[#787] util/attributes: Return consistent list of attributes

Attributes are linked to each other through parents, so they can
be returned in any order. However, it will be better to return
the list in consistent order to reduce entropy.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/util/attributes/parser.go

@@ -28,6 +28,7 @@ func ParseV2Attributes(attrs []string, excl []string) ([]*netmap.NodeAttribute,
 	}
 
 	cache := make(map[string]*netmap.NodeAttribute, len(attrs))
+	result := make([]*netmap.NodeAttribute, 0, len(attrs))
 
 	for i := range attrs {
 		line := strings.Trim(attrs[i], pairSeparator)
@@ -67,6 +68,7 @@ func ParseV2Attributes(attrs []string, excl []string) ([]*netmap.NodeAttribute,
 				attribute.SetValue(value)
 
 				cache[key] = attribute
+				result = append(result, attribute)
 			}
 
 			if parentKey != "" {
@@ -80,11 +82,6 @@ func ParseV2Attributes(attrs []string, excl []string) ([]*netmap.NodeAttribute,
 		}
 	}
 
-	result := make([]*netmap.NodeAttribute, 0, len(cache))
-	for _, v := range cache {
-		result = append(result, v)
-	}
-
 	return result, nil
 }
 

pkg/util/attributes/parser_test.go

@@ -94,4 +94,20 @@ func TestParseV2Attributes(t *testing.T) {
 		}
 		require.True(t, flag)
 	})
+
+	t.Run("consistent order in chain", func(t *testing.T) {
+		from := []string{"/a:1/b:2/c:3"}
+
+		for i := 0; i < 10000; i++ {
+			attrs, err := attributes.ParseV2Attributes(from, nil)
+			require.NoError(t, err)
+
+			require.Equal(t, attrs[0].Key(), "a")
+			require.Equal(t, attrs[0].Value(), "1")
+			require.Equal(t, attrs[1].Key(), "b")
+			require.Equal(t, attrs[1].Value(), "2")
+			require.Equal(t, attrs[2].Key(), "c")
+			require.Equal(t, attrs[2].Value(), "3")
+		}
+	})
 }