migrate to signal.Semaphore and Notifier

common/signal/notifier.go

@@ -0,0 +1,22 @@
+package signal
+
+type Notifier struct {
+	c chan bool
+}
+
+func NewNotifier() *Notifier {
+	return &Notifier{
+		c: make(chan bool, 1),
+	}
+}
+
+func (n *Notifier) Signal() {
+	select {
+	case n.c <- true:
+	default:
+	}
+}
+
+func (n *Notifier) Wait() <-chan bool {
+	return n.c
+}