:])
 	switch {
 	case node1Err == ErrGraphNodeNotFound:
@@ -551,15 +556,15 @@ func (c *ChannelGraph) AddChannelEdge(edge *ChannelEdgeInfo) error {
 		return err
 	}
 
-		// If the edge hasn't been created yet, then we'll first add it
+	// If the edge hasn't been created yet, then we'll first add it to the
-		// to the edge index in order to associate the edge between two
+	// edge index in order to associate the edge between two nodes and also
-		// nodes and also store the static components of the channel.
+	// store the static components of the channel.
 	if err := putChanEdgeInfo(edgeIndex, edge, chanKey); err != nil {
 		return err
 	}
 
-		// Mark edge policies for both sides as unknown. This is to
+	// Mark edge policies for both sides as unknown. This is to enable
-		// enable efficient incoming channel lookup for a node.
+	// efficient incoming channel lookup for a node.
 	for _, key := range []*[33]byte{&edge.NodeKey1Bytes,
 		&edge.NodeKey2Bytes} {
 
@@ -570,14 +575,13 @@ func (c *ChannelGraph) AddChannelEdge(edge *ChannelEdgeInfo) error {
 		}
 	}
 
-		// Finally we add it to the channel index which maps channel
+	// Finally we add it to the channel index which maps channel points
-		// points (outpoints) to the shorter channel ID's.
+	// (outpoints) to the shorter channel ID's.
 	var b bytes.Buffer
 	if err := writeOutpoint(&b, &edge.ChannelPoint); err != nil {
 		return err
 	}
 	return chanIndex.Put(b.Bytes(), chanKey[:])
-	})
 }
 
 // HasChannelEdge returns true if the database knows of a channel edge with the
@@ -1639,11 +1643,18 @@ func delChannelByEdge(edges *bbolt.Bucket, edgeIndex *bbolt.Bucket,
 // the nodes on either side of the channel.
 func (c *ChannelGraph) UpdateEdgePolicy(edge *ChannelEdgePolicy) error {
 	return c.db.Update(func(tx *bbolt.Tx) error {
+		return updateEdgePolicy(tx, edge)
+	})
+}
+
+// updateEdgePolicy attempts to update an edge's policy within the relevant
+// buckets using an existing database transaction.
+func updateEdgePolicy(tx *bbolt.Tx, edge *ChannelEdgePolicy) error {
 	edges := tx.Bucket(edgeBucket)
 	if edges == nil {
 		return ErrEdgeNotFound
-		}
 
+	}
 	edgeIndex := edges.Bucket(edgeIndexBucket)
 	if edgeIndex == nil {
 		return ErrEdgeNotFound
@@ -1653,15 +1664,6 @@ func (c *ChannelGraph) UpdateEdgePolicy(edge *ChannelEdgePolicy) error {
 		return err
 	}
 
-		return updateEdgePolicy(edges, edgeIndex, nodes, edge)
-	})
-}
-
-// updateEdgePolicy attempts to update an edge's policy within the relevant
-// buckets using an existing database transaction.
-func updateEdgePolicy(edges, edgeIndex, nodes *bbolt.Bucket,
-	edge *ChannelEdgePolicy) error {
-
 	// Create the channelID key be converting the channel ID
 	// integer into a byte slice.
 	var chanID [8]byte

channeldb/migrations.go

@@ -563,7 +563,7 @@ func migratePruneEdgeUpdateIndex(tx *bbolt.Tx) error {
 			return err
 		}
 
-		err = updateEdgePolicy(edges, edgeIndex, nodes, edgePolicy)
+		err = updateEdgePolicy(tx, edgePolicy)
 		if err != nil {
 			return err
 		}