func ExampleInformer() {
	// source simulates an apiserver object endpoint.
	source := framework.NewFakeControllerSource()

	// Let's do threadsafe output to get predictable test results.
	deletionCounter := make(chan string, 1000)

	// Make a controller that immediately deletes anything added to it, and
	// logs anything deleted.
	_, controller := framework.NewInformer(
		source,
		&api.Pod{},
		time.Millisecond*100,
		framework.ResourceEventHandlerFuncs{
			AddFunc: func(obj interface{}) {
				source.Delete(obj.(runtime.Object))
			},
			DeleteFunc: func(obj interface{}) {
				key, err := framework.DeletionHandlingMetaNamespaceKeyFunc(obj)
				if err != nil {
					key = "oops something went wrong with the key"
				}

				// Report this deletion.
				deletionCounter <- key
			},
		},
	)

	// Run the controller and run it until we close stop.
	stop := make(chan struct{})
	defer close(stop)
	go controller.Run(stop)

	// Let's add a few objects to the source.
	testIDs := []string{"a-hello", "b-controller", "c-framework"}
	for _, name := range testIDs {
		// Note that these pods are not valid-- the fake source doesn't
		// call validation or anything.
		source.Add(&api.Pod{ObjectMeta: api.ObjectMeta{Name: name}})
	}

	// Let's wait for the controller to process the things we just added.
	outputSet := util.StringSet{}
	for i := 0; i < len(testIDs); i++ {
		outputSet.Insert(<-deletionCounter)
	}

	for _, key := range outputSet.List() {
		fmt.Println(key)
	}
	// Output:
	// a-hello
	// b-controller
	// c-framework
}
func Example() {
	// source simulates an apiserver object endpoint.
	source := framework.NewFakeControllerSource()

	// This will hold the downstream state, as we know it.
	downstream := cache.NewStore(framework.DeletionHandlingMetaNamespaceKeyFunc)

	// This will hold incoming changes. Note how we pass downstream in as a
	// KeyLister, that way resync operations will result in the correct set
	// of update/delete deltas.
	fifo := cache.NewDeltaFIFO(cache.MetaNamespaceKeyFunc, nil, downstream)

	// Let's do threadsafe output to get predictable test results.
	deletionCounter := make(chan string, 1000)

	cfg := &framework.Config{
		Queue:            fifo,
		ListerWatcher:    source,
		ObjectType:       &api.Pod{},
		FullResyncPeriod: time.Millisecond * 100,
		RetryOnError:     false,

		// Let's implement a simple controller that just deletes
		// everything that comes in.
		Process: func(obj interface{}) error {
			// Obj is from the Pop method of the Queue we make above.
			newest := obj.(cache.Deltas).Newest()

			if newest.Type != cache.Deleted {
				// Update our downstream store.
				err := downstream.Add(newest.Object)
				if err != nil {
					return err
				}

				// Delete this object.
				source.Delete(newest.Object.(runtime.Object))
			} else {
				// Update our downstream store.
				err := downstream.Delete(newest.Object)
				if err != nil {
					return err
				}

				// fifo's KeyOf is easiest, because it handles
				// DeletedFinalStateUnknown markers.
				key, err := fifo.KeyOf(newest.Object)
				if err != nil {
					return err
				}

				// Report this deletion.
				deletionCounter <- key
			}
			return nil
		},
	}

	// Create the controller and run it until we close stop.
	stop := make(chan struct{})
	defer close(stop)
	go framework.New(cfg).Run(stop)

	// Let's add a few objects to the source.
	testIDs := []string{"a-hello", "b-controller", "c-framework"}
	for _, name := range testIDs {
		// Note that these pods are not valid-- the fake source doesn't
		// call validation or anything.
		source.Add(&api.Pod{ObjectMeta: api.ObjectMeta{Name: name}})
	}

	// Let's wait for the controller to process the things we just added.
	outputSet := util.StringSet{}
	for i := 0; i < len(testIDs); i++ {
		outputSet.Insert(<-deletionCounter)
	}

	for _, key := range outputSet.List() {
		fmt.Println(key)
	}
	// Output:
	// a-hello
	// b-controller
	// c-framework
}
func TestUpdate(t *testing.T) {
	// This test is going to exercise the various paths that result in a
	// call to update.

	// source simulates an apiserver object endpoint.
	source := framework.NewFakeControllerSource()

	const (
		FROM       = "from"
		ADD_MISSED = "missed the add event"
		TO         = "to"
	)

	// These are the transitions we expect to see; because this is
	// asynchronous, there are a lot of valid possibilities.
	type pair struct{ from, to string }
	allowedTransitions := map[pair]bool{
		pair{FROM, TO}:         true,
		pair{FROM, ADD_MISSED}: true,
		pair{ADD_MISSED, TO}:   true,

		// Because a resync can happen when we've already observed one
		// of the above but before the item is deleted.
		pair{TO, TO}: true,
		// Because a resync could happen before we observe an update.
		pair{FROM, FROM}: true,
	}

	var testDoneWG sync.WaitGroup

	// Make a controller that deletes things once it observes an update.
	// It calls Done() on the wait group on deletions so we can tell when
	// everything we've added has been deleted.
	_, controller := framework.NewInformer(
		source,
		&api.Pod{},
		time.Millisecond*1,
		framework.ResourceEventHandlerFuncs{
			UpdateFunc: func(oldObj, newObj interface{}) {
				o, n := oldObj.(*api.Pod), newObj.(*api.Pod)
				from, to := o.Labels["check"], n.Labels["check"]
				if !allowedTransitions[pair{from, to}] {
					t.Errorf("observed transition %q -> %q for %v", from, to, n.Name)
				}
				source.Delete(n)
			},
			DeleteFunc: func(obj interface{}) {
				testDoneWG.Done()
			},
		},
	)

	// Run the controller and run it until we close stop.
	stop := make(chan struct{})
	go controller.Run(stop)

	pod := func(name, check string) *api.Pod {
		return &api.Pod{
			ObjectMeta: api.ObjectMeta{
				Name:   name,
				Labels: map[string]string{"check": check},
			},
		}
	}

	tests := []func(string){
		func(name string) {
			name = "a-" + name
			source.Add(pod(name, FROM))
			source.Modify(pod(name, TO))
		},
		func(name string) {
			name = "b-" + name
			source.Add(pod(name, FROM))
			source.ModifyDropWatch(pod(name, TO))
		},
		func(name string) {
			name = "c-" + name
			source.AddDropWatch(pod(name, FROM))
			source.Modify(pod(name, ADD_MISSED))
			source.Modify(pod(name, TO))
		},
		func(name string) {
			name = "d-" + name
			source.Add(pod(name, FROM))
		},
	}

	// run every test a few times, in parallel
	const threads = 3
	var wg sync.WaitGroup
	wg.Add(threads * len(tests))
	testDoneWG.Add(threads * len(tests))
	for i := 0; i < threads; i++ {
		for j, f := range tests {
			go func(name string, f func(string)) {
				defer wg.Done()
				f(name)
			}(fmt.Sprintf("%v-%v", i, j), f)
		}
	}
	wg.Wait()

	// Let's wait for the controller to process the things we just added.
	testDoneWG.Wait()
	close(stop)
}
func TestHammerController(t *testing.T) {
	// This test executes a bunch of requests through the fake source and
	// controller framework to make sure there's no locking/threading
	// errors. If an error happens, it should hang forever or trigger the
	// race detector.

	// source simulates an apiserver object endpoint.
	source := framework.NewFakeControllerSource()

	// Let's do threadsafe output to get predictable test results.
	outputSetLock := sync.Mutex{}
	// map of key to operations done on the key
	outputSet := map[string][]string{}

	recordFunc := func(eventType string, obj interface{}) {
		key, err := framework.DeletionHandlingMetaNamespaceKeyFunc(obj)
		if err != nil {
			t.Errorf("something wrong with key: %v", err)
			key = "oops something went wrong with the key"
		}

		// Record some output when items are deleted.
		outputSetLock.Lock()
		defer outputSetLock.Unlock()
		outputSet[key] = append(outputSet[key], eventType)
	}

	// Make a controller which just logs all the changes it gets.
	_, controller := framework.NewInformer(
		source,
		&api.Pod{},
		time.Millisecond*100,
		framework.ResourceEventHandlerFuncs{
			AddFunc:    func(obj interface{}) { recordFunc("add", obj) },
			UpdateFunc: func(oldObj, newObj interface{}) { recordFunc("update", newObj) },
			DeleteFunc: func(obj interface{}) { recordFunc("delete", obj) },
		},
	)

	if controller.HasSynced() {
		t.Errorf("Expected HasSynced() to return false before we started the controller")
	}

	// Run the controller and run it until we close stop.
	stop := make(chan struct{})
	go controller.Run(stop)

	// Let's wait for the controller to do its initial sync
	time.Sleep(100 * time.Millisecond)
	if !controller.HasSynced() {
		t.Errorf("Expected HasSynced() to return true after the initial sync")
	}

	wg := sync.WaitGroup{}
	const threads = 3
	wg.Add(threads)
	for i := 0; i < threads; i++ {
		go func() {
			defer wg.Done()
			// Let's add a few objects to the source.
			currentNames := util.StringSet{}
			rs := rand.NewSource(rand.Int63())
			f := fuzz.New().NilChance(.5).NumElements(0, 2).RandSource(rs)
			r := rand.New(rs) // Mustn't use r and f concurrently!
			for i := 0; i < 100; i++ {
				var name string
				var isNew bool
				if currentNames.Len() == 0 || r.Intn(3) == 1 {
					f.Fuzz(&name)
					isNew = true
				} else {
					l := currentNames.List()
					name = l[r.Intn(len(l))]
				}

				pod := &api.Pod{}
				f.Fuzz(pod)
				pod.ObjectMeta.Name = name
				pod.ObjectMeta.Namespace = "default"
				// Add, update, or delete randomly.
				// Note that these pods are not valid-- the fake source doesn't
				// call validation or perform any other checking.
				if isNew {
					currentNames.Insert(name)
					source.Add(pod)
					continue
				}
				switch r.Intn(2) {
				case 0:
					currentNames.Insert(name)
					source.Modify(pod)
				case 1:
					currentNames.Delete(name)
					source.Delete(pod)
				}
			}
		}()
	}
	wg.Wait()

	// Let's wait for the controller to finish processing the things we just added.
	time.Sleep(100 * time.Millisecond)
	close(stop)

	outputSetLock.Lock()
	t.Logf("got: %#v", outputSet)
}