basant307/AI_Governance_Project

1'use strict'2 3const { LRUCache } = require('lru-cache')4const dns = require('dns')5 6// this is a factory so that each request can have its own opts (i.e. ttl)7// while still sharing the cache across all requests8const cache = new LRUCache({ max: 50 })9 10const getOptions = ({11  family = 0,12  hints = dns.ADDRCONFIG,13  all = false,14  verbatim = undefined,15  ttl = 5 * 60 * 1000,16  lookup = dns.lookup,17}) => ({18  // hints and lookup are returned since both are top level properties to (net|tls).connect19  hints,20  lookup: (hostname, ...args) => {21    const callback = args.pop() // callback is always last arg22    const lookupOptions = args[0] ?? {}23 24    const options = {25      family,26      hints,27      all,28      verbatim,29      ...(typeof lookupOptions === 'number' ? { family: lookupOptions } : lookupOptions),30    }31 32    const key = JSON.stringify({ hostname, ...options })33 34    if (cache.has(key)) {35      const cached = cache.get(key)36      return process.nextTick(callback, null, ...cached)37    }38 39    lookup(hostname, options, (err, ...result) => {40      if (err) {41        return callback(err)42      }43 44      cache.set(key, result, { ttl })45      return callback(null, ...result)46    })47  },48})49 50module.exports = {51  cache,52  getOptions,53}54