feat: free memory module

lib/models/system.js

@@ -8,6 +8,7 @@ import { KadiraModel } from './0model';
 import { EventLoopMonitor } from '../event_loop_monitor.js';
 import { Ntp } from '../ntp';
 import os from 'os';
+import { execSync } from 'child_process';
 
 export const MEMORY_ROUNDING_FACTOR = 100 * 1024; // 100kb
 const EVENT_LOOP_ROUNDING_FACTOR = 500; // microseconds
@@ -47,6 +48,50 @@ export function SystemModel () {
 
 _.extend(SystemModel.prototype, KadiraModel.prototype);
 
+function meminfo() {
+  var info = {};
+  var data = fs.readFileSync('/proc/meminfo').toString();
+  data.split(/\n/g).forEach(function(line){
+      line = line.split(':');
+
+      // Ignore invalid lines, if any
+      if (line.length < 2) {
+          return;
+      }
+
+      // Remove parseInt call to make all values strings
+      info[line[0]] = parseInt(line[1].trim(), 10);
+  });
+
+  return info;
+}
+
+function getFreeMemory(){
+  const isLinux = process.platform === "linux";
+  const isMac = process.platform === "darwin";
+
+  try {
+    if(isLinux){
+      const info = meminfo();
+      return info.MemFree + info.Buffers + info.Cached;
+    }
+    if(isMac){
+      const output = execSync('vm_stat').toString();
+      const pageSizeArray = [...output.matchAll(/page size of (\d*)/g)];
+      const pageSize = parseInt(pageSizeArray[0][1], 10)
+      const freePagesMatches = [...output.matchAll(/Pages free:\s*(\d*)/g)];
+      const freePages = parseInt(freePagesMatches[0][1], 10)
+      const inactivePagesMatches = [...output.matchAll(/Pages inactive:\s*(\d*)/g)];
+      const inactivePages = parseInt(inactivePagesMatches[0][1],10)
+      return pageSize * (freePages + inactivePages)
+    }
+  }catch(e){
+    console.error('failed to get native memory info, falling back to default option', e);
+  }
+
+  return os.freemem();
+}
+
 SystemModel.prototype.buildPayload = function () {
   let metrics = {};
   let now = Ntp._now();
@@ -60,7 +105,8 @@ SystemModel.prototype.buildPayload = function () {
   metrics.memoryExternal = roundUsingFactor(memoryUsage.external, MEMORY_ROUNDING_FACTOR) / (1024 * 1024);
   metrics.memoryHeapUsed = roundUsingFactor(memoryUsage.heapUsed, MEMORY_ROUNDING_FACTOR) / (1024 * 1024);
   metrics.memoryHeapTotal = roundUsingFactor(memoryUsage.heapTotal, MEMORY_ROUNDING_FACTOR) / (1024 * 1024);
-  metrics.freeMemory = roundUsingFactor(os.freemem(), MEMORY_ROUNDING_FACTOR) / (1024 * 1024);
+  const freeMemory = getFreeMemory();
+  metrics.freeMemory = roundUsingFactor(freeMemory, MEMORY_ROUNDING_FACTOR) / (1024 * 1024);
   metrics.totalMemory = roundUsingFactor(os.totalmem(), MEMORY_ROUNDING_FACTOR) / (1024 * 1024);
 
   metrics.newSessions = this.newSessions;