Keeping Node.js Fast

snippet-1.sh

npm install -g autocannon 

snippet-10.js

 server.on('after', (req, res) => {
  if (res.statusCode !== 200) return
  if (!res._body) return
  const key = crypto.createHash('sha512')
    .update(req.url)
    .digest()
    .toString('hex')
  const etag = crypto.createHash('sha512')
    .update(JSON.stringify(res._body))
    .digest()
    .toString('hex')
  if (cache[key] !== etag) cache[key] = etag
})

snippet-11.js

function etagger () {
  var cache = {}
  var afterEventAttached = false
  function attachAfterEvent (server) {
    if (attachAfterEvent === true) return
    afterEventAttached = true
    server.on('after', (req, res) => {})
  }
  return function (req, res, next) {
    attachAfterEvent(this)
    const key = crypto.createHash('sha512')
      .update(req.url)
      .digest()
      .toString('hex')
    if (key in cache) res.set('Etag', cache[key])
    res.set('Cache-Control', 'public, max-age=120')
    next()
  }
}

snippet-12.sh

clinic flame --on-port='autocannon -c100 localhost:$PORT/seed/v1' -- node index.js

snippet-13.js

require('events').defaultMaxListeners = Infinity

snippet-14.sh

node --trace-warnings index.js

snippet-15.sh

autocannon -c100 localhost:3000/seed/v1

snippet-16.js

var afterEventAttached = false
function attachAfterEvent (server) {
  if (attachAfterEvent === true) return
  afterEventAttached = true
  server.on('after', (req, res) => {})
}

snippet-17.js

function etagger () {
  var cache = {}
  var afterEventAttached = false
  function attachAfterEvent (server) {
    if (afterEventAttached === true) return
    afterEventAttached = true
    server.on('after', (req, res) => {
      if (res.statusCode !== 200) return
      if (!res._body) return
      const key = crypto.createHash('sha512')
        .update(req.url)
        .digest()
        .toString('hex')
      const etag = crypto.createHash('sha512')
        .update(JSON.stringify(res._body))
        .digest()
        .toString('hex')
      if (cache[key] !== etag) cache[key] = etag
    })
  }
  return function (req, res, next) {
    attachAfterEvent(this)
    const key = crypto.createHash('sha512')
      .update(req.url)
      .digest()
      .toString('hex')
    if (key in cache) res.set('Etag', cache[key])
    res.set('Cache-Control', 'public, max-age=120')
    next()
  }
}

snippet-18.sh

node index.js

snippet-19.sh

autocannon -c100 localhost:3000/seed/v1

snippet-2.sh

npm --install -g clinic 

snippet-3.js

'use strict'

const restify = require('restify')
const { etagger, timestamp, fetchContent } = require('./util')()
const server = restify.createServer()

server.use(etagger().bind(server))

server.get('/seed/v1', function (req, res, next) {
  fetchContent(req.url, (err, content) => {
    if (err) return next(err)
    res.send({data: content, url: req.url, ts: timestamp()})
    next()
  })
})

server.listen(3000)

snippet-4.js

'use strict'

require('events').defaultMaxListeners = Infinity
const crypto = require('crypto')

module.exports = () => {
  const content = crypto.rng(5000).toString('hex')
  const ONE_MINUTE = 60000
  var last = Date.now()

  function timestamp () {
    var now = Date.now()
    if (now - last >= ONE_MINUTE) last = now
    return last
  }
  
  function etagger () {
    var cache = {}
    var afterEventAttached = false
    function attachAfterEvent (server) {
      if (attachAfterEvent === true) return
      afterEventAttached = true
      server.on('after', (req, res) => {
        if (res.statusCode !== 200) return
        if (!res._body) return
        const key = crypto.createHash('sha512')
          .update(req.url)
          .digest()
          .toString('hex')
        const etag = crypto.createHash('sha512')
          .update(JSON.stringify(res._body))
          .digest()
          .toString('hex')
        if (cache[key] !== etag) cache[key] = etag
      })
    }
    return function (req, res, next) {
      attachAfterEvent(this)
      const key = crypto.createHash('sha512')
        .update(req.url)
        .digest()
        .toString('hex')
      if (key in cache) res.set('Etag', cache[key])
      res.set('Cache-Control', 'public, max-age=120')
      next()
    }
  }

  function fetchContent (url, cb) {
    setImmediate(() => {
      if (url !== '/seed/v1') cb(Object.assign(Error('Not Found'), {statusCode: 404}))
      else cb(null, content)
    })
  }

  return { timestamp, etagger, fetchContent }
  
}

snippet-5.sh

node index.js

snippet-6.sh

autocannon -c100 localhost:3000/seed/v1

snippet-7.sh

clinic doctor --on-port=’autocannon -c100 localhost:$PORT/seed/v1’ -- node index.js

snippet-8.js

console.time('timeout')
setTimeout(console.timeEnd, 100, 'timeout')
let n = 1e7
while (n--) Math.random()

snippet-9.sh

clinic flame --on-port=’autocannon -c100 localhost:$PORT/seed/v1’ -- node index.js