func makeKey(key cas.Key, typ string, level uint8) []byte {
k := make([]byte, 0, cas.KeySize+len(typ)+1)
k = append(k, key.Bytes()...)
k = append(k, typ...)
k = append(k, level)
return k
}
// Mkdir takes a snapshot of this volume and records it under the
// given name.
func (d *listSnaps) Mkdir(ctx context.Context, req *fuse.MkdirRequest) (fs.Node, error) {
var snapshot *wiresnap.Snapshot
record := func(tx *db.Tx) error {
s, err := d.fs.Snapshot(ctx, tx)
if err != nil {
return err
}
snapshot = s
return nil
}
if err := d.fs.db.View(record); err != nil {
return nil, fmt.Errorf("cannot record snapshot: %v", err)
}
snapshot.Name = req.Name
var key cas.Key
{
buf, err := proto.Marshal(snapshot)
if err != nil {
return nil, fmt.Errorf("cannot marshal snapshot: %v", err)
}
if len(buf) == 0 {
return nil, errors.New("marshaled snapshot become empty; this is a bug")
}
// store the snapshot as a chunk, for disaster recovery
key, err = d.fs.chunkStore.Add(&chunks.Chunk{
Type: "snap",
Level: 0,
Buf: buf,
})
if err != nil {
return nil, fmt.Errorf("cannot store snapshot: %v", err)
}
}
var ref = wire.SnapshotRef{
Key: key.Bytes(),
}
buf, err := proto.Marshal(&ref)
if err != nil {
return nil, fmt.Errorf("cannot marshal snapshot pointer: %v", err)
}
add := func(tx *db.Tx) error {
b := d.fs.bucket(tx).SnapBucket()
if b == nil {
return errors.New("snapshot bucket missing")
}
return b.Put([]byte(req.Name), buf)
}
if err := d.fs.db.Update(add); err != nil {
return nil, fmt.Errorf("cannot save snapshot pointer: %v", err)
}
n, err := snap.Open(d.fs.chunkStore, snapshot.Contents)
if err != nil {
return nil, fmt.Errorf("cannot serve snapshot: %v", err)
}
return n, nil
}