server.js

const http = require('http');
const url = require('url');
const faker = require('faker');
const bytes = require('bytes');
const _ = require('lodash');

const port = process.env.PORT || process.argv[2] || 8080;

const cache = {};

const server = http.createServer((req, res) => {

  const query = url.parse(req.url, true).query;
  const size = bytes.parse(String(query.size || '1KB'));
  const latency = query.latency ? parseInt(query.latency, 10) : 200;
  const time = query.time ? parseInt(query.time, 10) : 100;

  const mb = 1048576;
  const nbrOfChunks = size > (10 * mb) ? parseInt((size / mb).toFixed(0), 10) : 10;
  const timeout = parseInt((time / nbrOfChunks).toFixed(0), 10);
  const chunkSize = parseInt((size / nbrOfChunks).toFixed(0), 10);
  const range = _.range(nbrOfChunks).map(() => chunkSize + 1);

  res.writeHead(200, { 
    'Content-Type': 'text/plain',
    'Transfer-Encoding': 'chunked'
  });

  function pushChunk() {
    const item = range.pop();
    if (item) {
      let chunk = cache[`chunk-${chunkSize}`];
      if (!chunk) {
        chunk = faker.random.alphaNumeric(chunkSize);
        cache[`chunk-${chunkSize}`] = chunk;
      }
      res.write(chunk, 'utf-8');
      setTimeout(() => pushChunk(), timeout);
    } else {
      res.end('');
    }
  }

  setTimeout(() => pushChunk(), latency);
});

server.listen(port, () => {
  console.log(`Benchmark server started on port ${port}`);
});