Improve Start functions

staging/src/k8s.io/apimachinery/pkg/util/wait/wait.go

@@ -17,9 +17,9 @@ limitations under the License.
 package wait
 
 import (
+	"context"
 	"errors"
 	"math/rand"
-	"sync"
 	"time"
 
 	"k8s.io/apimachinery/pkg/util/runtime"
@@ -37,12 +37,34 @@ var ForeverTestTimeout = time.Second * 30
 // NeverStop may be passed to Until to make it never stop.
 var NeverStop <-chan struct{} = make(chan struct{})
 
-// StartUntil starts f in a new goroutine and calls done once f has finished.
-func StartUntil(stopCh <-chan struct{}, wg *sync.WaitGroup, f func(stopCh <-chan struct{})) {
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
+// Group is an interface to decouple code from sync.WaitGroup.
+type Group interface {
+	Add(delta int)
+	Done()
+}
+
+// StartWithChannelWithinGroup adds 1 to the group, starts f in a new goroutine and calls g.Done once f has finished.
+// stopCh is passed to f as an argument. f should stop when stopCh is available.
+func StartWithChannelWithinGroup(stopCh <-chan struct{}, g Group, f func(stopCh <-chan struct{})) {
+	StartWithinGroup(g, func() {
 		f(stopCh)
+	})
+}
+
+// StartWithContextWithinGroup adds 1 to the group, starts f in a new goroutine and calls g.Done once f has finished.
+// ctx is passed to f as an argument. f should stop when ctx.Done() is available.
+func StartWithContextWithinGroup(ctx context.Context, g Group, f func(context.Context)) {
+	StartWithinGroup(g, func() {
+		f(ctx)
+	})
+}
+
+// StartWithinGroup adds 1 to the group, starts f in a new goroutine and calls g.Done once f has finished.
+func StartWithinGroup(g Group, f func()) {
+	g.Add(1)
+	go func() {
+		defer g.Done()
+		f()
 	}()
 }
 

staging/src/k8s.io/client-go/tools/cache/controller.go

@@ -119,7 +119,7 @@ func (c *controller) Run(stopCh <-chan struct{}) {
 	var wg sync.WaitGroup
 	defer wg.Wait()
 
-	wait.StartUntil(stopCh, &wg, r.Run)
+	wait.StartWithChannelWithinGroup(stopCh, &wg, r.Run)
 
 	wait.Until(c.processLoop, time.Second, stopCh)
 }

staging/src/k8s.io/client-go/tools/cache/shared_informer.go

@@ -211,8 +211,8 @@ func (s *sharedIndexInformer) Run(stopCh <-chan struct{}) {
 
 	defer s.wg.Wait()
 
-	wait.StartUntil(stopCh, &s.wg, s.cacheMutationDetector.Run)
-	wait.StartUntil(stopCh, &s.wg, s.processor.run)
+	wait.StartWithChannelWithinGroup(stopCh, &s.wg, s.cacheMutationDetector.Run)
+	wait.StartWithChannelWithinGroup(stopCh, &s.wg, s.processor.run)
 	s.controller.Run(stopCh)
 }
 
@@ -327,8 +327,8 @@ func (s *sharedIndexInformer) AddEventHandlerWithResyncPeriod(handler ResourceEv
 
 	s.processor.addListener(listener)
 
-	wait.StartUntil(s.stopCh, &s.wg, listener.run)
-	wait.StartUntil(s.stopCh, &s.wg, listener.pop)
+	wait.StartWithChannelWithinGroup(s.stopCh, &s.wg, listener.run)
+	wait.StartWithChannelWithinGroup(s.stopCh, &s.wg, listener.pop)
 
 	items := s.indexer.List()
 	for i := range items {
@@ -403,8 +403,8 @@ func (p *sharedProcessor) run(stopCh <-chan struct{}) {
 		p.listenersLock.RLock()
 		defer p.listenersLock.RUnlock()
 		for _, listener := range p.listeners {
-			wait.StartUntil(stopCh, &wg, listener.run)
-			wait.StartUntil(stopCh, &wg, listener.pop)
+			wait.StartWithChannelWithinGroup(stopCh, &wg, listener.run)
+			wait.StartWithChannelWithinGroup(stopCh, &wg, listener.pop)
 		}
 	}()
 	wg.Wait()