From fa03a0be081ffb9a11279e91a25e0ecbe2c8afce Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Sat, 11 Nov 2017 14:19:46 +0000
Subject: [PATCH] Rewrite MapX2Host as a RenderFunc using joinResults

It's more efficient as many input Nodes map onto a few hosts.
---
 render/host.go | 56 ++++++++++++++++++--------------------------------
 1 file changed, 20 insertions(+), 36 deletions(-)

diff --git a/render/host.go b/render/host.go
index 19e1fb6a1..ec50dc03e 100644
--- a/render/host.go
+++ b/render/host.go
@@ -10,26 +10,14 @@ import (
 // not memoised
 var HostRenderer = MakeReduce(
 	endpoints2Hosts{},
-	MakeMap(
-		MapX2Host,
-		ColorConnectedProcessRenderer,
-	),
-	MakeMap(
-		MapX2Host,
-		ContainerRenderer,
-	),
-	MakeMap(
-		MapX2Host,
-		ContainerImageRenderer,
-	),
-	MakeMap(
-		MapX2Host,
-		PodRenderer,
-	),
+	CustomRenderer{RenderFunc: nodes2Hosts, Renderer: ColorConnectedProcessRenderer},
+	CustomRenderer{RenderFunc: nodes2Hosts, Renderer: ContainerRenderer},
+	CustomRenderer{RenderFunc: nodes2Hosts, Renderer: ContainerImageRenderer},
+	CustomRenderer{RenderFunc: nodes2Hosts, Renderer: PodRenderer},
 	SelectHost,
 )
 
-// MapX2Host maps any Nodes to host Nodes.
+// nodes2Hosts maps any Nodes to host Nodes.
 //
 // If this function is given a node without a hostname
 // (including other pseudo nodes), it will drop the node.
@@ -38,27 +26,23 @@ var HostRenderer = MakeReduce(
 // format for a host, 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 host graph to get that info.
-func MapX2Host(n report.Node, _ report.Networks) report.Nodes {
-	// Don't propagate pseudo nodes - we do this in MapEndpoint2Host
-	if n.Topology == Pseudo {
-		return report.Nodes{}
-	}
+func nodes2Hosts(nodes Nodes) Nodes {
+	ret := newJoinResults()
 
-	hostIDs, ok := n.Parents.Lookup(report.Host)
-	if !ok {
-		return report.Nodes{}
+	for _, n := range nodes.Nodes {
+		if n.Topology == Pseudo {
+			continue // Don't propagate pseudo nodes - we do this in MapEndpoint2Host
+		} else {
+			hostIDs, _ := n.Parents.Lookup(report.Host)
+			for _, id := range hostIDs {
+				ret.addToResults(n, id, false, func(id string) report.Node {
+					return report.MakeNode(id).WithTopology(report.Host)
+				}, n.Topology)
+			}
+		}
 	}
-
-	result := report.Nodes{}
-	children := report.MakeNodeSet(n)
-	for _, id := range hostIDs {
-		node := NewDerivedNode(id, n).WithTopology(report.Host)
-		node.Counters = node.Counters.Add(n.Topology, 1)
-		node.Children = children
-		result[id] = node
-	}
-
-	return result
+	ret.fixupAdjacencies(nodes)
+	return ret.result()
 }
 
 // endpoints2Hosts takes nodes from the endpoint topology and produces