Split implementations from generic code

core/pkg/task/queue.go

@@ -0,0 +1,123 @@
+/*
+Copyright 2015 The Kubernetes Authors.
+
+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 task
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/golang/glog"
+
+	"k8s.io/kubernetes/pkg/client/cache"
+	"k8s.io/kubernetes/pkg/util/wait"
+	"k8s.io/kubernetes/pkg/util/workqueue"
+)
+
+var (
+	keyFunc = cache.DeletionHandlingMetaNamespaceKeyFunc
+)
+
+// Queue manages a work queue through an independent worker that
+// invokes the given sync function for every work item inserted.
+type Queue struct {
+	// queue is the work queue the worker polls
+	queue workqueue.RateLimitingInterface
+	// sync is called for each item in the queue
+	sync func(interface{}) error
+	// workerDone is closed when the worker exits
+	workerDone chan struct{}
+
+	fn func(obj interface{}) (interface{}, error)
+}
+
+// Run ...
+func (t *Queue) Run(period time.Duration, stopCh <-chan struct{}) {
+	wait.Until(t.worker, period, stopCh)
+}
+
+// Enqueue enqueues ns/name of the given api object in the task queue.
+func (t *Queue) Enqueue(obj interface{}) {
+	glog.V(3).Infof("queuing item %v", obj)
+	key, err := t.fn(obj)
+	if err != nil {
+		glog.Errorf("%v", err)
+		return
+	}
+	t.queue.Add(key)
+}
+
+func (t *Queue) defaultKeyFunc(obj interface{}) (interface{}, error) {
+	key, err := keyFunc(obj)
+	if err != nil {
+		return "", fmt.Errorf("could not get key for object %+v: %v", obj, err)
+	}
+
+	return key, nil
+}
+
+// worker processes work in the queue through sync.
+func (t *Queue) worker() {
+	for {
+		key, quit := t.queue.Get()
+		if quit {
+			close(t.workerDone)
+			return
+		}
+		glog.V(3).Infof("syncing %v", key)
+		if err := t.sync(key); err != nil {
+			glog.Warningf("requeuing %v, err %v", key, err)
+			t.queue.AddRateLimited(key)
+		} else {
+			t.queue.Forget(key)
+		}
+
+		t.queue.Done(key)
+	}
+}
+
+// Shutdown shuts down the work queue and waits for the worker to ACK
+func (t *Queue) Shutdown() {
+	t.queue.ShutDown()
+	<-t.workerDone
+}
+
+// IsShuttingDown returns if the method Shutdown was invoked
+func (t *Queue) IsShuttingDown() bool {
+	return t.queue.ShuttingDown()
+}
+
+// NewTaskQueue creates a new task queue with the given sync function.
+// The sync function is called for every element inserted into the queue.
+func NewTaskQueue(syncFn func(interface{}) error) *Queue {
+	return NewCustomTaskQueue(syncFn, nil)
+}
+
+// NewCustomTaskQueue ...
+func NewCustomTaskQueue(syncFn func(interface{}) error, fn func(interface{}) (interface{}, error)) *Queue {
+	q := &Queue{
+		queue:      workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter()),
+		sync:       syncFn,
+		workerDone: make(chan struct{}),
+		fn:         fn,
+	}
+
+	if fn == nil {
+		q.fn = q.defaultKeyFunc
+	}
+
+	return q
+}