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Prevent multiple concurrent requests for packages

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Fixes #38
Fixes #41
This commit is contained in:
MICHAEL JACKSON
2017-08-10 22:11:55 -07:00
parent cb8061f3e1
commit a485858381
9 changed files with 207 additions and 200 deletions
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86
server/middleware/fetchPackage.js
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@ -1,71 +1,51 @@
const fs = require('fs')
const path = require('path')
const tmpdir = require('os-tmpdir')
const { maxSatisfying: maxSatisfyingVersion } = require('semver')
const PackageCache = require('../PackageCache')
const PackageInfo = require('../PackageInfo')
const { createPackageURL } = require('./PackageUtils')
const { getPackage } = require('./RegistryUtils')
function checkLocalCache(dir, callback) {
fs.stat(path.join(dir, 'package.json'), function (error, stats) {
callback(stats && stats.isFile())
})
}
function createTempPath(name) {
return path.join(tmpdir(), `unpkg-${name}`)
}
/**
* Fetch the package from the registry and store a local copy on disk.
* Redirect if the URL does not specify an exact req.packageVersion number.
*/
function fetchPackage() {
return function (req, res, next) {
req.packageDir = createTempPath(req.packageSpec)
function fetchPackage(req, res, next) {
PackageInfo.get(req.packageName, function (error, packageInfo) {
if (error) {
console.error(error)
return res.status(500).send(`Cannot get info for package "${req.packageName}"`)
}
// TODO: fix race condition! (see #38)
checkLocalCache(req.packageDir, function (isCached) {
if (isCached)
return next() // Best case: we already have this package on disk.
if (packageInfo == null || packageInfo.versions == null)
return res.status(404).send(`Cannot find package "${req.packageName}"`)
PackageInfo.get(req.packageName, function (error, packageInfo) {
req.packageInfo = packageInfo
const { versions, 'dist-tags': tags } = req.packageInfo
if (req.packageVersion in versions) {
// A valid request for a package we haven't downloaded yet.
req.packageConfig = versions[req.packageVersion]
PackageCache.get(req.packageConfig, function (error, outputDir) {
if (error) {
console.error(error)
return res.status(500).send(`Cannot get info for package "${req.packageName}"`)
}
if (packageInfo == null || packageInfo.versions == null)
return res.status(404).send(`Cannot find package "${req.packageName}"`)
const { versions, 'dist-tags': tags } = packageInfo
if (req.packageVersion in versions) {
// A valid request for a package we haven't downloaded yet.
const packageConfig = versions[req.packageVersion]
const tarballURL = packageConfig.dist.tarball
getPackage(tarballURL, req.packageDir, function (error) {
if (error) {
res.status(500).send(error.message || error)
} else {
next()
}
})
} else if (req.packageVersion in tags) {
res.redirect(createPackageURL(req.packageName, tags[req.packageVersion], req.filename, req.search))
res.status(500).send(`Cannot fetch package ${req.packageSpec}`)
} else {
const maxVersion = maxSatisfyingVersion(Object.keys(versions), req.packageVersion)
if (maxVersion) {
res.redirect(createPackageURL(req.packageName, maxVersion, req.filename, req.search))
} else {
res.status(404).send(`Cannot find package ${req.packageSpec}`)
}
req.packageDir = outputDir
next()
}
})
})
}
} else if (req.packageVersion in tags) {
res.redirect(createPackageURL(req.packageName, tags[req.packageVersion], req.filename, req.search))
} else {
const maxVersion = maxSatisfyingVersion(Object.keys(versions), req.packageVersion)
if (maxVersion) {
res.redirect(createPackageURL(req.packageName, maxVersion, req.filename, req.search))
} else {
res.status(404).send(`Cannot find package ${req.packageSpec}`)
}
}
})
}
module.exports = fetchPackage