69 lines
2.0 KiB
JavaScript
69 lines
2.0 KiB
JavaScript
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require('isomorphic-fetch')
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const PackageInfoCache = require('./PackageInfoCache')
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const createMutex = require('./createMutex')
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const RegistryURL = process.env.NPM_REGISTRY_URL || 'https://registry.npmjs.org'
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function fetchPackageInfo(packageName) {
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console.log(`Fetching info for package ${packageName} from NPM`)
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let encodedPackageName
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if (packageName.charAt(0) === '@') {
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encodedPackageName = `@${encodeURIComponent(packageName.substring(1))}`
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} else {
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encodedPackageName = encodeURIComponent(packageName)
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}
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const url = `${RegistryURL}/${encodedPackageName}`
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return fetch(url, {
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headers: { 'Accept': 'application/json' }
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}).then(function (response) {
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return response.status === 404 ? null : response.json()
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})
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}
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const PackageNotFound = 'PackageNotFound'
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// This mutex prevents multiple concurrent requests to
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// the registry for the same package info.
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const fetchMutex = createMutex(function (packageName, callback) {
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fetchPackageInfo(packageName).then(function (value) {
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if (value == null) {
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// Cache 404s for 5 minutes. This prevents us from making
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// unnecessary requests to the registry for bad package names.
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// In the worst case, a brand new package's info will be
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// available within 5 minutes.
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PackageInfoCache.set(packageName, PackageNotFound, 300, function () {
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callback(null, value)
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})
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} else {
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// Cache valid package info for one minute.
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PackageInfoCache.set(packageName, value, 60, function () {
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callback(null, value)
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})
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}
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}, function (error) {
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// Do not cache errors.
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PackageInfoCache.del(packageName, function () {
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callback(error)
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})
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})
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})
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function getPackageInfo(packageName, callback) {
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PackageInfoCache.get(packageName, function (error, value) {
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if (error) {
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callback(error)
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} else if (value) {
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callback(null, value === PackageNotFound ? null : value)
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} else {
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fetchMutex(packageName, callback)
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}
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})
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}
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module.exports = {
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get: getPackageInfo
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}
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