Fix map ordering in consumers

Signed-off-by: dusan <borovcanindusan1@gmail.com>

queue/consumer/group.go

@@ -227,6 +227,9 @@ type Group struct {
 	id        string
 	queueName string
 	consumers map[string]*types.Consumer
+	sortedIDs []string
+	idsDirty  bool
+	rrIndex   int
 	mu        sync.RWMutex
 }
 
@@ -250,6 +253,7 @@ func (cg *Group) AddConsumer(consumer *types.Consumer) {
 	defer cg.mu.Unlock()
 
 	cg.consumers[consumer.ID] = consumer
+	cg.idsDirty = true
 }
 
 // RemoveConsumer removes a consumer from the group.
@@ -258,6 +262,11 @@ func (cg *Group) RemoveConsumer(consumerID string) {
 	defer cg.mu.Unlock()
 
 	delete(cg.consumers, consumerID)
+	cg.idsDirty = true
+	if len(cg.consumers) == 0 {
+		cg.sortedIDs = nil
+		cg.rrIndex = 0
+	}
 }
 
 // GetConsumer returns a consumer by ID.
@@ -291,16 +300,35 @@ func (cg *Group) Size() int {
 
 // GetNextConsumer returns the next consumer for round-robin message delivery.
 func (cg *Group) GetNextConsumer() (*types.Consumer, bool) {
-	cg.mu.RLock()
-	defer cg.mu.RUnlock()
+	cg.mu.Lock()
+	defer cg.mu.Unlock()
 
 	if len(cg.consumers) == 0 {
 		return nil, false
 	}
 
-	// Simple round-robin: return first consumer
-	// For proper round-robin with state, use an external counter
-	for _, consumer := range cg.consumers {
+	if cg.idsDirty {
+		ids := make([]string, 0, len(cg.consumers))
+		for id := range cg.consumers {
+			ids = append(ids, id)
+		}
+		sort.Strings(ids)
+		cg.sortedIDs = ids
+		cg.idsDirty = false
+	}
+
+	if cg.rrIndex >= len(cg.sortedIDs) {
+		cg.rrIndex = 0
+	}
+
+	id := cg.sortedIDs[cg.rrIndex]
+	cg.rrIndex++
+	if cg.rrIndex >= len(cg.sortedIDs) {
+		cg.rrIndex = 0
+	}
+
+	consumer, exists := cg.consumers[id]
+	if exists {
 		return consumer, true
 	}