Improve resiliency of STOMP subscription

vstp/subscribe.go

@@ -1,37 +1,63 @@
 package vstp
 
 import (
+	"fmt"
 	"time"
 
 	"git.fjla.uk/owlboard/timetable-mgr/log"
 	"git.fjla.uk/owlboard/timetable-mgr/messaging"
 	"github.com/go-stomp/stomp/v3"
+	"go.uber.org/zap"
 )
 
 func Subscribe() {
-	sub, err := messaging.Client.Subscribe("/topic/VSTP_ALL", stomp.AckAuto)
-	if err != nil {
-		log.Fatal("Unable to start subscription: " + err.Error())
+	var sub *stomp.Subscription
+	var err error
+	retryCount := 0
+	maxRetries := 5
+
+	for retryCount < maxRetries {
+		sub, err = messaging.Client.Subscribe("/topic/VSTP_ALL", stomp.AckAuto)
+		if err != nil {
+			log.Warn("Unable to start subscription", zap.Error(err))
+			time.Sleep(10 * time.Second)
+			retryCount++
+			continue
+		}
+		break
 	}
+
+	if sub == nil {
+		log.Fatal("Failed to subscribe to VSTP topic", zap.Int("attempts", maxRetries))
+	}
+
 	log.Info("Subscription to VSTP topic successful, listening")
 
 	go func() {
-		log.Debug("GOROUTINE: VSTP Message Handler Started")
-		defer func() {
-			if r := recover(); r != nil {
-				log.Warn("GOROUTINE: VSTP Message Handler Stopped")
-				time.Sleep(time.Second * 10)
-				log.Fatal("GOROUTINE: VSTP Message Handler Failed")
-			}
-		}()
 		for {
-			msg := <-sub.C
-			if msg.Err != nil {
-				log.Error("STOMP Message Error: " + msg.Err.Error())
-			} else {
-				log.Info("STOMP Message Received")
-				handle(msg)
-			}
+			func() {
+				defer func() {
+					if r := recover(); r != nil {
+						log.Warn("VSTP Message Handler Stopped, waiting for recovery")
+						time.Sleep(time.Second * 10)
+					}
+				}()
+				log.Info("VSTP Message handler started")
+				for {
+					msg := <-sub.C
+					if msg.Err != nil {
+						log.Error("STOMP Message Error", zap.Error(msg.Err))
+					} else {
+						if msg != nil {
+							log.Info("STOMP Message Received")
+							fmt.Println(string(msg.Body))
+							handle(msg)
+						} else {
+							log.Info("STOMP Message Empty")
+						}
+					}
+				}
+			}()
 		}
 	}()