Refactor gateway module to remove mqtt dependency

pkg/events/events.go

@@ -0,0 +1,145 @@
+package events
+
+import (
+	"fmt"
+	"github.com/cyrilix/robocar-simulator/pkg/gateway"
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+	"github.com/golang/protobuf/proto"
+	log "github.com/sirupsen/logrus"
+	"sync"
+	"time"
+)
+
+func NewMsgPublisher(srcEvents gateway.SimulatorSource, p Publisher, topicFrame, topicSteering, topicThrottle string) *MsgPublisher {
+	return &MsgPublisher{
+		p:             p,
+		topicFrame:    topicFrame,
+		topicSteering: topicSteering,
+		topicThrottle: topicThrottle,
+		srcEvents:     srcEvents,
+		muCancel:      sync.Mutex{},
+		cancel:        nil,
+	}
+}
+
+type MsgPublisher struct {
+	p             Publisher
+	topicFrame    string
+	topicSteering string
+	topicThrottle string
+
+	srcEvents gateway.SimulatorSource
+
+	muCancel sync.Mutex
+	cancel   chan interface{}
+}
+
+func (m *MsgPublisher) Start() {
+	m.muCancel.Lock()
+	defer m.muCancel.Unlock()
+
+	m.cancel = make(chan interface{})
+
+	if m.topicThrottle != "" {
+		go m.listenThrottle()
+	}
+	if m.topicSteering != "" {
+		go m.listenSteering()
+	}
+	if m.topicFrame != "" {
+		go m.listenFrame()
+	}
+}
+
+func (m *MsgPublisher) Stop() {
+	m.muCancel.Lock()
+	defer m.muCancel.Unlock()
+	close(m.cancel)
+	m.cancel = nil
+}
+
+func (m *MsgPublisher) listenThrottle() {
+	logr := log.WithField("msg_type", "throttleChan")
+	msgChan := m.srcEvents.SubscribeThrottle()
+	for {
+		select {
+		case <-m.cancel:
+			logr.Debug("exit listen throttleChan loop")
+			return
+		case msg := <-msgChan:
+
+			payload, err := proto.Marshal(msg)
+			if err != nil {
+				logr.Errorf("unable to marshal protobuf message: %v", err)
+			} else {
+
+				err = m.p.Publish(m.topicThrottle, payload)
+				if err != nil {
+					logr.Errorf("unable to publish events message: %v", err)
+				}
+			}
+		}
+	}
+}
+
+func (m *MsgPublisher) listenSteering() {
+	logr := log.WithField("msg_type", "steeringChan")
+	msgChan := m.srcEvents.SubscribeSteering()
+	for {
+		select {
+
+		case msg := <-msgChan:
+			if m.topicSteering == "" {
+				return
+			}
+
+			payload, err := proto.Marshal(msg)
+			if err != nil {
+				logr.Errorf("unable to marshal protobuf message: %v", err)
+			} else {
+				err = m.p.Publish(m.topicSteering, payload)
+				if err != nil {
+					logr.Errorf("unable to publish events message: %v", err)
+				}
+			}
+		}
+	}
+}
+
+func (m *MsgPublisher) listenFrame() {
+	logr := log.WithField("msg_type", "frame")
+	msgChan := m.srcEvents.SubscribeFrame()
+	for {
+		msg := <-msgChan
+		if m.topicFrame == "" {
+			return
+		}
+
+		payload, err := proto.Marshal(msg)
+		if err != nil {
+			logr.Errorf("unable to marshal protobuf message: %v", err)
+			continue
+		}
+		err = m.p.Publish(m.topicFrame, payload)
+		if err != nil {
+			logr.Errorf("unable to publish events message: %v", err)
+		}
+	}
+}
+
+type Publisher interface {
+	Publish(topic string, payload []byte) error
+}
+
+type MqttPublisher struct {
+	client mqtt.Client
+}
+
+func (m *MqttPublisher) Publish(topic string, payload []byte) error {
+	token := m.client.Publish(topic, 0, false, payload)
+	token.WaitTimeout(10 * time.Millisecond)
+	if err := token.Error(); err != nil {
+		return fmt.Errorf("unable to events to topic: %v", err)
+	}
+	return nil
+}