Merge pull request #135580 from serathius/client-go-transformer

Embed proper interface in TransformingStore to ensure DeltaFIFO and RealFIFO are implementing it

Kubernetes-commit: 04e8064bccebd04981ee0094457550c9de4f92e3

go.mod

@@ -24,8 +24,8 @@ require (
 	golang.org/x/time v0.9.0
 	google.golang.org/protobuf v1.36.8
 	gopkg.in/evanphx/json-patch.v4 v4.13.0
-	k8s.io/api v0.0.0
-	k8s.io/apimachinery v0.0.0
+	k8s.io/api v0.0.0-20251204222945-bbcbaa8f8665
+	k8s.io/apimachinery v0.0.0-20251204222403-72d71eac265e
 	k8s.io/klog/v2 v2.130.1
 	k8s.io/kube-openapi v0.0.0-20250910181357-589584f1c912
 	k8s.io/utils v0.0.0-20251002143259-bc988d571ff4
@@ -62,8 +62,3 @@ require (
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
-
-replace (
-	k8s.io/api => ../api
-	k8s.io/apimachinery => ../apimachinery
-)

go.sum

@@ -1,10 +1,7 @@
-cloud.google.com/go/compute/metadata v0.3.0/go.mod h1:zFmK7XCadkQkj6TtorcaGlCW1hT1fIilQDwofLpJ20k=
 github.com/Masterminds/semver/v3 v3.4.0 h1:Zog+i5UMtVoCU8oKka5P7i9q9HgrJeGzI9SA1Xbatp0=
 github.com/Masterminds/semver/v3 v3.4.0/go.mod h1:4V+yj/TJE1HU9XfppCwVMZq3I84lprf4nC11bSS5beM=
-github.com/NYTimes/gziphandler v1.1.1/go.mod h1:n/CVRwUEOgIxrgPvAQhUUr9oeUtvrhMomdKFjzJNB0c=
 github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5 h1:0CwZNZbxp69SHPdPJAN/hZIm0C4OItdklCFmMRWYpio=
 github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5/go.mod h1:wHh0iHkYZB8zMSxRWpUBQtwG5a7fFgvEO+odwuTv2gs=
-github.com/chzyer/readline v1.5.1/go.mod h1:Eh+b79XXUwfKfcPLepksvw2tcLE/Ct21YObkaSkeBlk=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
@@ -25,7 +22,6 @@ github.com/go-openapi/swag v0.23.0 h1:vsEVJDUo2hPJ2tu0/Xc+4noaxyEffXNIs3cOULZ+Gr
 github.com/go-openapi/swag v0.23.0/go.mod h1:esZ8ITTYEsH1V2trKHjAN8Ai7xHb8RV+YSZ577vPjgQ=
 github.com/go-task/slim-sprig/v3 v3.0.0 h1:sUs3vkvUymDpBKi3qH1YSqBQk9+9D/8M2mN1vB6EwHI=
 github.com/go-task/slim-sprig/v3 v3.0.0/go.mod h1:W848ghGpv3Qj3dhTPRyJypKRiqCdHZiAzKg9hl15HA8=
-github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
 github.com/google/btree v1.1.3 h1:CVpQJjYgC4VbzxeGVHfvZrv1ctoYCAI8vbl07Fcxlyg=
 github.com/google/btree v1.1.3/go.mod h1:qOPhT0dTNdNzV6Z/lhRX0YXUafgPLFUh+gZMl761Gm4=
 github.com/google/gnostic-models v0.7.0 h1:qwTtogB15McXDaNqTZdzPJRHvaVJlAl+HVQnLmJEJxo=
@@ -41,7 +37,6 @@ github.com/gorilla/websocket v1.5.4-0.20250319132907-e064f32e3674 h1:JeSE6pjso5T
 github.com/gorilla/websocket v1.5.4-0.20250319132907-e064f32e3674/go.mod h1:r4w70xmWCQKmi1ONH4KIaBptdivuRPyosB9RmPlGEwA=
 github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79 h1:+ngKgrYPPJrOjhax5N+uePQ0Fh1Z7PheYoUI/0nzkPA=
 github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79/go.mod h1:FecbI9+v66THATjSRHfNgh1IVFe/9kFxbXtjV0ctIMA=
-github.com/ianlancetaylor/demangle v0.0.0-20240312041847-bd984b5ce465/go.mod h1:gx7rwoVhcfuVKG5uya9Hs3Sxj7EIvldVofAWIUtGouw=
 github.com/josharian/intern v1.0.0 h1:vlS4z54oSdjm0bgjRigI+G1HpF+tI+9rE5LLzOg8HmY=
 github.com/josharian/intern v1.0.0/go.mod h1:5DoeVV0s6jJacbCEi61lwdGj/aVlrQvzHFFd8Hwg//Y=
 github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
@@ -98,7 +93,6 @@ go.yaml.in/yaml/v2 v2.4.3 h1:6gvOSjQoTB3vt1l+CU+tSyi/HOjfOjRLJ4YwYZGwRO0=
 go.yaml.in/yaml/v2 v2.4.3/go.mod h1:zSxWcmIDjOzPXpjlTTbAsKokqkDNAVtZO0WOMiT90s8=
 go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
-golang.org/x/crypto v0.44.0/go.mod h1:013i+Nw79BMiQiMsOPcVCB5ZIJbYkerPrGnOa00tvmc=
 golang.org/x/mod v0.29.0 h1:HV8lRxZC4l2cr3Zq1LvtOsi/ThTgWnUk/y64QSs8GwA=
 golang.org/x/mod v0.29.0/go.mod h1:NyhrlYXJ2H4eJiRy/WDBO6HMqZQ6q9nk4JzS3NuCK+w=
 golang.org/x/net v0.47.0 h1:Mx+4dIFzqraBXUugkia1OOvlD6LemFo1ALMHjrXDOhY=
@@ -117,9 +111,6 @@ golang.org/x/time v0.9.0 h1:EsRrnYcQiGH+5FfbgvV4AP7qEZstoyrHB0DzarOQ4ZY=
 golang.org/x/time v0.9.0/go.mod h1:3BpzKBy/shNhVucY/MWOyx10tF3SFh9QdLuxbVysPQM=
 golang.org/x/tools v0.38.0 h1:Hx2Xv8hISq8Lm16jvBZ2VQf+RLmbd7wVUsALibYI/IQ=
 golang.org/x/tools v0.38.0/go.mod h1:yEsQ/d/YK8cjh0L6rZlY8tgtlKiBNTL14pGDJPJpYQs=
-golang.org/x/tools/go/expect v0.1.0-deprecated/go.mod h1:eihoPOH+FgIqa3FpoTwguz/bVUSGBlGQU67vpBeOrBY=
-golang.org/x/tools/go/packages/packagestest v0.1.1-deprecated/go.mod h1:RVAQXBGNv1ib0J382/DPCRS/BPnsGebyM1Gj5VSDpG8=
-golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/protobuf v1.36.8 h1:xHScyCOEuuwZEc6UtSOvPbAT4zRh0xcNRYekJwfqyMc=
 google.golang.org/protobuf v1.36.8/go.mod h1:fuxRtAxBytpl4zzqUh6/eyUujkJdNiuEkXntxiD/uRU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
@@ -132,7 +123,10 @@ gopkg.in/inf.v0 v0.9.1/go.mod h1:cWUDdTG/fYaXco+Dcufb5Vnc6Gp2YChqWtbxRZE0mXw=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-k8s.io/gengo/v2 v2.0.0-20250604051438-85fd79dbfd9f/go.mod h1:EJykeLsmFC60UQbYJezXkEsG2FLrt0GPNkU5iK5GWxU=
+k8s.io/api v0.0.0-20251204222945-bbcbaa8f8665 h1:yCdvBpHA4R+NYVHh6B+ZWOmN0FhnqP1uGX9oNLhDWLw=
+k8s.io/api v0.0.0-20251204222945-bbcbaa8f8665/go.mod h1:etlr1bA5uFLXrSHE4hq3fjX6JCVC4aD10YGu8kktjJM=
+k8s.io/apimachinery v0.0.0-20251204222403-72d71eac265e h1:j68TlPomsB5ecepACqUXTMgiob1Hmx4N+VTd+jzORI8=
+k8s.io/apimachinery v0.0.0-20251204222403-72d71eac265e/go.mod h1:jQCgFZFR1F4Ik7hvr2g84RTJSZegBc8yHgFWKn//hns=
 k8s.io/klog/v2 v2.130.1 h1:n9Xl7H1Xvksem4KFG4PYbdQCQxqc/tTUyrgXaOhHSzk=
 k8s.io/klog/v2 v2.130.1/go.mod h1:3Jpz1GvMt720eyJH1ckRHK1EDfpxISzJ7I9OYgaDtPE=
 k8s.io/kube-openapi v0.0.0-20250910181357-589584f1c912 h1:Y3gxNAuB0OBLImH611+UDZcmKS3g6CthxToOb37KgwE=

tools/cache/controller.go

@@ -708,20 +708,7 @@ func newInformer(clientState Store, options InformerOptions) Controller {
 	// KeyLister, that way resync operations will result in the correct set
 	// of update/delete deltas.
 
-	var fifo Queue
-	if clientgofeaturegate.FeatureGates().Enabled(clientgofeaturegate.InOrderInformers) {
-		fifo = NewRealFIFOWithOptions(RealFIFOOptions{
-			KeyFunction:  MetaNamespaceKeyFunc,
-			KnownObjects: clientState,
-			Transformer:  options.Transform,
-		})
-	} else {
-		fifo = NewDeltaFIFOWithOptions(DeltaFIFOOptions{
-			KnownObjects:          clientState,
-			EmitDeltaTypeReplaced: true,
-			Transformer:           options.Transform,
-		})
-	}
+	fifo := newQueueFIFO(clientState, options.Transform)
 
 	cfg := &Config{
 		Queue:            fifo,
@@ -742,3 +729,19 @@ func newInformer(clientState Store, options InformerOptions) Controller {
 	}
 	return New(cfg)
 }
+
+func newQueueFIFO(clientState Store, transform TransformFunc) Queue {
+	if clientgofeaturegate.FeatureGates().Enabled(clientgofeaturegate.InOrderInformers) {
+		return NewRealFIFOWithOptions(RealFIFOOptions{
+			KeyFunction:  MetaNamespaceKeyFunc,
+			KnownObjects: clientState,
+			Transformer:  transform,
+		})
+	} else {
+		return NewDeltaFIFOWithOptions(DeltaFIFOOptions{
+			KnownObjects:          clientState,
+			EmitDeltaTypeReplaced: true,
+			Transformer:           transform,
+		})
+	}
+}

tools/cache/delta_fifo.go

@@ -270,7 +270,8 @@ func NewDeltaFIFOWithOptions(opts DeltaFIFOOptions) *DeltaFIFO {
 }
 
 var (
-	_ = Queue(&DeltaFIFO{}) // DeltaFIFO is a Queue
+	_ = Queue(&DeltaFIFO{})             // DeltaFIFO is a Queue
+	_ = TransformingStore(&DeltaFIFO{}) // DeltaFIFO implements TransformingStore to allow memory optimizations
 )
 
 var (

tools/cache/delta_fifo_test.go

@@ -28,7 +28,7 @@ import (
 // from the most recent Delta.
 // You should treat the items returned inside the deltas as immutable.
 // This function was moved here because it is not consistent with normal list semantics, but is used in unit testing.
-func (f *DeltaFIFO) List() []interface{} {
+func (f *DeltaFIFO) list() []interface{} {
 	f.lock.RLock()
 	defer f.lock.RUnlock()
 	return f.listLocked()
@@ -46,7 +46,7 @@ func (f *DeltaFIFO) listLocked() []interface{} {
 // ListKeys returns a list of all the keys of the objects currently
 // in the FIFO.
 // This function was moved here because it is not consistent with normal list semantics, but is used in unit testing.
-func (f *DeltaFIFO) ListKeys() []string {
+func (f *DeltaFIFO) listKeys() []string {
 	f.lock.RLock()
 	defer f.lock.RUnlock()
 	list := make([]string, 0, len(f.queue))
@@ -60,19 +60,19 @@ func (f *DeltaFIFO) ListKeys() []string {
 // or sets exists=false.
 // You should treat the items returned inside the deltas as immutable.
 // This function was moved here because it is not consistent with normal list semantics, but is used in unit testing.
-func (f *DeltaFIFO) Get(obj interface{}) (item interface{}, exists bool, err error) {
+func (f *DeltaFIFO) get(obj interface{}) (item interface{}, exists bool, err error) {
 	key, err := f.KeyOf(obj)
 	if err != nil {
 		return nil, false, KeyError{obj, err}
 	}
-	return f.GetByKey(key)
+	return f.getByKey(key)
 }
 
 // GetByKey returns the complete list of deltas for the requested item,
 // setting exists=false if that list is empty.
 // You should treat the items returned inside the deltas as immutable.
 // This function was moved here because it is not consistent with normal list semantics, but is used in unit testing.
-func (f *DeltaFIFO) GetByKey(key string) (item interface{}, exists bool, err error) {
+func (f *DeltaFIFO) getByKey(key string) (item interface{}, exists bool, err error) {
 	f.lock.RLock()
 	defer f.lock.RUnlock()
 	d, exists := f.items[key]
@@ -320,10 +320,10 @@ func TestDeltaFIFO_addUpdate(t *testing.T) {
 	f.Update(mkFifoObj("foo", 12))
 	f.Delete(mkFifoObj("foo", 15))
 
-	if e, a := []interface{}{mkFifoObj("foo", 15)}, f.List(); !reflect.DeepEqual(e, a) {
+	if e, a := []interface{}{mkFifoObj("foo", 15)}, f.list(); !reflect.DeepEqual(e, a) {
 		t.Errorf("Expected %+v, got %+v", e, a)
 	}
-	if e, a := []string{"foo"}, f.ListKeys(); !reflect.DeepEqual(e, a) {
+	if e, a := []string{"foo"}, f.listKeys(); !reflect.DeepEqual(e, a) {
 		t.Errorf("Expected %+v, got %+v", e, a)
 	}
 
@@ -349,7 +349,7 @@ func TestDeltaFIFO_addUpdate(t *testing.T) {
 		t.Errorf("Got second value %v", unexpected.val)
 	case <-time.After(50 * time.Millisecond):
 	}
-	_, exists, _ := f.Get(mkFifoObj("foo", ""))
+	_, exists, _ := f.get(mkFifoObj("foo", ""))
 	if exists {
 		t.Errorf("item did not get removed")
 	}
@@ -397,7 +397,7 @@ func TestDeltaFIFO_transformer(t *testing.T) {
 	must(f.Replace([]interface{}{}, ""))
 
 	// Should be empty
-	if e, a := []string{"foo", "bar"}, f.ListKeys(); !reflect.DeepEqual(e, a) {
+	if e, a := []string{"foo", "bar"}, f.listKeys(); !reflect.DeepEqual(e, a) {
 		t.Errorf("Expected %+v, got %+v", e, a)
 	}
 
@@ -507,7 +507,7 @@ func TestDeltaFIFO_addReplace(t *testing.T) {
 		t.Errorf("Got second value %v", unexpected.val)
 	case <-time.After(50 * time.Millisecond):
 	}
-	_, exists, _ := f.Get(mkFifoObj("foo", ""))
+	_, exists, _ := f.get(mkFifoObj("foo", ""))
 	if exists {
 		t.Errorf("item did not get removed")
 	}
@@ -991,7 +991,7 @@ func BenchmarkDeltaFIFOListKeys(b *testing.B) {
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
-			_ = f.ListKeys()
+			_ = f.listKeys()
 		}
 	})
 	b.StopTimer()

tools/cache/reflector.go

@@ -79,7 +79,7 @@ type ReflectorStore interface {
 // TransformingStore is an optional interface that can be implemented by the provided store.
 // If implemented on the provided store reflector will use the same transformer in its internal stores.
 type TransformingStore interface {
-	Store
+	ReflectorStore
 	Transformer() TransformFunc
 }
 
@@ -733,9 +733,11 @@ func (r *Reflector) watchList(ctx context.Context) (watch.Interface, error) {
 		return false
 	}
 
+	var transformer TransformFunc
 	storeOpts := []StoreOption{}
 	if tr, ok := r.store.(TransformingStore); ok && tr.Transformer() != nil {
-		storeOpts = append(storeOpts, WithTransformer(tr.Transformer()))
+		transformer = tr.Transformer()
+		storeOpts = append(storeOpts, WithTransformer(transformer))
 	}
 
 	initTrace := trace.New("Reflector WatchList", trace.Field{Key: "name", Value: r.name})
@@ -795,7 +797,7 @@ func (r *Reflector) watchList(ctx context.Context) (watch.Interface, error) {
 	// we utilize the temporaryStore to ensure independence from the current store implementation.
 	// as of today, the store is implemented as a queue and will be drained by the higher-level
 	// component as soon as it finishes replacing the content.
-	checkWatchListDataConsistencyIfRequested(ctx, r.name, resourceVersion, r.listerWatcher.ListWithContext, temporaryStore.List)
+	checkWatchListDataConsistencyIfRequested(ctx, r.name, resourceVersion, r.listerWatcher.ListWithContext, transformer, temporaryStore.List)
 
 	if err := r.store.Replace(temporaryStore.List(), resourceVersion); err != nil {
 		return nil, fmt.Errorf("unable to sync watch-list result: %w", err)

tools/cache/reflector_data_consistency_detector.go

@@ -33,11 +33,11 @@ import (
 //
 // Note that this function will panic when data inconsistency is detected.
 // This is intentional because we want to catch it in the CI.
-func checkWatchListDataConsistencyIfRequested[T runtime.Object, U any](ctx context.Context, identity string, lastSyncedResourceVersion string, listFn consistencydetector.ListFunc[T], retrieveItemsFn consistencydetector.RetrieveItemsFunc[U]) {
+func checkWatchListDataConsistencyIfRequested[T runtime.Object, U any](ctx context.Context, identity string, lastSyncedResourceVersion string, listFn consistencydetector.ListFunc[T], listItemTransformFunc func(interface{}) (interface{}, error), retrieveItemsFn consistencydetector.RetrieveItemsFunc[U]) {
 	if !consistencydetector.IsDataConsistencyDetectionForWatchListEnabled() {
 		return
 	}
 	// for informers we pass an empty ListOptions because
 	// listFn might be wrapped for filtering during informer construction.
-	consistencydetector.CheckDataConsistency(ctx, identity, lastSyncedResourceVersion, listFn, metav1.ListOptions{}, retrieveItemsFn)
+	consistencydetector.CheckDataConsistency(ctx, identity, lastSyncedResourceVersion, listFn, listItemTransformFunc, metav1.ListOptions{}, retrieveItemsFn)
 }

tools/cache/reflector_data_consistency_detector_test.go

@@ -0,0 +1,114 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cache
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/apimachinery/pkg/watch"
+	clientfeatures "k8s.io/client-go/features"
+	clientfeaturestesting "k8s.io/client-go/features/testing"
+	"k8s.io/client-go/util/consistencydetector"
+	"k8s.io/klog/v2/ktesting"
+)
+
+func TestReflectorDataConsistencyDetector(t *testing.T) {
+	clientfeaturestesting.SetFeatureDuringTest(t, clientfeatures.WatchListClient, true)
+	restore := consistencydetector.SetDataConsistencyDetectionForWatchListEnabledForTest(true)
+	defer restore()
+
+	markTransformed := func(obj interface{}) (interface{}, error) {
+		pod, ok := obj.(*v1.Pod)
+		if !ok {
+			return obj, nil
+		}
+		newPod := pod.DeepCopy()
+		if newPod.Labels == nil {
+			newPod.Labels = make(map[string]string)
+		}
+		newPod.Labels["transformed"] = "true"
+		return newPod, nil
+	}
+
+	for _, inOrder := range []bool{false, true} {
+		t.Run(fmt.Sprintf("InOrder=%v", inOrder), func(t *testing.T) {
+			clientfeaturestesting.SetFeatureDuringTest(t, clientfeatures.InOrderInformers, inOrder)
+			for _, transformerEnabled := range []bool{false, true} {
+				var transformer TransformFunc
+				if transformerEnabled {
+					transformer = markTransformed
+				}
+				t.Run(fmt.Sprintf("Transformer=%v", transformerEnabled), func(t *testing.T) {
+					runTestReflectorDataConsistencyDetector(t, transformer)
+				})
+			}
+		})
+	}
+}
+
+func runTestReflectorDataConsistencyDetector(t *testing.T, transformer TransformFunc) {
+	_, ctx := ktesting.NewTestContext(t)
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	store := NewStore(MetaNamespaceKeyFunc)
+	fifo := newQueueFIFO(store, transformer)
+
+	lw := &ListWatch{
+		ListFunc: func(options metav1.ListOptions) (runtime.Object, error) {
+			return &v1.PodList{
+				ListMeta: metav1.ListMeta{ResourceVersion: "1"},
+				Items: []v1.Pod{
+					{ObjectMeta: metav1.ObjectMeta{Name: "pod-1", ResourceVersion: "1"}},
+				},
+			}, nil
+		},
+		WatchFunc: func(options metav1.ListOptions) (watch.Interface, error) {
+			w := watch.NewFake()
+			go func() {
+				w.Add(&v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "pod-1", ResourceVersion: "1"}})
+				w.Action(watch.Bookmark, &v1.Pod{ObjectMeta: metav1.ObjectMeta{
+					Name:            "pod-1",
+					ResourceVersion: "1",
+					Annotations:     map[string]string{metav1.InitialEventsAnnotationKey: "true"},
+				}})
+			}()
+			return w, nil
+		},
+	}
+
+	r := NewReflector(lw, &v1.Pod{}, fifo, 0)
+
+	go func() {
+		_ = wait.PollUntilContextTimeout(ctx, 10*time.Millisecond, 5*time.Second, true, func(ctx context.Context) (bool, error) {
+			return r.LastSyncResourceVersion() != "", nil
+		})
+		cancel()
+	}()
+
+	err := r.ListAndWatchWithContext(ctx)
+	if err != nil {
+		t.Errorf("ListAndWatchWithContext returned error: %v", err)
+	}
+}

tools/cache/reflector_test.go

@@ -20,10 +20,12 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"maps"
 	"math/rand"
 	"net/http"
 	"reflect"
 	goruntime "runtime"
+	"slices"
 	"strconv"
 	"sync"
 	"sync/atomic"
@@ -1962,7 +1964,7 @@ func TestReflectorReplacesStoreOnUnsafeDelete(t *testing.T) {
 	s := NewFIFO(MetaNamespaceKeyFunc)
 	var replaceInvoked atomic.Int32
 	store := &fakeStore{
-		Store: s,
+		ReflectorStore: s,
 		beforeReplace: func(list []interface{}, rv string) {
 			// interested in the Replace call that happens after the Error event
 			if rv == lastExpectedRV {
@@ -2057,131 +2059,165 @@ func TestReflectorReplacesStoreOnUnsafeDelete(t *testing.T) {
 }
 
 func TestReflectorRespectStoreTransformer(t *testing.T) {
-	mkPod := func(id string, rv string) *v1.Pod {
-		return &v1.Pod{
-			ObjectMeta: metav1.ObjectMeta{Namespace: "ns", Name: id, ResourceVersion: rv},
-			Spec: v1.PodSpec{
-				Hostname: "test",
+	for name, test := range map[string]struct {
+		storeBuilder func(counter *atomic.Int32) ReflectorStore
+		items        func(rs ReflectorStore) []interface{}
+	}{
+		"real-fifo": {
+			storeBuilder: func(counter *atomic.Int32) ReflectorStore {
+				return NewRealFIFO(MetaNamespaceKeyFunc, NewStore(MetaNamespaceKeyFunc), func(i interface{}) (interface{}, error) {
+					counter.Add(1)
+					cast := i.(*v1.Pod)
+					cast.Spec.Hostname = "transformed"
+					return cast, nil
+				})
 			},
-		}
-	}
-
-	preExisting1 := mkPod("foo-1", "1")
-	preExisting2 := mkPod("foo-2", "2")
-	pod3 := mkPod("foo-3", "3")
-
-	lastExpectedRV := "3"
-	events := []watch.Event{
-		{Type: watch.Added, Object: preExisting1},
-		{Type: watch.Added, Object: preExisting2},
-		{Type: watch.Bookmark, Object: &v1.Pod{
-			ObjectMeta: metav1.ObjectMeta{
-				ResourceVersion: lastExpectedRV,
-				Annotations: map[string]string{
-					metav1.InitialEventsAnnotationKey: "true",
-				},
+			items: func(rs ReflectorStore) []interface{} {
+				store := rs.(*RealFIFO)
+				objects := make(map[string]interface{})
+				for _, item := range store.getItems() {
+					key, _ := store.keyFunc(item.Object)
+					if item.Type == Deleted {
+						delete(objects, key)
+					} else {
+						objects[key] = item.Object
+					}
+				}
+				return slices.Collect(maps.Values(objects))
 			},
-		}},
-		{Type: watch.Added, Object: pod3},
-	}
-
-	s := NewFIFO(MetaNamespaceKeyFunc)
-	var replaceInvoked atomic.Int32
-	store := &fakeStore{
-		Store: s,
-		beforeReplace: func(list []interface{}, rv string) {
-			replaceInvoked.Add(1)
-			// Only two pods are present at the point when Replace is called.
-			if len(list) != 2 {
-				t.Errorf("unexpected nb of objects: expected 2 received %d", len(list))
+		},
+		"delta-fifo": {
+			storeBuilder: func(counter *atomic.Int32) ReflectorStore {
+				return NewDeltaFIFOWithOptions(DeltaFIFOOptions{
+					KeyFunction: MetaNamespaceKeyFunc,
+					Transformer: func(i interface{}) (interface{}, error) {
+						counter.Add(1)
+						cast := i.(*v1.Pod)
+						cast.Spec.Hostname = "transformed"
+						return cast, nil
+					},
+				})
+			},
+			items: func(rs ReflectorStore) []interface{} {
+				return rs.(*DeltaFIFO).list()
+			},
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			mkPod := func(id string, rv string) *v1.Pod {
+				return &v1.Pod{
+					ObjectMeta: metav1.ObjectMeta{Namespace: "ns", Name: id, ResourceVersion: rv},
+					Spec: v1.PodSpec{
+						Hostname: "test",
+					},
+				}
 			}
-			for _, obj := range list {
-				cast := obj.(*v1.Pod)
+
+			preExisting1 := mkPod("foo-1", "1")
+			preExisting2 := mkPod("foo-2", "2")
+			pod3 := mkPod("foo-3", "3")
+
+			lastExpectedRV := "3"
+			events := []watch.Event{
+				{Type: watch.Added, Object: preExisting1},
+				{Type: watch.Added, Object: preExisting2},
+				{Type: watch.Bookmark, Object: &v1.Pod{
+					ObjectMeta: metav1.ObjectMeta{
+						ResourceVersion: lastExpectedRV,
+						Annotations: map[string]string{
+							metav1.InitialEventsAnnotationKey: "true",
+						},
+					},
+				}},
+				{Type: watch.Added, Object: pod3},
+			}
+
+			var transformerInvoked atomic.Int32
+			s := test.storeBuilder(&transformerInvoked)
+
+			var once sync.Once
+			lw := &ListWatch{
+				WatchFunc: func(metav1.ListOptions) (watch.Interface, error) {
+					fw := watch.NewFake()
+					go func() {
+						once.Do(func() {
+							for _, e := range events {
+								fw.Action(e.Type, e.Object)
+							}
+						})
+					}()
+					return fw, nil
+				},
+				// ListFunc should never be used in WatchList mode
+				ListFunc: func(metav1.ListOptions) (runtime.Object, error) {
+					return nil, errors.New("list call not expected in WatchList mode")
+				},
+			}
+
+			clientfeaturestesting.SetFeatureDuringTest(t, clientfeatures.WatchListClient, true)
+			r := NewReflector(lw, &v1.Pod{}, s, 0)
+			ctx, cancel := context.WithCancel(context.Background())
+			doneCh := make(chan struct{})
+			go func() {
+				defer close(doneCh)
+				r.RunWithContext(ctx)
+			}()
+
+			// wait for the RV to sync to the version returned by the final list
+			err := wait.PollUntilContextTimeout(context.Background(), 100*time.Millisecond, 5*time.Second, true, func(ctx context.Context) (done bool, err error) {
+				if rv := r.LastSyncResourceVersion(); rv == lastExpectedRV {
+					return true, nil
+				}
+				return false, nil
+			})
+			if err != nil {
+				t.Fatalf("reflector never caught up with expected revision: %q, err: %v", lastExpectedRV, err)
+			}
+
+			if want, got := lastExpectedRV, r.LastSyncResourceVersion(); want != got {
+				t.Errorf("expected LastSyncResourceVersion to be %q, but got: %q", want, got)
+			}
+
+			informerItems := test.items(s)
+			if want, got := 3, len(informerItems); want != got {
+				t.Errorf("expected informer to contain %d objects, but got: %d", want, got)
+			}
+			for _, item := range informerItems {
+				cast := item.(*v1.Pod)
 				if cast.Spec.Hostname != "transformed" {
 					t.Error("Object was not transformed prior to replacement")
 				}
 			}
-		},
-		afterReplace: func(rv string, err error) {},
-		transformer: func(i interface{}) (interface{}, error) {
-			cast := i.(*v1.Pod)
-			cast.Spec.Hostname = "transformed"
-			return cast, nil
-		},
-	}
 
-	var once sync.Once
-	lw := &ListWatch{
-		WatchFunc: func(metav1.ListOptions) (watch.Interface, error) {
-			fw := watch.NewFake()
-			go func() {
-				once.Do(func() {
-					for _, e := range events {
-						fw.Action(e.Type, e.Object)
-					}
-				})
-			}()
-			return fw, nil
-		},
-		// ListFunc should never be used in WatchList mode
-		ListFunc: func(metav1.ListOptions) (runtime.Object, error) {
-			return nil, errors.New("list call not expected in WatchList mode")
-		},
-	}
+			// Transformer should have been invoked twice for the initial sync in the informer on the temporary store,
+			// then twice on replace, then once on the following update.
+			if want, got := 5, int(transformerInvoked.Load()); want != got {
+				t.Errorf("expected transformer to be invoked %d times, but got: %d", want, got)
+			}
 
-	clientfeaturestesting.SetFeatureDuringTest(t, clientfeatures.WatchListClient, true)
-	r := NewReflector(lw, &v1.Pod{}, store, 0)
-	ctx, cancel := context.WithCancel(context.Background())
-	doneCh := make(chan struct{})
-	go func() {
-		defer close(doneCh)
-		r.RunWithContext(ctx)
-	}()
-
-	// wait for the RV to sync to the version returned by the final list
-	err := wait.PollUntilContextTimeout(context.Background(), 100*time.Millisecond, 5*time.Second, true, func(ctx context.Context) (done bool, err error) {
-		if rv := r.LastSyncResourceVersion(); rv == lastExpectedRV {
-			return true, nil
-		}
-		return false, nil
-	})
-	if err != nil {
-		t.Fatalf("reflector never caught up with expected revision: %q, err: %v", lastExpectedRV, err)
-	}
-
-	if want, got := lastExpectedRV, r.LastSyncResourceVersion(); want != got {
-		t.Errorf("expected LastSyncResourceVersion to be %q, but got: %q", want, got)
-	}
-	if want, got := 1, int(replaceInvoked.Load()); want != got {
-		t.Errorf("expected replace to be invoked %d times, but got: %d", want, got)
-	}
-
-	cancel()
-	select {
-	case <-doneCh:
-	case <-time.After(wait.ForeverTestTimeout):
-		t.Errorf("timed out waiting for Run to return")
+			cancel()
+			select {
+			case <-doneCh:
+			case <-time.After(wait.ForeverTestTimeout):
+				t.Errorf("timed out waiting for Run to return")
+			}
+		})
 	}
 }
 
 type fakeStore struct {
-	Store
+	ReflectorStore
 	beforeReplace func(list []interface{}, s string)
 	afterReplace  func(rv string, err error)
-	transformer   TransformFunc
 }
 
 func (f *fakeStore) Replace(list []interface{}, rv string) error {
 	f.beforeReplace(list, rv)
-	err := f.Store.Replace(list, rv)
+	err := f.ReflectorStore.Replace(list, rv)
 	f.afterReplace(rv, err)
 	return err
 }
 
-func (f *fakeStore) Transformer() TransformFunc {
-	return f.transformer
-}
-
 func BenchmarkExtractList(b *testing.B) {
 	_, _, podList := getPodListItems(0, fakeItemsNum)
 	_, _, configMapList := getConfigmapListItems(0, fakeItemsNum)

tools/cache/shared_informer.go

@@ -539,20 +539,7 @@ func (s *sharedIndexInformer) RunWithContext(ctx context.Context) {
 		s.startedLock.Lock()
 		defer s.startedLock.Unlock()
 
-		var fifo Queue
-		if clientgofeaturegate.FeatureGates().Enabled(clientgofeaturegate.InOrderInformers) {
-			fifo = NewRealFIFOWithOptions(RealFIFOOptions{
-				KeyFunction:  MetaNamespaceKeyFunc,
-				KnownObjects: s.indexer,
-				Transformer:  s.transform,
-			})
-		} else {
-			fifo = NewDeltaFIFOWithOptions(DeltaFIFOOptions{
-				KnownObjects:          s.indexer,
-				EmitDeltaTypeReplaced: true,
-				Transformer:           s.transform,
-			})
-		}
+		fifo := newQueueFIFO(s.indexer, s.transform)
 
 		cfg := &Config{
 			Queue:             fifo,

tools/cache/the_real_fifo.go

@@ -89,7 +89,8 @@ type RealFIFO struct {
 }
 
 var (
-	_ = Queue(&RealFIFO{}) // RealFIFO is a Queue
+	_ = Queue(&RealFIFO{})             // RealFIFO is a Queue
+	_ = TransformingStore(&RealFIFO{}) // RealFIFO implements TransformingStore to allow memory optimizations
 )
 
 // Close the queue.

util/consistencydetector/data_consistency_detector.go

@@ -45,16 +45,28 @@ func IsDataConsistencyDetectionForWatchListEnabled() bool {
 	return dataConsistencyDetectionForWatchListEnabled
 }
 
+// SetDataConsistencyDetectionForWatchListEnabledForTest allows to enable/disable data consistency detection for testing purposes.
+// It returns a function that restores the original value.
+func SetDataConsistencyDetectionForWatchListEnabledForTest(enabled bool) func() {
+	original := dataConsistencyDetectionForWatchListEnabled
+	dataConsistencyDetectionForWatchListEnabled = enabled
+	return func() {
+		dataConsistencyDetectionForWatchListEnabled = original
+	}
+}
+
 type RetrieveItemsFunc[U any] func() []U
 
 type ListFunc[T runtime.Object] func(ctx context.Context, options metav1.ListOptions) (T, error)
 
+type TransformFunc func(interface{}) (interface{}, error)
+
 // CheckDataConsistency exists solely for testing purposes.
 // we cannot use checkWatchListDataConsistencyIfRequested because
 // it is guarded by an environmental variable.
 // we cannot manipulate the environmental variable because
 // it will affect other tests in this package.
-func CheckDataConsistency[T runtime.Object, U any](ctx context.Context, identity string, lastSyncedResourceVersion string, listFn ListFunc[T], listOptions metav1.ListOptions, retrieveItemsFn RetrieveItemsFunc[U]) {
+func CheckDataConsistency[T runtime.Object, U any](ctx context.Context, identity string, lastSyncedResourceVersion string, listFn ListFunc[T], listItemTransformFunc TransformFunc, listOptions metav1.ListOptions, retrieveItemsFn RetrieveItemsFunc[U]) {
 	if !canFormAdditionalListCall(lastSyncedResourceVersion, listOptions) {
 		klog.V(4).Infof("data consistency check for %s is enabled but the parameters (RV, ListOptions) doesn't allow for creating a valid LIST request. Skipping the data consistency check.", identity)
 		return
@@ -84,6 +96,15 @@ func CheckDataConsistency[T runtime.Object, U any](ctx context.Context, identity
 	if err != nil {
 		panic(err) // this should never happen
 	}
+	if listItemTransformFunc != nil {
+		for i := range rawListItems {
+			obj, err := listItemTransformFunc(rawListItems[i])
+			if err != nil {
+				panic(err)
+			}
+			rawListItems[i] = obj.(runtime.Object)
+		}
+	}
 	listItems := toMetaObjectSliceOrDie(rawListItems)
 
 	sort.Sort(byUID(listItems))

util/consistencydetector/data_consistency_detector_test.go

@@ -215,10 +215,10 @@ func TestDataConsistencyChecker(t *testing.T) {
 
 			if scenario.expectPanic {
 				require.Panics(t, func() {
-					CheckDataConsistency(ctx, "", scenario.lastSyncedResourceVersion, fakeLister.List, scenario.requestOptions, retrievedItemsFunc)
+					CheckDataConsistency(ctx, "", scenario.lastSyncedResourceVersion, fakeLister.List, nil, scenario.requestOptions, retrievedItemsFunc)
 				})
 			} else {
-				CheckDataConsistency(ctx, "", scenario.lastSyncedResourceVersion, fakeLister.List, scenario.requestOptions, retrievedItemsFunc)
+				CheckDataConsistency(ctx, "", scenario.lastSyncedResourceVersion, fakeLister.List, nil, scenario.requestOptions, retrievedItemsFunc)
 			}
 
 			require.Equal(t, scenario.expectedListRequests, fakeLister.counter)
@@ -235,7 +235,7 @@ func TestDataConsistencyCheckerRetry(t *testing.T) {
 	stopListErrorAfter := 5
 	fakeErrLister := &errorLister{stopErrorAfter: stopListErrorAfter}
 
-	CheckDataConsistency(ctx, "", "", fakeErrLister.List, metav1.ListOptions{}, retrievedItemsFunc)
+	CheckDataConsistency(ctx, "", "", fakeErrLister.List, nil, metav1.ListOptions{}, retrievedItemsFunc)
 	require.Equal(t, fakeErrLister.listCounter, fakeErrLister.stopErrorAfter)
 }