stop the service properly and update doc

services/sender.go

@@ -5,8 +5,10 @@ import (
 	"mailsrv/mail"
 	"mailsrv/runtime"
 	"os"
+	"os/signal"
 	"path"
 	"strings"
+	"syscall"
 	"time"
 
 	"github.com/go-kit/kit/log"
@@ -50,7 +52,7 @@ func (s Sender) SendMail(email mail.Email) error {
 	return nil
 }
 
-// every `TickerInterval` reads the `outbox` directory and put JSON format e-mail in the queue
+// watchOutbox reads the `outbox` directory every `TickInterval` and put JSON format e-mail in the queue
 func (s Sender) watchOutbox() {
 	ticker := time.NewTicker(TickerInterval)
 	go func() {
@@ -75,8 +77,8 @@ func (s Sender) watchOutbox() {
 	}()
 }
 
-// loops over the queue and send email
-func (s Sender) processNextMail() bool {
+// processNextEmail loops over the queue and send email
+func (s Sender) processNextEmail() bool {
 	item, quit := s.queue.Get()
 	if quit {
 		return false
@@ -104,10 +106,32 @@ func (s Sender) processNextMail() bool {
 	return true
 }
 
+// run starts processing the queue
+func (s Sender) run() <-chan struct{} {
+	queueCh := make(chan struct{})
+	go func() {
+		for s.processNextEmail() {
+		}
+		queueCh <- struct{}{}
+	}()
+	return queueCh
+}
+
+// Run launches the queue processing and the outbox watcher
+// catches `SIGINT` and `SIGTERM` to properly stopped the queue
 func (s Sender) Run() {
 	s.logger.Log("msg", "sender service is running")
 
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
+
 	s.watchOutbox()
-	for s.processNextMail() {
-	}
+	queueCh := s.run()
+
+	<-sigCh
+	s.logger.Log("msg", "stop signal received, stopping e-mail queue...")
+	s.queue.Shutdown()
+
+	<-queueCh
+	s.logger.Log("msg", "sender service stopped successfully")
 }