hidden goroutine++

go/statemachine.go

@@ -6,6 +6,19 @@ package main
 type fooReq struct{}
 type barReq struct{}
 
+// really though this should take a context, pass it to loop(),
+// and select on ctx.Done()
+func NewStateMachine() *stateMachine {
+    sm := &stateMachine{
+	state: "initial",
+	fooc: make(chan fooReq),
+	barc: make(chan fooReq),
+	quitc: make(chan chan struct{}),
+    }
+    go sm.loop()
+    return sm
+}
+
 type stateMachine struct {
     state string
     fooc chan fooReq
@@ -19,6 +32,14 @@ func (sm *stateMachine) foo() int {
     return <-c
 }
 
+func (sm *stateMachine) stop() {
+    q := make(chan struct{})
+    sm.quitc <- q
+
+    // block return until the select in loop() hits
+    <-q
+}
+
 func (sm *stateMachine) loop() {
     for {
 	select {
@@ -26,7 +47,8 @@ func (sm *stateMachine) loop() {
 	    sm.handleFoo(r)
 	case r := <-sm.barc:
 	    sm.handleBar(r)
-	case: <-sm.quitc:
+	case: q := <-sm.quitc:
+	    close(q)
 	    return
 	}
     }