[#337] shard: Get container size estimation from metabase

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/local_object_storage/shard/container.go

@@ -0,0 +1,46 @@
+package shard
+
+import (
+	"github.com/nspcc-dev/neofs-api-go/pkg/container"
+	"github.com/pkg/errors"
+)
+
+type ContainerSizePrm struct {
+	cid *container.ID
+}
+
+type ContainerSizeRes struct {
+	size uint64
+}
+
+func (p *ContainerSizePrm) WithContainerID(cid *container.ID) *ContainerSizePrm {
+	if p != nil {
+		p.cid = cid
+	}
+
+	return p
+}
+
+func (r *ContainerSizeRes) Size() uint64 {
+	return r.size
+}
+
+func (s *Shard) ContainerSize(prm *ContainerSizePrm) (*ContainerSizeRes, error) {
+	size, err := s.metaBase.ContainerSize(prm.cid)
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get container size")
+	}
+
+	return &ContainerSizeRes{
+		size: size,
+	}, nil
+}
+
+func ContainerSize(s *Shard, cid *container.ID) (uint64, error) {
+	res, err := s.ContainerSize(&ContainerSizePrm{cid: cid})
+	if err != nil {
+		return 0, err
+	}
+
+	return res.Size(), nil
+}