From 3679d2844af7901cc06f75867eeba1c0cd9ef237 Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@helsinki.at>
Date: Sat, 18 Jul 2015 03:03:06 +0200
Subject: clock now uses a ntp-style sync format


diff --git a/www/js/utils.js b/www/js/utils.js
index 74614f0..ea4f42b 100644
--- a/www/js/utils.js
+++ b/www/js/utils.js
@@ -124,12 +124,12 @@ function Clock(draw_callback) {
   this.draw_callback = draw_callback;
   this.daynames = new Array('So', 'Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa');
 
-  this.last_update = { timestamp: 0, tz_offset: 3600, week: 3 };
+  this.last_message = { t1: 0, t2: 0, t3: 0, t4: 0, tz_offset: 3600, week: 3 };
   this.clock_offset = 0;
+  this.clock_rtt = 0;
 
   this.redraw = function() {
-//    console.log("redraw called");
-    var rdtime_ms = (+new Date()) + (this.last_update.tz_offset * 1000) + this.clock_offset;
+    var rdtime_ms = (+new Date()) + (this.last_message.tz_offset * 1000) + this.clock_offset;
 
     var rdtime = new Date(rdtime_ms);
     var date_str = this.daynames[rdtime.getUTCDay()]  + ', ';
@@ -139,24 +139,40 @@ function Clock(draw_callback) {
     time_str += (rdtime.getUTCMinutes() > 9 ? ':' : ':0') + rdtime.getUTCMinutes();
     time_str += (rdtime.getUTCSeconds() > 9 ? ':' : ':0') + rdtime.getUTCSeconds();
 
-    this.draw_callback(date_str, time_str, this.last_update.week);
+    this.draw_callback(date_str, time_str, this.last_message.week);
   }
 
-  this.update = function(event) {
-    var update = JSON.parse(event.data);
-    this.last_update = update;
-    this.clock_offset = (update.timestamp*1000) - (+new Date())        ;
-//    console.log("got new timeupdate from rhrdtime: new offset = " + this.clock_offset + " ms");
+  this.ntp_update = function(event) {
+    var t4 = (+new Date());
+
+    var msg = JSON.parse(event.data);
+    msg.t4 = t4;
+    this.last_message = msg;
+    this.clock_offset = ((msg.t2 - msg.t1) + (msg.t3 - msg.t4)) / 2;
+    this.clock_rtt = (msg.t4 - msg.t1) - (msg.t3 - msg.t2);
+    console.log("got new ntp message from rhrdtime (rtt=" + this.clock_rtt + " ms): new offset = " + this.clock_offset + " ms");
+  }
+
+  this.ntp_request = function() {
+    this.sock.send(JSON.stringify({ t1: (+new Date()), t2: 0, t3: 0, t4: 0, tz_offset: 0, week: 0 }));
+  }
+
+  this.sock_onopen = function() {
+    this.ntp_request();
+    this.interval_redraw = setInterval(this.ntp_request.bind(this), 5000);
   }
 
   this.start = function() {
-    this.sock = new WebSocket("wss://import.helsinki.at/time");
-    this.sock.onmessage = this.update.bind(this);
-    this.interval = setInterval(this.redraw.bind(this), 500);
+    this.sock = new WebSocket("wss://import.helsinki.at/ntp");
+    this.sock.onmessage = this.ntp_update.bind(this);
+    this.sock.onopen = this.sock_onopen.bind(this);
+    this.interval_redraw = setInterval(this.redraw.bind(this), 200);
   }
   this.stop = function() {
-    clearInterval(this.interval);
-    delete this.interval;
+    clearInterval(this.interval_redraw);
+    delete this.interval_redraw;
+    clearInterval(this.interval_request);
+    delete this.interval_request;
     this.sock.close();
   }
 }
-- 
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