54 lines
1.2 KiB
JavaScript
54 lines
1.2 KiB
JavaScript
'use strict'
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const { LRUCache } = require('lru-cache')
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const dns = require('dns')
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// this is a factory so that each request can have its own opts (i.e. ttl)
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// while still sharing the cache across all requests
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const cache = new LRUCache({ max: 50 })
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const getOptions = ({
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family = 0,
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hints = dns.ADDRCONFIG,
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all = false,
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verbatim = undefined,
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ttl = 5 * 60 * 1000,
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lookup = dns.lookup,
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}) => ({
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// hints and lookup are returned since both are top level properties to (net|tls).connect
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hints,
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lookup: (hostname, ...args) => {
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const callback = args.pop() // callback is always last arg
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const lookupOptions = args[0] ?? {}
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const options = {
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family,
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hints,
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all,
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verbatim,
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...(typeof lookupOptions === 'number' ? { family: lookupOptions } : lookupOptions),
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}
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const key = JSON.stringify({ hostname, ...options })
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if (cache.has(key)) {
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const cached = cache.get(key)
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return process.nextTick(callback, null, ...cached)
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}
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lookup(hostname, options, (err, ...result) => {
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if (err) {
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return callback(err)
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}
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cache.set(key, result, { ttl })
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return callback(null, ...result)
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})
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},
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})
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module.exports = {
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cache,
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getOptions,
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}
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