Implement a DAGService

dag/service.go

@@ -0,0 +1,77 @@
+package ipld
+
+import (
+	"github.com/ipfs/go-ipfs/blocks"
+	"github.com/ipfs/go-ipfs/blocks/key"
+	"github.com/ipfs/go-ipfs/blockservice"
+	"github.com/ipfs/go-ipfs/util"
+	"github.com/ipfs/go-ipld/coding"
+	"github.com/ipfs/go-ipld/memory"
+	"github.com/ipfs/go-ipld/stream"
+	"golang.org/x/net/context"
+
+	mh "github.com/jbenet/go-multihash"
+)
+
+var ErrNotFound error = blockservice.ErrNotFound
+
+type Node struct {
+	stream.NodeReader
+	Key key.Key
+}
+
+func (n *Node) Multihash() mh.Multihash {
+	return mh.Multihash(n.Key.ToMultihash())
+}
+
+type DAGService interface {
+
+	// Add a memory Node to the BlockService
+	Add(node memory.Node) (key.Key, error)
+
+	// Get a node from the BlockService
+	Get(ctx context.Context, key key.Key) (*Node, error)
+
+	// Removes a node thom the BlockService
+	Remove(key key.Key) error
+}
+
+type dagService struct {
+	bs *blockservice.BlockService
+}
+
+func NewDAGService(bs *blockservice.BlockService) DAGService {
+	return &dagService{bs}
+}
+
+func (ds *dagService) Add(node memory.Node) (key.Key, error) {
+	data, err := coding.EncodeBytes(coding.CodecProtobuf, node)
+	if err != nil {
+		return "", err
+	}
+
+	return ds.bs.AddBlock(&blocks.Block{
+		Data:      data,
+		Multihash: util.Hash(data),
+	})
+}
+
+func (ds *dagService) Get(ctx context.Context, key key.Key) (*Node, error) {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	b, err := ds.bs.GetBlock(ctx, key)
+	if err != nil {
+		if err == blockservice.ErrNotFound {
+			return nil, ErrNotFound
+		}
+		return nil, err
+	}
+
+	n, err := coding.DecodeBytes(b.Data)
+	return &Node{n, key}, err
+}
+
+func (ds *dagService) Remove(key key.Key) error {
+	return ds.bs.DeleteBlock(key)
+}