Initial commit

Initial public review release v0.10.0

lib/transformer/restore.go

@@ -0,0 +1,126 @@
+package transformer
+
+import (
+	"context"
+	"sync"
+
+	"github.com/nspcc-dev/neofs-api-go/object"
+	"github.com/pkg/errors"
+)
+
+type (
+	// ObjectRestorer is an interface of object restorer.
+	ObjectRestorer interface {
+		Type() object.Transform_Type
+		Restore(context.Context, ...Object) ([]Object, error)
+	}
+
+	restorePipeline struct {
+		ObjectRestorer
+		*sync.RWMutex
+		items map[object.Transform_Type]ObjectRestorer
+	}
+
+	splitRestorer struct{}
+)
+
+var errEmptyObjList = errors.New("object list is empty")
+
+var errMissingParentLink = errors.New("missing parent link")
+
+func (s *restorePipeline) Restore(ctx context.Context, srcObjs ...Object) ([]Object, error) {
+	if len(srcObjs) == 0 {
+		return nil, errEmptyInput
+	}
+
+	s.RLock()
+	defer s.RUnlock()
+
+	var (
+		objs = srcObjs
+		err  error
+	)
+
+	for {
+		_, th := objs[0].LastHeader(object.HeaderType(object.TransformHdr))
+		if th == nil {
+			break
+		}
+
+		transform := th.Value.(*object.Header_Transform).Transform
+
+		tr, ok := s.items[transform.Type]
+		if !ok {
+			return nil, errors.Errorf("missing restorer (%s)", transform.Type)
+		}
+
+		if objs, err = tr.Restore(ctx, objs...); err != nil {
+			return nil, errors.Wrapf(err, "restoration failed (%s)", transform.Type)
+		}
+	}
+
+	return objs, nil
+}
+
+// NewRestorePipeline is a constructor of the pipeline of object restorers.
+func NewRestorePipeline(t ...ObjectRestorer) ObjectRestorer {
+	m := make(map[object.Transform_Type]ObjectRestorer, len(t))
+
+	for i := range t {
+		m[t[i].Type()] = t[i]
+	}
+
+	return &restorePipeline{
+		RWMutex: new(sync.RWMutex),
+		items:   m,
+	}
+}
+
+func (*splitRestorer) Type() object.Transform_Type {
+	return object.Transform_Split
+}
+
+func (*splitRestorer) Restore(ctx context.Context, objs ...Object) ([]Object, error) {
+	if len(objs) == 0 {
+		return nil, errEmptyObjList
+	}
+
+	chain, err := GetChain(objs...)
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get chain of objects")
+	}
+
+	obj := chain[len(chain)-1]
+
+	var (
+		size uint64
+		p    = make([]byte, 0, len(chain[0].Payload)*len(chain))
+	)
+
+	for j := 0; j < len(chain); j++ {
+		p = append(p, chain[j].Payload...)
+		size += chain[j].SystemHeader.PayloadLength
+	}
+
+	obj.SystemHeader.PayloadLength = size
+	obj.Payload = p
+
+	parent, err := lastLink(&obj, object.Link_Parent)
+	if err != nil {
+		return nil, errMissingParentLink
+	}
+
+	obj.SystemHeader.ID = parent
+
+	err = deleteTransformer(&obj, object.Transform_Split)
+	if err != nil {
+		return nil, err
+	}
+
+	return []Object{obj}, nil
+}
+
+// SplitRestorer is a splitted object restorer's constructor.
+func SplitRestorer() ObjectRestorer {
+	return new(splitRestorer)
+}