From 740b824ac2ebdf64c11acd585f6e5a896f8241d5 Mon Sep 17 00:00:00 2001
From: Clayton Coleman <ccoleman@redhat.com>
Date: Fri, 28 Nov 2014 15:14:49 -0500
Subject: [PATCH] Add a util.Forever variant that ends on a stop channel

---
 pkg/util/util.go      | 12 ++++++++++++
 pkg/util/util_test.go | 20 ++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/pkg/util/util.go b/pkg/util/util.go
index 7baffc31af7..3216146b90a 100644
--- a/pkg/util/util.go
+++ b/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()
diff --git a/pkg/util/util_test.go b/pkg/util/util_test.go
index 2c253c33a27..48bc07e2e0f 100644
--- a/pkg/util/util_test.go
+++ b/pkg/util/util_test.go
@@ -24,6 +24,26 @@ import (
 	"gopkg.in/v1/yaml"
 )
 
+func TestUntil(t *testing.T) {
+	ch := make(chan struct{})
+	close(ch)
+	Until(func() {
+		t.Fatal("should not have been invoked")
+	}, 0, ch)
+
+	ch = make(chan struct{})
+	called := make(chan struct{})
+	go func() {
+		Until(func() {
+			called <- struct{}{}
+		}, 0, ch)
+		close(called)
+	}()
+	<-called
+	close(ch)
+	<-called
+}
+
 func TestHandleCrash(t *testing.T) {
 	count := 0
 	expect := 10