Merge pull request weaveworks#3135 from weaveworks/map-one

Simplify Map.Render()

render/container.go

@@ -255,10 +255,10 @@ func MapContainer2IP(m report.Node) []string {
 // format for a container, but without any Major or Minor labels.
 // It does not have enough info to do that, and the resulting graph
 // must be merged with a container graph to get that info.
-func MapProcess2Container(n report.Node) report.Nodes {
+func MapProcess2Container(n report.Node) report.Node {
 	// Propagate pseudo nodes
 	if n.Topology == Pseudo {
-		return report.Nodes{n.ID: n}
+		return n
 	}
 
 	// Otherwise, if the process is not in a container, group it into
@@ -275,7 +275,7 @@ func MapProcess2Container(n report.Node) report.Nodes {
 		id = MakePseudoNodeID(UncontainedID, hostID)
 		node = NewDerivedPseudoNode(id, n)
 	}
-	return report.Nodes{id: node}
+	return node
 }
 
 // MapContainer2ContainerImage maps container Nodes to container
@@ -290,68 +290,68 @@ func MapProcess2Container(n report.Node) report.Nodes {
 // format for a container image, but without any Major or Minor
 // labels.  It does not have enough info to do that, and the resulting
 // graph must be merged with a container image graph to get that info.
-func MapContainer2ContainerImage(n report.Node) report.Nodes {
+func MapContainer2ContainerImage(n report.Node) report.Node {
 	// Propagate all pseudo nodes
 	if n.Topology == Pseudo {
-		return report.Nodes{n.ID: n}
+		return n
 	}
 
 	// Otherwise, if some some reason the container doesn't have a image_id
 	// (maybe slightly out of sync reports), just drop it
 	imageID, ok := n.Latest.Lookup(docker.ImageID)
 	if !ok {
-		return report.Nodes{}
+		return report.Node{}
 	}
 
 	// Add container id key to the counters, which will later be
 	// counted to produce the minor label
 	id := report.MakeContainerImageNodeID(imageID)
 	result := NewDerivedNode(id, n).WithTopology(report.ContainerImage)
 	result.Counters = result.Counters.Add(n.Topology, 1)
-	return report.Nodes{id: result}
+	return result
 }
 
 // MapContainerImage2Name ignores image versions
-func MapContainerImage2Name(n report.Node) report.Nodes {
+func MapContainerImage2Name(n report.Node) report.Node {
 	// Propagate all pseudo nodes
 	if n.Topology == Pseudo {
-		return report.Nodes{n.ID: n}
+		return n
 	}
 
 	imageName, ok := n.Latest.Lookup(docker.ImageName)
 	if !ok {
-		return report.Nodes{}
+		return report.Node{}
 	}
 
 	imageNameWithoutVersion := docker.ImageNameWithoutVersion(imageName)
 	n.ID = report.MakeContainerImageNodeID(imageNameWithoutVersion)
 
-	return report.Nodes{n.ID: n}
+	return n
 }
 
 var containerHostnameTopology = MakeGroupNodeTopology(report.Container, docker.ContainerHostname)
 
 // MapContainer2Hostname maps container Nodes to 'hostname' renderabled nodes..
-func MapContainer2Hostname(n report.Node) report.Nodes {
+func MapContainer2Hostname(n report.Node) report.Node {
 	// Propagate all pseudo nodes
 	if n.Topology == Pseudo {
-		return report.Nodes{n.ID: n}
+		return n
 	}
 
 	// Otherwise, if some some reason the container doesn't have a hostname
 	// (maybe slightly out of sync reports), just drop it
 	id, ok := n.Latest.Lookup(docker.ContainerHostname)
 	if !ok {
-		return report.Nodes{}
+		return report.Node{}
 	}
 
 	node := NewDerivedNode(id, n).WithTopology(containerHostnameTopology)
 	node.Counters = node.Counters.Add(n.Topology, 1)
-	return report.Nodes{id: node}
+	return node
 }
 
 // MapToEmpty removes all the attributes, children, etc, of a node. Useful when
 // we just want to count the presence of nodes.
-func MapToEmpty(n report.Node) report.Nodes {
-	return report.Nodes{n.ID: report.MakeNode(n.ID).WithTopology(n.Topology)}
+func MapToEmpty(n report.Node) report.Node {
+	return report.MakeNode(n.ID).WithTopology(n.Topology)
 }

render/container_test.go

@@ -43,7 +43,7 @@ type testcase struct {
 }
 
 func testMap(t *testing.T, f render.MapFunc, input testcase) {
-	if have := f(input.n); input.ok != (len(have) > 0) {
+	if have := f(input.n); input.ok != (have.ID != "") {
 		name := input.name
 		if name == "" {
 			name = fmt.Sprintf("%v", input.n)

render/pod.go

@@ -50,16 +50,14 @@ var PodRenderer = Memoise(ConditionalRenderer(renderKubernetesTopologies,
 		},
 		MakeReduce(
 			PropagateSingleMetrics(report.Container,
-				MakeMap(
-					Map2Parent([]string{report.Pod}, UnmanagedID),
-					MakeFilter(
+				Map2Parent{topologies: []string{report.Pod}, noParentsPseudoID: UnmanagedID,
+					chainRenderer: MakeFilter(
 						ComposeFilterFuncs(
 							IsRunning,
 							Complement(isPauseContainer),
 						),
 						ContainerWithImageNameRenderer,
-					),
-				),
+					)},
 			),
 			ConnectionJoin(MapPod2IP, report.Pod),
 		),
@@ -101,10 +99,8 @@ func renderParents(childTopology string, parentTopologies []string, noParentsPse
 	return MakeReduce(append(
 		selectors,
 		PropagateSingleMetrics(childTopology,
-			MakeMap(
-				Map2Parent(parentTopologies, noParentsPseudoID),
-				childRenderer,
-			),
+			Map2Parent{topologies: parentTopologies, noParentsPseudoID: noParentsPseudoID,
+				chainRenderer: childRenderer},
 		),
 	)...)
 }
@@ -126,46 +122,52 @@ func MapPod2IP(m report.Node) []string {
 	return []string{report.MakeScopedEndpointNodeID("", ip, "")}
 }
 
-// Map2Parent returns a MapFunc which maps Nodes to some parent grouping.
-func Map2Parent(
+// Map2Parent is a Renderer which maps Nodes to some parent grouping.
+type Map2Parent struct {
+	// Renderer to chain from
+	chainRenderer Renderer
 	// The topology IDs to look for parents in
-	topologies []string,
+	topologies []string
 	// Either the ID prefix of the pseudo node to use for nodes without
 	// any parents in the group, eg. UnmanagedID, or "" to drop nodes without any parents.
-	noParentsPseudoID string,
-) MapFunc {
-	return func(n report.Node) report.Nodes {
+	noParentsPseudoID string
+}
+
+// Render implements Renderer
+func (m Map2Parent) Render(rpt report.Report) Nodes {
+	input := m.chainRenderer.Render(rpt)
+	ret := newJoinResults(nil)
+
+	for _, n := range input.Nodes {
 		// Uncontained becomes Unmanaged/whatever if noParentsPseudoID is set
-		if noParentsPseudoID != "" && strings.HasPrefix(n.ID, UncontainedIDPrefix) {
-			id := MakePseudoNodeID(noParentsPseudoID, n.ID[len(UncontainedIDPrefix):])
-			node := NewDerivedPseudoNode(id, n)
-			return report.Nodes{id: node}
+		if m.noParentsPseudoID != "" && strings.HasPrefix(n.ID, UncontainedIDPrefix) {
+			id := MakePseudoNodeID(m.noParentsPseudoID, n.ID[len(UncontainedIDPrefix):])
+			ret.addChildAndChildren(n, id, Pseudo)
+			continue
 		}
 
 		// Propagate all pseudo nodes
 		if n.Topology == Pseudo {
-			return report.Nodes{n.ID: n}
+			ret.passThrough(n)
+			continue
 		}
 
+		added := false
 		// For each topology, map to any parents we can find
-		result := report.Nodes{}
-		for _, topology := range topologies {
+		for _, topology := range m.topologies {
 			if groupIDs, ok := n.Parents.Lookup(topology); ok {
 				for _, id := range groupIDs {
-					node := NewDerivedNode(id, n).WithTopology(topology)
-					node.Counters = node.Counters.Add(n.Topology, 1)
-					result[id] = node
+					ret.addChildAndChildren(n, id, topology)
+					added = true
 				}
 			}
 		}
 
-		if len(result) == 0 && noParentsPseudoID != "" {
+		if !added && m.noParentsPseudoID != "" {
 			// Map to pseudo node
-			id := MakePseudoNodeID(noParentsPseudoID, report.ExtractHostID(n))
-			node := NewDerivedPseudoNode(id, n)
-			result[id] = node
+			id := MakePseudoNodeID(m.noParentsPseudoID, report.ExtractHostID(n))
+			ret.addChildAndChildren(n, id, Pseudo)
 		}
-
-		return result
 	}
+	return ret.result(input)
 }

render/render.go

@@ -5,10 +5,11 @@ import (
 )
 
 // MapFunc is anything which can take an arbitrary Node and
-// return a set of other Nodes.
+// return another Node.
 //
-// If the output is empty, the node shall be omitted from the rendered topology.
-type MapFunc func(report.Node) report.Nodes
+// If the output ID is blank, the node shall be omitted from the rendered topology.
+// (we chose not to return an extra bool because it adds clutter)
+type MapFunc func(report.Node) report.Node
 
 // Renderer is something that can render a report to a set of Nodes.
 type Renderer interface {
@@ -99,37 +100,19 @@ func MakeMap(f MapFunc, r Renderer) Renderer {
 // using a map function
 func (m Map) Render(rpt report.Report) Nodes {
 	var (
-		input       = m.Renderer.Render(rpt)
-		output      = report.Nodes{}
-		mapped      = map[string]report.IDList{} // input node ID -> output node IDs
-		adjacencies = map[string]report.IDList{} // output node ID -> input node Adjacencies
+		input  = m.Renderer.Render(rpt)
+		output = newJoinResults(nil)
 	)
 
 	// Rewrite all the nodes according to the map function
 	for _, inRenderable := range input.Nodes {
-		for _, outRenderable := range m.MapFunc(inRenderable) {
-			if existing, ok := output[outRenderable.ID]; ok {
-				outRenderable = outRenderable.Merge(existing)
-			}
-
-			output[outRenderable.ID] = outRenderable
-			mapped[inRenderable.ID] = mapped[inRenderable.ID].Add(outRenderable.ID)
-			adjacencies[outRenderable.ID] = adjacencies[outRenderable.ID].Merge(inRenderable.Adjacency)
+		outRenderable := m.MapFunc(inRenderable)
+		if outRenderable.ID != "" {
+			output.add(inRenderable.ID, outRenderable)
 		}
 	}
 
-	// Rewrite Adjacency for new node IDs.
-	for outNodeID, inAdjacency := range adjacencies {
-		outAdjacency := report.MakeIDList()
-		for _, inAdjacent := range inAdjacency {
-			outAdjacency = outAdjacency.Merge(mapped[inAdjacent])
-		}
-		outNode := output[outNodeID]
-		outNode.Adjacency = outAdjacency
-		output[outNodeID] = outNode
-	}
-
-	return Nodes{Nodes: output}
+	return output.result(input)
 }
 
 func propagateLatest(key string, from, to report.Node) report.Node {
@@ -184,6 +167,15 @@ func (ret *joinResults) mapChild(from, to string) {
 	}
 }
 
+// Add m into the results as a top-level node, mapped from original ID
+func (ret *joinResults) add(from string, m report.Node) {
+	if existing, ok := ret.nodes[m.ID]; ok {
+		m = m.Merge(existing)
+	}
+	ret.nodes[m.ID] = m
+	ret.mapChild(from, m.ID)
+}
+
 // Add m as a child of the node at id, creating a new result node in
 // the specified topology if not already there.
 func (ret *joinResults) addUnmappedChild(m report.Node, id string, topology string) {

render/render_test.go

@@ -36,8 +36,8 @@ func TestReduceRender(t *testing.T) {
 func TestMapRender1(t *testing.T) {
 	// 1. Check when we return false, the node gets filtered out
 	mapper := render.Map{
-		MapFunc: func(nodes report.Node) report.Nodes {
-			return report.Nodes{}
+		MapFunc: func(nodes report.Node) report.Node {
+			return report.Node{}
 		},
 		Renderer: mockRenderer{Nodes: report.Nodes{
 			"foo": report.MakeNode("foo"),
@@ -53,10 +53,8 @@ func TestMapRender1(t *testing.T) {
 func TestMapRender2(t *testing.T) {
 	// 2. Check we can remap two nodes into one
 	mapper := render.Map{
-		MapFunc: func(nodes report.Node) report.Nodes {
-			return report.Nodes{
-				"bar": report.MakeNode("bar"),
-			}
+		MapFunc: func(nodes report.Node) report.Node {
+			return report.MakeNode("bar")
 		},
 		Renderer: mockRenderer{Nodes: report.Nodes{
 			"foo": report.MakeNode("foo"),
@@ -75,9 +73,9 @@ func TestMapRender2(t *testing.T) {
 func TestMapRender3(t *testing.T) {
 	// 3. Check we can remap adjacencies
 	mapper := render.Map{
-		MapFunc: func(nodes report.Node) report.Nodes {
+		MapFunc: func(nodes report.Node) report.Node {
 			id := "_" + nodes.ID
-			return report.Nodes{id: report.MakeNode(id)}
+			return report.MakeNode(id)
 		},
 		Renderer: mockRenderer{Nodes: report.Nodes{
 			"foo": report.MakeNode("foo").WithAdjacent("baz"),

render/weave.go

@@ -14,10 +14,10 @@ var WeaveRenderer = MakeMap(
 )
 
 // MapWeaveIdentity maps an overlay topology node to a weave topology node.
-func MapWeaveIdentity(m report.Node) report.Nodes {
+func MapWeaveIdentity(m report.Node) report.Node {
 	peerPrefix, _ := report.ParseOverlayNodeID(m.ID)
 	if peerPrefix != report.WeaveOverlayPeerPrefix {
-		return nil
+		return report.Node{}
 	}
 
 	var (
@@ -33,5 +33,5 @@ func MapWeaveIdentity(m report.Node) report.Nodes {
 		node = NewDerivedPseudoNode(id, m)
 	}
 
-	return report.Nodes{node.ID: node}
+	return node
 }