From 6af67197a779f431e9e3e056cae0a3a8e58f10f4 Mon Sep 17 00:00:00 2001
From: Todd Treece <360020+toddtreece@users.noreply.github.com>
Date: Fri, 7 Feb 2025 09:17:53 -0500
Subject: [PATCH] Dual Writer: Remove list comparisons in mode 2 & 3 (#100215)

---
 pkg/apiserver/rest/dualwriter_mode2.go      | 45 ------------------
 pkg/apiserver/rest/dualwriter_mode3.go      | 28 -----------
 pkg/apiserver/rest/dualwriter_mode3_test.go | 52 ---------------------
 3 files changed, 125 deletions(-)

diff --git a/pkg/apiserver/rest/dualwriter_mode2.go b/pkg/apiserver/rest/dualwriter_mode2.go
index 105f450da4d..cc064ff4d5c 100644
--- a/pkg/apiserver/rest/dualwriter_mode2.go
+++ b/pkg/apiserver/rest/dualwriter_mode2.go
@@ -156,51 +156,6 @@ func (d *DualWriterMode2) List(ctx context.Context, options *metainternalversion
 		return ll, err
 	}
 	d.recordLegacyDuration(false, mode2Str, d.resource, method, startLegacy)
-
-	legacyList, err := meta.ExtractList(ll)
-	if err != nil {
-		log.Error(err, "unable to extract list from legacy storage")
-		return nil, err
-	}
-
-	// Record the index of each LegacyStorage object so it can later be replaced by
-	// an equivalent Storage object if it exists.
-	legacyNames, err := parseList(legacyList)
-	if err != nil {
-		return nil, err
-	}
-
-	startStorage := time.Now()
-	sl, err := d.Storage.List(ctx, options)
-	if err != nil {
-		log.Error(err, "unable to list objects from storage")
-		d.recordStorageDuration(true, mode2Str, d.resource, method, startStorage)
-		return sl, err
-	}
-	d.recordStorageDuration(false, mode2Str, d.resource, method, startStorage)
-
-	storageList, err := meta.ExtractList(sl)
-	if err != nil {
-		log.Error(err, "unable to extract list from storage")
-		return nil, err
-	}
-
-	for _, obj := range storageList {
-		name := getName(obj)
-		if i, ok := legacyNames[name]; ok {
-			areEqual := Compare(obj, legacyList[i])
-			d.recordOutcome(mode2Str, name, areEqual, method)
-			if !areEqual {
-				log.WithValues("name", name).Info("object from legacy and storage are not equal")
-			}
-		}
-	}
-
-	if err = meta.SetList(ll, legacyList); err != nil {
-		return nil, err
-	}
-
-	// always return the list from legacy storage
 	return ll, nil
 }
 
diff --git a/pkg/apiserver/rest/dualwriter_mode3.go b/pkg/apiserver/rest/dualwriter_mode3.go
index 1e7358c62e2..8b68c748769 100644
--- a/pkg/apiserver/rest/dualwriter_mode3.go
+++ b/pkg/apiserver/rest/dualwriter_mode3.go
@@ -162,37 +162,9 @@ func (d *DualWriterMode3) List(ctx context.Context, options *metainternalversion
 	if err != nil {
 		log.Error(err, "unable to list object in storage")
 	}
-
-	//nolint:errcheck
-	go d.listFromLegacyStorage(ctx, options, objFromStorage)
-
 	return objFromStorage, err
 }
 
-func (d *DualWriterMode3) listFromLegacyStorage(ctx context.Context, options *metainternalversion.ListOptions, objFromStorage runtime.Object) error {
-	var method = "list"
-	log := d.Log.WithValues("resourceVersion", options.ResourceVersion, "method", method)
-	startLegacy := time.Now()
-
-	ctx, cancel := context.WithTimeoutCause(context.WithoutCancel(ctx), time.Second*10, errors.New("legacy list timeout"))
-	defer cancel()
-
-	objFromLegacy, err := d.Legacy.List(ctx, options)
-	d.recordLegacyDuration(err != nil, mode3Str, d.resource, method, startLegacy)
-	if err != nil {
-		log.Error(err, "unable to list object in legacy storage")
-		cancel()
-	}
-
-	areEqual := Compare(objFromStorage, objFromLegacy)
-	d.recordOutcome(mode3Str, getName(objFromStorage), areEqual, method)
-	if !areEqual {
-		log.WithValues("name", getName(objFromStorage)).Info("object from legacy and storage are not equal")
-	}
-
-	return err
-}
-
 func (d *DualWriterMode3) Delete(ctx context.Context, name string, deleteValidation rest.ValidateObjectFunc, options *metav1.DeleteOptions) (runtime.Object, bool, error) {
 	var method = "delete"
 	log := d.Log.WithValues("name", name, "method", method)
diff --git a/pkg/apiserver/rest/dualwriter_mode3_test.go b/pkg/apiserver/rest/dualwriter_mode3_test.go
index ee1bcb888dd..d5ddbe04a88 100644
--- a/pkg/apiserver/rest/dualwriter_mode3_test.go
+++ b/pkg/apiserver/rest/dualwriter_mode3_test.go
@@ -250,58 +250,6 @@ func TestMode3_List(t *testing.T) {
 	}
 }
 
-func TestMode1_ListFromLegacyStorage(t *testing.T) {
-	ctxCanceled, cancel := context.WithCancel(context.TODO())
-	cancel()
-
-	type testCase struct {
-		ctx           *context.Context
-		name          string
-		setupLegacyFn func(m *mock.Mock)
-	}
-	tests :=
-		[]testCase{
-			{
-				name: "list from legacy storage",
-				setupLegacyFn: func(m *mock.Mock) {
-					m.On("List", mock.Anything, mock.Anything).Return(anotherList, nil)
-				},
-			},
-			{
-				name: "list from legacy storage works even if parent context is canceled",
-				ctx:  &ctxCanceled,
-				setupLegacyFn: func(m *mock.Mock) {
-					m.On("List", mock.Anything, mock.Anything).Return(anotherList, nil)
-				},
-			},
-		}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			l := (LegacyStorage)(nil)
-			s := (Storage)(nil)
-			m := &mock.Mock{}
-
-			ls := legacyStoreMock{m, l}
-			us := storageMock{m, s}
-
-			if tt.setupLegacyFn != nil {
-				tt.setupLegacyFn(m)
-			}
-
-			ctx := context.TODO()
-			if tt.ctx != nil {
-				ctx = *tt.ctx
-			}
-
-			dw := NewDualWriter(Mode3, ls, us, p, kind)
-
-			err := dw.(*DualWriterMode3).listFromLegacyStorage(ctx, &metainternalversion.ListOptions{}, anotherList)
-			assert.NoError(t, err)
-		})
-	}
-}
-
 func TestMode3_Delete(t *testing.T) {
 	type testCase struct {
 		setupLegacyFn  func(m *mock.Mock, input string)