fixing panic on EdgeMetadatas deserialization by making valid zero value

report/edge_metadatas.go

@@ -32,6 +32,9 @@ func (c EdgeMetadatas) Copy() EdgeMetadatas {
 
 // Add value to the counter 'key'
 func (c EdgeMetadatas) Add(key string, value EdgeMetadata) EdgeMetadatas {
+	if c.psMap == nil {
+		c = EmptyEdgeMetadatas
+	}
 	if existingValue, ok := c.psMap.Lookup(key); ok {
 		value = value.Merge(existingValue.(EdgeMetadata))
 	}
@@ -42,15 +45,20 @@ func (c EdgeMetadatas) Add(key string, value EdgeMetadata) EdgeMetadatas {
 
 // Lookup the counter 'key'
 func (c EdgeMetadatas) Lookup(key string) (EdgeMetadata, bool) {
-	existingValue, ok := c.psMap.Lookup(key)
-	if ok {
-		return existingValue.(EdgeMetadata), true
+	if c.psMap != nil {
+		existingValue, ok := c.psMap.Lookup(key)
+		if ok {
+			return existingValue.(EdgeMetadata), true
+		}
 	}
 	return EdgeMetadata{}, false
 }
 
 // Size is the number of elements
 func (c EdgeMetadatas) Size() int {
+	if c.psMap == nil {
+		return 0
+	}
 	return c.psMap.Size()
 }
 
@@ -85,21 +93,26 @@ func (c EdgeMetadatas) Merge(other EdgeMetadatas) EdgeMetadatas {
 // The original is not modified.
 func (c EdgeMetadatas) Flatten() EdgeMetadata {
 	result := EdgeMetadata{}
-	c.psMap.ForEach(func(_ string, v interface{}) {
-		result = result.Flatten(v.(EdgeMetadata))
+	c.ForEach(func(_ string, e EdgeMetadata) {
+		result = result.Flatten(e)
 	})
 	return result
 }
 
 // ForEach executes f on each key value pair in the map
 func (c EdgeMetadatas) ForEach(fn func(k string, v EdgeMetadata)) {
-	c.psMap.ForEach(func(key string, value interface{}) {
-		fn(key, value.(EdgeMetadata))
-	})
+	if c.psMap != nil {
+		c.psMap.ForEach(func(key string, value interface{}) {
+			fn(key, value.(EdgeMetadata))
+		})
+	}
 }
 
 func (c EdgeMetadatas) String() string {
 	keys := []string{}
+	if c.psMap == nil {
+		c = EmptyEdgeMetadatas
+	}
 	for _, k := range c.psMap.Keys() {
 		keys = append(keys, k)
 	}
@@ -121,9 +134,12 @@ func (c EdgeMetadatas) DeepEqual(i interface{}) bool {
 		return false
 	}
 
-	if c.psMap.Size() != d.psMap.Size() {
+	if c.Size() != d.Size() {
 		return false
 	}
+	if c.Size() == 0 {
+		return true
+	}
 
 	equal := true
 	c.psMap.ForEach(func(k string, val interface{}) {
@@ -138,9 +154,11 @@ func (c EdgeMetadatas) DeepEqual(i interface{}) bool {
 
 func (c EdgeMetadatas) toIntermediate() map[string]EdgeMetadata {
 	intermediate := map[string]EdgeMetadata{}
-	c.psMap.ForEach(func(key string, val interface{}) {
-		intermediate[key] = val.(EdgeMetadata)
-	})
+	if c.psMap != nil {
+		c.psMap.ForEach(func(key string, val interface{}) {
+			intermediate[key] = val.(EdgeMetadata)
+		})
+	}
 	return intermediate
 }
 

report/edge_metadatas_internal_test.go

@@ -38,10 +38,22 @@ func TestEdgeMetadatasAdd(t *testing.T) {
 	})
 }
 
+func TestEdgeMetadatasAddNil(t *testing.T) {
+	have := EdgeMetadatas{}.Add("foo", EdgeMetadata{EgressPacketCount: newu64(1)})
+	if have.Size() != 1 {
+		t.Errorf("Adding to a zero-value EdgeMetadatas failed, got: %v", have)
+	}
+}
+
 func TestEdgeMetadatasMerge(t *testing.T) {
 	for name, c := range map[string]struct {
 		a, b, want EdgeMetadatas
 	}{
+		"nils": {
+			a:    EdgeMetadatas{},
+			b:    EdgeMetadatas{},
+			want: EdgeMetadatas{},
+		},
 		"Empty a": {
 			a: EmptyEdgeMetadatas,
 			b: EmptyEdgeMetadatas.
@@ -171,6 +183,15 @@ func TestEdgeMetadataFlatten(t *testing.T) {
 			t.Error(test.Diff(want, have))
 		}
 	}
+
+	{
+		// Should not panic on nil
+		have := EdgeMetadatas{}.Flatten()
+		want := EdgeMetadata{}
+		if !reflect.DeepEqual(want, have) {
+			t.Error(test.Diff(want, have))
+		}
+	}
 }
 
 func TestEdgeMetadataReversed(t *testing.T) {
@@ -185,7 +206,7 @@ func TestEdgeMetadataReversed(t *testing.T) {
 	}
 }
 
-func TestEdgeMetadataEncoding(t *testing.T) {
+func TestEdgeMetadatasEncoding(t *testing.T) {
 	want := EmptyEdgeMetadatas.
 		Add("foo", EdgeMetadata{
 		EgressPacketCount: newu64(1),
@@ -221,4 +242,32 @@ func TestEdgeMetadataEncoding(t *testing.T) {
 	}
 }
 
+func TestEdgeMetadatasEncodingNil(t *testing.T) {
+	want := EdgeMetadatas{}
+
+	{
+		gobs, err := want.GobEncode()
+		if err != nil {
+			t.Fatal(err)
+		}
+		have := EmptyEdgeMetadatas
+		have.GobDecode(gobs)
+		if have.psMap == nil {
+			t.Error("needed to get back a non-nil psMap for EdgeMetadata")
+		}
+	}
+
+	{
+		json, err := want.MarshalJSON()
+		if err != nil {
+			t.Fatal(err)
+		}
+		have := EmptyEdgeMetadatas
+		have.UnmarshalJSON(json)
+		if have.psMap == nil {
+			t.Error("needed to get back a non-nil psMap for EdgeMetadata")
+		}
+	}
+}
+
 func newu64(value uint64) *uint64 { return &value }