channeldb: embed the instance of boltb within DB struct

This commit modifies the composition of the boltdb pointer within the
DB struct to use embedding.

The rationale for this change is that the daemon may soon store some
semi-transient items within the database which requires us to expose
the boltdb’s transaction API. The logic for serialization of this data
will likely lie outside of the channeldb package as the items that may
be stored in the future will be specific to the current sub-systems
within the daemon and not generic channel related data.

channeldb/db.go

@@ -51,17 +51,17 @@ var bufPool = &sync.Pool{
 	New: func() interface{} { return new(bytes.Buffer) },
 }
 
-// DB is the primary datastore for the LND daemon. The database stores
+// DB is the primary datastore for the lnd daemon. The database stores
 // information related to nodes, routing data, open/closed channels, fee
 // schedules, and reputation data.
 type DB struct {
-	store     *bolt.DB
+	*bolt.DB
 	netParams *chaincfg.Params
 	dbPath    string
 }
 
-// Open opens an existing channeldb created under the passed namespace with
-// sensitive data encrypted by the passed EncryptorDecryptor implementation.
+// Open opens an existing channeldb. Any necessary schemas migrations due to
+// udpates will take plave as necessary.
 func Open(dbPath string, netParams *chaincfg.Params) (*DB, error) {
 	path := filepath.Join(dbPath, dbName)
 
@@ -77,7 +77,7 @@ func Open(dbPath string, netParams *chaincfg.Params) (*DB, error) {
 	}
 
 	chanDB := &DB{
-		store:     bdb,
+		DB:        bdb,
 		netParams: netParams,
 		dbPath:    dbPath,
 	}
@@ -95,7 +95,6 @@ func Open(dbPath string, netParams *chaincfg.Params) (*DB, error) {
 // database. The deletion is done in a single transaction, therefore this
 // operation is fully atomic.
 func (d *DB) Wipe() error {
-	return d.store.Update(func(tx *bolt.Tx) error {
 		err := tx.DeleteBucket(openChannelBucket)
 		if err != nil && err != bolt.ErrBucketNotFound {
 			return err
@@ -120,11 +119,6 @@ func (d *DB) Wipe() error {
 	})
 }
 
-// Close terminates the underlying database handle manually.
-func (d *DB) Close() error {
-	return d.store.Close()
-}
-
 // createChannelDB creates and initializes a fresh version of channeldb. In
 // the case that the target path has not yet been created or doesn't yet exist,
 // then the path is created. Additionally, all required top-level buckets used
@@ -189,7 +183,7 @@ func fileExists(path string) bool {
 // returned.
 func (d *DB) FetchOpenChannels(nodeID *btcec.PublicKey) ([]*OpenChannel, error) {
 	var channels []*OpenChannel
-	err := d.store.View(func(tx *bolt.Tx) error {
+	err := d.View(func(tx *bolt.Tx) error {
 		// Get the bucket dedicated to storing the meta-data for open
 		// channels.
 		openChanBucket := tx.Bucket(openChannelBucket)
@@ -269,7 +263,7 @@ func (d *DB) fetchNodeChannels(openChanBucket,
 func (d *DB) FetchAllChannels() ([]*OpenChannel, error) {
 	var channels []*OpenChannel
 
-	err := d.store.View(func(tx *bolt.Tx) error {
+	err := d.View(func(tx *bolt.Tx) error {
 		// Get the bucket dedicated to storing the meta-data for open
 		// channels.
 		openChanBucket := tx.Bucket(openChannelBucket)
@@ -327,7 +321,7 @@ func (d *DB) syncVersions(versions []version) error {
 	// execute them serially within a single database transaction to ensure
 	// the migration is atomic.
 	migrations := getMigrationsToApply(versions, meta.DbVersionNumber)
-	return d.store.Update(func(tx *bolt.Tx) error {
+	return d.Update(func(tx *bolt.Tx) error {
 		for _, migration := range migrations {
 			if migration == nil {
 				continue