Extract watch cache store to separate file and cover with tests

staging/src/k8s.io/apiserver/pkg/storage/cacher/store.go

@@ -0,0 +1,91 @@
+/*
+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 cacher
+
+import (
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/client-go/tools/cache"
+)
+
+type storeIndexer interface {
+	Add(obj interface{}) error
+	Update(obj interface{}) error
+	Delete(obj interface{}) error
+	List() []interface{}
+	ListKeys() []string
+	Get(obj interface{}) (item interface{}, exists bool, err error)
+	GetByKey(key string) (item interface{}, exists bool, err error)
+	Replace([]interface{}, string) error
+	ByIndex(indexName, indexedValue string) ([]interface{}, error)
+}
+
+func newStoreIndexer(indexers *cache.Indexers) storeIndexer {
+	return cache.NewIndexer(storeElementKey, storeElementIndexers(indexers))
+}
+
+// Computing a key of an object is generally non-trivial (it performs
+// e.g. validation underneath). Similarly computing object fields and
+// labels. To avoid computing them multiple times (to serve the event
+// in different List/Watch requests), in the underlying store we are
+// keeping structs (key, object, labels, fields).
+type storeElement struct {
+	Key    string
+	Object runtime.Object
+	Labels labels.Set
+	Fields fields.Set
+}
+
+func storeElementKey(obj interface{}) (string, error) {
+	elem, ok := obj.(*storeElement)
+	if !ok {
+		return "", fmt.Errorf("not a storeElement: %v", obj)
+	}
+	return elem.Key, nil
+}
+
+func storeElementObject(obj interface{}) (runtime.Object, error) {
+	elem, ok := obj.(*storeElement)
+	if !ok {
+		return nil, fmt.Errorf("not a storeElement: %v", obj)
+	}
+	return elem.Object, nil
+}
+
+func storeElementIndexFunc(objIndexFunc cache.IndexFunc) cache.IndexFunc {
+	return func(obj interface{}) (strings []string, e error) {
+		seo, err := storeElementObject(obj)
+		if err != nil {
+			return nil, err
+		}
+		return objIndexFunc(seo)
+	}
+}
+
+func storeElementIndexers(indexers *cache.Indexers) cache.Indexers {
+	if indexers == nil {
+		return cache.Indexers{}
+	}
+	ret := cache.Indexers{}
+	for indexName, indexFunc := range *indexers {
+		ret[indexName] = storeElementIndexFunc(indexFunc)
+	}
+	return ret
+}

staging/src/k8s.io/apiserver/pkg/storage/cacher/store_test.go

@@ -0,0 +1,157 @@
+/*
+Copyright 2022 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 cacher
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/client-go/tools/cache"
+)
+
+func TestStoreSingleKey(t *testing.T) {
+	store := newStoreIndexer(nil)
+	assertStoreEmpty(t, store, "foo")
+
+	require.NoError(t, store.Add(testStorageElement("foo", "bar", 1)))
+	assertStoreSingleKey(t, store, "foo", "bar", 1)
+
+	require.NoError(t, store.Update(testStorageElement("foo", "baz", 2)))
+	assertStoreSingleKey(t, store, "foo", "baz", 2)
+
+	require.NoError(t, store.Update(testStorageElement("foo", "baz", 3)))
+	assertStoreSingleKey(t, store, "foo", "baz", 3)
+
+	require.NoError(t, store.Replace([]interface{}{testStorageElement("foo", "bar", 4)}, ""))
+	assertStoreSingleKey(t, store, "foo", "bar", 4)
+
+	require.NoError(t, store.Delete(testStorageElement("foo", "", 0)))
+	assertStoreEmpty(t, store, "foo")
+
+	require.NoError(t, store.Delete(testStorageElement("foo", "", 0)))
+}
+
+func TestStoreIndexerSingleKey(t *testing.T) {
+	store := newStoreIndexer(testStoreIndexers())
+	items, err := store.ByIndex("by_val", "bar")
+	require.NoError(t, err)
+	assert.Empty(t, items)
+
+	require.NoError(t, store.Add(testStorageElement("foo", "bar", 1)))
+	items, err = store.ByIndex("by_val", "bar")
+	require.NoError(t, err)
+	assert.Equal(t, []interface{}{
+		testStorageElement("foo", "bar", 1),
+	}, items)
+
+	require.NoError(t, store.Update(testStorageElement("foo", "baz", 2)))
+	items, err = store.ByIndex("by_val", "bar")
+	require.NoError(t, err)
+	assert.Empty(t, items)
+	items, err = store.ByIndex("by_val", "baz")
+	require.NoError(t, err)
+	assert.Equal(t, []interface{}{
+		testStorageElement("foo", "baz", 2),
+	}, items)
+
+	require.NoError(t, store.Update(testStorageElement("foo", "baz", 3)))
+	items, err = store.ByIndex("by_val", "bar")
+	require.NoError(t, err)
+	assert.Empty(t, items)
+	items, err = store.ByIndex("by_val", "baz")
+	require.NoError(t, err)
+	assert.Equal(t, []interface{}{
+		testStorageElement("foo", "baz", 3),
+	}, items)
+
+	require.NoError(t, store.Replace([]interface{}{
+		testStorageElement("foo", "bar", 4),
+	}, ""))
+	items, err = store.ByIndex("by_val", "bar")
+	require.NoError(t, err)
+	assert.Equal(t, []interface{}{
+		testStorageElement("foo", "bar", 4),
+	}, items)
+	items, err = store.ByIndex("by_val", "baz")
+	require.NoError(t, err)
+	assert.Empty(t, items)
+
+	require.NoError(t, store.Delete(testStorageElement("foo", "", 0)))
+	items, err = store.ByIndex("by_val", "baz")
+	require.NoError(t, err)
+	assert.Empty(t, items)
+
+	require.NoError(t, store.Delete(testStorageElement("foo", "", 0)))
+}
+
+func assertStoreEmpty(t *testing.T, store storeIndexer, nonExistingKey string) {
+	item, ok, err := store.Get(testStorageElement(nonExistingKey, "", 0))
+	require.NoError(t, err)
+	assert.False(t, ok)
+	assert.Nil(t, item)
+
+	item, ok, err = store.GetByKey(nonExistingKey)
+	require.NoError(t, err)
+	assert.False(t, ok)
+	assert.Nil(t, item)
+
+	items := store.List()
+	assert.Empty(t, items)
+}
+
+func assertStoreSingleKey(t *testing.T, store storeIndexer, expectKey, expectValue string, expectRV int) {
+	item, ok, err := store.Get(testStorageElement(expectKey, "", expectRV))
+	require.NoError(t, err)
+	assert.True(t, ok)
+	assert.Equal(t, expectValue, item.(*storeElement).Object.(fakeObj).value)
+
+	item, ok, err = store.GetByKey(expectKey)
+	require.NoError(t, err)
+	assert.True(t, ok)
+	assert.Equal(t, expectValue, item.(*storeElement).Object.(fakeObj).value)
+
+	items := store.List()
+	assert.Equal(t, []interface{}{testStorageElement(expectKey, expectValue, expectRV)}, items)
+}
+
+func testStorageElement(key, value string, rv int) *storeElement {
+	return &storeElement{Key: key, Object: fakeObj{value: value, rv: rv}}
+}
+
+type fakeObj struct {
+	value string
+	rv    int
+}
+
+func (f fakeObj) GetObjectKind() schema.ObjectKind { return nil }
+func (f fakeObj) DeepCopyObject() runtime.Object   { return nil }
+
+var _ runtime.Object = (*fakeObj)(nil)
+
+func testStoreIndexFunc(obj interface{}) ([]string, error) {
+	return []string{obj.(fakeObj).value}, nil
+}
+
+func testStoreIndexers() *cache.Indexers {
+	indexers := cache.Indexers{}
+	indexers["by_val"] = testStoreIndexFunc
+	return &indexers
+}

staging/src/k8s.io/apiserver/pkg/storage/cacher/watch_cache.go

@@ -83,55 +83,6 @@ type watchCacheEvent struct {
 	RecordTime      time.Time
 }
 
-// Computing a key of an object is generally non-trivial (it performs
-// e.g. validation underneath). Similarly computing object fields and
-// labels. To avoid computing them multiple times (to serve the event
-// in different List/Watch requests), in the underlying store we are
-// keeping structs (key, object, labels, fields).
-type storeElement struct {
-	Key    string
-	Object runtime.Object
-	Labels labels.Set
-	Fields fields.Set
-}
-
-func storeElementKey(obj interface{}) (string, error) {
-	elem, ok := obj.(*storeElement)
-	if !ok {
-		return "", fmt.Errorf("not a storeElement: %v", obj)
-	}
-	return elem.Key, nil
-}
-
-func storeElementObject(obj interface{}) (runtime.Object, error) {
-	elem, ok := obj.(*storeElement)
-	if !ok {
-		return nil, fmt.Errorf("not a storeElement: %v", obj)
-	}
-	return elem.Object, nil
-}
-
-func storeElementIndexFunc(objIndexFunc cache.IndexFunc) cache.IndexFunc {
-	return func(obj interface{}) (strings []string, e error) {
-		seo, err := storeElementObject(obj)
-		if err != nil {
-			return nil, err
-		}
-		return objIndexFunc(seo)
-	}
-}
-
-func storeElementIndexers(indexers *cache.Indexers) cache.Indexers {
-	if indexers == nil {
-		return cache.Indexers{}
-	}
-	ret := cache.Indexers{}
-	for indexName, indexFunc := range *indexers {
-		ret[indexName] = storeElementIndexFunc(indexFunc)
-	}
-	return ret
-}
-
 // watchCache implements a Store interface.
 // However, it depends on the elements implementing runtime.Object interface.
 //
@@ -173,7 +124,7 @@ type watchCache struct {
 	// history" i.e. from the moment just after the newest cached watched event.
 	// It is necessary to effectively allow clients to start watching at now.
 	// NOTE: We assume that <store> is thread-safe.
-	store cache.Indexer
+	store storeIndexer
 
 	// ResourceVersion up to which the watchCache is propagated.
 	resourceVersion uint64
@@ -223,7 +174,7 @@ func newWatchCache(
 		upperBoundCapacity:  defaultUpperBoundCapacity,
 		startIndex:          0,
 		endIndex:            0,
-		store:               cache.NewIndexer(storeElementKey, storeElementIndexers(indexers)),
+		store:               newStoreIndexer(indexers),
 		resourceVersion:     0,
 		listResourceVersion: 0,
 		eventHandler:        eventHandler,

staging/src/k8s.io/apiserver/pkg/storage/cacher/watch_cache_interval.go

@@ -25,7 +25,6 @@ import (
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/watch"
-	"k8s.io/client-go/tools/cache"
 )
 
 // watchCacheInterval serves as an abstraction over a source
@@ -133,7 +132,7 @@ func (s sortableWatchCacheEvents) Swap(i, j int) {
 // returned by Next() need to be events from a List() done on the underlying store of
 // the watch cache.
 // The items returned in the interval will be sorted by Key.
-func newCacheIntervalFromStore(resourceVersion uint64, store cache.Indexer, getAttrsFunc attrFunc, key string, matchesSingle bool) (*watchCacheInterval, error) {
+func newCacheIntervalFromStore(resourceVersion uint64, store storeIndexer, getAttrsFunc attrFunc, key string, matchesSingle bool) (*watchCacheInterval, error) {
 	buffer := &watchCacheIntervalBuffer{}
 	var allItems []interface{}