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const disyuntor = require('disyuntor');

const dnsSafeLookup = disyuntor.wrapCallbackApi({
  //This is used in error messages.
  name: 'dns.lookup',

  //Timeout for the protected function.
  // timeout: '2s',

  //The number of consecutive failures before switching to open mode
  //and stop calling the underlying service.
  // maxFailures: 5,

  //The minimum time the circuit remains open before doing another attempt.
  // cooldown: '15s',

  //The maximum amount of time the circuit remains open before doing a new attempt.
  // maxCooldown: '60s',

  //optionally log errors
  onTrip: (err, failures, cooldown) => {
    console.log(`dns.lookup triped because it failed ${failures} times.
Last error was ${err.message}! There will be no more attempts for ${cooldown}ms.`);
  },

  onClose: (cooldown) => {
    console.log(`dns.lookup circuit closed after ${cooldown}ms.`;
  }

  // //optional callback to prevent some errors to trigger the disyuntor logic
  // //in this case ENOTFOUND is passed to the callback and will
  // //not trigger the breaker eg:
  // trigger: (err) => err.code !== 'ENOTFOUND'
}, dns.lookup);

//then use as you will normally use dns.lookup
dnsSafeLookup('google.com', (err, ip) => {
  if (err) { return console.error(err.message); }
  console.log(ip);
})

const lookup = Promise.promisify(require('dns').lookup);

const protectedLookup = disyuntor.wrapPromise({
  name: 'dns.lookup',
  timeout: '2s',
  maxFailures: 2
}, lookup);

protectedLookup('google.com')
  .then((ip)  => console.log(ip),
        (err) => console.error(err));

const Disyuntor = require('disyuntor').Disyuntor;

const disyuntor = new Disyuntor({
  name: 'dns.lookup',
  timeout: '2s',
  maxFailures: 2
});

await disyuntor.protect(() => dns.lookupAsync('google.com'));