[service] Add utility module to manage services

cli/cli.go

@@ -3,6 +3,7 @@ package cli
 import (
 	"flag"
 	"fmt"
+	"github.com/cyrilix/robocar-base/service"
 	MQTT "github.com/eclipse/paho.mqtt.golang"
 	"log"
 	"os"
@@ -49,12 +50,7 @@ func SetFloat64DefaultValueFromEnv(value *float64, key string, defaultValue floa
 	return nil
 }
 
-type Part interface {
-	Start() error
-	Stop()
-}
-
-func HandleExit(p Part) {
+func HandleExit(p service.Part) {
 	signals := make(chan os.Signal, 1)
 	signal.Notify(signals, os.Kill, os.Interrupt, syscall.SIGTERM)
 

service/part.go

@@ -0,0 +1,33 @@
+package service
+
+import (
+	"fmt"
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+	"log"
+)
+
+func StopService(name string, client mqtt.Client, topics ...string) {
+	log.Printf("Stop %s service", name)
+	token := client.Unsubscribe(topics...)
+	token.Wait()
+	if token.Error() != nil {
+		log.Printf("unable to unsubscribe service: %v", token.Error())
+	}
+	client.Disconnect(50)
+}
+
+func RegisterCallback(client mqtt.Client, topic string, callback mqtt.MessageHandler) error {
+	log.Printf("Register callback on topic %v", topic)
+	token := client.Subscribe(topic, 0, callback)
+	token.Wait()
+	if token.Error() != nil {
+		return fmt.Errorf("unable to register callback on topic %s: %v", topic, token.Error())
+	}
+	return nil
+}
+
+type Part interface {
+	Start() error
+	Stop()
+}
+