etcd+channeldb: fix linter issues, rename receiver

With this commit we address some issues the linter picked up after
touching older code.

channeldb/db.go

@@ -24,8 +24,7 @@ import (
 )
 
 const (
-	dbName           = "channel.db"
-	dbFilePermission = 0600
+	dbName = "channel.db"
 )
 
 var (
@@ -408,7 +407,7 @@ func (d *DB) FetchOpenChannels(nodeID *btcec.PublicKey) ([]*OpenChannel, error)
 // stored currently active/open channels associated with the target nodeID. In
 // the case that no active channels are known to have been created with this
 // node, then a zero-length slice is returned.
-func (db *DB) fetchOpenChannels(tx kvdb.RTx,
+func (d *DB) fetchOpenChannels(tx kvdb.RTx,
 	nodeID *btcec.PublicKey) ([]*OpenChannel, error) {
 
 	// Get the bucket dedicated to storing the metadata for open channels.
@@ -444,7 +443,7 @@ func (db *DB) fetchOpenChannels(tx kvdb.RTx,
 
 		// Finally, we both of the necessary buckets retrieved, fetch
 		// all the active channels related to this node.
-		nodeChannels, err := db.fetchNodeChannels(chainBucket)
+		nodeChannels, err := d.fetchNodeChannels(chainBucket)
 		if err != nil {
 			return fmt.Errorf("unable to read channel for "+
 				"chain_hash=%x, node_key=%x: %v",
@@ -461,7 +460,7 @@ func (db *DB) fetchOpenChannels(tx kvdb.RTx,
 // fetchNodeChannels retrieves all active channels from the target chainBucket
 // which is under a node's dedicated channel bucket. This function is typically
 // used to fetch all the active channels related to a particular node.
-func (db *DB) fetchNodeChannels(chainBucket kvdb.RBucket) ([]*OpenChannel, error) {
+func (d *DB) fetchNodeChannels(chainBucket kvdb.RBucket) ([]*OpenChannel, error) {
 
 	var channels []*OpenChannel
 
@@ -487,7 +486,7 @@ func (db *DB) fetchNodeChannels(chainBucket kvdb.RBucket) ([]*OpenChannel, error
 			return fmt.Errorf("unable to read channel data for "+
 				"chan_point=%v: %v", outPoint, err)
 		}
-		oChannel.Db = db
+		oChannel.Db = d
 
 		channels = append(channels, oChannel)
 
@@ -949,8 +948,8 @@ func (d *DB) MarkChanFullyClosed(chanPoint *wire.OutPoint) error {
 // pruneLinkNode determines whether we should garbage collect a link node from
 // the database due to no longer having any open channels with it. If there are
 // any left, then this acts as a no-op.
-func (db *DB) pruneLinkNode(tx kvdb.RwTx, remotePub *btcec.PublicKey) error {
-	openChannels, err := db.fetchOpenChannels(tx, remotePub)
+func (d *DB) pruneLinkNode(tx kvdb.RwTx, remotePub *btcec.PublicKey) error {
+	openChannels, err := d.fetchOpenChannels(tx, remotePub)
 	if err != nil {
 		return fmt.Errorf("unable to fetch open channels for peer %x: "+
 			"%v", remotePub.SerializeCompressed(), err)
@@ -963,7 +962,7 @@ func (db *DB) pruneLinkNode(tx kvdb.RwTx, remotePub *btcec.PublicKey) error {
 	log.Infof("Pruning link node %x with zero open channels from database",
 		remotePub.SerializeCompressed())
 
-	return db.deleteLinkNode(tx, remotePub)
+	return d.deleteLinkNode(tx, remotePub)
 }
 
 // PruneLinkNodes attempts to prune all link nodes found within the databse with
@@ -1099,16 +1098,16 @@ func (d *DB) AddrsForNode(nodePub *btcec.PublicKey) ([]net.Addr, error) {
 // database. If the channel was already removed (has a closed channel entry),
 // then we'll return a nil error. Otherwise, we'll insert a new close summary
 // into the database.
-func (db *DB) AbandonChannel(chanPoint *wire.OutPoint, bestHeight uint32) error {
+func (d *DB) AbandonChannel(chanPoint *wire.OutPoint, bestHeight uint32) error {
 	// With the chanPoint constructed, we'll attempt to find the target
 	// channel in the database. If we can't find the channel, then we'll
 	// return the error back to the caller.
-	dbChan, err := db.FetchChannel(*chanPoint)
+	dbChan, err := d.FetchChannel(*chanPoint)
 	switch {
 	// If the channel wasn't found, then it's possible that it was already
 	// abandoned from the database.
 	case err == ErrChannelNotFound:
-		_, closedErr := db.FetchClosedChannel(chanPoint)
+		_, closedErr := d.FetchClosedChannel(chanPoint)
 		if closedErr != nil {
 			return closedErr
 		}
@@ -1271,9 +1270,9 @@ func fetchHistoricalChanBucket(tx kvdb.RTx,
 
 // FetchHistoricalChannel fetches open channel data from the historical channel
 // bucket.
-func (db *DB) FetchHistoricalChannel(outPoint *wire.OutPoint) (*OpenChannel, error) {
+func (d *DB) FetchHistoricalChannel(outPoint *wire.OutPoint) (*OpenChannel, error) {
 	var channel *OpenChannel
-	err := kvdb.View(db, func(tx kvdb.RTx) error {
+	err := kvdb.View(d, func(tx kvdb.RTx) error {
 		chanBucket, err := fetchHistoricalChanBucket(tx, outPoint)
 		if err != nil {
 			return err