server.js

const vm = require('vm');
const fs = require('fs');
const redis = require("redis");

global.atob = require("atob");

global.Canvas = require("canvas");
global.Image = Canvas.Image;

global.tracking = createLibrarySandbox([
  'node_modules/tracking/build/tracking.js',
  'node_modules/tracking/build/data/eye.js',
  'node_modules/tracking/build/data/face.js',
  'node_modules/tracking/build/data/mouth.js'
], {
  window: {},
  navigator: {},
  tracking: {}
}).tracking;

global.Tesseract = require('tesseract.js');

global.redisClient = redis.createClient(6379, "redis");
global.id = 0;
global.callback = function(result) {
  var cache = [];
  var serialized = JSON.stringify(result, function(key, value) {
    if (typeof value === 'object' && value !== null) {
      if (cache.indexOf(value) !== -1) {
        return;
      }
      cache.push(value);
    }
    return value;
  });
  cache = null;

  console.timeEnd("Run");
  console.log("Computed: " + serialized.substring(0, 100) + '...');
  redisClient.lpush(id, serialized);
  main();
};

global.main = function() {
  redisClient.brpop("requests", 5, function(err, reply) {
    if (!reply) {
      console.log("No messages to handle.")
      main();
      return;
    }

    try {
      const obj = JSON.parse(decodeURIComponent(reply[1]));
      global.id = obj.id;
      console.log('Received: ' + JSON.stringify(obj.code).substring(0, 200) + '...');
      // fs.writeFile("./data/args" + global.id, obj.args, function(err) {});

      console.time("Compile");
      const script = new vm.Script('f = ' + obj.code + '; f(' + args(obj.args) + ');', {
        displayErrors: true,
        timeout: 500000
      });
      console.timeEnd("Compile");
      console.time("Run");
      const result = JSON.stringify(script.runInThisContext({
        displayErrors: true,
        timeout: 500000
      }));
      // const result = JSON.stringify(eval('f = ' + obj.code + '; f(' + args(obj.args) + ');'));
      if (!obj.withCallback) {
        console.timeEnd("Run");
        console.log('Computed: ' + result.substring(0, 100) + '...');
        redisClient.lpush(id, result);
        main();
      }
    } catch (e) {
      console.error("Error while handling a message: ", e);
      redisClient.lpush(id, "error");
      main();
    }
  });
}
exports.main = main;
if (require.main === module) {
  main();
}

function createLibrarySandbox(files, sandbox) {
  var source, script, result;
  if (!(files instanceof Array)) {
    files = [files];
  }
  source = files.map(function(file) {
    return fs.readFileSync(file, 'utf8');
  }).join('');
  script = new vm.Script(source);
  result = script.runInNewContext(sandbox);
  return sandbox;
};

function args(a) {
  var arguments = '';
  for (var i = 0; i < a.length; i++) {
    if (typeof a[i] === 'string') arguments += '\"' + a[i] + '\"'
    else arguments += JSON.stringify(a[i]);

    if (i < a.length - 1) arguments += ', ';
  }
  return arguments;
}