mirror of https://github.com/BTCPrivate/lnd.git
81 lines
2.0 KiB
Go
81 lines
2.0 KiB
Go
package channeldb
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import (
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"github.com/coreos/bbolt"
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)
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var (
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// metaBucket stores all the meta information concerning the state of
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// the database.
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metaBucket = []byte("metadata")
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// dbVersionKey is a boltdb key and it's used for storing/retrieving
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// current database version.
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dbVersionKey = []byte("dbp")
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)
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// Meta structure holds the database meta information.
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type Meta struct {
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// DbVersionNumber is the current schema version of the database.
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DbVersionNumber uint32
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}
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// FetchMeta fetches the meta data from boltdb and returns filled meta
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// structure.
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func (d *DB) FetchMeta(tx *bolt.Tx) (*Meta, error) {
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meta := &Meta{}
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err := d.View(func(tx *bolt.Tx) error {
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return fetchMeta(meta, tx)
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})
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if err != nil {
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return nil, err
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}
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return meta, nil
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}
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// fetchMeta is an internal helper function used in order to allow callers to
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// re-use a database transaction. See the publicly exported FetchMeta method
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// for more information.
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func fetchMeta(meta *Meta, tx *bolt.Tx) error {
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metaBucket := tx.Bucket(metaBucket)
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if metaBucket == nil {
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return ErrMetaNotFound
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}
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data := metaBucket.Get(dbVersionKey)
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if data == nil {
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meta.DbVersionNumber = getLatestDBVersion(dbVersions)
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} else {
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meta.DbVersionNumber = byteOrder.Uint32(data)
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}
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return nil
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}
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// PutMeta writes the passed instance of the database met-data struct to disk.
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func (d *DB) PutMeta(meta *Meta) error {
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return d.Update(func(tx *bolt.Tx) error {
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return putMeta(meta, tx)
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})
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}
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// putMeta is an internal helper function used in order to allow callers to
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// re-use a database transaction. See the publicly exported PutMeta method for
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// more information.
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func putMeta(meta *Meta, tx *bolt.Tx) error {
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metaBucket, err := tx.CreateBucketIfNotExists(metaBucket)
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if err != nil {
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return err
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}
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return putDbVersion(metaBucket, meta)
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}
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func putDbVersion(metaBucket *bolt.Bucket, meta *Meta) error {
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scratch := make([]byte, 4)
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byteOrder.PutUint32(scratch, meta.DbVersionNumber)
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return metaBucket.Put(dbVersionKey, scratch)
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}
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