How to use the socketcluster/fsutil.waitForFile function in socketcluster

/*
  This is the SocketCluster master controller file.
  It is responsible for bootstrapping the SocketCluster master process.
  Be careful when modifying the options object below.
  If you plan to run SCC on Kubernetes or another orchestrator at some point
  in the future, avoid changing the environment variable names below as
  each one has a specific meaning within the SC ecosystem.
*/

var path = require('path');
var argv = require('minimist')(process.argv.slice(2));
var scHotReboot = require('sc-hot-reboot');

var fsUtil = require('socketcluster/fsutil');
var waitForFile = fsUtil.waitForFile;

var SocketCluster = require('socketcluster');

var workerControllerPath = argv.wc || process.env.SOCKETCLUSTER_WORKER_CONTROLLER;
var brokerControllerPath = argv.bc || process.env.SOCKETCLUSTER_BROKER_CONTROLLER;
var workerClusterControllerPath = argv.wcc || process.env.SOCKETCLUSTER_WORKERCLUSTER_CONTROLLER;
var environment = process.env.ENV || 'dev';

var options = {
  workers: Number(argv.w) || Number(process.env.SOCKETCLUSTER_WORKERS) || 1,
  brokers: Number(argv.b) || Number(process.env.SOCKETCLUSTER_BROKERS) || 1,
  port: Number(argv.p) || Number(process.env.SOCKETCLUSTER_PORT) || 8000,
  // You can switch to 'sc-uws' for improved performance.
  wsEngine: process.env.SOCKETCLUSTER_WS_ENGINE || 'ws',
  appName: argv.n || process.env.SOCKETCLUSTER_APP_NAME || null,
  workerController: workerControllerPath || path.join(__dirname, 'worker.js'),

/*
  This is the SocketCluster master controller file.
  It is responsible for bootstrapping the SocketCluster master process.
  Be careful when modifying the options object below.
  If you plan to run SCC on Kubernetes or another orchestrator at some point
  in the future, avoid changing the environment variable names below as
  each one has a specific meaning within the SC ecosystem.
*/

var path = require('path');
var argv = require('minimist')(process.argv.slice(2));
var scHotReboot = require('sc-hot-reboot');

var fsUtil = require('socketcluster/fsutil');
var waitForFile = fsUtil.waitForFile;

var SocketCluster = require('socketcluster');

var workerControllerPath = argv.wc || process.env.SOCKETCLUSTER_WORKER_CONTROLLER;
var brokerControllerPath = argv.bc || process.env.SOCKETCLUSTER_BROKER_CONTROLLER;
var workerClusterControllerPath = argv.wcc || process.env.SOCKETCLUSTER_WORKERCLUSTER_CONTROLLER;
var environment = process.env.ENV || 'dev';

var options = {
  workers: Number(argv.w) || Number(process.env.SOCKETCLUSTER_WORKERS) || 1,
  brokers: Number(argv.b) || Number(process.env.SOCKETCLUSTER_BROKERS) || 1,
  port: Number(argv.p) || Number(process.env.SOCKETCLUSTER_PORT) || 8000,
  // You can switch to 'sc-uws' for improved performance.
  wsEngine: process.env.SOCKETCLUSTER_WS_ENGINE || 'sc-uws',
  appName: argv.n || process.env.SOCKETCLUSTER_APP_NAME || null,
  workerController: workerControllerPath || './worker.js',

/*
  This script waits for the master controller script to become available.
  With orchestrators like Kubernetes, the master controller file may be fed in through
  a volume container at runtime and so it is necessary to wait for it before launch.
*/

var fsUtil = require('socketcluster/fsutil');
var waitForFile = fsUtil.waitForFile;

var SOCKETCLUSTER_MASTER_DEFAULT_CONTROLLER = './server.js';
var masterControllerPath = process.env.SOCKETCLUSTER_MASTER_CONTROLLER || SOCKETCLUSTER_MASTER_DEFAULT_CONTROLLER;
var bootCheckInterval = Number(process.env.SOCKETCLUSTER_BOOT_CHECK_INTERVAL) || 200;
var bootTimeout = Number(process.env.SOCKETCLUSTER_CONTROLLER_BOOT_TIMEOUT) || 10000;
var bootStartTime = Date.now();

var errorMessage = `Failed to locate the master controller file at path ${masterControllerPath} before SOCKETCLUSTER_CONTROLLER_BOOT_TIMEOUT`;

waitForFile(masterControllerPath, bootCheckInterval, bootStartTime, bootTimeout, errorMessage)
.catch((err) => {
  console.error('> Boot error: ' + err.message);
  process.exit(1);
});

/*
  This is the SocketCluster master controller file.
  It is responsible for bootstrapping the SocketCluster master process.
  Be careful when modifying the options object below.
  If you plan to run SCC on Kubernetes or another orchestrator at some point
  in the future, avoid changing the environment variable names below as
  each one has a specific meaning within the SC ecosystem.
*/

const fs = require('fs');
const config = require('../config');
const path = require('path');

const fsUtil = require('socketcluster/fsutil');
const waitForFile = fsUtil.waitForFile;

const SocketCluster = require('socketcluster');

const workerControllerPath = path.join(__dirname, 'worker.js');
const brokerControllerPath = path.join(__dirname, 'broker.js');
const environment = 'prod';

const public_key = fs.readFileSync(path.join(__dirname, '../../storage/oauth-public.key'));
const private_key = fs.readFileSync(path.join(__dirname, '../../storage/oauth-private.key'));

const options = {
    path: '/socket',
    workers: config.SOCKET_WORKERS,
    brokers: config.SOCKET_BROKERS,
    port: config.SOCKET_PORT,
    authPublicKey: public_key,