fix(kuma-cp): don't wait before ticking the first time in watchdog (#…

…11105)

This delays xds config generation unnecessarily. Closes #11094

* fix(kuma-cp): don't wait before ticking the first time in watchdog
* test(watchdog): update test flow because we immedately trigger once

Signed-off-by: Mike Beaumont <[email protected]>

pkg/util/watchdog/watchdog.go

@@ -32,23 +32,26 @@ func (w *SimpleWatchdog) Start(stop <-chan struct{}) {
 			case <-ctx.Done():
 			}
 		}()
+
 		select {
-		case <-ticker.C:
-			select {
-			case <-stop:
-			default:
-				if err := w.onTick(ctx); err != nil && !errors.Is(err, context.Canceled) {
-					w.OnError(err)
-				}
+		case <-stop:
+		default:
+			if err := w.onTick(ctx); err != nil && !errors.Is(err, context.Canceled) {
+				w.OnError(err)
 			}
+		}
+		cancel()
+
+		select {
+		case <-ticker.C:
+			continue
 		case <-stop:
 			if w.OnStop != nil {
 				w.OnStop()
 			}
 			// cancel will be called by the above goroutine
 			return
 		}
-		cancel()
 	}
 }
 

pkg/util/watchdog/watchdog_test.go

@@ -51,11 +51,7 @@ var _ = Describe("SimpleWatchdog", func() {
 			close(doneCh)
 		}()
 
-		By("simulating 1st tick")
-		// when
-		timeTicks <- time.Time{}
-
-		// then
+		// then first tick happens "immediately"
 		<-onTickCalls
 
 		By("simulating 2nd tick")
@@ -98,11 +94,7 @@ var _ = Describe("SimpleWatchdog", func() {
 			close(doneCh)
 		}()
 
-		By("simulating 1st tick")
-		// when
-		timeTicks <- time.Time{}
-
-		// then
+		// then first tick happens "immediately"
 		actualErr := <-onErrorCalls
 		Expect(actualErr).To(MatchError(expectedErr))
 
@@ -135,7 +127,6 @@ var _ = Describe("SimpleWatchdog", func() {
 			watchdog.Start(stopCh)
 			close(doneCh)
 		}()
-		timeTicks <- time.Time{}
 
 		// then watchdog returned an error
 		Expect(<-onErrorCalls).To(HaveOccurred())