feat: CPU usage stat (#12)

stats.js

@@ -1,5 +1,34 @@
 'use strict'
 
+var os = require('os')
+
+var startMeasure = cpuAverage()
+
+function cpuAverage () {
+  var totalIdle = 0
+  var totalTick = 0
+  var cpus = os.cpus()
+  for (var i = 0, len = cpus.length; i < len; i++) {
+    var cpu = cpus[i]
+    for (var type in cpu.times) {
+      totalTick += cpu.times[type]
+    }
+    totalIdle += cpu.times.idle
+  }
+  return {
+    idle: totalIdle / cpus.length,
+    total: totalTick / cpus.length
+  }
+}
+
+function cpuCalculation () {
+  var endMeasure = cpuAverage()
+  var idleDifference = endMeasure.idle - startMeasure.idle
+  var totalDifference = endMeasure.total - startMeasure.total
+  var cpuPercentage = 100 - ~~(100 * idleDifference / totalDifference)
+  return cpuPercentage
+}
+
 function client () {
   this.stats.connectedClients++
   if (this.stats.connectedClients > this.stats.maxConnectedClients) {
@@ -35,7 +64,8 @@ function wire (aedesInstance, options) {
     connectedClients: 0,
     publishedMessages: 0,
     started: new Date(),
-    time: new Date()
+    time: new Date(),
+    cpuUsage: 0
   }
 
   function doPub (topic, value) {
@@ -48,19 +78,28 @@ function wire (aedesInstance, options) {
   }
 
   var timer = setInterval(iterate, options.interval || (1 * 1000))
+  var cpuUsageTimer = setInterval(function () { aedesInstance.stats.cpuUsage = cpuCalculation() }, 1000)
 
   function iterate () {
     var stats = aedesInstance.stats
     stats.time = new Date()
     var uptime = Math.round((stats.time - stats.started) / 1000)
     var mem = process.memoryUsage()
+    var cpu = os.loadavg()
     doPub('uptime', uptime)
     doPub('time', aedesInstance.stats.time.toISOString())
     doPub('clients/total', stats.connectedClients)
     doPub('clients/maximum', stats.maxConnectedClients)
     doPub('messages/publish/sent', stats.publishedMessages)
     doPub('memory/heap/current', mem.heapUsed)
     doPub('memory/heap/maximum', mem.heapTotal)
+    doPub('cpu/usage', stats.cpuUsage)
+    if (cpu && cpu.length >= 3) {
+      // ref: http://nodejs.org/api/os.html#os_os_loadavg
+      doPub('cpu/avg/last/1', cpu[0])
+      doPub('cpu/avg/last/5', cpu[1])
+      doPub('cpu/avg/last/15', cpu[2])
+    }
   }
 
   aedesEvents.forEach(function (event) {
@@ -69,6 +108,7 @@ function wire (aedesInstance, options) {
 
   aedesInstance.once('closed', function () {
     clearInterval(timer)
+    clearInterval(cpuUsageTimer)
     aedesEvents.forEach(function (event) {
       aedesInstance.removeListener(event.name, event)
     })

test.js

@@ -160,7 +160,7 @@ test('Connect a client and and subscribe to get current heap usage', function (t
   })
 })
 
-test('Connect a client and and subscribe to get maximum heap usage', function (t) {
+test('Connect a client and subscribe to get maximum heap usage', function (t) {
   t.plan(2)
 
   var sysTopic = '$SYS/+/memory/heap/maximum'
@@ -175,3 +175,67 @@ test('Connect a client and and subscribe to get maximum heap usage', function (t
     t.end()
   })
 })
+
+test('Connect a client and subscribe to get cpu usage', function (t) {
+  t.plan(2)
+
+  var sysTopic = '$SYS/+/cpu/usage'
+  var subscriber = connect(setup())
+
+  subscriber.subscribe(sysTopic)
+
+  subscriber.on('message', function (topic, message) {
+    t.ok(checkTopic(topic, sysTopic))
+    t.pass(message.toString(), 'cpu usage')
+    subscriber.end()
+    t.end()
+  })
+})
+
+test('Connect a client and subscribe to get cpu avg of last 1 min', function (t) {
+  t.plan(2)
+
+  var sysTopic = '$SYS/+/cpu/avg/last/1'
+  var subscriber = connect(setup())
+
+  subscriber.subscribe(sysTopic)
+
+  subscriber.on('message', function (topic, message) {
+    t.ok(checkTopic(topic, sysTopic))
+    t.pass(message.toString(), 'cpu avg of last 1 min')
+    subscriber.end()
+    t.end()
+  })
+})
+
+test('Connect a client and subscribe to get cpu avg of last 5 min', function (t) {
+  t.plan(2)
+
+  var sysTopic = '$SYS/+/cpu/avg/last/5'
+  var subscriber = connect(setup())
+
+  subscriber.subscribe(sysTopic)
+
+  subscriber.on('message', function (topic, message) {
+    t.ok(checkTopic(topic, sysTopic))
+    t.pass(message.toString(), 'cpu avg of last 5 min')
+    subscriber.end()
+    t.end()
+  })
+})
+
+test('Connect a client and subscribe to get cpu avg of last 15 min', function (t) {
+  t.plan(2)
+
+  var sysTopic = '$SYS/+/cpu/avg/last/15'
+  var subscriber = connect(setup())
+
+  subscriber.subscribe(sysTopic)
+
+  subscriber.on('message', function (topic, message) {
+    t.ok(checkTopic(topic, sysTopic))
+    t.pass(message.toString(), 'cpu avg of last 15 min')
+    subscriber.end()
+    t.end()
+  })
+})