Merge pull request #35218 from wojtek-t/get_to_list_support_resource_version

Automatic merge from submit-queue

Support resourceVersion in GetToList - unify interface of List and Ge…

This pretty much unifies the interface of List() and GetToList() methods of storage interface.

I'm going to use it in a subsequent PR to improve performance of the whole cluster.

pkg/registry/generic/registry/store.go

@@ -201,18 +201,18 @@ func (e *Store) List(ctx api.Context, options *api.ListOptions) (runtime.Object,
 
 // ListPredicate returns a list of all the items matching m.
 func (e *Store) ListPredicate(ctx api.Context, p storage.SelectionPredicate, options *api.ListOptions) (runtime.Object, error) {
+	if options == nil {
+		options = &api.ListOptions{ResourceVersion: "0"}
+	}
 	list := e.NewListFunc()
 	if name, ok := p.MatchesSingle(); ok {
 		if key, err := e.KeyFunc(ctx, name); err == nil {
-			err := e.Storage.GetToList(ctx, key, p, list)
+			err := e.Storage.GetToList(ctx, key, options.ResourceVersion, p, list)
 			return list, storeerr.InterpretListError(err, e.QualifiedResource)
 		}
 		// if we cannot extract a key based on the current context, the optimization is skipped
 	}
 
-	if options == nil {
-		options = &api.ListOptions{ResourceVersion: "0"}
-	}
 	err := e.Storage.List(ctx, e.KeyRootFunc(ctx), options.ResourceVersion, p, list)
 	return list, storeerr.InterpretListError(err, e.QualifiedResource)
 }

pkg/storage/cacher.go

@@ -344,8 +344,59 @@ func (c *Cacher) Get(ctx context.Context, key string, objPtr runtime.Object, ign
 }
 
 // Implements storage.Interface.
-func (c *Cacher) GetToList(ctx context.Context, key string, pred SelectionPredicate, listObj runtime.Object) error {
-	return c.storage.GetToList(ctx, key, pred, listObj)
+func (c *Cacher) GetToList(ctx context.Context, key string, resourceVersion string, pred SelectionPredicate, listObj runtime.Object) error {
+	if resourceVersion == "" {
+		// If resourceVersion is not specified, serve it from underlying
+		// storage (for backward compatibility).
+		return c.storage.GetToList(ctx, key, resourceVersion, pred, 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 := ParseListResourceVersion(resourceVersion)
+	if err != nil {
+		return err
+	}
+
+	trace := util.NewTrace(fmt.Sprintf("cacher %v: List", 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 || listVal.Kind() != reflect.Slice {
+		return fmt.Errorf("need a pointer to slice, got %v", listVal.Kind())
+	}
+	filter := filterFunction(key, pred)
+
+	obj, exists, readResourceVersion, err := c.watchCache.WaitUntilFreshAndGet(listRV, key, trace)
+	if err != nil {
+		return fmt.Errorf("failed to wait for fresh list: %v", 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.Object) {
+			listVal.Set(reflect.Append(listVal, reflect.ValueOf(elem.Object).Elem()))
+		}
+	}
+	if c.versioner != nil {
+		if err := c.versioner.UpdateList(listObj, readResourceVersion); err != nil {
+			return err
+		}
+	}
+	return nil
 }
 
 // Implements storage.Interface.
@@ -359,7 +410,6 @@ func (c *Cacher) List(ctx context.Context, key string, resourceVersion string, p
 	// 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 := ParseListResourceVersion(resourceVersion)
 	if err != nil {
 		return err
@@ -371,7 +421,7 @@ func (c *Cacher) List(ctx context.Context, key string, resourceVersion string, p
 	c.ready.wait()
 	trace.Step("Ready")
 
-	// List elements from cache, with at least 'listRV'.
+	// List elements with at least 'listRV' from cache.
 	listPtr, err := meta.GetItemsPtr(listObj)
 	if err != nil {
 		return err

pkg/storage/etcd/etcd_helper.go

@@ -297,7 +297,7 @@ func (h *etcdHelper) extractObj(response *etcd.Response, inErr error, objPtr run
 }
 
 // Implements storage.Interface.
-func (h *etcdHelper) GetToList(ctx context.Context, key string, pred storage.SelectionPredicate, listObj runtime.Object) error {
+func (h *etcdHelper) GetToList(ctx context.Context, key string, resourceVersion string, pred storage.SelectionPredicate, listObj runtime.Object) error {
 	if ctx == nil {
 		glog.Errorf("Context is nil")
 	}

pkg/storage/etcd3/store.go

@@ -270,7 +270,7 @@ func (s *store) GuaranteedUpdate(ctx context.Context, key string, out runtime.Ob
 }
 
 // GetToList implements storage.Interface.GetToList.
-func (s *store) GetToList(ctx context.Context, key string, pred storage.SelectionPredicate, listObj runtime.Object) error {
+func (s *store) GetToList(ctx context.Context, key string, resourceVersion string, pred storage.SelectionPredicate, listObj runtime.Object) error {
 	listPtr, err := meta.GetItemsPtr(listObj)
 	if err != nil {
 		return err

pkg/storage/etcd3/store_test.go

@@ -253,7 +253,7 @@ func TestGetToList(t *testing.T) {
 
 	for i, tt := range tests {
 		out := &api.PodList{}
-		err := store.GetToList(ctx, tt.key, tt.pred, out)
+		err := store.GetToList(ctx, tt.key, "", tt.pred, out)
 		if err != nil {
 			t.Fatalf("GetToList failed: %v", err)
 		}

pkg/storage/interfaces.go

@@ -128,7 +128,9 @@ type Interface interface {
 
 	// GetToList unmarshals json found at key and opaque it into *List api object
 	// (an object that satisfies the runtime.IsList definition).
-	GetToList(ctx context.Context, key string, p SelectionPredicate, listObj runtime.Object) error
+	// The returned contents may be delayed, but it is guaranteed that they will
+	// be have at least 'resourceVersion'.
+	GetToList(ctx context.Context, key string, resourceVersion string, p SelectionPredicate, listObj runtime.Object) error
 
 	// List unmarshalls jsons found at directory defined by key and opaque them
 	// into *List api object (an object that satisfies runtime.IsList definition).

pkg/storage/watch_cache.go

@@ -245,8 +245,10 @@ func (w *watchCache) List() []interface{} {
 	return w.store.List()
 }
 
-// WaitUntilFreshAndList returns list of pointers to <storeElement> objects.
-func (w *watchCache) WaitUntilFreshAndList(resourceVersion uint64, trace *util.Trace) ([]interface{}, uint64, error) {
+// waitUntilFreshAndBlock waits until cache is at least as fresh as given <resourceVersion>.
+// NOTE: This function acquired lock and doesn't release it.
+// You HAVE TO explicitly call w.RUnlock() after this function.
+func (w *watchCache) waitUntilFreshAndBlock(resourceVersion uint64, trace *util.Trace) error {
 	startTime := w.clock.Now()
 	go func() {
 		// Wake us up when the time limit has expired.  The docs
@@ -261,22 +263,42 @@ func (w *watchCache) WaitUntilFreshAndList(resourceVersion uint64, trace *util.T
 	}()
 
 	w.RLock()
-	defer w.RUnlock()
 	if trace != nil {
 		trace.Step("watchCache locked acquired")
 	}
 	for w.resourceVersion < resourceVersion {
 		if w.clock.Since(startTime) >= MaximumListWait {
-			return nil, 0, fmt.Errorf("time limit exceeded while waiting for resource version %v (current value: %v)", resourceVersion, w.resourceVersion)
+			return fmt.Errorf("time limit exceeded while waiting for resource version %v (current value: %v)", resourceVersion, w.resourceVersion)
 		}
 		w.cond.Wait()
 	}
 	if trace != nil {
 		trace.Step("watchCache fresh enough")
 	}
+	return nil
+}
+
+// WaitUntilFreshAndList returns list of pointers to <storeElement> objects.
+func (w *watchCache) WaitUntilFreshAndList(resourceVersion uint64, trace *util.Trace) ([]interface{}, uint64, error) {
+	err := w.waitUntilFreshAndBlock(resourceVersion, trace)
+	defer w.RUnlock()
+	if err != nil {
+		return nil, 0, err
+	}
 	return w.store.List(), w.resourceVersion, nil
 }
 
+// WaitUntilFreshAndGet returns a pointers to <storeElement> object.
+func (w *watchCache) WaitUntilFreshAndGet(resourceVersion uint64, key string, trace *util.Trace) (interface{}, bool, uint64, error) {
+	err := w.waitUntilFreshAndBlock(resourceVersion, trace)
+	defer w.RUnlock()
+	if err != nil {
+		return nil, false, 0, err
+	}
+	value, exists, err := w.store.GetByKey(key)
+	return value, exists, w.resourceVersion, err
+}
+
 func (w *watchCache) ListKeys() []string {
 	w.RLock()
 	defer w.RUnlock()

pkg/storage/watch_cache_test.go

@@ -263,6 +263,30 @@ func TestWaitUntilFreshAndList(t *testing.T) {
 	}
 }
 
+func TestWaitUntilFreshAndGet(t *testing.T) {
+	store := newTestWatchCache(3)
+
+	// In background, update the store.
+	go func() {
+		store.Add(makeTestPod("foo", 2))
+		store.Add(makeTestPod("bar", 5))
+	}()
+
+	obj, exists, resourceVersion, err := store.WaitUntilFreshAndGet(5, "prefix/ns/bar", nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resourceVersion != 5 {
+		t.Errorf("unexpected resourceVersion: %v, expected: 5", resourceVersion)
+	}
+	if !exists {
+		t.Fatalf("no results returned: %#v", obj)
+	}
+	if !api.Semantic.DeepEqual(&storeElement{Key: "prefix/ns/bar", Object: makeTestPod("bar", 5)}, obj) {
+		t.Errorf("unexpected element returned: %#v", obj)
+	}
+}
+
 func TestWaitUntilFreshAndListTimeout(t *testing.T) {
 	store := newTestWatchCache(3)
 	fc := store.clock.(*clock.FakeClock)