[#176] localstore: Draft storage engine structure and ops

Implement the primary structure and operation of the local object
storage engine.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/local_object_storage/engine/delete.go

@@ -0,0 +1,52 @@
+package engine
+
+import (
+	objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
+	"go.uber.org/zap"
+)
+
+// DeletePrm groups the parameters of Delete operation.
+type DeletePrm struct {
+	addr *objectSDK.Address
+}
+
+// DeleteRes groups resulting values of Delete operation.
+type DeleteRes struct{}
+
+// WithAddress is a Delete option to set the address of the object to delete.
+//
+// Option is required.
+func (p *DeletePrm) WithAddress(addr *objectSDK.Address) *DeletePrm {
+	if p != nil {
+		p.addr = addr
+	}
+
+	return p
+}
+
+// Delete marks object to delete from local storage.
+//
+// Returns any error encountered that did not allow to completely
+// mark the object to delete.
+func (e *StorageEngine) Delete(prm *DeletePrm) (*DeleteRes, error) {
+	e.mtx.RLock()
+	defer e.mtx.RUnlock()
+
+	shPrm := new(shard.DeletePrm)
+
+	e.iterateOverSortedShards(prm.addr, func(sh *shard.Shard) (stop bool) {
+		_, err := sh.Delete(shPrm)
+		if err != nil {
+			// TODO: smth wrong with shard, need to be processed
+			e.log.Warn("could not get object from shard",
+				zap.Stringer("shard", sh.ID()),
+				zap.String("error", err.Error()),
+			)
+		}
+
+		return false
+	})
+
+	return nil, nil
+}