channeldb: refactor methods to allow using existing db transaction

channeldb/nodes.go

@@ -6,9 +6,9 @@ import (
 	"net"
 	"time"
 
-	"github.com/coreos/bbolt"
 	"github.com/btcsuite/btcd/btcec"
 	"github.com/btcsuite/btcd/wire"
+	"github.com/coreos/bbolt"
 )
 
 var (
@@ -183,32 +183,48 @@ func (db *DB) FetchLinkNode(identity *btcec.PublicKey) (*LinkNode, error) {
 	return node, nil
 }
 
-// FetchAllLinkNodes attempts to fetch all active LinkNodes from the database.
-// If there haven't been any channels explicitly linked to LinkNodes written to
-// the database, then this function will return an empty slice.
+// FetchAllLinkNodes starts a new database transaction to fetch all nodes with
+// whom we have active channels with.
 func (db *DB) FetchAllLinkNodes() ([]*LinkNode, error) {
 	var linkNodes []*LinkNode
-
 	err := db.View(func(tx *bolt.Tx) error {
-		nodeMetaBucket := tx.Bucket(nodeInfoBucket)
-		if nodeMetaBucket == nil {
-			return ErrLinkNodesNotFound
+		nodes, err := db.fetchAllLinkNodes(tx)
+		if err != nil {
+			return err
 		}
 
-		return nodeMetaBucket.ForEach(func(k, v []byte) error {
-			if v == nil {
-				return nil
-			}
+		linkNodes = nodes
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
 
-			nodeReader := bytes.NewReader(v)
-			linkNode, err := deserializeLinkNode(nodeReader)
-			if err != nil {
-				return err
-			}
+	return linkNodes, nil
+}
 
-			linkNodes = append(linkNodes, linkNode)
+// fetchAllLinkNodes uses an existing database transaction to fetch all nodes
+// with whom we have active channels with.
+func (db *DB) fetchAllLinkNodes(tx *bolt.Tx) ([]*LinkNode, error) {
+	nodeMetaBucket := tx.Bucket(nodeInfoBucket)
+	if nodeMetaBucket == nil {
+		return nil, ErrLinkNodesNotFound
+	}
+
+	var linkNodes []*LinkNode
+	err := nodeMetaBucket.ForEach(func(k, v []byte) error {
+		if v == nil {
 			return nil
-		})
+		}
+
+		nodeReader := bytes.NewReader(v)
+		linkNode, err := deserializeLinkNode(nodeReader)
+		if err != nil {
+			return err
+		}
+
+		linkNodes = append(linkNodes, linkNode)
+		return nil
 	})
 	if err != nil {
 		return nil, err