[#263] pkg/netmap: Do not allocate nil repeated fields during conversion

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/netmap/filter.go

@@ -230,14 +230,16 @@ func (f *Filter) InnerFilters() []*Filter {
 	)
 }
 
-func filtersToV2(fs []*Filter) []*netmap.Filter {
+func filtersToV2(fs []*Filter) (fsV2 []*netmap.Filter) {
-	fsV2 := make([]*netmap.Filter, 0, len(fs))
+	if fs != nil {
+		fsV2 = make([]*netmap.Filter, 0, len(fs))
 
-	for i := range fs {
+		for i := range fs {
-		fsV2 = append(fsV2, fs[i].ToV2())
+			fsV2 = append(fsV2, fs[i].ToV2())
+		}
 	}
 
-	return fsV2
+	return
 }
 
 // SetInnerFilters sets list of inner filters.

pkg/netmap/policy.go

@@ -38,10 +38,14 @@ func (p *PlacementPolicy) Replicas() []*Replica {
 
 // SetReplicas sets list of object replica descriptors.
 func (p *PlacementPolicy) SetReplicas(rs ...*Replica) {
-	rsV2 := make([]*netmap.Replica, 0, len(rs))
+	var rsV2 []*netmap.Replica
 
-	for i := range rs {
+	if rs != nil {
-		rsV2 = append(rsV2, rs[i].ToV2())
+		rsV2 = make([]*netmap.Replica, 0, len(rs))
+
+		for i := range rs {
+			rsV2 = append(rsV2, rs[i].ToV2())
+		}
 	}
 
 	(*netmap.PlacementPolicy)(p).
@@ -76,14 +80,18 @@ func (p *PlacementPolicy) Selectors() []*Selector {
 
 // SetSelectors sets set of selectors to form the container's nodes subset.
 func (p *PlacementPolicy) SetSelectors(ss ...*Selector) {
-	rsV2 := make([]*netmap.Selector, 0, len(ss))
+	var ssV2 []*netmap.Selector
 
-	for i := range ss {
+	if ss != nil {
-		rsV2 = append(rsV2, ss[i].ToV2())
+		ssV2 = make([]*netmap.Selector, 0, len(ss))
+
+		for i := range ss {
+			ssV2 = append(ssV2, ss[i].ToV2())
+		}
 	}
 
 	(*netmap.PlacementPolicy)(p).
-		SetSelectors(rsV2)
+		SetSelectors(ssV2)
 }
 
 // Filters returns list of named filters to reference in selectors.