remove filtering of unconnected pseudo nodes from ordinary filters

It's now done via a special filter, once, after all other filters have
been applied.

Some tests need updating since they were relying on ordinary filters
doing that filtering.

render/container_test.go

@@ -16,8 +16,14 @@ import (
 )
 
 var (
-	filterApplication = render.AnyFilterFunc(render.IsPseudoTopology, render.IsApplication)
-	filterSystem      = render.AnyFilterFunc(render.IsPseudoTopology, render.IsSystem)
+	filterApplication = render.Transformers([]render.Transformer{
+		render.AnyFilterFunc(render.IsPseudoTopology, render.IsApplication),
+		render.FilterUnconnectedPseudo,
+	})
+	filterSystem = render.Transformers([]render.Transformer{
+		render.AnyFilterFunc(render.IsPseudoTopology, render.IsSystem),
+		render.FilterUnconnectedPseudo,
+	})
 )
 
 func TestMapProcess2Container(t *testing.T) {

render/filters.go

@@ -63,12 +63,10 @@ func Complement(f FilterFunc) FilterFunc {
 // Transform applies the filter to all nodes
 func (f FilterFunc) Transform(nodes Nodes) Nodes {
 	output := report.Nodes{}
-	inDegrees := map[string]int{}
 	filtered := nodes.Filtered
 	for id, node := range nodes.Nodes {
 		if f(node) {
 			output[id] = node
-			inDegrees[id] = 0
 		} else {
 			filtered++
 		}
@@ -80,25 +78,12 @@ func (f FilterFunc) Transform(nodes Nodes) Nodes {
 		for _, dstID := range node.Adjacency {
 			if _, ok := output[dstID]; ok {
 				newAdjacency = newAdjacency.Add(dstID)
-				inDegrees[dstID]++
 			}
 		}
 		node.Adjacency = newAdjacency
 		output[id] = node
 	}
 
-	// Remove unconnected pseudo nodes, see #483.
-	for id, inDegree := range inDegrees {
-		if inDegree > 0 {
-			continue
-		}
-		node := output[id]
-		if node.Topology != Pseudo || len(node.Adjacency) > 0 {
-			continue
-		}
-		delete(output, id)
-		filtered++
-	}
 	return Nodes{Nodes: output, Filtered: filtered}
 }
 

render/filters_test.go

@@ -9,9 +9,12 @@ import (
 	"github.com/weaveworks/scope/test/reflect"
 )
 
-func isNotBar(node report.Node) bool {
-	return node.ID != "bar"
-}
+var filterBar = render.Transformers([]render.Transformer{
+	render.FilterFunc(func(node report.Node) bool {
+		return node.ID != "bar"
+	}),
+	render.FilterUnconnectedPseudo,
+})
 
 func TestFilterRender(t *testing.T) {
 	renderer := mockRenderer{Nodes: report.Nodes{
@@ -36,7 +39,7 @@ func TestFilterRender2(t *testing.T) {
 		"bar": report.MakeNode("bar").WithAdjacent("foo"),
 		"baz": report.MakeNode("baz"),
 	}}
-	have := render.Render(report.MakeReport(), renderer, render.FilterFunc(isNotBar)).Nodes
+	have := render.Render(report.MakeReport(), renderer, filterBar).Nodes
 	if have["foo"].Adjacency.Contains("bar") {
 		t.Error("adjacencies for removed nodes should have been removed")
 	}
@@ -64,7 +67,7 @@ func TestFilterUnconnectedPseudoNodes(t *testing.T) {
 			"bar": report.MakeNode("bar").WithAdjacent("baz"),
 			"baz": report.MakeNode("baz").WithTopology(render.Pseudo),
 		}}
-		have := render.Render(report.MakeReport(), renderer, render.FilterFunc(isNotBar)).Nodes
+		have := render.Render(report.MakeReport(), renderer, filterBar).Nodes
 		if _, ok := have["baz"]; ok {
 			t.Error("expected the unconnected pseudonode baz to have been removed")
 		}
@@ -75,7 +78,7 @@ func TestFilterUnconnectedPseudoNodes(t *testing.T) {
 			"bar": report.MakeNode("bar").WithAdjacent("foo"),
 			"baz": report.MakeNode("baz").WithTopology(render.Pseudo).WithAdjacent("bar"),
 		}}
-		have := render.Render(report.MakeReport(), renderer, render.FilterFunc(isNotBar)).Nodes
+		have := render.Render(report.MakeReport(), renderer, filterBar).Nodes
 		if _, ok := have["baz"]; ok {
 			t.Error("expected the unconnected pseudonode baz to have been removed")
 		}

render/pod_test.go

@@ -20,7 +20,10 @@ func TestPodRenderer(t *testing.T) {
 	}
 }
 
-var filterNonKubeSystem = render.Complement(render.IsNamespace("kube-system"))
+var filterNonKubeSystem = render.Transformers([]render.Transformer{
+	render.Complement(render.IsNamespace("kube-system")),
+	render.FilterUnconnectedPseudo,
+})
 
 func TestPodFilterRenderer(t *testing.T) {
 	// tag on containers or pod namespace in the topology and ensure