p2p/discovery: fix issues raised in the nodeDb PR

p2p/discover/table.go

@@ -62,13 +62,12 @@ type bucket struct {
 }
 
 func newTable(t transport, ourID NodeID, ourAddr *net.UDPAddr, nodeDBPath string) *Table {
-	// If no seed cache was given, use an in-memory one
+	// If no node database was given, use an in-memory one
 	db, err := newNodeDB(nodeDBPath)
 	if err != nil {
 		glog.V(logger.Warn).Infoln("Failed to open node database:", err)
 		db, _ = newNodeDB("")
 	}
-	// Create the bootstrap table
 	tab := &Table{
 		net:       t,
 		db:        db,
@@ -90,7 +89,7 @@ func (tab *Table) Self() *Node {
 	return tab.self
 }
 
-// Close terminates the network listener and flushes the seed cache.
+// Close terminates the network listener and flushes the node database.
 func (tab *Table) Close() {
 	tab.net.close()
 	tab.db.close()