AddParent() function to optimise the case where there is only one parent

Avoids creating and discarding a StringSet just to carry the
parameters, and makes the code more readable too.

probe/awsecs/reporter.go

@@ -187,7 +187,7 @@ func (r Reporter) Tag(rpt report.Report) (report.Report, error) {
 				serviceID := report.MakeECSServiceNodeID(cluster, serviceName)
 				parentsSets = parentsSets.AddString(report.ECSService, serviceID)
 				// in addition, make service parent of task
-				rpt.ECSTask.Nodes[taskID] = rpt.ECSTask.Nodes[taskID].WithParents(report.MakeSets().Add(report.ECSService, report.MakeStringSet(serviceID)))
+				rpt.ECSTask.Nodes[taskID] = rpt.ECSTask.Nodes[taskID].WithParent(report.ECSService, serviceID)
 			}
 			for _, containerID := range info.ContainerIDs {
 				if containerNode, ok := rpt.Container.Nodes[containerID]; ok {

probe/docker/container.go

@@ -407,9 +407,7 @@ func (c *container) getBaseNode() report.Node {
 		ContainerCommand:  c.getSanitizedCommand(),
 		ImageID:           c.Image(),
 		ContainerHostname: c.Hostname(),
-	}).WithParents(report.MakeSets().
-		Add(report.ContainerImage, report.MakeStringSet(report.MakeContainerImageNodeID(c.Image()))),
-	)
+	}).WithParent(report.ContainerImage, report.MakeContainerImageNodeID(c.Image()))
 	result = result.AddPrefixPropertyList(LabelPrefix, c.container.Config.Labels)
 	if !c.noEnvironmentVariables {
 		result = result.AddPrefixPropertyList(EnvPrefix, c.env())

probe/docker/tagger.go

@@ -74,7 +74,7 @@ func (t *Tagger) Tag(r report.Report) (report.Report, error) {
 		})
 		r.SwarmService.AddNode(node)
 
-		r.Container.Nodes[containerID] = container.WithParents(container.Parents.Add(report.SwarmService, report.MakeStringSet(nodeID)))
+		r.Container.Nodes[containerID] = container.WithParent(report.SwarmService, nodeID)
 	}
 
 	return r, nil
@@ -116,17 +116,13 @@ func (t *Tagger) tag(tree process.Tree, topology *report.Topology) {
 		}
 
 		node = node.WithLatest(ContainerID, mtime.Now(), c.ID())
-		node = node.WithParents(report.MakeSets().
-			Add(report.Container, report.MakeStringSet(report.MakeContainerNodeID(c.ID()))),
-		)
+		node = node.WithParent(report.Container, report.MakeContainerNodeID(c.ID()))
 
 		// If we can work out the image name, add a parent tag for it
 		image, ok := t.registry.GetContainerImage(c.Image())
 		if ok && len(image.RepoTags) > 0 {
 			imageName := ImageNameWithoutTag(image.RepoTags[0])
-			node = node.WithParents(report.MakeSets().
-				Add(report.ContainerImage, report.MakeStringSet(report.MakeContainerImageNodeID(imageName))),
-			)
+			node = node.WithParent(report.ContainerImage, report.MakeContainerImageNodeID(imageName))
 		}
 
 		topology.ReplaceNode(node)

probe/host/tagger.go

@@ -26,14 +26,13 @@ func (Tagger) Name() string { return "Host" }
 func (t Tagger) Tag(r report.Report) (report.Report, error) {
 	var (
 		metadata = map[string]string{report.HostNodeID: t.hostNodeID}
-		parents  = report.MakeSets().Add(report.Host, report.MakeStringSet(t.hostNodeID))
 	)
 
 	// Explicitly don't tag Endpoints, Addresses and Overlay nodes - These topologies include pseudo nodes,
 	// and as such do their own host tagging.
 	for _, topology := range []report.Topology{r.Process, r.Container, r.ContainerImage, r.Host, r.Pod} {
 		for _, node := range topology.Nodes {
-			topology.ReplaceNode(node.WithLatests(metadata).WithParents(parents))
+			topology.ReplaceNode(node.WithLatests(metadata).WithParent(report.Host, t.hostNodeID))
 		}
 	}
 	return r, nil

probe/kubernetes/reporter.go

@@ -249,10 +249,7 @@ func (r *Reporter) Tag(rpt report.Report) (report.Report, error) {
 			n = n.WithLatest(report.DoesNotMakeConnections, mtime.Now(), "")
 		}
 
-		rpt.Container.Nodes[id] = n.WithParents(report.MakeSets().Add(
-			report.Pod,
-			report.MakeStringSet(report.MakePodNodeID(uid)),
-		))
+		rpt.Container.Nodes[id] = n.WithParent(report.Pod, report.MakePodNodeID(uid))
 	}
 	return rpt, nil
 }

probe/overlay/weave.go

@@ -330,7 +330,7 @@ func (w *Weave) addCurrentPeerInfo(latests map[string]string, node report.Node)
 		latests[WeavePluginDriver] = w.statusCache.Plugin.DriverName
 	}
 	node = node.AddPrefixMulticolumnTable(WeaveConnectionsMulticolumnTablePrefix, getConnectionsTable(w.statusCache.Router))
-	node = node.WithParents(report.MakeSets().Add(report.Host, report.MakeStringSet(w.hostID)))
+	node = node.WithParent(report.Host, w.hostID)
 
 	return latests, node
 }