Return receive-only channel in GetMsgChan() (#350)

This is a small improvement: the message channel retrieved from the
collecting process should be "receive-only".

Signed-off-by: Antonin Bas <antonin.bas@broadcom.com>

pkg/collector/process.go

@@ -127,7 +127,7 @@ func (cp *CollectingProcess) GetAddress() net.Addr {
 	return cp.netAddress
 }
 
-func (cp *CollectingProcess) GetMsgChan() chan *entities.Message {
+func (cp *CollectingProcess) GetMsgChan() <-chan *entities.Message {
 	return cp.messageChan
 }
 

pkg/intermediate/aggregate.go

@@ -43,7 +43,7 @@ type AggregationProcess struct {
 	// mutex allows multiple readers or one writer at the same time
 	mutex sync.RWMutex
 	// messageChan is the channel to receive the message
-	messageChan chan *entities.Message
+	messageChan <-chan *entities.Message
 	// workerNum is the number of workers to process the messages
 	workerNum int
 	// workerList is the list of workers
@@ -71,7 +71,7 @@ type AggregationProcess struct {
 }
 
 type AggregationInput struct {
-	MessageChan           chan *entities.Message
+	MessageChan           <-chan *entities.Message
 	WorkerNum             int
 	CorrelateFields       []string
 	AggregateElements     *AggregationElements

pkg/intermediate/worker.go

@@ -8,12 +8,12 @@ import (
 
 type worker struct {
 	id          int
-	messageChan chan *entities.Message
+	messageChan <-chan *entities.Message
 	errChan     chan bool
 	job         func(*entities.Message) error
 }
 
-func createWorker(id int, messageChan chan *entities.Message, job func(*entities.Message) error) *worker {
+func createWorker(id int, messageChan <-chan *entities.Message, job func(*entities.Message) error) *worker {
 	return &worker{
 		id,
 		messageChan,

pkg/kafka/producer/kafka.go

@@ -186,7 +186,7 @@ func (kp *KafkaProducer) SendFlowMessage(msg protoreflect.Message, kafkaDelimitM
 // PublishIPFIXMessages takes in a message channel as input and converts all the messages on
 // the message channel to flow messages in proto schema. This function exits when
 // the input message channel is closed.
-func (kp *KafkaProducer) PublishIPFIXMessages(msgCh chan *entities.Message) {
+func (kp *KafkaProducer) PublishIPFIXMessages(msgCh <-chan *entities.Message) {
 	for msg := range msgCh {
 		flowMsgs := kp.input.ProtoSchemaConvertor.ConvertIPFIXMsgToFlowMsgs(msg)
 		for _, flowMsg := range flowMsgs {