Wrote forwarder.

initiator/worker.go

@@ -1,6 +1,7 @@
 package initiator
 
 import (
+	"container/list"
 	"git.wisehodl.dev/jay/go-honeybee/transport"
 	"sync"
 	"time"
@@ -8,6 +9,11 @@ import (
 
 // Worker
 
+type receivedMessage struct {
+	data       []byte
+	receivedAt time.Time
+}
+
 type Worker struct {
 	id     string
 	stop   <-chan struct{}
@@ -49,8 +55,9 @@ func (w *Worker) Start(
 ) {
 }
 
-func (w *Worker) runReader(conn *transport.Connection,
-	messages chan<- []byte,
+func (w *Worker) runReader(
+	conn *transport.Connection,
+	messages chan<- receivedMessage,
 	heartbeat chan<- time.Time,
 	reconnect chan<- struct{},
 	newConn <-chan *transport.Connection,
@@ -61,12 +68,49 @@ func (w *Worker) runReader(conn *transport.Connection,
 }
 
 func (w *Worker) runForwarder(
-	messages <-chan []byte,
-	inbox chan<- []byte,
+	messages <-chan receivedMessage,
+	inbox chan<- InboxMessage,
 	stop <-chan struct{},
 	poolDone <-chan struct{},
 	maxQueueSize int,
 ) {
+	queue := list.New()
+
+	for {
+		var out chan<- InboxMessage
+		var next receivedMessage
+
+		// enable inbox if it is populated
+		if queue.Len() > 0 {
+			out = inbox
+
+			// read the first message in the queue
+			next = queue.Front().Value.(receivedMessage)
+		}
+
+		select {
+		case <-stop:
+			return
+		case <-poolDone:
+			return
+		case msg := <-messages:
+			// limit queue size if maximum is configured
+			if maxQueueSize > 0 && queue.Len() >= maxQueueSize {
+				// drop oldest message
+				queue.Remove(queue.Front())
+			}
+			// add new message
+			queue.PushBack(msg)
+		// send next message to inbox
+		case out <- InboxMessage{
+			ID:         w.id,
+			Data:       next.data,
+			ReceivedAt: next.receivedAt,
+		}:
+			// drop message from queue
+			queue.Remove(queue.Front())
+		}
+	}
 }
 
 func (w *Worker) runHealthMonitor(