feat($markdown): cache parser (#1359)

Author: shigma

packages/@vuepress/markdown-loader/index.js

@@ -6,11 +6,10 @@
 
 const { EventEmitter } = require('events')
 const { getOptions } = require('loader-utils')
-const { fs, path, hash, parseFrontmatter, inferTitle, extractHeaders } = require('@vuepress/shared-utils')
+const { fs, path, parseFrontmatter, inferTitle, extractHeaders } = require('@vuepress/shared-utils')
 const LRU = require('lru-cache')
 const md = require('@vuepress/markdown')
 
-const cache = new LRU({ max: 1000 })
 const devCache = new LRU({ max: 1000 })
 
 /**
@@ -32,26 +31,18 @@ module.exports = function (src) {
   // vue-loader, and will be applied on the same file multiple times when
   // selecting the individual blocks.
   const file = this.resourcePath
-  const key = hash(file + src)
-  const cached = cache.get(key)
-  if (cached && (isProd || /\?vue/.test(this.resourceQuery))) {
-    return cached
-  }
-
-  const frontmatter = parseFrontmatter(src)
-  const content = frontmatter.content
+  const { content, data } = parseFrontmatter(src)
 
   if (!isProd && !isServer) {
-    const inferredTitle = inferTitle(frontmatter.data, frontmatter.content)
+    const inferredTitle = inferTitle(data, content)
     const headers = extractHeaders(content, ['h2', 'h3'], markdown)
-    delete frontmatter.content
 
     // diff frontmatter and title, since they are not going to be part of the
     // returned component, changes in frontmatter do not trigger proper updates
     const cachedData = devCache.get(file)
     if (cachedData && (
       cachedData.inferredTitle !== inferredTitle
-      || JSON.stringify(cachedData.frontmatterData) !== JSON.stringify(frontmatter.data)
+      || JSON.stringify(cachedData.frontmatterData) !== JSON.stringify(data)
       || headersChanged(cachedData.headers, headers)
     )) {
       // frontmatter changed... need to do a full reload
@@ -60,7 +51,7 @@ module.exports = function (src) {
 
     devCache.set(file, {
       headers,
-      frontmatterData: frontmatter.data,
+      frontmatterData: data,
       inferredTitle
     })
   }
@@ -73,7 +64,7 @@ module.exports = function (src) {
     dataBlockString
   } = markdown.render(content, {
     loader,
-    frontmatter: frontmatter.data,
+    frontmatter: data,
     relPath: path.relative(sourceDir, file)
   })
 
@@ -114,7 +105,6 @@ module.exports = function (src) {
     + (hoistedTags || []).join('\n')
     + `\n${dataBlockString}\n`
   )
-  cache.set(key, res)
   return res
 }
 

packages/@vuepress/markdown-loader/package.json

@@ -19,7 +19,8 @@
   ],
   "dependencies": {
     "@vuepress/markdown": "^1.0.0-alpha.39",
-    "loader-utils": "^1.1.0"
+    "loader-utils": "^1.1.0",
+    "lru-cache": "^5.1.1"
   },
   "author": "Evan You",
   "maintainers": [

packages/@vuepress/markdown/index.js

@@ -5,6 +5,7 @@
  */
 
 const Config = require('markdown-it-chain')
+const LRUCache = require('lru-cache')
 const highlight = require('./lib/highlight')
 const { PLUGINS, REQUIRED_PLUGINS } = require('./lib/constant')
 const highlightLinesPlugin = require('./lib/highlightLines')
@@ -19,7 +20,7 @@ const snippetPlugin = require('./lib/snippet')
 const emojiPlugin = require('markdown-it-emoji')
 const anchorPlugin = require('markdown-it-anchor')
 const tocPlugin = require('markdown-it-table-of-contents')
-const { parseHeaders, slugify: _slugify, logger, chalk } = require('@vuepress/shared-utils')
+const { parseHeaders, slugify: _slugify, logger, chalk, hash } = require('@vuepress/shared-utils')
 
 /**
  * Create markdown by config.
@@ -115,6 +116,21 @@ module.exports = (markdown = {}) => {
 
   afterInstantiate && afterInstantiate(md)
 
+  // override parse to allow cache
+  const parse = md.parse
+  const cache = new LRUCache({ max: 1000 })
+  md.parse = (src, env) => {
+    const key = hash(src + env.relPath)
+    const cached = cache.get(key)
+    if (cached) {
+      return cached
+    } else {
+      const tokens = parse.call(md, src, env)
+      cache.set(key, tokens)
+      return tokens
+    }
+  }
+
   module.exports.dataReturnable(md)
 
   // expose slugify

packages/@vuepress/markdown/package.json

@@ -20,6 +20,7 @@
   ],
   "dependencies": {
     "@vuepress/shared-utils": "^1.0.0-alpha.39",
+    "lru-cache": "^5.1.1",
     "markdown-it": "^8.4.1",
     "markdown-it-anchor": "^5.0.2",
     "markdown-it-chain": "^1.3.0",