From 8efa0d147bca1d08cc5a4752895ecce2c53186ba Mon Sep 17 00:00:00 2001
From: Tom Wilkie <tom.wilkie@gmail.com>
Date: Wed, 16 Dec 2015 14:14:23 +0000
Subject: [PATCH] Review feedback

---
 probe/process/walker.go      | 11 ++++-------
 probe/process/walker_test.go | 17 +++++++++--------
 render/detailed_node.go      |  2 +-
 3 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/probe/process/walker.go b/probe/process/walker.go
index 620268462..36eaa9c89 100644
--- a/probe/process/walker.go
+++ b/probe/process/walker.go
@@ -20,7 +20,7 @@ type Walker interface {
 // CachingWalker is a walker than caches a copy of the output from another
 // Walker, and then allows other concurrent readers to Walk that copy.
 type CachingWalker struct {
-	cache         []Process
+	cache         map[int]Process
 	previousByPID map[int]Process
 	cacheLock     sync.RWMutex
 	source        Walker
@@ -47,9 +47,9 @@ func (c *CachingWalker) Walk(f func(Process, Process)) error {
 
 // Tick updates cached copy of process list
 func (c *CachingWalker) Tick() error {
-	newCache := []Process{}
+	newCache := map[int]Process{}
 	err := c.source.Walk(func(p, _ Process) {
-		newCache = append(newCache, p)
+		newCache[p.PID] = p
 	})
 	if err != nil {
 		return err
@@ -57,10 +57,7 @@ func (c *CachingWalker) Tick() error {
 
 	c.cacheLock.Lock()
 	defer c.cacheLock.Unlock()
-	c.previousByPID = map[int]Process{}
-	for _, p := range c.cache {
-		c.previousByPID[p.PID] = p
-	}
+	c.previousByPID = c.cache
 	c.cache = newCache
 	return nil
 }
diff --git a/probe/process/walker_test.go b/probe/process/walker_test.go
index f12e0aa26..f5e448c0e 100644
--- a/probe/process/walker_test.go
+++ b/probe/process/walker_test.go
@@ -34,15 +34,16 @@ func TestCache(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	want, err := all(walker)
 	have, err := all(cachingWalker)
-	if err != nil || !reflect.DeepEqual(processes, have) {
-		t.Errorf("%v (%v)", test.Diff(processes, have), err)
+	if err != nil || !reflect.DeepEqual(want, have) {
+		t.Errorf("%v (%v)", test.Diff(want, have), err)
 	}
 
 	walker.processes = []process.Process{}
 	have, err = all(cachingWalker)
-	if err != nil || !reflect.DeepEqual(processes, have) {
-		t.Errorf("%v (%v)", test.Diff(processes, have), err)
+	if err != nil || !reflect.DeepEqual(want, have) {
+		t.Errorf("%v (%v)", test.Diff(want, have), err)
 	}
 
 	err = cachingWalker.Tick()
@@ -51,16 +52,16 @@ func TestCache(t *testing.T) {
 	}
 
 	have, err = all(cachingWalker)
-	want := []process.Process{}
+	want = map[process.Process]struct{}{}
 	if err != nil || !reflect.DeepEqual(want, have) {
 		t.Errorf("%v (%v)", test.Diff(want, have), err)
 	}
 }
 
-func all(w process.Walker) ([]process.Process, error) {
-	all := []process.Process{}
+func all(w process.Walker) (map[process.Process]struct{}, error) {
+	all := map[process.Process]struct{}{}
 	err := w.Walk(func(p, _ process.Process) {
-		all = append(all, p)
+		all[p] = struct{}{}
 	})
 	return all, err
 }
diff --git a/render/detailed_node.go b/render/detailed_node.go
index 26ca8c086..bd516e86e 100644
--- a/render/detailed_node.go
+++ b/render/detailed_node.go
@@ -539,7 +539,7 @@ func hostOriginTable(nmd report.Node) (Table, bool) {
 		fmt        formatter
 	}{
 		{host.CPUUsage, "CPU Usage", formatPercent},
-		{host.MemUsage, "Memory Usage", formatPercent},
+		{host.MemUsage, "Memory Usage", formatMemory},
 	} {
 		if val, ok := nmd.Metrics[tuple.key]; ok {
 			rows = append(rows, sparklineRow(tuple.human, val, tuple.fmt))