Merge pull request #116623 from lavalamp/xfrmr

change where transformers are called

Kubernetes-commit: 76d351065e504e23b7962158ef0e9067b6bd96ed

tools/cache/controller.go

@@ -394,17 +394,6 @@ func NewIndexerInformer(
 	return clientState, newInformer(lw, objType, resyncPeriod, h, clientState, nil)
 }
 
-// TransformFunc allows for transforming an object before it will be processed
-// and put into the controller cache and before the corresponding handlers will
-// be called on it.
-// TransformFunc (similarly to ResourceEventHandler functions) should be able
-// to correctly handle the tombstone of type cache.DeletedFinalStateUnknown
-//
-// The most common usage pattern is to clean-up some parts of the object to
-// reduce component memory usage if a given component doesn't care about them.
-// given controller doesn't care for them
-type TransformFunc func(interface{}) (interface{}, error)
-
 // NewTransformingInformer returns a Store and a controller for populating
 // the store while also providing event notifications. You should only used
 // the returned Store for Get/List operations; Add/Modify/Deletes will cause
@@ -452,20 +441,12 @@ func processDeltas(
 	// Object which receives event notifications from the given deltas
 	handler ResourceEventHandler,
 	clientState Store,
-	transformer TransformFunc,
 	deltas Deltas,
 	isInInitialList bool,
 ) error {
 	// from oldest to newest
 	for _, d := range deltas {
 		obj := d.Object
-		if transformer != nil {
-			var err error
-			obj, err = transformer(obj)
-			if err != nil {
-				return err
-			}
-		}
 
 		switch d.Type {
 		case Sync, Replaced, Added, Updated:
@@ -517,6 +498,7 @@ func newInformer(
 	fifo := NewDeltaFIFOWithOptions(DeltaFIFOOptions{
 		KnownObjects:          clientState,
 		EmitDeltaTypeReplaced: true,
+		Transformer:           transformer,
 	})
 
 	cfg := &Config{
@@ -528,7 +510,7 @@ func newInformer(
 
 		Process: func(obj interface{}, isInInitialList bool) error {
 			if deltas, ok := obj.(Deltas); ok {
-				return processDeltas(h, clientState, transformer, deltas, isInInitialList)
+				return processDeltas(h, clientState, deltas, isInInitialList)
 			}
 			return errors.New("object given as Process argument is not Deltas")
 		},

tools/cache/controller_test.go

@@ -23,7 +23,7 @@ import (
 	"testing"
 	"time"
 
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	apiequality "k8s.io/apimachinery/pkg/api/equality"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -32,7 +32,7 @@ import (
 	"k8s.io/apimachinery/pkg/watch"
 	fcache "k8s.io/client-go/tools/cache/testing"
 
-	"github.com/google/gofuzz"
+	fuzz "github.com/google/gofuzz"
 )
 
 func Example() {

tools/cache/delta_fifo.go

@@ -51,6 +51,10 @@ type DeltaFIFOOptions struct {
 	// When true, `Replaced` events will be sent for items passed to a Replace() call.
 	// When false, `Sync` events will be sent instead.
 	EmitDeltaTypeReplaced bool
+
+	// If set, will be called for objects before enqueueing them. Please
+	// see the comment on TransformFunc for details.
+	Transformer TransformFunc
 }
 
 // DeltaFIFO is like FIFO, but differs in two ways.  One is that the
@@ -129,8 +133,32 @@ type DeltaFIFO struct {
 	// emitDeltaTypeReplaced is whether to emit the Replaced or Sync
 	// DeltaType when Replace() is called (to preserve backwards compat).
 	emitDeltaTypeReplaced bool
+
+	// Called with every object if non-nil.
+	transformer TransformFunc
 }
 
+// TransformFunc allows for transforming an object before it will be processed.
+// TransformFunc (similarly to ResourceEventHandler functions) should be able
+// to correctly handle the tombstone of type cache.DeletedFinalStateUnknown.
+//
+// New in v1.27: In such cases, the contained object will already have gone
+// through the transform object separately (when it was added / updated prior
+// to the delete), so the TransformFunc can likely safely ignore such objects
+// (i.e., just return the input object).
+//
+// The most common usage pattern is to clean-up some parts of the object to
+// reduce component memory usage if a given component doesn't care about them.
+//
+// New in v1.27: unless the object is a DeletedFinalStateUnknown, TransformFunc
+// sees the object before any other actor, and it is now safe to mutate the
+// object in place instead of making a copy.
+//
+// Note that TransformFunc is called while inserting objects into the
+// notification queue and is therefore extremely performance sensitive; please
+// do not do anything that will take a long time.
+type TransformFunc func(interface{}) (interface{}, error)
+
 // DeltaType is the type of a change (addition, deletion, etc)
 type DeltaType string
 
@@ -227,6 +255,7 @@ func NewDeltaFIFOWithOptions(opts DeltaFIFOOptions) *DeltaFIFO {
 		knownObjects: opts.KnownObjects,
 
 		emitDeltaTypeReplaced: opts.EmitDeltaTypeReplaced,
+		transformer:           opts.Transformer,
 	}
 	f.cond.L = &f.lock
 	return f
@@ -415,6 +444,21 @@ func (f *DeltaFIFO) queueActionLocked(actionType DeltaType, obj interface{}) err
 	if err != nil {
 		return KeyError{obj, err}
 	}
+
+	// Every object comes through this code path once, so this is a good
+	// place to call the transform func.  If obj is a
+	// DeletedFinalStateUnknown tombstone, then the containted inner object
+	// will already have gone through the transformer, but we document that
+	// this can happen. In cases involving Replace(), such an object can
+	// come through multiple times.
+	if f.transformer != nil {
+		var err error
+		obj, err = f.transformer(obj)
+		if err != nil {
+			return err
+		}
+	}
+
 	oldDeltas := f.items[id]
 	newDeltas := append(oldDeltas, Delta{actionType, obj})
 	newDeltas = dedupDeltas(newDeltas)

tools/cache/delta_fifo_test.go

@@ -327,6 +327,88 @@ func TestDeltaFIFO_addUpdate(t *testing.T) {
 	}
 }
 
+type rvAndXfrm struct {
+	rv   int
+	xfrm int
+}
+
+func TestDeltaFIFO_transformer(t *testing.T) {
+	mk := func(name string, rv int) testFifoObject {
+		return mkFifoObj(name, &rvAndXfrm{rv, 0})
+	}
+	xfrm := TransformFunc(func(obj interface{}) (interface{}, error) {
+		switch v := obj.(type) {
+		case testFifoObject:
+			v.val.(*rvAndXfrm).xfrm++
+		case DeletedFinalStateUnknown:
+			if x := v.Obj.(testFifoObject).val.(*rvAndXfrm).xfrm; x != 1 {
+				return nil, fmt.Errorf("object has been transformed wrong number of times: %#v", obj)
+			}
+		default:
+			return nil, fmt.Errorf("unexpected object: %#v", obj)
+		}
+		return obj, nil
+	})
+
+	must := func(err error) {
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	f := NewDeltaFIFOWithOptions(DeltaFIFOOptions{
+		KeyFunction: testFifoObjectKeyFunc,
+		Transformer: xfrm,
+	})
+	must(f.Add(mk("foo", 10)))
+	must(f.Add(mk("bar", 11)))
+	must(f.Update(mk("foo", 12)))
+	must(f.Delete(mk("foo", 15)))
+	must(f.Replace([]interface{}{}, ""))
+	must(f.Add(mk("bar", 16)))
+	must(f.Replace([]interface{}{}, ""))
+
+	// Should be empty
+	if e, a := []string{"foo", "bar"}, f.ListKeys(); !reflect.DeepEqual(e, a) {
+		t.Errorf("Expected %+v, got %+v", e, a)
+	}
+
+	for i := 0; i < 2; i++ {
+		obj, err := f.Pop(func(o interface{}, isInInitialList bool) error { return nil })
+		if err != nil {
+			t.Fatalf("got nothing on try %v?", i)
+		}
+		obj = obj.(Deltas).Newest().Object
+		switch v := obj.(type) {
+		case testFifoObject:
+			if v.name != "foo" {
+				t.Errorf("expected regular deletion of foo, got %q", v.name)
+			}
+			rx := v.val.(*rvAndXfrm)
+			if rx.rv != 15 {
+				t.Errorf("expected last message, got %#v", obj)
+			}
+			if rx.xfrm != 1 {
+				t.Errorf("obj %v transformed wrong number of times.", obj)
+			}
+		case DeletedFinalStateUnknown:
+			tf := v.Obj.(testFifoObject)
+			rx := tf.val.(*rvAndXfrm)
+			if tf.name != "bar" {
+				t.Errorf("expected tombstone deletion of bar, got %q", tf.name)
+			}
+			if rx.rv != 16 {
+				t.Errorf("expected last message, got %#v", obj)
+			}
+			if rx.xfrm != 1 {
+				t.Errorf("tombstoned obj %v transformed wrong number of times.", obj)
+			}
+		default:
+			t.Errorf("unknown item %#v", obj)
+		}
+	}
+}
+
 func TestDeltaFIFO_enqueueingNoLister(t *testing.T) {
 	f := NewDeltaFIFOWithOptions(DeltaFIFOOptions{KeyFunction: testFifoObjectKeyFunc})
 	f.Add(mkFifoObj("foo", 10))

tools/cache/shared_informer.go

@@ -205,10 +205,7 @@ type SharedInformer interface {
 	//
 	// Must be set before starting the informer.
 	//
-	// Note: Since the object given to the handler may be already shared with
+	// Please see the comment on TransformFunc for more details.
-	//	other goroutines, it is advisable to copy the object being
-	//  transform before mutating it at all and returning the copy to prevent
-	//	data races.
 	SetTransform(handler TransformFunc) error
 
 	// IsStopped reports whether the informer has already been stopped.
@@ -465,6 +462,7 @@ func (s *sharedIndexInformer) Run(stopCh <-chan struct{}) {
 	fifo := NewDeltaFIFOWithOptions(DeltaFIFOOptions{
 		KnownObjects:          s.indexer,
 		EmitDeltaTypeReplaced: true,
+		Transformer:           s.transform,
 	})
 
 	cfg := &Config{
@@ -637,7 +635,7 @@ func (s *sharedIndexInformer) HandleDeltas(obj interface{}, isInInitialList bool
 	defer s.blockDeltas.Unlock()
 
 	if deltas, ok := obj.(Deltas); ok {
-		return processDeltas(s, s.indexer, s.transform, deltas, isInInitialList)
+		return processDeltas(s, s.indexer, deltas, isInInitialList)
 	}
 	return errors.New("object given as Process argument is not Deltas")
 }

tools/cache/shared_informer_test.go

@@ -406,9 +406,8 @@ func TestSharedInformerTransformer(t *testing.T) {
 			name := pod.GetName()
 
 			if upper := strings.ToUpper(name); upper != name {
-				copied := pod.DeepCopyObject().(*v1.Pod)
+				pod.SetName(upper)
-				copied.SetName(upper)
+				return pod, nil
-				return copied, nil
 			}
 		}
 		return obj, nil