unpkg/server/middleware/utils/getPackageInfo.js

69 lines
2.0 KiB
JavaScript

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