Add a util.Forever variant that ends on a stop channel

pkg/util/util.go

@@ -51,7 +51,19 @@ func HandleCrash() {
 
 // Forever loops forever running f every d.  Catches any panics, and keeps going.
 func Forever(f func(), period time.Duration) {
+	Until(f, period, nil)
+}
+
+// Until loops until stop channel is closed, running f every d.
+// Catches any panics, and keeps going. f may not be invoked if
+// stop channel is already closed.
+func Until(f func(), period time.Duration, stopCh <-chan struct{}) {
 	for {
+		select {
+		case <-stopCh:
+			return
+		default:
+		}
 		func() {
 			defer HandleCrash()
 			f()