From 7508df7e5bdc4a600ebc0508a19260a142950e4a Mon Sep 17 00:00:00 2001
From: Tom Wilkie <tom@weave.works>
Date: Wed, 19 Aug 2015 14:24:21 +0000
Subject: [PATCH] Add NodeMetadata.Counters with appropriate merge semantics

---
 app/api_topology_test.go |  3 +++
 render/mapping.go        | 22 ++++++----------------
 report/merge.go          |  3 +++
 report/topology.go       |  5 +++++
 4 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/app/api_topology_test.go b/app/api_topology_test.go
index 0cc249faf..5f74babad 100644
--- a/app/api_topology_test.go
+++ b/app/api_topology_test.go
@@ -22,6 +22,9 @@ func fixNodeMetadatas(nodes render.RenderableNodes) render.RenderableNodes {
 		if node.NodeMetadata.Metadata == nil {
 			node.NodeMetadata.Metadata = map[string]string{}
 		}
+		if node.NodeMetadata.Counters == nil {
+			node.NodeMetadata.Counters = map[string]int{}
+		}
 		result[id] = node
 	}
 	return result
diff --git a/render/mapping.go b/render/mapping.go
index faec5173e..7c76fedaa 100644
--- a/render/mapping.go
+++ b/render/mapping.go
@@ -20,8 +20,8 @@ const (
 	TheInternetID    = "theinternet"
 	TheInternetMajor = "The Internet"
 
-	containersPrefix = "container-"
-	processesPrefix  = "process-"
+	containersKey = "containers"
+	processesKey  = "processes"
 )
 
 // LeafMapFunc is anything which can take an arbitrary NodeMetadata, which is
@@ -252,20 +252,10 @@ func MapProcess2Name(n RenderableNode) (RenderableNode, bool) {
 	node := newDerivedNode(name, n)
 	node.LabelMajor = name
 	node.Rank = name
-	node.NodeMetadata.Metadata[processesPrefix+n.ID] = ""
+	node.NodeMetadata.Counters[processesKey] = 1
 	return node, true
 }
 
-func countPrefix(prefix string, n RenderableNode) int {
-	count := 0
-	for key := range n.NodeMetadata.Metadata {
-		if strings.HasPrefix(key, prefix) {
-			count++
-		}
-	}
-	return count
-}
-
 // MapCountProcessName maps 1:1 process name nodes, counting
 // the number of processes grouped together and putting
 // that info in the minor label.
@@ -274,7 +264,7 @@ func MapCountProcessName(n RenderableNode) (RenderableNode, bool) {
 		return n, true
 	}
 
-	processes := countPrefix(processesPrefix, n)
+	processes := n.NodeMetadata.Counters[processesKey]
 	if processes == 1 {
 		n.LabelMinor = "1 process"
 	} else {
@@ -309,7 +299,7 @@ func MapContainer2ContainerImage(n RenderableNode) (RenderableNode, bool) {
 
 	// Add container-<id> key to NMD, which will later be counted to produce the minor label
 	result := newDerivedNode(id, n)
-	result.NodeMetadata.Metadata[containersPrefix+n.ID] = ""
+	result.NodeMetadata.Counters[containersKey] = 1
 	return result, true
 }
 
@@ -349,7 +339,7 @@ func MapCountContainers(n RenderableNode) (RenderableNode, bool) {
 		return n, true
 	}
 
-	containers := countPrefix(containersPrefix, n)
+	containers := n.NodeMetadata.Counters[containersKey]
 	if containers == 1 {
 		n.LabelMinor = "1 container"
 	} else {
diff --git a/report/merge.go b/report/merge.go
index 406abe6ce..223ffa433 100644
--- a/report/merge.go
+++ b/report/merge.go
@@ -48,6 +48,9 @@ func (nm NodeMetadata) Merge(other NodeMetadata) NodeMetadata {
 	for k, v := range other.Metadata {
 		nm.Metadata[k] = v // other takes precedence
 	}
+	for k, v := range other.Counters {
+		nm.Counters[k] = nm.Counters[k] + v
+	}
 	return nm
 }
 
diff --git a/report/topology.go b/report/topology.go
index 2ca9b3e0a..8ad4b1393 100644
--- a/report/topology.go
+++ b/report/topology.go
@@ -42,6 +42,7 @@ type EdgeMetadata struct {
 // about a given node in a given topology.
 type NodeMetadata struct {
 	Metadata map[string]string
+	Counters map[string]int
 }
 
 // MakeNodeMetadata creates a new NodeMetadata with no initial metadata.
@@ -53,6 +54,7 @@ func MakeNodeMetadata() NodeMetadata {
 func MakeNodeMetadataWith(m map[string]string) NodeMetadata {
 	return NodeMetadata{
 		Metadata: m,
+		Counters: map[string]int{},
 	}
 }
 
@@ -62,6 +64,9 @@ func (nm NodeMetadata) Copy() NodeMetadata {
 	for k, v := range nm.Metadata {
 		cp.Metadata[k] = v
 	}
+	for k, v := range nm.Counters {
+		cp.Counters[k] = v
+	}
 	return cp
 }