fix: memory leak in blog (#5097)

* fix: memory leak in blog

* chore: pr feedback

lib/blog.js

@@ -1,9 +1,15 @@
 const markdownToHtml = require('electron-markdown')
-const i18n = require('../lib/i18n')
 const graymatter = require('gray-matter')
 const fs = require('fs-extra')
 const path = require('path')
 
+const blogPosts = new Map()
+const POSTS_PATH = path.join(__dirname, '..', 'data', 'blog')
+
+/**
+ * @param {string} markdown
+ * @returns {Promise<string>}
+ */
 function parseMarkdown(markdown) {
   // Using unsafe options as we trust the blog content from this repo
   return markdownToHtml(markdown, {
@@ -16,115 +22,66 @@ function parseMarkdown(markdown) {
   })
 }
 
-const POSTS_PATH = path.join(__dirname, '..', 'data', 'blog')
-class BlogPost {
-  static async getAll(language) {
-    const files = await fs.readdir(POSTS_PATH)
-    const slugs = files.map((file) => path.basename(file, '.md'))
-    return slugs.map((slug) => BlogPost.get(slug, language))
-  }
-
-  static get(slug, language) {
-    return new BlogPost(slug, language)
-  }
-
-  constructor(slug, language) {
-    this._cache = new Map()
-    this._slug = slug
-    this._language = language
-  }
-
-  exists() {
-    return fs.stat(path.join(POSTS_PATH, this.filename()))
-  }
-
-  async cache(key, computation) {
-    if (this._cache.has(key)) {
-      return this._cache.get(key)
-    } else {
-      const value = await computation()
-      this._cache.set(key, value)
-      return value
-    }
-  }
-
-  _getRawMarkdown() {
-    // This block looks not very good, but they give confidence,
-    // and security that we do not get the crash when the content
-    // not synchronized in the i18n, e.g. when we publish a new post,
-    // languages that don't have the copy on the own language get the
-    // version from the disk.
-    //
-    // Why not use the English version from the i18n module?
-    // We get the desync between this repo and i18n, the save
-    // and simple way it's using the good saved copy from the disk.
-    //
-    // drink some water, be kind to yourself and others.
-
-    // If you ask why this code block is disabled?
-    // So, the Electron translations for blogs is so bad,
-    // that it's better to currently disable this and not search
-    // for fixes. The comment above this still actual for this code block.
-    // if (this._language) {
-    //   const blog = i18n.blogs[this._language][this.href()]
-    //   if (blog) {
-    //     return this.cache('_getRawMarkdown', () => blog.content)
-    //   }
-    // }
-
-    const fullPath = path.join(POSTS_PATH, this.filename())
-    return this.cache('_getRawMarkdown', () => fs.readFile(fullPath))
-  }
-
-  async _frontmatter() {
-    const markdown = await this._getRawMarkdown()
-    return this.cache('frontmatter', () => {
-      return graymatter(markdown, {
-        excerpt: true,
-        excerpt_separator: '---',
-      })
-    })
-  }
-
-  async frontmatter(key) {
-    const fm = await this._frontmatter()
-    return fm.data[key]
-  }
-
-  slug() {
-    return this._slug
-  }
-
-  filename() {
-    return `${this.slug()}.md`
-  }
-
-  title() {
-    return this.frontmatter('title')
-  }
-
-  date() {
-    return this.frontmatter('date')
-  }
-
-  href() {
-    return `/blog/${this.slug()}`
-  }
-
-  async authors() {
-    const authors = await this.frontmatter('author')
-    return Array.isArray(authors) ? authors : [authors]
-  }
-
-  async excerpt() {
-    const { excerpt } = await this._frontmatter()
-    return this.cache('excerpt', () => parseMarkdown(excerpt))
-  }
-
-  async content() {
-    const { content } = await this._frontmatter()
-    return this.cache('content', () => parseMarkdown(content))
-  }
+/**
+ * @param {string} markdown
+ * @returns {graymatter.GrayMatterFile<string>}
+ */
+function parseFrontMatter(markdown) {
+  return graymatter(markdown, {
+    excerpt: true,
+    excerpt_separator: '---',
+  })
 }
 
-module.exports = BlogPost
+/**
+ * @returns {Map}
+ */
+async function getAllPosts() {
+  if (blogPosts.size !== 0) {
+    return blogPosts
+  }
+
+  const files = await fs.readdir(POSTS_PATH)
+  const slugs = files.map((file) => path.basename(file, '.md'))
+
+  for (const slug of slugs) {
+    blogPosts.set(slug, await loadPost(slug))
+  }
+
+  return blogPosts
+}
+
+/**
+ * @param {string} slug
+ */
+async function loadPost(slug) {
+  let markdown = await fs.readFile(path.join(POSTS_PATH, `${slug}.md`))
+
+  const frontmatter = parseFrontMatter(markdown)
+  const authors = Array.isArray(frontmatter.data.author)
+    ? frontmatter.data.author
+    : [frontmatter.data.author]
+
+  const post = {
+    title: frontmatter.data.title,
+    href: `/blog/${slug}`,
+    date: frontmatter.data.date,
+    authors,
+    excerpt: await parseMarkdown(frontmatter.excerpt),
+    content: await parseMarkdown(frontmatter.content),
+  }
+
+  return post
+}
+
+/**
+ * @param {string} slug
+ */
+async function getPost(slug) {
+  return (await getAllPosts()).get(slug)
+}
+
+module.exports = {
+  getAllPosts,
+  getPost,
+}

package-lock.json

@@ -8508,8 +8508,7 @@
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/is-extglob/-/is-extglob-2.1.1.tgz",
       "integrity": "sha1-qIwCU1eR8C7TfHahueqXc8gz+MI=",
-      "dev": true,
-      "optional": true
+      "dev": true
     },
     "is-finite": {
       "version": "1.1.0",
@@ -17038,11 +17037,6 @@
       "integrity": "sha1-AI4G2AlDIMNy28L47XagymyKxBk=",
       "dev": true
     },
-    "yubikiri": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/yubikiri/-/yubikiri-2.0.0.tgz",
-      "integrity": "sha512-gPLdm8Om6zZn6lsjQGZf3OdB+3OnxEX46S+TP6slcgLOArydrZan/OtEemyBmC73SG2Y0QYzYts3+5p2VzqvKw=="
-    },
     "zwitch": {
       "version": "1.0.5",
       "resolved": "https://registry.npmjs.org/zwitch/-/zwitch-1.0.5.tgz",

package.json

@@ -83,8 +83,7 @@
     "search-with-your-keyboard": "^2.0.0",
     "semver": "^7.3.2",
     "set-query-string": "^2.2.0",
-    "ultimate-pagination": "^1.0.0",
-    "yubikiri": "^2.0.0"
+    "ultimate-pagination": "^1.0.0"
   },
   "devDependencies": {
     "browser-sync": "^2.26.14",

routes/blog/index.js

@@ -1,20 +1,14 @@
-const yubikiri = require('yubikiri')
-const BlogPost = require('../../lib/blog')
+const { getAllPosts } = require('../../lib/blog')
 
-function hydrateViewModel(blogPost) {
-  return yubikiri({
-    title: blogPost.title(),
-    href: blogPost.href(),
-    date: blogPost.date(),
-    authors: blogPost.authors(),
-    excerpt: blogPost.excerpt(),
-  })
-}
+let postsInOrder = []
 
 module.exports = async (req, res) => {
-  const blogPosts = await BlogPost.getAll(req.language)
-  const posts = await Promise.all(blogPosts.map(hydrateViewModel))
-  const postsInOrder = posts.sort((a, b) => b.date.localeCompare(a.date))
+  if (postsInOrder.length === 0) {
+    const blogPosts = await getAllPosts()
+    const posts = Array.from(blogPosts.values())
+    postsInOrder = posts.sort((a, b) => b.date.localeCompare(a.date))
+  }
+
   Object.assign(req.context, {
     posts: postsInOrder,
   })

routes/blog/show.js

@@ -1,27 +1,12 @@
-const yubikiri = require('yubikiri')
-const BlogPost = require('../../lib/blog')
-
-function hydrateViewModel(blogPost) {
-  return yubikiri({
-    title: blogPost.title(),
-    href: blogPost.href(),
-    date: blogPost.date(),
-    authors: blogPost.authors(),
-    excerpt: blogPost.excerpt(),
-    content: blogPost.content(),
-  })
-}
+const { getPost } = require('../../lib/blog')
 
 module.exports = async (req, res, next) => {
-  const blogPost = BlogPost.get(req.params.slug, req.language)
-  try {
-    await blogPost.exists()
-  } catch (e) {
+  const post = await getPost(req.params.slug)
+
+  if (!post) {
     return next()
   }
 
-  const post = await hydrateViewModel(blogPost)
-
   // redirect /blog/2016/09/27/foo to /blog/foo
   if (req.path !== post.href) {
     return res.redirect(post.href)

routes/feed/blog.js

@@ -1,8 +1,12 @@
 const { setupFeed } = require('./mainFeed')
-const BlogPost = require('../../lib/blog')
+const { getAllPosts } = require('../../lib/blog')
+let feed
 
 module.exports = async function feedHandler(req, res, next) {
-  const feed = await setupFeed('blog', await BlogPost.getAll())
+  if (!feed) {
+    const posts = await getAllPosts()
+    feed = await setupFeed('blog', Array.from(posts.values()))
+  }
 
   if (req.path === '/blog.xml') {
     res.set('content-type', 'text/xml')

routes/feed/mainFeed.js

@@ -1,7 +1,6 @@
 const Feed = require('feed').Feed
 const description = require('description')
 const memoize = require('fast-memoize')
-const yubikiri = require('yubikiri')
 
 const types = {
   blog: 'blog',
@@ -37,21 +36,16 @@ module.exports.setupFeed = memoize(async (type, items) => {
       })
       break
     case types.blog: {
-      const posts = await Promise.all(
-        items.map((post) =>
-          yubikiri({
-            href: post.href(),
-            title: post.title(),
-            content: post.content(),
-            date: post.date(),
-            author: async () => {
-              const authors = await post.authors()
-              return { name: authors[0] }
-            },
-            image: null, // TODO
-          })
-        )
-      )
+      const posts = items.map((post) => {
+        return {
+          href: post.href,
+          title: post.title,
+          content: post.content,
+          date: post.date,
+          author: post.authors[0],
+          image: null, // TODO
+        }
+      })
       posts
         .sort((a, b) => b.date.localeCompare(a.date))
         .forEach((post) => {