From dcc3cfa44f0173c58f9714c4c631f2ee3eb3a471 Mon Sep 17 00:00:00 2001
From: Paul Brinkmeier <hallo@pbrinkmeier.de>
Date: Fri, 25 Apr 2025 12:30:19 +0200
Subject: [PATCH] Send requests to different servers using round-robin

---
 main.go | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/main.go b/main.go
index 44a2b9b..967b8e2 100644
--- a/main.go
+++ b/main.go
@@ -10,6 +10,7 @@ import "os"
 import "slices"
 import "strings"
 import "strconv"
+import "sync/atomic"
 import "time"
 
 // JSON unmarshaling types for departure monitor API
@@ -110,8 +111,7 @@ func (c KVVEFAClient) BuildRequest(stopId string) (*http.Request, error) {
 	return req, nil
 }
 
-func FetchDepartures(stopId string) (DMResponse, error) {
-	var c EFAClient = KVVEFAClient{}
+func FetchDepartures(c EFAClient, stopId string) (DMResponse, error) {
 	req, err := c.BuildRequest(stopId)
 	if err != nil {
 		return DMResponse{}, err
@@ -203,6 +203,13 @@ func main() {
 		panic("Required environment variable VRNP_PASSWORD is not set")
 	}
 
+	// Use round-robin to send incoming requests to different servers
+	var efaClient atomic.Uint64
+	efaClients := []EFAClient{
+		VRNEFAClient{},
+		KVVEFAClient{},
+	}
+
 	http.HandleFunc("/departures", func(w http.ResponseWriter, r *http.Request) {
 		user, pass, ok := r.BasicAuth()
 		if !(ok && user == "admin" && pass == password) {
@@ -224,7 +231,8 @@ func main() {
 			platform = &query["platform"][0]
 		}
 
-		ds, err := FetchDepartures(stopId)
+		c := efaClients[(efaClient.Add(1) - 1) % uint64(len(efaClients))]
+		ds, err := FetchDepartures(c, stopId)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return