Improve fake clientset performance

The fake clientset used a slice to store each kind of objects, it's
quite slow to init the clientset with massive objects because it checked
existence of an object by traversing all objects before adding it, which
leads to O(n^2) time complexity. Also, the Create, Update, Get, Delete
methods needs to traverse all objects, which affects the time statistic
of code that calls them.

This patch changed to use a map to store each kind of objects, reduced
the time complexity of initializing clientset to O(n) and the Create,
Update, Get, Delete to O(1).

For example:
Before this patch, it took ~29s to init a clientset with 30000 Pods,
and 2~4ms to create and get an Pod.
After this patch, it took ~50ms to init a clientset with 30000 Pods,
and tens of µs to create and get an Pod.

Author: tnqn

staging/src/k8s.io/client-go/dynamic/fake/simple_test.go

@@ -75,9 +75,9 @@ func TestList(t *testing.T) {
 	}
 
 	expected := []unstructured.Unstructured{
-		*newUnstructured("group/version", "TheKind", "ns-foo", "name-foo"),
 		*newUnstructured("group/version", "TheKind", "ns-foo", "name-bar"),
 		*newUnstructured("group/version", "TheKind", "ns-foo", "name-baz"),
+		*newUnstructured("group/version", "TheKind", "ns-foo", "name-foo"),
 	}
 	if !equality.Semantic.DeepEqual(listFirst.Items, expected) {
 		t.Fatal(diff.ObjectGoPrintDiff(expected, listFirst.Items))

staging/src/k8s.io/client-go/metadata/fake/simple_test.go

@@ -79,9 +79,9 @@ func TestList(t *testing.T) {
 	}
 
 	expected := []metav1.PartialObjectMetadata{
-		*newPartialObjectMetadata("group/version", "TheKind", "ns-foo", "name-foo"),
 		*newPartialObjectMetadata("group/version", "TheKind", "ns-foo", "name-bar"),
 		*newPartialObjectMetadata("group/version", "TheKind", "ns-foo", "name-baz"),
+		*newPartialObjectMetadata("group/version", "TheKind", "ns-foo", "name-foo"),
 	}
 	if !equality.Semantic.DeepEqual(listFirst.Items, expected) {
 		t.Fatal(diff.ObjectGoPrintDiff(expected, listFirst.Items))

staging/src/k8s.io/client-go/testing/fixture.go

@@ -19,6 +19,7 @@ package testing
 import (
 	"fmt"
 	"reflect"
+	"sort"
 	"sync"
 
 	jsonpatch "github.com/evanphx/json-patch"
@@ -197,7 +198,7 @@ type tracker struct {
 	scheme  ObjectScheme
 	decoder runtime.Decoder
 	lock    sync.RWMutex
-	objects map[schema.GroupVersionResource][]runtime.Object
+	objects map[schema.GroupVersionResource]map[types.NamespacedName]runtime.Object
 	// The value type of watchers is a map of which the key is either a namespace or
 	// all/non namespace aka "" and its value is list of fake watchers.
 	// Manipulations on resources will broadcast the notification events into the
@@ -214,7 +215,7 @@ func NewObjectTracker(scheme ObjectScheme, decoder runtime.Decoder) ObjectTracke
 	return &tracker{
 		scheme:   scheme,
 		decoder:  decoder,
-		objects:  make(map[schema.GroupVersionResource][]runtime.Object),
+		objects:  make(map[schema.GroupVersionResource]map[types.NamespacedName]runtime.Object),
 		watchers: make(map[schema.GroupVersionResource]map[string][]*watch.RaceFreeFakeWatcher),
 	}
 }
@@ -282,31 +283,15 @@ func (t *tracker) Get(gvr schema.GroupVersionResource, ns, name string) (runtime
 		return nil, errNotFound
 	}
 
-	var matchingObjs []runtime.Object
-	for _, obj := range objs {
-		acc, err := meta.Accessor(obj)
-		if err != nil {
-			return nil, err
-		}
-		if acc.GetNamespace() != ns {
-			continue
-		}
-		if acc.GetName() != name {
-			continue
-		}
-		matchingObjs = append(matchingObjs, obj)
-	}
-	if len(matchingObjs) == 0 {
+	matchingObj, ok := objs[types.NamespacedName{Namespace: ns, Name: name}]
+	if !ok {
 		return nil, errNotFound
 	}
-	if len(matchingObjs) > 1 {
-		return nil, fmt.Errorf("more than one object matched gvr %s, ns: %q name: %q", gvr, ns, name)
-	}
 
 	// Only one object should match in the tracker if it works
 	// correctly, as Add/Update methods enforce kind/namespace/name
 	// uniqueness.
-	obj := matchingObjs[0].DeepCopyObject()
+	obj := matchingObj.DeepCopyObject()
 	if status, ok := obj.(*metav1.Status); ok {
 		if status.Status != metav1.StatusSuccess {
 			return nil, &errors.StatusError{ErrStatus: *status}
@@ -405,29 +390,29 @@ func (t *tracker) add(gvr schema.GroupVersionResource, obj runtime.Object, ns st
 		return errors.NewBadRequest(msg)
 	}
 
-	for i, existingObj := range t.objects[gvr] {
-		oldMeta, err := meta.Accessor(existingObj)
-		if err != nil {
-			return err
-		}
-		if oldMeta.GetNamespace() == newMeta.GetNamespace() && oldMeta.GetName() == newMeta.GetName() {
-			if replaceExisting {
-				for _, w := range t.getWatches(gvr, ns) {
-					w.Modify(obj)
-				}
-				t.objects[gvr][i] = obj
-				return nil
+	_, ok := t.objects[gvr]
+	if !ok {
+		t.objects[gvr] = make(map[types.NamespacedName]runtime.Object)
+	}
+
+	namespacedName := types.NamespacedName{Namespace: newMeta.GetNamespace(), Name: newMeta.GetName()}
+	if _, ok = t.objects[gvr][namespacedName]; ok {
+		if replaceExisting {
+			for _, w := range t.getWatches(gvr, ns) {
+				w.Modify(obj)
 			}
-			return errors.NewAlreadyExists(gr, newMeta.GetName())
+			t.objects[gvr][namespacedName] = obj
+			return nil
 		}
+		return errors.NewAlreadyExists(gr, newMeta.GetName())
 	}
 
 	if replaceExisting {
 		// Tried to update but no matching object was found.
 		return errors.NewNotFound(gr, newMeta.GetName())
 	}
 
-	t.objects[gvr] = append(t.objects[gvr], obj)
+	t.objects[gvr][namespacedName] = obj
 
 	for _, w := range t.getWatches(gvr, ns) {
 		w.Add(obj)
@@ -457,35 +442,28 @@ func (t *tracker) Delete(gvr schema.GroupVersionResource, ns, name string) error
 	t.lock.Lock()
 	defer t.lock.Unlock()
 
-	found := false
-
-	for i, existingObj := range t.objects[gvr] {
-		objMeta, err := meta.Accessor(existingObj)
-		if err != nil {
-			return err
-		}
-		if objMeta.GetNamespace() == ns && objMeta.GetName() == name {
-			obj := t.objects[gvr][i]
-			t.objects[gvr] = append(t.objects[gvr][:i], t.objects[gvr][i+1:]...)
-			for _, w := range t.getWatches(gvr, ns) {
-				w.Delete(obj)
-			}
-			found = true
-			break
-		}
+	objs, ok := t.objects[gvr]
+	if !ok {
+		return errors.NewNotFound(gvr.GroupResource(), name)
 	}
 
-	if found {
-		return nil
+	namespacedName := types.NamespacedName{Namespace: ns, Name: name}
+	obj, ok := objs[namespacedName]
+	if !ok {
+		return errors.NewNotFound(gvr.GroupResource(), name)
 	}
 
-	return errors.NewNotFound(gvr.GroupResource(), name)
+	delete(objs, namespacedName)
+	for _, w := range t.getWatches(gvr, ns) {
+		w.Delete(obj)
+	}
+	return nil
 }
 
 // filterByNamespace returns all objects in the collection that
 // match provided namespace. Empty namespace matches
 // non-namespaced objects.
-func filterByNamespace(objs []runtime.Object, ns string) ([]runtime.Object, error) {
+func filterByNamespace(objs map[types.NamespacedName]runtime.Object, ns string) ([]runtime.Object, error) {
 	var res []runtime.Object
 
 	for _, obj := range objs {
@@ -499,6 +477,15 @@ func filterByNamespace(objs []runtime.Object, ns string) ([]runtime.Object, erro
 		res = append(res, obj)
 	}
 
+	// Sort res to get deterministic order.
+	sort.Slice(res, func(i, j int) bool {
+		acc1, _ := meta.Accessor(res[i])
+		acc2, _ := meta.Accessor(res[j])
+		if acc1.GetNamespace() != acc2.GetNamespace() {
+			return acc1.GetNamespace() < acc2.GetNamespace()
+		}
+		return acc1.GetName() < acc2.GetName()
+	})
 	return res, nil
 }