Optimize and clean the controller code (#1639)

- fix outdated comments
- reorder the code to reduce the  number of defer calls
- various other nits
"

controller/controller.go

@@ -216,10 +216,13 @@ type ControllerOptions struct {
 
 // NewImpl instantiates an instance of our controller that will feed work to the
 // provided Reconciler as it is enqueued.
+// Deprecated: use NewImplFull.
 func NewImpl(r Reconciler, logger *zap.SugaredLogger, workQueueName string) *Impl {
 	return NewImplFull(r, ControllerOptions{WorkQueueName: workQueueName, Logger: logger})
 }
 
+// NewImplWithStats creates a controller.Impl with stats reporter.
+// Deprecated: use NewImplFull.
 func NewImplWithStats(r Reconciler, logger *zap.SugaredLogger, workQueueName string, reporter StatsReporter) *Impl {
 	return NewImplFull(r, ControllerOptions{WorkQueueName: workQueueName, Logger: logger, Reporter: reporter})
 }
@@ -416,15 +419,14 @@ func (c *Impl) EnqueueKeyAfter(key types.NamespacedName, delay time.Duration) {
 // internal work queue and waits for workers to finish processing their current
 // work items.
 func (c *Impl) RunContext(ctx context.Context, threadiness int) error {
-	logger := c.logger
-	defer runtime.HandleCrash()
 	sg := sync.WaitGroup{}
-	defer sg.Wait()
 	defer func() {
 		c.workQueue.ShutDown()
 		for c.workQueue.Len() > 0 {
 			time.Sleep(time.Millisecond * 100)
 		}
+		sg.Wait()
+		runtime.HandleCrash()
 	}()
 
 	if la, ok := c.Reconciler.(reconciler.LeaderAware); ok {
@@ -441,7 +443,7 @@ func (c *Impl) RunContext(ctx context.Context, threadiness int) error {
 	}
 
 	// Launch workers to process resources that get enqueued to our workqueue.
-	logger.Info("Starting controller and workers")
+	c.logger.Info("Starting controller and workers")
 	for i := 0; i < threadiness; i++ {
 		sg.Add(1)
 		go func() {
@@ -451,9 +453,9 @@ func (c *Impl) RunContext(ctx context.Context, threadiness int) error {
 		}()
 	}
 
-	logger.Info("Started workers")
+	c.logger.Info("Started workers")
 	<-ctx.Done()
-	logger.Info("Shutting down workers")
+	c.logger.Info("Shutting down workers")
 
 	return nil
 }
@@ -485,13 +487,6 @@ func (c *Impl) processNextWorkItem() bool {
 	// Send the metrics for the current queue depth
 	c.statsReporter.ReportQueueDepth(int64(c.workQueue.Len()))
 
-	// We call Done here so the workqueue knows we have finished
-	// processing this item. We also must remember to call Forget if
-	// reconcile succeeds. If a transient error occurs, we do not call
-	// Forget and put the item back to the queue with an increased
-	// delay.
-	defer c.workQueue.Done(key)
-
 	var err error
 	defer func() {
 		status := trueString
@@ -499,6 +494,13 @@ func (c *Impl) processNextWorkItem() bool {
 			status = falseString
 		}
 		c.statsReporter.ReportReconcile(time.Since(startTime), status)
+
+		// We call Done here so the workqueue knows we have finished
+		// processing this item. We also must remember to call Forget if
+		// reconcile succeeds. If a transient error occurs, we do not call
+		// Forget and put the item back to the queue with an increased
+		// delay.
+		c.workQueue.Done(key)
 	}()
 
 	// Embed the key into the logger and attach that to the context we pass
@@ -544,8 +546,8 @@ func (c *Impl) GlobalResync(si cache.SharedInformer) {
 	c.FilteredGlobalResync(alwaysTrue, si)
 }
 
-// FilteredGlobalResync enqueues (with a delay) all objects from the
-// SharedInformer that pass the filter function
+// FilteredGlobalResync enqueues all objects from the
+// SharedInformer that pass the filter function in to the slow queue.
 func (c *Impl) FilteredGlobalResync(f func(interface{}) bool, si cache.SharedInformer) {
 	if c.workQueue.ShuttingDown() {
 		return