Add Inner Ring code

pkg/local_object_storage/bucket/bucket.go

@@ -0,0 +1,41 @@
+package bucket
+
+import (
+	"errors"
+)
+
+// FilterHandler where you receive key/val in your closure.
+type FilterHandler func(key, val []byte) bool
+
+// BucketItem used in filter.
+type BucketItem struct {
+	Key []byte
+	Val []byte
+}
+
+// Bucket is sub-store interface.
+type Bucket interface {
+	Get(key []byte) ([]byte, error)
+	Set(key, value []byte) error
+	Del(key []byte) error
+	Has(key []byte) bool
+	Size() int64
+	List() ([][]byte, error)
+	Iterate(FilterHandler) error
+	// Steam can be implemented by badger.Stream, but not for now
+	// Stream(ctx context.Context, key []byte, cb func(io.ReadWriter) error) error
+	Close() error
+}
+
+var (
+	// ErrNilFilterHandler when FilterHandler is empty
+	ErrNilFilterHandler = errors.New("handler can't be nil")
+
+	// ErrNotFound is returned by key-value storage methods
+	// that could not find element by key.
+	ErrNotFound = errors.New("key not found")
+)
+
+// ErrIteratingAborted is returned by storage iterator
+// after iteration has been interrupted.
+var ErrIteratingAborted = errors.New("iteration aborted")