perf(replication): replicate number accordion to cpu usage

src/background/api.js

@@ -4,6 +4,7 @@ const compareVersions = require('compare-versions');
 const getTorrent = require('./gettorrent')
 const _ = require('lodash')
 const asyncForEach = require('./asyncForEach')
+const cpuUsage = require('./bt/cpu-usage-global')
 
 module.exports = async ({
 	sphinx,
@@ -213,7 +214,10 @@ module.exports = async ({
 			if(sphinxSingle.state === 'disconnected')
 				return
 
-			sphinxSingle.query('SELECT * FROM `torrents` ORDER BY rand() limit 5', (error, torrents) => {
+			const cpu = cpuUsage()
+			const limit = Math.max(1, 5 - (cpu / 20) | 0)
+
+			sphinxSingle.query(`SELECT * FROM torrents ORDER BY rand() limit ${limit}`, (error, torrents) => {
 				if(!torrents || torrents.length == 0) {
 					callback(undefined)
 					return;

src/background/bt/cpu-usage-global.js

@@ -0,0 +1,51 @@
+var os = require("os");
+
+//Create function to get CPU information
+function cpuAverage() {
+
+  //Initialise sum of idle and time of cores and fetch CPU info
+  let totalIdle = 0, totalTick = 0;
+  const cpus = os.cpus();
+
+  //Loop through CPU cores
+  for(let i = 0, len = cpus.length; i < len; i++) {
+
+    //Select CPU core
+    const cpu = cpus[i];
+
+    //Total up the time in the cores tick
+    for(const type in cpu.times) {
+      totalTick += cpu.times[type];
+    }     
+
+    //Total up the idle time of the core
+    totalIdle += cpu.times.idle;
+  }
+
+  //Return the average Idle and Tick times
+  return {idle: totalIdle / cpus.length,  total: totalTick / cpus.length};
+}
+
+//Grab first CPU Measure
+let startMeasure = cpuAverage();
+let percentageCPU = 0
+
+//Set delay for second Measure
+const cpuTimer = setInterval(function() { 
+
+  //Grab second Measure
+  const endMeasure = cpuAverage(); 
+
+  //Calculate the difference in idle and total time between the measures
+  const idleDifference = endMeasure.idle - startMeasure.idle;
+  const totalDifference = endMeasure.total - startMeasure.total;
+
+  //Calculate the average percentage CPU usage
+  percentageCPU = 100 - ~~(100 * idleDifference / totalDifference);
+  startMeasure = endMeasure
+
+}, 300);
+
+cpuTimer.unref()
+
+module.exports = () => percentageCPU