add copy dagservice function

daghelpers.go

@@ -89,6 +89,25 @@ func GetNodes(ctx context.Context, ds NodeGetter, keys []*cid.Cid) []*NodePromis
 	return promises
 }
 
+func Copy(ctx context.Context, from, to DAGService, root *cid.Cid) error {
+	node, err := from.Get(ctx, root)
+	if err != nil {
+		return err
+	}
+	links := node.Links()
+	for _, link := range links {
+		err := Copy(ctx, from, to, link.Cid)
+		if err != nil {
+			return err
+		}
+	}
+	err = to.Add(ctx, node)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
 // Remove duplicates from a list of keys
 func dedupeKeys(cids []*cid.Cid) []*cid.Cid {
 	set := cid.NewSet()

daghelpers_test.go

@@ -0,0 +1,141 @@
+package format
+
+import (
+	"context"
+	"github.com/ipfs/go-cid"
+	mh "github.com/multiformats/go-multihash"
+	"testing"
+)
+
+type TestNode struct {
+	links   []*Link
+	data    []byte
+	builder cid.Builder
+}
+
+var v0CidPrefix = cid.Prefix{
+	Codec:    cid.DagProtobuf,
+	MhLength: -1,
+	MhType:   mh.SHA2_256,
+	Version:  0,
+}
+
+func InitNode(d []byte) *TestNode {
+	return &TestNode{
+		data:    d,
+		builder: v0CidPrefix,
+	}
+}
+
+func (n *TestNode) Resolve([]string) (interface{}, []string, error) {
+	return nil, nil, EmptyNodeError
+}
+
+func (n *TestNode) Tree(string, int) []string {
+	return nil
+}
+
+func (n *TestNode) ResolveLink([]string) (*Link, []string, error) {
+	return nil, nil, EmptyNodeError
+}
+
+func (n *TestNode) Copy() Node {
+	return &EmptyNode{}
+}
+
+func (n *TestNode) Cid() *cid.Cid {
+	c, err := n.builder.Sum(n.RawData())
+	if err != nil {
+		return nil
+	}
+	return c
+}
+
+func (n *TestNode) Links() []*Link {
+	return n.links
+}
+
+func (n *TestNode) Loggable() map[string]interface{} {
+	return nil
+}
+
+func (n *TestNode) String() string {
+	return string(n.data)
+}
+
+func (n *TestNode) RawData() []byte {
+	return n.data
+}
+
+func (n *TestNode) Size() (uint64, error) {
+	return 0, nil
+}
+
+func (n *TestNode) Stat() (*NodeStat, error) {
+	return &NodeStat{}, nil
+}
+
+// AddNodeLink adds a link to another node.
+func (n *TestNode) AddNodeLink(name string, that Node) error {
+
+	lnk, err := MakeLink(that)
+	if err != nil {
+		return err
+	}
+
+	lnk.Name = name
+
+	n.AddRawLink(name, lnk)
+
+	return nil
+}
+
+func (n *TestNode) AddRawLink(name string, l *Link) error {
+
+	n.links = append(n.links, &Link{
+		Name: name,
+		Size: l.Size,
+		Cid:  l.Cid,
+	})
+	return nil
+}
+
+func TestCopy(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	from := newTestDag()
+
+	root := InitNode([]byte("level0"))
+	l11 := InitNode([]byte("leve1_node1"))
+	l12 := InitNode([]byte("leve1_node2"))
+	l21 := InitNode([]byte("leve2_node1"))
+	l22 := InitNode([]byte("leve2_node2"))
+	l23 := InitNode([]byte("leve2_node3"))
+
+	l11.AddNodeLink(l21.Cid().String(), l21)
+	l11.AddNodeLink(l22.Cid().String(), l22)
+	l11.AddNodeLink(l23.Cid().String(), l23)
+	root.AddNodeLink(l11.Cid().String(), l11)
+	root.AddNodeLink(l12.Cid().String(), l12)
+
+	for _, n := range []Node{l23, l22, l21, l12, l11, root} {
+		err := from.Add(ctx, n)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+	to := newTestDag()
+	err := Copy(ctx, from, to, root.Cid())
+	if err != nil {
+		t.Error(err)
+	}
+
+	r, err := to.Get(ctx, root.Cid())
+	if err != nil || len(r.Links()) != 2 {
+		t.Error("fail to copy dag")
+	}
+	l1, err := to.Get(ctx, l11.Cid())
+	if err != nil || len(l1.Links()) != 3 {
+		t.Error("fail to copy dag")
+	}
+}