eventstore: boltdb (copied from lmdb)

eventstore/boltdb/migration.go

@@ -0,0 +1,47 @@
+package bolt
+
+import (
+	"encoding/binary"
+	"log"
+
+	"go.etcd.io/bbolt"
+)
+
+const (
+	DB_VERSION byte = 'v'
+)
+
+const target = 1
+
+func (b *BoltBackend) migrate() error {
+	return b.DB.Update(func(txn *bbolt.Tx) error {
+		bucket := txn.Bucket(settingsStore)
+
+		val := bucket.Get([]byte("version"))
+
+		var version uint16 = target
+		if val == nil {
+			version = binary.BigEndian.Uint16(val)
+		}
+
+		// do the migrations in increasing steps (there is no rollback)
+		if version < target {
+			log.Printf("[bolt] migration %d: reindex everything\n", target)
+
+			// bump version
+			if err := b.setVersion(txn, target); err != nil {
+				return err
+			}
+		}
+
+		return nil
+	})
+}
+
+func (b *BoltBackend) setVersion(txn *bbolt.Tx, v uint16) error {
+	bucket := txn.Bucket(settingsStore)
+
+	var newVersion [2]byte
+	binary.BigEndian.PutUint16(newVersion[:], v)
+	return bucket.Put([]byte("version"), newVersion[:])
+}