Refactored

Removed the unnecessary extract function and result struct. Now preTraverse
directly acceses flatbuffers to get values and uidmatrix.
Renamed struct fields in the protocol buffer schema file.

client/go/main.go

@@ -23,7 +23,7 @@ import (
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 
-	"github.com/dgraph-io/dgraph/query/pb"
+	"github.com/dgraph-io/dgraph/query/graph"
 	"github.com/dgraph-io/dgraph/x"
 )
 
@@ -40,9 +40,9 @@ func main() {
 	}
 	defer conn.Close()
 
-	c := pb.NewDGraphClient(conn)
+	c := graph.NewDGraphClient(conn)
 
-	r, err := c.Query(context.Background(), &pb.GraphRequest{Query: *q})
+	r, err := c.Query(context.Background(), &graph.Request{Query: *q})
 	if err != nil {
 		x.Err(glog, err).Fatal("Error in getting response from server")
 	}

query/pb/graphresponse.pb.go → query/graph/graphresponse.pb.go

@@ -3,17 +3,17 @@
 // DO NOT EDIT!
 
 /*
-Package pb is a generated protocol buffer package.
+Package graph is a generated protocol buffer package.
 
 It is generated from these files:
 	graphresponse.proto
 
 It has these top-level messages:
-	GraphRequest
+	Request
 	Value
-	GraphResponse
+	Node
 */
-package pb
+package graph
 
 import proto "github.com/golang/protobuf/proto"
 import fmt "fmt"
@@ -33,17 +33,17 @@ var _ = math.Inf
 // is compatible with the proto package it is being compiled against.
 const _ = proto.ProtoPackageIsVersion1
 
-type GraphRequest struct {
+type Request struct {
 	Query string `protobuf:"bytes,1,opt,name=query" json:"query,omitempty"`
 }
 
-func (m *GraphRequest) Reset()                    { *m = GraphRequest{} }
-func (m *GraphRequest) String() string            { return proto.CompactTextString(m) }
-func (*GraphRequest) ProtoMessage()               {}
-func (*GraphRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
+func (m *Request) Reset()                    { *m = Request{} }
+func (m *Request) String() string            { return proto.CompactTextString(m) }
+func (*Request) ProtoMessage()               {}
+func (*Request) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
 
 type Value struct {
-	Byte []byte `protobuf:"bytes,1,opt,name=byte,proto3" json:"byte,omitempty"`
+	Binary []byte `protobuf:"bytes,1,opt,name=binary,proto3" json:"binary,omitempty"`
 }
 
 func (m *Value) Reset()                    { *m = Value{} }
@@ -51,25 +51,26 @@ func (m *Value) String() string            { return proto.CompactTextString(m) }
 func (*Value) ProtoMessage()               {}
 func (*Value) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{1} }
 
-type GraphResponse struct {
-	Attribute string            `protobuf:"bytes,1,opt,name=attribute" json:"attribute,omitempty"`
-	Values    map[string]*Value `protobuf:"bytes,2,rep,name=values" json:"values,omitempty" protobuf_key:"bytes,1,opt,name=key" protobuf_val:"bytes,2,opt,name=value"`
-	Children  []*GraphResponse  `protobuf:"bytes,3,rep,name=children" json:"children,omitempty"`
+type Node struct {
+	Uid        uint64            `protobuf:"varint,1,opt,name=uid" json:"uid,omitempty"`
+	Attribute  string            `protobuf:"bytes,2,opt,name=attribute" json:"attribute,omitempty"`
+	Properties map[string]*Value `protobuf:"bytes,3,rep,name=properties" json:"properties,omitempty" protobuf_key:"bytes,1,opt,name=key" protobuf_val:"bytes,2,opt,name=value"`
+	Children   []*Node           `protobuf:"bytes,4,rep,name=children" json:"children,omitempty"`
 }
 
-func (m *GraphResponse) Reset()                    { *m = GraphResponse{} }
-func (m *GraphResponse) String() string            { return proto.CompactTextString(m) }
-func (*GraphResponse) ProtoMessage()               {}
-func (*GraphResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{2} }
+func (m *Node) Reset()                    { *m = Node{} }
+func (m *Node) String() string            { return proto.CompactTextString(m) }
+func (*Node) ProtoMessage()               {}
+func (*Node) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{2} }
 
-func (m *GraphResponse) GetValues() map[string]*Value {
+func (m *Node) GetProperties() map[string]*Value {
 	if m != nil {
-		return m.Values
+		return m.Properties
 	}
 	return nil
 }
 
-func (m *GraphResponse) GetChildren() []*GraphResponse {
+func (m *Node) GetChildren() []*Node {
 	if m != nil {
 		return m.Children
 	}
@@ -77,9 +78,9 @@ func (m *GraphResponse) GetChildren() []*GraphResponse {
 }
 
 func init() {
-	proto.RegisterType((*GraphRequest)(nil), "pb.GraphRequest")
-	proto.RegisterType((*Value)(nil), "pb.Value")
-	proto.RegisterType((*GraphResponse)(nil), "pb.GraphResponse")
+	proto.RegisterType((*Request)(nil), "graph.Request")
+	proto.RegisterType((*Value)(nil), "graph.Value")
+	proto.RegisterType((*Node)(nil), "graph.Node")
 }
 
 // Reference imports to suppress errors if they are not otherwise used.
@@ -93,7 +94,7 @@ const _ = grpc.SupportPackageIsVersion2
 // Client API for DGraph service
 
 type DGraphClient interface {
-	Query(ctx context.Context, in *GraphRequest, opts ...grpc.CallOption) (*GraphResponse, error)
+	Query(ctx context.Context, in *Request, opts ...grpc.CallOption) (*Node, error)
 }
 
 type dGraphClient struct {
@@ -104,9 +105,9 @@ func NewDGraphClient(cc *grpc.ClientConn) DGraphClient {
 	return &dGraphClient{cc}
 }
 
-func (c *dGraphClient) Query(ctx context.Context, in *GraphRequest, opts ...grpc.CallOption) (*GraphResponse, error) {
-	out := new(GraphResponse)
-	err := grpc.Invoke(ctx, "/pb.DGraph/Query", in, out, c.cc, opts...)
+func (c *dGraphClient) Query(ctx context.Context, in *Request, opts ...grpc.CallOption) (*Node, error) {
+	out := new(Node)
+	err := grpc.Invoke(ctx, "/graph.DGraph/Query", in, out, c.cc, opts...)
 	if err != nil {
 		return nil, err
 	}
@@ -116,7 +117,7 @@ func (c *dGraphClient) Query(ctx context.Context, in *GraphRequest, opts ...grpc
 // Server API for DGraph service
 
 type DGraphServer interface {
-	Query(context.Context, *GraphRequest) (*GraphResponse, error)
+	Query(context.Context, *Request) (*Node, error)
 }
 
 func RegisterDGraphServer(s *grpc.Server, srv DGraphServer) {
@@ -124,7 +125,7 @@ func RegisterDGraphServer(s *grpc.Server, srv DGraphServer) {
 }
 
 func _DGraph_Query_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(GraphRequest)
+	in := new(Request)
 	if err := dec(in); err != nil {
 		return nil, err
 	}
@@ -133,16 +134,16 @@ func _DGraph_Query_Handler(srv interface{}, ctx context.Context, dec func(interf
 	}
 	info := &grpc.UnaryServerInfo{
 		Server:     srv,
-		FullMethod: "/pb.DGraph/Query",
+		FullMethod: "/graph.DGraph/Query",
 	}
 	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(DGraphServer).Query(ctx, req.(*GraphRequest))
+		return srv.(DGraphServer).Query(ctx, req.(*Request))
 	}
 	return interceptor(ctx, in, info, handler)
 }
 
 var _DGraph_serviceDesc = grpc.ServiceDesc{
-	ServiceName: "pb.DGraph",
+	ServiceName: "graph.DGraph",
 	HandlerType: (*DGraphServer)(nil),
 	Methods: []grpc.MethodDesc{
 		{
@@ -154,21 +155,22 @@ var _DGraph_serviceDesc = grpc.ServiceDesc{
 }
 
 var fileDescriptor0 = []byte{
-	// 253 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0x64, 0x90, 0x31, 0x4f, 0xc3, 0x30,
-	0x10, 0x85, 0x71, 0x42, 0x22, 0x72, 0x2d, 0x52, 0x39, 0x18, 0xa2, 0x02, 0xa2, 0x8a, 0x18, 0xba,
-	0xe0, 0xa1, 0x08, 0xa9, 0x62, 0x2e, 0x62, 0xc6, 0x03, 0x7b, 0x0c, 0x27, 0x5a, 0x51, 0x25, 0xc6,
-	0x76, 0x90, 0xf2, 0x53, 0xf9, 0x37, 0xc4, 0x97, 0x00, 0x45, 0xdd, 0xce, 0x77, 0xf7, 0xbe, 0x77,
-	0x7e, 0x70, 0xfa, 0x66, 0x4b, 0xb3, 0xb6, 0xe4, 0x4c, 0x5d, 0x39, 0x92, 0xc6, 0xd6, 0xbe, 0xc6,
-	0xc8, 0xe8, 0xe2, 0x1a, 0xc6, 0x8f, 0x61, 0xa4, 0xe8, 0xa3, 0x21, 0xe7, 0xf1, 0x0c, 0x92, 0xae,
-	0xb0, 0x6d, 0x2e, 0x66, 0x62, 0x9e, 0xa9, 0xfe, 0x51, 0x9c, 0x43, 0xf2, 0x5c, 0x6e, 0x1b, 0x42,
-	0x84, 0x43, 0xdd, 0x7a, 0xe2, 0xe9, 0x58, 0x71, 0x5d, 0x7c, 0x09, 0x38, 0x1e, 0x18, 0x3d, 0x1e,
-	0x2f, 0x20, 0x2b, 0xbd, 0xb7, 0x1b, 0xdd, 0x0c, 0xab, 0x99, 0xfa, 0x6b, 0xe0, 0x1d, 0xa4, 0x9f,
-	0x01, 0xe6, 0xf2, 0x68, 0x16, 0xcf, 0x47, 0x8b, 0x4b, 0x69, 0xb4, 0xfc, 0x07, 0x90, 0x6c, 0xe6,
-	0x1e, 0x2a, 0x6f, 0x5b, 0x35, 0x2c, 0xe3, 0x0d, 0x1c, 0xbd, 0xac, 0x37, 0xdb, 0x57, 0x4b, 0x55,
-	0x1e, 0xb3, 0xf0, 0x64, 0x4f, 0xa8, 0x7e, 0x57, 0xa6, 0x2b, 0x18, 0xed, 0x50, 0x70, 0x02, 0xf1,
-	0x3b, 0xfd, 0xfc, 0x2a, 0x94, 0x78, 0x05, 0x09, 0x93, 0xbb, 0x2b, 0x44, 0x07, 0xcb, 0x02, 0x8c,
-	0x15, 0xaa, 0xef, 0xdf, 0x47, 0x4b, 0xb1, 0x58, 0x42, 0xba, 0x62, 0x07, 0x94, 0x90, 0x3c, 0x85,
-	0x2c, 0x70, 0xb2, 0xe3, 0xca, 0x99, 0x4d, 0xf7, 0xef, 0x28, 0x0e, 0x74, 0xca, 0x19, 0xdf, 0x7e,
-	0x07, 0x00, 0x00, 0xff, 0xff, 0xfb, 0x05, 0xc8, 0x3f, 0x7a, 0x01, 0x00, 0x00,
+	// 266 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0x5c, 0x90, 0x41, 0x4b, 0xc3, 0x40,
+	0x10, 0x85, 0x4d, 0x93, 0x8d, 0x76, 0x52, 0x54, 0x46, 0x91, 0x50, 0x05, 0x4b, 0x0e, 0xda, 0x53,
+	0x90, 0x78, 0x11, 0xbd, 0x2a, 0x1e, 0x04, 0xd1, 0x3d, 0x78, 0x4f, 0xcc, 0x60, 0x17, 0x4b, 0x12,
+	0x37, 0x1b, 0xa1, 0x3f, 0xd9, 0x7f, 0x61, 0x76, 0xba, 0xd6, 0xd0, 0xdb, 0xcc, 0x7c, 0x33, 0x8f,
+	0x37, 0x0f, 0x8e, 0x3e, 0x74, 0xde, 0x2c, 0x34, 0xb5, 0x4d, 0x5d, 0xb5, 0x94, 0x36, 0xba, 0x36,
+	0x35, 0x0a, 0x1e, 0x26, 0xe7, 0xb0, 0x2b, 0xe9, 0xab, 0xa3, 0xd6, 0xe0, 0x31, 0x88, 0xbe, 0xd0,
+	0xab, 0xd8, 0x9b, 0x79, 0xf3, 0xb1, 0x5c, 0x37, 0xfd, 0x82, 0x78, 0xcb, 0x97, 0x1d, 0xe1, 0x09,
+	0x84, 0x85, 0xaa, 0x72, 0xc7, 0x27, 0xd2, 0x75, 0xc9, 0x8f, 0x07, 0xc1, 0x73, 0x5d, 0x12, 0x1e,
+	0x82, 0xdf, 0xa9, 0x92, 0x69, 0x20, 0x6d, 0x89, 0x67, 0x30, 0xce, 0x8d, 0xd1, 0xaa, 0xe8, 0x0c,
+	0xc5, 0x23, 0x56, 0xfd, 0x1f, 0xe0, 0x1d, 0x40, 0x6f, 0xa5, 0x21, 0x6d, 0x14, 0xb5, 0xb1, 0x3f,
+	0xf3, 0xe7, 0x51, 0x76, 0x9a, 0xb2, 0xad, 0xd4, 0x0a, 0xa6, 0x2f, 0x1b, 0xfa, 0x50, 0x19, 0xbd,
+	0x92, 0x83, 0x75, 0xbc, 0x84, 0xbd, 0xf7, 0x85, 0x5a, 0x96, 0x9a, 0xaa, 0x38, 0xe0, 0xd3, 0x68,
+	0x70, 0x2a, 0x37, 0x70, 0xfa, 0x04, 0x07, 0x5b, 0x3a, 0xd6, 0xe8, 0x27, 0xfd, 0xbd, 0x69, 0x4b,
+	0x4c, 0x40, 0x7c, 0xdb, 0x27, 0xd9, 0x64, 0x94, 0x4d, 0x9c, 0x14, 0x3f, 0x2e, 0xd7, 0xe8, 0x76,
+	0x74, 0xe3, 0x65, 0x57, 0x10, 0xde, 0x3f, 0x5a, 0x84, 0x17, 0x20, 0x5e, 0x6d, 0x3e, 0xb8, 0xef,
+	0x76, 0x5d, 0x8a, 0xd3, 0xa1, 0x8d, 0x64, 0xa7, 0x08, 0x39, 0xed, 0xeb, 0xdf, 0x00, 0x00, 0x00,
+	0xff, 0xff, 0x2c, 0xc9, 0x79, 0xe9, 0x84, 0x01, 0x00, 0x00,
 }

query/graph/graphresponse.proto

+// To compile this file run the command below from inside the graph directory
+// protoc --go_out=plugins=grpc:. *.proto
+
+syntax="proto3";
+package graph;
+
+service DGraph {
+  rpc Query (Request) returns (Node) {}
+}
+
+message Request {
+  string query = 1;
+}
+
+message Value {
+  bytes binary = 1;
+}
+
+message Node {
+  uint64 uid = 1;
+  string attribute = 2;
+  map<string, Value> properties = 3;
+  repeated Node children = 4; // Each node can have multiple children
+}

query/pb/graphresponse.proto

-// To compile this file run the command below from inside the pb directory
-// protoc --go_out=plugins=grpc:. *.proto
-
-syntax="proto3";
-package pb;
-
-service DGraph {
-  rpc Query (GraphRequest) returns (GraphResponse) {}
-}
-
-message GraphRequest {
-  string query = 1;
-}
-
-message Value {
-  bytes byte = 1;
-}
-
-message GraphResponse {
-  string attribute = 1;
-  map<string, Value> values = 2;
-  repeated GraphResponse children = 3; // Each node can have multiple children
-}

query/query.go

@@ -26,7 +26,7 @@ import (
 	"github.com/Sirupsen/logrus"
 	"github.com/dgraph-io/dgraph/gql"
 	"github.com/dgraph-io/dgraph/posting"
-	"github.com/dgraph-io/dgraph/query/pb"
+	"github.com/dgraph-io/dgraph/query/graph"
 	"github.com/dgraph-io/dgraph/task"
 	"github.com/dgraph-io/dgraph/worker"
 	"github.com/dgraph-io/dgraph/x"
@@ -253,111 +253,15 @@ func (g *SubGraph) ToJson(l *Latency) (js []byte, rerr error) {
 	return json.Marshal(r)
 }
 
-// Struct to retrieve values from flatbuffers, so that they can later be used
-// to control the entity based protocol buffer subgraph.
-type result struct {
-	values    [][]byte
-	uidmatrix [][]uint64
-}
-
-// This method takes in a flatbuffer query and result extracts values.
-func extract(q *task.Query, r *task.Result) ([]uint64, *result, error) {
-	re := new(result)
-	var qu []uint64
-	var ul task.UidList
-
-	for i := 0; i < q.UidsLength(); i++ {
-		uid := q.Uids(i)
-		qu = append(qu, uid)
-	}
-
-	for i := 0; i < r.UidmatrixLength(); i++ {
-		if ok := r.Uidmatrix(&ul, i); !ok {
-			return qu, re, fmt.Errorf("While parsing UidList")
-		}
-
-		var uidList []uint64
-		for j := 0; j < ul.UidsLength(); j++ {
-			uid := ul.Uids(j)
-			uidList = append(uidList, uid)
-		}
-		re.uidmatrix = append(re.uidmatrix, uidList)
-	}
-
-	var tv task.Value
-	for i := 0; i < r.ValuesLength(); i++ {
-		if ok := r.Values(&tv, i); !ok {
-			return qu, re, fmt.Errorf("While parsing value")
-		}
-
-		var ival interface{}
-		if err := posting.ParseValue(&ival, tv.ValBytes()); err != nil {
-			return qu, re, err
-		}
-
-		if ival == nil {
-			ival = ""
-		}
-		re.values = append(re.values, []byte(ival.(string)))
-	}
-	return qu, re, nil
-}
-
-// Struct to store reference to the subgraph associated with a protocol buffer
-// graph response
-type sgReference struct {
-	uid uint64
-	sg  *SubGraph
-}
-
-// This method converts a subgraph to a protocol buffer response. It transforms
-// the predicate based subgraph to an entity based protocol buffer subgraph.
-func (g *SubGraph) ToProtocolBuffer(l *Latency) (gr *pb.GraphResponse,
-	rerr error) {
-	gr = &pb.GraphResponse{}
-	gr.Attribute = g.Attr
-	if len(g.query) == 0 {
-		return gr, nil
-	}
-
-	ro := flatbuffers.GetUOffsetT(g.result)
-	r := new(task.Result)
-	r.Init(g.result, ro)
-
-	uo := flatbuffers.GetUOffsetT(g.query)
-	q := new(task.Query)
-	q.Init(g.query, uo)
-
-	_, result, err := extract(q, r)
-	if err != nil {
-		x.Err(glog, err).Error("Error while extracting query, result")
-		return gr, err
-	}
-
-	re := &sgReference{}
-	// Storing reference to root node.
-	re.sg = g
-	// Stores the uid for the root node in the reference struct.
-	re.uid = result.uidmatrix[0][0]
-	gr.Values, gr.Children, rerr = re.preTraverse()
-	if rerr != nil {
-		x.Err(glog, rerr).Error("Error while traversal")
-		return gr, rerr
-	}
-
-	l.ProtocolBuffer = time.Since(l.Start) - l.Parsing - l.Processing
-	return gr, nil
-}
-
 // This function performs a binary search on the uids slice and returns the
 // index at which it finds the uid, else returns -1
-func indexOf(uid uint64, uids []uint64) int {
-	low, mid, high := 0, 0, len(uids)-1
+func indexOf(uid uint64, q *task.Query) int {
+	low, mid, high := 0, 0, q.UidsLength()-1
 	for low <= high {
 		mid = (low + high) / 2
-		if uids[mid] == uid {
+		if q.Uids(mid) == uid {
 			return mid
-		} else if uids[mid] > uid {
+		} else if q.Uids(mid) > uid {
 			high = mid - 1
 		} else {
 			low = mid + 1
@@ -366,67 +270,104 @@ func indexOf(uid uint64, uids []uint64) int {
 	return -1
 }
 
-// This method gets the values and children for a GraphResponse.
-func (re *sgReference) preTraverse() (map[string]*pb.Value,
-	[]*pb.GraphResponse, error) {
-	values := make(map[string]*pb.Value)
-	var children []*pb.GraphResponse
+// This method gets the values and children for a subgraph.
+func preTraverse(uid uint64, g *SubGraph) (map[string]*graph.Value, []*graph.Node, error) {
+	values := make(map[string]*graph.Value)
+	var children []*graph.Node
 
-	for _, child := range re.sg.Children {
-		ro := flatbuffers.GetUOffsetT(child.result)
+	for _, predChild := range g.Children {
+		ro := flatbuffers.GetUOffsetT(predChild.result)
 		r := new(task.Result)
-		r.Init(child.result, ro)
+		r.Init(predChild.result, ro)
 
-		uo := flatbuffers.GetUOffsetT(child.query)
+		uo := flatbuffers.GetUOffsetT(predChild.query)
 		q := new(task.Query)
-		q.Init(child.query, uo)
+		q.Init(predChild.query, uo)
 
-		query, result, err := extract(q, r)
-		if err != nil {
-			x.Err(glog, err).Error("Error while extracting query, result")
-			return values, children, fmt.Errorf("While extracting query, result")
-		}
+		idx := indexOf(uid, q)
 
-		idx := indexOf(re.uid, query)
 		if idx == -1 {
 			glog.WithFields(logrus.Fields{
-				"uid":            re.uid,
-				"attribute":      re.sg.Attr,
-				"childAttribute": child.Attr,
+				"uid":            uid,
+				"attribute":      g.Attr,
+				"childAttribute": predChild.Attr,
 			}).Fatal("Attribute with uid not found in child Query uids")
 			return values, children, fmt.Errorf("Attribute with uid not found")
 		}
 
-		// This means the child is a leaf node hence we just extract its value.
-		if len(child.Children) == 0 {
-			v := new(pb.Value)
-			v.Byte = result.values[idx]
-			values[child.Attr] = v
-		} else {
-			uids := result.uidmatrix[idx]
-			// We create as many predicate children as the number of uids.
-			for _, uid := range uids {
-				predChild := new(pb.GraphResponse)
-				predChild.Attribute = child.Attr
+		var ul task.UidList
+		var tv task.Value
+		if ok := r.Uidmatrix(&ul, idx); !ok {
+			return values, children, fmt.Errorf("While parsing UidList")
+		}
 
-				ref := new(sgReference)
-				ref.sg = child
-				ref.uid = uid
+		if ul.UidsLength() > 0 {
+			// We create as many predicate entity children as the length of uids for
+			// this predicate.
+			for i := 0; i < ul.UidsLength(); i++ {
+				uid := ul.Uids(i)
+				uidChild := new(graph.Node)
+				uidChild.Attribute = predChild.Attr
+				uidChild.Uid = uid
 
-				vals, ch, rerr := ref.preTraverse()
+				vals, ch, rerr := preTraverse(uid, predChild)
 				if rerr != nil {
 					x.Err(glog, rerr).Error("Error while traversal")
 					return values, children, rerr
 				}
 
-				predChild.Values, predChild.Children = vals, ch
-				children = append(children, predChild)
+				uidChild.Properties, uidChild.Children = vals, ch
+				children = append(children, uidChild)
+			}
+		} else {
+			v := new(graph.Value)
+			if ok := r.Values(&tv, idx); !ok {
+				return values, children, fmt.Errorf("While parsing value")
+			}
+
+			var ival interface{}
+			if err := posting.ParseValue(&ival, tv.ValBytes()); err != nil {
+				return values, children, err
 			}
+
+			if ival == nil {
+				ival = ""
+			}
+
+			v.Binary = []byte(ival.(string))
+			values[predChild.Attr] = v
 		}
 	}
 	return values, children, nil
 }
 
+// This method transforms the predicate based subgraph to an
+// predicate-entity based protocol buffer subgraph.
+func (g *SubGraph) ToProtocolBuffer(l *Latency) (n *graph.Node, rerr error) {
+	n = &graph.Node{}
+	n.Attribute = g.Attr
+	if len(g.query) == 0 {
+		return n, nil
+	}
+
+	ro := flatbuffers.GetUOffsetT(g.result)
+	r := new(task.Result)
+	r.Init(g.result, ro)
+
+	var ul task.UidList
+	r.Uidmatrix(&ul, 0)
+	n.Uid = ul.Uids(0)
+
+	n.Properties, n.Children, rerr = preTraverse(n.Uid, g)
+	if rerr != nil {
+		x.Err(glog, rerr).Error("Error while traversal")
+		return n, rerr
+	}
+
+	l.ProtocolBuffer = time.Since(l.Start) - l.Parsing - l.Processing
+	return n, nil
+}
+
 func treeCopy(gq *gql.GraphQuery, sg *SubGraph) {
 	for _, gchild := range gq.Children {
 		dst := new(SubGraph)

query/query_test.go

@@ -333,6 +333,8 @@ func TestToProtocolBuffer(t *testing.T) {
 				friend {
 					name
 				}
+				friend {
+				}
 			}
 		}
 	`
@@ -362,29 +364,50 @@ func TestToProtocolBuffer(t *testing.T) {
 	if gr.Attribute != "_root_" {
 		t.Errorf("Expected attribute _root_, Got: %v", gr.Attribute)
 	}
-	if len(gr.Values) != 3 {
+	if gr.Uid != 1 {
+		t.Errorf("Expected uid 1, Got: %v", gr.Uid)
+	}
+	if len(gr.Properties) != 3 {
 		t.Errorf("Expected values map to contain 3 properties, Got: %v",
-			len(gr.Values))
+			len(gr.Properties))
 	}
-	if string(gr.Values["name"].Byte) != "Michonne" {
+	if string(gr.Properties["name"].Binary) != "Michonne" {
 		t.Errorf("Expected property name to have value Michonne, Got: %v",
-			string(gr.Values["name"].Byte))
+			string(gr.Properties["name"].Binary))
 	}
-	if len(gr.Children) != 5 {
-		t.Errorf("Expected 5 children, Got: %v", len(gr.Children))
+	if len(gr.Children) != 10 {
+		t.Errorf("Expected 10 children, Got: %v", len(gr.Children))
 	}
 
 	child := gr.Children[0]
+	if child.Uid != 23 {
+		t.Errorf("Expected uid 23, Got: %v", gr.Uid)
+	}
 	if child.Attribute != "friend" {
 		t.Errorf("Expected attribute friend, Got: %v", child.Attribute)
 	}
-	if len(child.Values) != 1 {
+	if len(child.Properties) != 1 {
 		t.Errorf("Expected values map to contain 1 property, Got: %v",
-			len(child.Values))
+			len(child.Properties))
 	}
-	if string(child.Values["name"].Byte) != "Rick Grimes" {
+	if string(child.Properties["name"].Binary) != "Rick Grimes" {
 		t.Errorf("Expected property name to have value Rick Grimes, Got: %v",
-			string(child.Values["name"].Byte))
+			string(child.Properties["name"].Binary))
+	}
+	if len(child.Children) != 0 {
+		t.Errorf("Expected 0 children, Got: %v", len(child.Children))
+	}
+
+	child = gr.Children[5]
+	if child.Uid != 23 {
+		t.Errorf("Expected uid 23, Got: %v", gr.Uid)
+	}
+	if child.Attribute != "friend" {
+		t.Errorf("Expected attribute friend, Got: %v", child.Attribute)
+	}
+	if len(child.Properties) != 0 {
+		t.Errorf("Expected values map to contain 0 properties, Got: %v",
+			len(child.Properties))
 	}
 	if len(child.Children) != 0 {
 		t.Errorf("Expected 0 children, Got: %v", len(child.Children))

server/main.go

@@ -36,7 +36,7 @@ import (
 	"github.com/dgraph-io/dgraph/gql"
 	"github.com/dgraph-io/dgraph/posting"
 	"github.com/dgraph-io/dgraph/query"
-	"github.com/dgraph-io/dgraph/query/pb"
+	"github.com/dgraph-io/dgraph/query/graph"
 	"github.com/dgraph-io/dgraph/rdf"
 	"github.com/dgraph-io/dgraph/store"
 	"github.com/dgraph-io/dgraph/uid"
@@ -203,14 +203,14 @@ func queryHandler(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprint(w, string(js))
 }
 
-// server is used to implement pb.DGraphServer
+// server is used to implement graph.DGraphServer
 type server struct{}
 
 // This method is used to execute the query and return the response to the
 // client as a protocol buffer message.
 func (s *server) Query(ctx context.Context,
-	req *pb.GraphRequest) (*pb.GraphResponse, error) {
-	resp := new(pb.GraphResponse)
+	req *graph.Request) (*graph.Node, error) {
+	resp := new(graph.Node)
 	if len(req.Query) == 0 {
 		glog.Error("While reading query")
 		return resp, fmt.Errorf("Empty query")
@@ -265,7 +265,7 @@ func runGrpcServer(address string) error {
 	glog.WithField("address", ln.Addr()).Info("Client Worker listening")
 
 	s := grpc.NewServer()
-	pb.RegisterDGraphServer(s, &server{})
+	graph.RegisterDGraphServer(s, &server{})
 	if err = s.Serve(ln); err != nil {
 		glog.Fatalf("While serving gRpc requests", err)
 	}