use a single, shared timestamps array between all pings

lib/app.js

@@ -2,6 +2,7 @@ const Database = require('./database')
 const MojangUpdater = require('./mojang')
 const PingController = require('./ping')
 const Server = require('./server')
+const TimeTracker = require('./time')
 const MessageOf = require('./message')
 
 const config = require('../config')
@@ -14,6 +15,7 @@ class App {
     this.mojangUpdater = new MojangUpdater(this)
     this.pingController = new PingController(this)
     this.server = new Server(this.handleClientConnection)
+    this.timeTracker = new TimeTracker()
   }
 
   loadDatabase (callback) {
@@ -73,6 +75,7 @@ class App {
         }
       })(),
       mojangServices: this.mojangUpdater.getLastUpdate(),
+      timestampPoints: this.timeTracker.getPoints(),
       servers: this.serverRegistrations.map(serverRegistration => serverRegistration.getPingHistory())
     }
 

lib/ping.js

@@ -97,7 +97,7 @@ class PingController {
   }
 
   pingAll = () => {
-    const timestamp = new Date().getTime()
+    const timestamp = this._app.timeTracker.newTimestamp()
 
     this.startPingTasks(results => {
       const updates = []

lib/servers.js

@@ -16,7 +16,7 @@ class ServerRegistration {
 
   handlePing (timestamp, resp, err, version) {
     // Store into in-memory ping data
-    this.addPing(timestamp, resp)
+    this.addPing(resp)
 
     // Only notify the frontend to append to the historical graph
     // if both the graphing behavior is enabled and the backend agrees
@@ -89,10 +89,8 @@ class ServerRegistration {
     return update
   }
 
-  addPing (timestamp, resp) {
-    const ping = {
-      timestamp: timestamp
-    }
+  addPing (resp) {
+    const ping = {}
 
     if (resp) {
       // Append a result object
@@ -127,7 +125,6 @@ class ServerRegistration {
 
       const payload = {
         serverId: this.serverId,
-        timestamp: lastPing.timestamp,
         versions: this.versions,
         recordData: this.recordData,
         favicon: this.lastFavicon
@@ -157,7 +154,6 @@ class ServerRegistration {
 
     return [{
       serverId: this.serverId,
-      timestamp: new Date().getTime(),
       error: {
         message: 'Waiting...',
         placeholder: true

lib/time.js

@@ -0,0 +1,23 @@
+class TimeTracker {
+  constructor () {
+    this._points = []
+  }
+
+  newTimestamp () {
+    const timestamp = new Date().getTime()
+
+    this._points.push(timestamp)
+
+    if (this._points.length > 72) {
+      this._points.shift()
+    }
+
+    return timestamp
+  }
+
+  getPoints () {
+    return this._points
+  }
+}
+
+module.exports = TimeTracker