[#337] engine: Get all container sizes estimation from shards

Objects of one container can be split among shards, so engine
should iterate over all available shards to sum all size
estimations.

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

pkg/local_object_storage/engine/container.go

@@ -0,0 +1,59 @@
+package engine
+
+import (
+	"github.com/nspcc-dev/neofs-api-go/pkg/container"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"go.uber.org/zap"
+)
+
+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
+}
+
+// ContainerSize returns sum of estimation container sizes among all shards.
+func (e *StorageEngine) ContainerSize(prm *ContainerSizePrm) *ContainerSizeRes {
+	return &ContainerSizeRes{
+		size: e.containerSize(prm.cid),
+	}
+}
+
+// ContainerSize returns sum of estimation container sizes among all shards.
+func ContainerSize(e *StorageEngine, id *container.ID) uint64 {
+	return e.ContainerSize(&ContainerSizePrm{cid: id}).Size()
+}
+
+func (e *StorageEngine) containerSize(id *container.ID) (total uint64) {
+	e.iterateOverUnsortedShards(func(s *shard.Shard) (stop bool) {
+		size, err := shard.ContainerSize(s, id)
+		if err != nil {
+			e.log.Warn("can't get container size",
+				zap.Stringer("shard_id", s.ID()),
+				zap.Stringer("container_id", id),
+				zap.String("error", err.Error()))
+
+			return false
+		}
+
+		total += size
+
+		return false
+	})
+
+	return total
+}