From 420b0c60d75241f92f56dc8d8311a49c86bb4092 Mon Sep 17 00:00:00 2001
From: Jakob Ketterl <jakob.ketterl@gmx.de>
Date: Sat, 13 Jul 2019 21:44:48 +0200
Subject: [PATCH] exponential backoff, part 2

---
 htdocs/map.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/htdocs/map.js b/htdocs/map.js
index 82f4a59..b5f905a 100644
--- a/htdocs/map.js
+++ b/htdocs/map.js
@@ -115,10 +115,13 @@
         rectangles = {};
     };
 
+    var reconnect_timeout = false;
+
     var connect = function(){
         var ws = new WebSocket(ws_url);
         ws.onopen = function(){
             ws.send("SERVER DE CLIENT client=map.js type=map");
+            reconnect_timeout = false
         };
 
         ws.onmessage = function(e){
@@ -163,7 +166,14 @@
         };
         ws.onclose = function(){
             clearMap();
-            setTimeout(connect, 5000);
+            if (reconnect_timeout) {
+                // max value: roundabout 8 and a half minutes
+                reconnect_timeout = Math.min(reconnect_timeout * 2, 512000);
+            } else {
+                // initial value: 1s
+                reconnect_timeout = 1000;
+            }
+            setTimeout(connect, reconnect_timeout);
         };
 
         window.onbeforeunload = function() { //http://stackoverflow.com/questions/4812686/closing-websocket-correctly-html5-javascript