// Clone is like Get but clones the chunk if it's not already private.
// Chunks that are already private are returned as-is.
//
// A cloned chunk will have a buffer of size bytes. This is intended
// to use for re-inflating zero-trimmed chunks.
//
// Modifying the returned chunk *will* cause the locally stored data
// to change. This is the intended usage of a stash.
func (s *Stash) Clone(key cas.Key, typ string, level uint8, size uint32) (cas.Key, *chunks.Chunk, error) {
priv, ok := key.Private()
if ok {
chunk, ok := s.local[priv]
if !ok {
return key, nil, cas.NotFound{
Type: typ,
Level: level,
Key: key,
}
}
return key, chunk, nil
}
chunk, err := s.chunks.Get(key, typ, level)
if err != nil {
return key, nil, err
}
// clone the byte slice
tmp := make([]byte, size)
copy(tmp, chunk.Buf)
chunk.Buf = tmp
priv = s.ids.Get()
privkey := cas.NewKeyPrivateNum(priv)
s.local[priv] = chunk
return privkey, chunk, nil
}
// Drop forgets a Private chunk. The key may be reused, so caller must
// not remember the old key.
func (s *Stash) Drop(key cas.Key) {
priv, ok := key.Private()
if !ok {
return
}
s.drop(priv)
}
// Get returns a chunk either from the local stash, or from the
// Store (for Private keys).
//
// For Private keys, modifying the returned chunk *will* cause the
// locally stored data to change. This is the intended usage of a
// stash.
func (s *Stash) Get(key cas.Key, typ string, level uint8) (*chunks.Chunk, error) {
priv, ok := key.Private()
if ok {
chunk, ok := s.local[priv]
if !ok {
return nil, cas.NotFound{
Type: typ,
Level: level,
Key: key,
}
}
return chunk, nil
}
chunk, err := s.chunks.Get(key, typ, level)
return chunk, err
}
// Save the local Chunk to the Store.
//
// On success, the old key becomes invalid.
func (s *Stash) Save(key cas.Key) (cas.Key, error) {
priv, ok := key.Private()
if !ok {
return key, nil
}
chunk, ok := s.local[priv]
if !ok {
return key, cas.NotFound{
Key: key,
}
}
newkey, err := s.chunks.Add(chunk)
if err != nil {
return key, err
}
s.drop(priv)
return newkey, nil
}