in-memory cache the changelog RSS downloads (github#23582)

* in-memory cache the changelog RSS downloads * fix tests
maied12 · Dec 11, 2021 · 6363640 · 6363640
1 parent e2fb5e1
commit 6363640
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Showing 3 changed files with 40 additions and 17 deletions.
diff --git a/lib/changelog.js b/lib/changelog.js
@@ -1,6 +1,6 @@
 import Parser from 'rss-parser'
 
-export async function getRssFeed(url) {
+async function getRssFeed(url) {
   const parser = new Parser({ timeout: 5000 })
   const feedUrl = `${url}/feed`
   let feed
@@ -15,7 +15,16 @@ export async function getRssFeed(url) {
   return feed
 }
 
-export async function getChangelogItems(prefix, feed) {
+const globalCache = new Map()
+
+export async function getChangelogItems(prefix, feedUrl) {
+  const cacheKey = prefix + feedUrl
+  if (globalCache.get(cacheKey)) {
+    return globalCache.get(cacheKey)
+  }
+
+  const feed = await getRssFeed(feedUrl)
+
   if (!feed || !feed.items) {
     console.log(feed)
     console.error('feed is not valid or has no items')
@@ -34,7 +43,10 @@ export async function getChangelogItems(prefix, feed) {
     }
   })
 
+  // We don't cache the raw payload we'd get from the network request
+  // because it would waste memory. Instead we store the "serialized"
+  // object that's created from the raw payload.
+  globalCache.set(cacheKey, changelog)
+
   return changelog
 }
-
-export default { getRssFeed, getChangelogItems }
diff --git a/middleware/contextualizers/whats-new-changelog.js b/middleware/contextualizers/whats-new-changelog.js
@@ -1,10 +1,10 @@
-import { getRssFeed, getChangelogItems } from '../../lib/changelog.js'
+import { getChangelogItems } from '../../lib/changelog.js'
 import getApplicableVersions from '../../lib/get-applicable-versions.js'
 
 export default async function whatsNewChangelog(req, res, next) {
   if (!req.context.page) return next()
   if (!req.context.page.changelog) return next()
-  const label = req.context.page.changelog.label
+  const label = req.context.page.changelog.label.split(/\s+/g).join('')
 
   // If there is no `versions` prop in the changelog frontmatter, assume the changelog should display in all versions.
   if (req.context.page.changelog.versions) {
@@ -23,7 +23,9 @@ export default async function whatsNewChangelog(req, res, next) {
 
   req.context.changelogUrl = labelUrls[label] || `https://github.blog/changelog/label/${label}`
 
-  const feed = await getRssFeed(req.context.changelogUrl)
-  req.context.whatsNewChangelog = await getChangelogItems(req.context.page.changelog.prefix, feed)
+  req.context.whatsNewChangelog = await getChangelogItems(
+    req.context.page.changelog.prefix,
+    req.context.changelogUrl
+  )
   return next()
 }
diff --git a/tests/unit/get-rss-feeds.js b/tests/unit/get-rss-feeds.js
@@ -1,20 +1,29 @@
-import Parser from 'rss-parser'
-import { getChangelogItems } from '../../lib/changelog.js'
 import fs from 'fs/promises'
 import path from 'path'
-const parser = new Parser({ timeout: 5000 })
-const rssFeedContent = await fs.readFile(
-  path.join(process.cwd(), 'tests/fixtures/rss-feed.xml'),
-  'utf8'
-)
+
+import nock from 'nock'
+
+import { getChangelogItems } from '../../lib/changelog.js'
 
 describe('getChangelogItems module', () => {
   let changelog
+
   beforeAll(async () => {
-    const feed = await parser.parseString(rssFeedContent)
-    changelog = await getChangelogItems('GitHub Actions:', feed)
+    const rssFeedContent = await fs.readFile(
+      path.join(process.cwd(), 'tests/fixtures/rss-feed.xml'),
+      'utf8'
+    )
+
+    nock('https://github.blog').get('/changelog/label/packages/feed').reply(200, rssFeedContent)
+
+    changelog = await getChangelogItems(
+      'GitHub Actions:',
+      'https://github.blog/changelog/label/packages'
+    )
   })
 
+  afterAll(() => nock.cleanAll())
+
   it('changelog contains 3 items', async () => {
     expect(changelog.length).toEqual(3)
   })