fix: rework sync logic

README.md

@@ -10,5 +10,6 @@ waiter.AddCloseHandler(func() {
 		nacl.FinalizeStan()
 	}, false)
 
+// blocking wait, if no need to block (with http server, for example), you can omit .Wait() call
 waiter.Wait()
 ```

close_handler.go

@@ -2,7 +2,7 @@ package grawt
 
 type CloseHandler struct {
 	waiter      *Waiter
-	Quit        chan bool
+	Quit        chan struct{}
 	active      bool
 	autoDone    bool
 	handlerFunc *func()
@@ -11,7 +11,3 @@ type CloseHandler struct {
 func (ch *CloseHandler) Halt(err error) {
 	ch.waiter.Halt(err)
 }
-
-func (ch *CloseHandler) Done() {
-	ch.waiter.terminateHandler(ch, true)
-}

go.mod

@@ -1,3 +1,5 @@
 module github.com/jar3b/grawt
 
-require github.com/sirupsen/logrus v1.4.1
+go 1.15
+
+require github.com/sirupsen/logrus v1.7.0

go.sum

@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.7.0 h1:ShrD1U9pZB12TX0cVy0DtePoCH97K8EtX+mg7ZARUtM=
+github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/sys v0.0.0-20191026070338-33540a1f6037 h1:YyJpGZS1sBuBCzLAR1VEpK193GlqGZbnPFnPV/5Rsb4=
+golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

waiter.go

@@ -9,32 +9,45 @@ import (
 )
 
 type Waiter struct {
+	sync.RWMutex
+	blockingMode  bool
 	waitGroup     sync.WaitGroup
 	closeHandlers []*CloseHandler
+	isHalting     bool
 }
 
 func (w *Waiter) addHandler(f *func(), autoDone bool) *CloseHandler {
 	ch := CloseHandler{
-		w,
+		waiter:      w,
-		make(chan bool, 1),
+		Quit:        make(chan struct{}, 1),
-		true,
+		active:      true,
-		autoDone,
+		autoDone:    autoDone,
-		f,
+		handlerFunc: f,
 	}
+
+	w.Lock()
 	w.waitGroup.Add(1)
 	w.closeHandlers = append(w.closeHandlers, &ch)
+	w.Unlock()
 
 	return &ch
 }
 
 func (w *Waiter) terminateHandler(h *CloseHandler, forceWaitGroupDone bool) {
+	if !h.active {
+		return
+	}
 	if h.handlerFunc != nil && *h.handlerFunc != nil {
 		(*h.handlerFunc)()
 	}
-	h.Quit <- true
+
+	if h.active {
+		close(h.Quit)
+	}
 	if h.autoDone || forceWaitGroupDone {
 		w.waitGroup.Done()
 	}
+
 	h.active = false
 }
 
@@ -43,19 +56,35 @@ func (w *Waiter) AddCloseHandler(f func(), waitForChannel bool) *CloseHandler {
 }
 
 func (w *Waiter) Halt(err error) {
+	if w.isHalting {
+		return
+	}
+	w.isHalting = true
+
+	w.RLock()
 	for _, h := range w.closeHandlers {
-		if h.active {
 		w.terminateHandler(h, false)
 	}
-	}
+	w.RUnlock()
+
 	if err != nil {
 		log.Errorf("Program was terminated with error: %v", err)
 	} else {
 		log.Info("Program was terminated gracefully.")
 	}
+	if !w.blockingMode {
+		if err != nil {
+			os.Exit(1)
+		} else {
+			os.Exit(0)
+		}
+	}
+
+	w.isHalting = false
 }
 
 func (w *Waiter) Wait() {
+	w.blockingMode = true
 	log.Info("Waiting...")
 	w.waitGroup.Wait()
 }
@@ -67,8 +96,11 @@ func (w *Waiter) onSignal(sig os.Signal) {
 
 func NewWaiter() *Waiter {
 	w := Waiter{
+		sync.RWMutex{},
+		false,
 		sync.WaitGroup{},
 		make([]*CloseHandler, 0),
+		false,
 	}
 	sigs := make(chan os.Signal, 1)
 	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)