Fix error handling when query fails (#2255)

plugin/loop/loop.go

@@ -77,6 +77,12 @@ func (l *Loop) inc() {
 	l.i++
 }
 
+func (l *Loop) reset() {
+	l.Lock()
+	defer l.Unlock()
+	l.i = 0
+}
+
 func (l *Loop) setDisabled() {
 	l.Lock()
 	defer l.Unlock()

plugin/loop/setup.go

@@ -42,6 +42,7 @@ func setup(c *caddy.Controller) error {
 
 			for time.Now().Before(deadline) {
 				if _, err := l.exchange(addr); err != nil {
+					l.reset()
 					time.Sleep(1 * time.Second)
 					continue
 				}