Exemple #1
0
// applyOrderAndPagination orders each posting list by a given attribute
// before applying pagination.
func (sg *SubGraph) applyOrderAndPagination(ctx context.Context) error {
	if len(sg.Params.Order) == 0 {
		return nil
	}
	if sg.Params.Count == 0 {
		// Only retrieve up to 1000 results by default.
		sg.Params.Count = 1000
	}

	sort := &task.Sort{
		Attr:      sg.Params.Order,
		UidMatrix: sg.uidMatrix,
		Offset:    int32(sg.Params.Offset),
		Count:     int32(sg.Params.Count),
		Desc:      sg.Params.OrderDesc,
	}
	result, err := worker.SortOverNetwork(ctx, sort)
	if err != nil {
		return err
	}

	x.AssertTrue(len(result.UidMatrix) == len(sg.uidMatrix))
	sg.uidMatrix = result.GetUidMatrix()

	// Update sg.destUID. Iterate over the UID matrix (which is not sorted by
	// UID). For each element in UID matrix, we do a binary search in the
	// current destUID and mark it. Then we scan over this bool array and
	// rebuild destUIDs.
	included := make([]bool, len(sg.DestUIDs.Uids))
	for _, ul := range sg.uidMatrix {
		for _, uid := range ul.Uids {
			idx := algo.IndexOf(sg.DestUIDs, uid) // Binary search.
			if idx >= 0 {
				included[idx] = true
			}
		}
	}
	algo.ApplyFilter(sg.DestUIDs,
		func(uid uint64, idx int) bool { return included[idx] })
	return nil
}
Exemple #2
0
// This method gets the values and children for a subgraph.
func (sg *SubGraph) preTraverse(uid uint64, dst outputNode) error {
	invalidUids := make(map[uint64]bool)
	// We go through all predicate children of the subgraph.
	for _, pc := range sg.Children {
		idx := algo.IndexOf(pc.SrcUIDs, uid)
		if idx < 0 {
			continue
		}
		ul := pc.uidMatrix[idx]

		fieldName := pc.Attr
		if pc.Params.Alias != "" {
			fieldName = pc.Params.Alias
		}
		if sg.Params.GetUID || sg.Params.isDebug {
			dst.SetUID(uid)
		}
		if len(pc.counts) > 0 {
			c := types.Int32(pc.counts[idx])
			uc := dst.New(fieldName)
			uc.AddValue("_count_", &c)
			dst.AddChild(fieldName, uc)

		} else if len(ul.Uids) > 0 || len(pc.Children) > 0 {
			// We create as many predicate entity children as the length of uids for
			// this predicate.
			for _, childUID := range ul.Uids {
				if invalidUids[childUID] {
					continue
				}
				uc := dst.New(fieldName)

				// Doing check for UID here is no good because some of these might be
				// invalid nodes.
				// if pc.Params.GetUID || pc.Params.isDebug {
				//	dst.SetUID(uid)
				// }
				if rerr := pc.preTraverse(childUID, uc); rerr != nil {
					if rerr.Error() == "_INV_" {
						invalidUids[childUID] = true
						continue // next UID.
					}
					// Some other error.
					log.Printf("Error while traversal: %v", rerr)
					return rerr
				}
				if !uc.IsEmpty() {
					dst.AddChild(fieldName, uc)
				}
			}
		} else {
			tv := pc.values[idx]
			v, err := getValue(tv)
			if err != nil {
				return err
			}

			if pc.Attr == "_xid_" {
				txt, err := v.MarshalText()
				if err != nil {
					return err
				}
				dst.SetXID(string(txt))
			} else {
				globalType := schema.TypeOf(pc.Attr)
				schemaType := pc.Params.AttrType
				sv := v
				if schemaType != nil {
					// Do type checking on response values
					if !schemaType.IsScalar() {
						return x.Errorf("Unknown Scalar:%v. Leaf predicate:'%v' must be"+
							" one of the scalar types defined in the schema.", pc.Params.AttrType, pc.Attr)
					}
					st := schemaType.(types.Scalar)
					// Convert to schema type.
					sv, err = st.Convert(v)
					if bytes.Equal(tv.Val, nil) || err != nil {
						// skip values that don't convert.
						return x.Errorf("_INV_")
					}
				} else if globalType != nil {
					// Try to coerce types if this is an optional scalar outside an
					// object definition.
					if !globalType.IsScalar() {
						return x.Errorf("Leaf predicate:'%v' must be a scalar.", pc.Attr)
					}
					gt := globalType.(types.Scalar)
					// Convert to schema type.
					sv, err = gt.Convert(v)
					if bytes.Equal(tv.Val, nil) || err != nil {
						continue
					}
				}
				if bytes.Equal(tv.Val, nil) {
					continue
				}
				dst.AddValue(fieldName, sv)
			}
		}
	}
	return nil
}