Begin a controller framework.

pkg/controller/framework/controller.go

+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package framework
+
+import (
+	"time"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/cache"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+)
+
+// Config contains all the settings for a Controller.
+type Config struct {
+	// The queue for your objects; either a cache.FIFO or
+	// a cache.DeltaFIFO. Your Process() function should accept
+	// the output of this Oueue's Pop() method.
+	cache.Queue
+
+	// Something that can list and watch your objects.
+	cache.ListerWatcher
+
+	// Something that can process your objects.
+	Process ProcessFunc
+
+	// The type of your objects.
+	ObjectType runtime.Object
+
+	// Reprocess everything at least this often.
+	// Note that if it takes longer for you to clear the queue than this
+	// period, you will end up processing items in the order determined
+	// by cache.FIFO.Replace(). Currently, this is random. If this is a
+	// problem, we can change that replacement policy to append new
+	// things to the end of the queue instead of replacing the entire
+	// queue.
+	FullResyncPeriod time.Duration
+
+	// If true, when Process() returns an error, re-enqueue the object.
+	// TODO: add interface to let you inject a delay/backoff or drop
+	//       the object completely if desired. Pass the object in
+	//       question to this interface as a parameter.
+	RetryOnError bool
+}
+
+// ProcessFunc processes a single object.
+type ProcessFunc func(obj interface{}) error
+
+// Controller is a generic controller framework.
+type Controller struct {
+	config Config
+}
+
+// New makes a new Controller from the given Config.
+func New(c *Config) *Controller {
+	ctlr := &Controller{
+		config: *c,
+	}
+	return ctlr
+}
+
+// Run begins processing items, and will continue until a value is sent down stopCh.
+// It's an error to call Run more than once.
+// Run does not block.
+func (c *Controller) Run(stopCh <-chan struct{}) {
+	cache.NewReflector(
+		c.config.ListerWatcher,
+		c.config.ObjectType,
+		c.config.Queue,
+		c.config.FullResyncPeriod,
+	).RunUntil(stopCh)
+
+	go util.Until(c.processLoop, time.Second, stopCh)
+}
+
+// processLoop drains the work queue.
+// TODO: Consider doing the processing in parallel. This will require a little thought
+// to make sure that we don't end up processing the same object multiple times
+// concurrently.
+func (c *Controller) processLoop() {
+	for {
+		obj := c.config.Queue.Pop()
+		err := c.config.Process(obj)
+		if err != nil {
+			if c.config.RetryOnError {
+				// This is the safe way to re-enqueue.
+				c.config.Queue.AddIfNotPresent(obj)
+			}
+		}
+	}
+}

pkg/controller/framework/controller_test.go

+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package framework_test
+
+import (
+	"fmt"
+	"sync"
+	"time"
+	// "testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/cache"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/controller/framework"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+)
+
+func Example() {
+	// source simulates an apiserver object endpoint.
+	source := framework.NewFakeControllerSource()
+
+	// This will hold the downstream state, as we know it.
+	downstream := cache.NewStore(cache.MetaNamespaceKeyFunc)
+
+	// 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.
+	outputSetLock := sync.Mutex{}
+	outputSet := util.StringSet{}
+
+	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
+				}
+
+				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
+				}
+
+				// Record some output.
+				outputSetLock.Lock()
+				defer outputSetLock.Unlock()
+				outputSet.Insert(key)
+			}
+			return nil
+		},
+	}
+
+	// Create the controller and run it until we close stop.
+	stop := make(chan struct{})
+	framework.New(cfg).Run(stop)
+
+	// Let's add a few objects to the source.
+	for _, name := range []string{"a-hello", "b-controller", "c-framework"} {
+		// 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.
+	time.Sleep(500 * time.Millisecond)
+	close(stop)
+
+	outputSetLock.Lock()
+	for _, key := range outputSet.List() {
+		fmt.Println(key)
+	}
+	// Output:
+	// a-hello
+	// b-controller
+	// c-framework
+}

pkg/controller/framework/doc.go

+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package framework implements all the grunt work involved in running a simple controller.
+package framework

pkg/controller/framework/fake_controller_source.go

+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package framework
+
+import (
+	"errors"
+	"strconv"
+	"sync"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/types"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/watch"
+)
+
+func NewFakeControllerSource() *FakeControllerSource {
+	return &FakeControllerSource{
+		items:       map[nnu]runtime.Object{},
+		broadcaster: watch.NewBroadcaster(100, watch.WaitIfChannelFull),
+	}
+}
+
+// FakeControllerSource implements listing/watching for testing.
+type FakeControllerSource struct {
+	lock        sync.RWMutex
+	items       map[nnu]runtime.Object
+	changes     []watch.Event // one change per resourceVersion
+	broadcaster *watch.Broadcaster
+}
+
+// namespace, name, uid to be used as a key.
+type nnu struct {
+	namespace, name string
+	uid             types.UID
+}
+
+// Add adds an object to the set and sends an add event to watchers.
+// obj's ResourceVersion is set.
+func (f *FakeControllerSource) Add(obj runtime.Object) {
+	f.change(watch.Event{watch.Added, obj})
+}
+
+// Modify updates an object in the set and sends a modified event to watchers.
+// obj's ResourceVersion is set.
+func (f *FakeControllerSource) Modify(obj runtime.Object) {
+	f.change(watch.Event{watch.Modified, obj})
+}
+
+// Delete deletes an object from the set and sends a delete event to watchers.
+// obj's ResourceVersion is set.
+func (f *FakeControllerSource) Delete(lastValue runtime.Object) {
+	f.change(watch.Event{watch.Deleted, lastValue})
+}
+
+func (f *FakeControllerSource) key(meta *api.ObjectMeta) nnu {
+	return nnu{meta.Namespace, meta.Name, meta.UID}
+}
+
+func (f *FakeControllerSource) change(e watch.Event) {
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	objMeta, err := api.ObjectMetaFor(e.Object)
+	if err != nil {
+		panic(err) // this is test code only
+	}
+
+	resourceVersion := len(f.changes)
+	objMeta.ResourceVersion = strconv.Itoa(resourceVersion)
+	f.changes = append(f.changes, e)
+	key := f.key(objMeta)
+	switch e.Type {
+	case watch.Added, watch.Modified:
+		f.items[key] = e.Object
+	case watch.Deleted:
+		delete(f.items, key)
+	}
+	f.broadcaster.Action(e.Type, e.Object)
+}
+
+// List returns a list object, with its resource version set.
+func (f *FakeControllerSource) List() (runtime.Object, error) {
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+	list := make([]runtime.Object, 0, len(f.items))
+	for _, obj := range f.items {
+		// TODO: should copy obj first
+		list = append(list, obj)
+	}
+	listObj := &api.List{}
+	if err := runtime.SetList(listObj, list); err != nil {
+		return nil, err
+	}
+	objMeta, err := api.ListMetaFor(listObj)
+	if err != nil {
+		return nil, err
+	}
+	resourceVersion := len(f.changes)
+	objMeta.ResourceVersion = strconv.Itoa(resourceVersion)
+	return listObj, nil
+}
+
+// Watch returns a watch, which will be pre-populated with all changes
+// after resourceVersion.
+func (f *FakeControllerSource) Watch(resourceVersion string) (watch.Interface, error) {
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+	rc, err := strconv.Atoi(resourceVersion)
+	if err != nil {
+		return nil, err
+	}
+	if rc < len(f.changes) {
+		return f.broadcaster.WatchWithPrefix(f.changes[rc:]), nil
+	} else if rc > len(f.changes) {
+		return nil, errors.New("resource version in the future not supported by this fake")
+	}
+	return f.broadcaster.Watch(), nil
+}

pkg/util/util.go

@@ -88,10 +88,14 @@ func logError(err error) {
 }
 
 // Forever loops forever running f every period.  Catches any panics, and keeps going.
+// Deprecated. Please use Until and pass NeverStop as the stopCh.
 func Forever(f func(), period time.Duration) {
 	Until(f, period, nil)
 }
 
+// NeverStop may be passed to Until to make it never stop.
+var NeverStop <-chan struct{} = make(chan struct{})
+
 // Until loops until stop channel is closed, running f every period.
 // Catches any panics, and keeps going. f may not be invoked if
 // stop channel is already closed.

pkg/watch/mux.go

@@ -89,6 +89,32 @@ func (m *Broadcaster) Watch() Interface {
 	return w
 }
 
+// WatchWithPrefix adds a new watcher to the list and returns an Interface for it. It sends
+// queuedEvents down the new watch before beginning to send ordinary events from Broadcaster.
+// The returned watch will have a queue length that is at least large enough to accomodate
+// all of the items in queuedEvents.
+func (m *Broadcaster) WatchWithPrefix(queuedEvents []Event) Interface {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+	id := m.nextWatcher
+	m.nextWatcher++
+	length := m.watchQueueLength
+	if n := len(queuedEvents) + 1; n > length {
+		length = n
+	}
+	w := &broadcasterWatcher{
+		result:  make(chan Event, length),
+		stopped: make(chan struct{}),
+		id:      id,
+		m:       m,
+	}
+	m.watchers[id] = w
+	for _, e := range queuedEvents {
+		w.result <- e
+	}
+	return w
+}
+
 // stopWatching stops the given watcher and removes it from the list.
 func (m *Broadcaster) stopWatching(id int64) {
 	m.lock.Lock()