From c86543d9cb302859510604256fdb81ea1b0d46fb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Wojciech=20Tyczy=C5=84ski?= <wojtekt@google.com>
Date: Thu, 18 Nov 2021 16:41:36 +0100
Subject: [PATCH] Unify List and GetToList functions of cacher.

---
 .../apiserver/pkg/storage/cacher/cacher.go    | 93 ++++++-------------
 1 file changed, 29 insertions(+), 64 deletions(-)

diff --git a/staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher.go b/staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher.go
index 217fa72588c..617552144f1 100644
--- a/staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher.go
+++ b/staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher.go
@@ -610,75 +610,40 @@ func shouldDelegateList(opts storage.ListOptions) bool {
 
 // GetToList implements storage.Interface.
 func (c *Cacher) GetToList(ctx context.Context, key string, opts storage.ListOptions, listObj runtime.Object) error {
-	resourceVersion := opts.ResourceVersion
-	pred := opts.Predicate
-	if shouldDelegateList(opts) {
-		return c.storage.GetToList(ctx, key, opts, listObj)
-	}
-
-	// If resourceVersion is specified, serve it from cache.
-	// It's guaranteed that the returned value is at least that
-	// fresh as the given resourceVersion.
-	listRV, err := c.versioner.ParseResourceVersion(resourceVersion)
-	if err != nil {
-		return err
-	}
-
-	if listRV == 0 && !c.ready.check() {
-		// If Cacher is not yet initialized and we don't require any specific
-		// minimal resource version, simply forward the request to storage.
-		return c.storage.GetToList(ctx, key, opts, listObj)
-	}
-
-	trace := utiltrace.New("cacher list", utiltrace.Field{"type", c.objectType.String()})
-	defer trace.LogIfLong(500 * time.Millisecond)
-
-	c.ready.wait()
-	trace.Step("Ready")
-
-	// List elements with at least 'listRV' from cache.
-	listPtr, err := meta.GetItemsPtr(listObj)
-	if err != nil {
-		return err
-	}
-	listVal, err := conversion.EnforcePtr(listPtr)
-	if err != nil {
-		return err
-	}
-	if listVal.Kind() != reflect.Slice {
-		return fmt.Errorf("need a pointer to slice, got %v", listVal.Kind())
-	}
-	filter := filterWithAttrsFunction(key, pred)
-
-	obj, exists, readResourceVersion, err := c.watchCache.WaitUntilFreshAndGet(listRV, key, trace)
-	if err != nil {
-		return err
-	}
-	trace.Step("Got from cache")
-
-	if exists {
-		elem, ok := obj.(*storeElement)
-		if !ok {
-			return fmt.Errorf("non *storeElement returned from storage: %v", obj)
-		}
-		if filter(elem.Key, elem.Labels, elem.Fields) {
-			listVal.Set(reflect.Append(listVal, reflect.ValueOf(elem.Object).Elem()))
-		}
-	}
-	if c.versioner != nil {
-		if err := c.versioner.UpdateList(listObj, readResourceVersion, "", nil); err != nil {
-			return err
-		}
-	}
-	return nil
+	return c.list(ctx, key, opts, listObj, false)
 }
 
 // List implements storage.Interface.
 func (c *Cacher) List(ctx context.Context, key string, opts storage.ListOptions, listObj runtime.Object) error {
+	return c.list(ctx, key, opts, listObj, true)
+}
+
+func (c *Cacher) delegateList(ctx context.Context, key string, opts storage.ListOptions, listObj runtime.Object, recursive bool) error {
+	if !recursive {
+		return c.storage.GetToList(ctx, key, opts, listObj)
+	}
+	return c.storage.List(ctx, key, opts, listObj)
+}
+
+func (c *Cacher) listItems(listRV uint64, key string, pred storage.SelectionPredicate, trace *utiltrace.Trace, recursive bool) ([]interface{}, uint64, string, error) {
+	if !recursive {
+		obj, exists, readResourceVersion, err := c.watchCache.WaitUntilFreshAndGet(listRV, key, trace)
+		if err != nil {
+			return nil, 0, "", err
+		}
+		if exists {
+			return []interface{}{obj}, readResourceVersion, "", nil
+		}
+		return nil, readResourceVersion, "", nil
+	}
+	return c.watchCache.WaitUntilFreshAndList(listRV, pred.MatcherIndex(), trace)
+}
+
+func (c *Cacher) list(ctx context.Context, key string, opts storage.ListOptions, listObj runtime.Object, recursive bool) error {
 	resourceVersion := opts.ResourceVersion
 	pred := opts.Predicate
 	if shouldDelegateList(opts) {
-		return c.storage.List(ctx, key, opts, listObj)
+		return c.delegateList(ctx, key, opts, listObj, recursive)
 	}
 
 	// If resourceVersion is specified, serve it from cache.
@@ -692,7 +657,7 @@ func (c *Cacher) List(ctx context.Context, key string, opts storage.ListOptions,
 	if listRV == 0 && !c.ready.check() {
 		// If Cacher is not yet initialized and we don't require any specific
 		// minimal resource version, simply forward the request to storage.
-		return c.storage.List(ctx, key, opts, listObj)
+		return c.delegateList(ctx, key, opts, listObj, recursive)
 	}
 
 	trace := utiltrace.New("cacher list", utiltrace.Field{"type", c.objectType.String()})
@@ -715,7 +680,7 @@ func (c *Cacher) List(ctx context.Context, key string, opts storage.ListOptions,
 	}
 	filter := filterWithAttrsFunction(key, pred)
 
-	objs, readResourceVersion, indexUsed, err := c.watchCache.WaitUntilFreshAndList(listRV, pred.MatcherIndex(), trace)
+	objs, readResourceVersion, indexUsed, err := c.listItems(listRV, key, pred, trace, recursive)
 	if err != nil {
 		return err
 	}