centralize timestamp/point filtering, move magic numbers into named constants

lib/servers.js

@@ -1,7 +1,7 @@
 const crypto = require('crypto')
 const dns = require('dns')
 
-const TimeTracker = require('./time')
+const { GRAPH_UPDATE_TIME_GAP, TimeTracker } = require('./time')
 const Server = require('./server')
 
 const { getPlayerCountOrNull } = require('./util')
@@ -124,18 +124,7 @@ class ServerRegistration {
   }
 
   loadGraphPoints (startTime, timestamps, points) {
-    // Filter pings so each result is a minute apart
-    let lastTimestamp = startTime
-
-    for (let i = 0; i < timestamps.length; i++) {
-      const timestamp = timestamps[i]
-
-      if (timestamp - lastTimestamp >= 60 * 1000) {
-        lastTimestamp = timestamp
-
-        this.graphData.push(points[i])
-      }
-    }
+    this.graphData = TimeTracker.everyN(timestamps, startTime, GRAPH_UPDATE_TIME_GAP, (i) => points[i])
   }
 
   findNewGraphPeak () {