From a8735646e8aae04d7091decc8c4fd54025ceb181 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Sat, 16 May 2020 22:43:43 -0400
Subject: [PATCH] feat: use hashed page file names

---
 lib/app/index.js    | 23 +++++++++++++++++------
 lib/shim.d.ts       |  1 +
 src/build/build.ts  | 27 +++++++++++++++++++++++++--
 src/build/bundle.ts | 33 ++++++++++++++++++++++++---------
 src/build/render.ts | 36 ++++++++++++++++++++++--------------
 5 files changed, 89 insertions(+), 31 deletions(-)

diff --git a/lib/app/index.js b/lib/app/index.js
index 7ff96f5e..b47f4339 100644
--- a/lib/app/index.js
+++ b/lib/app/index.js
@@ -56,12 +56,23 @@ export function createApp() {
     } else {
       // in production, each .md file is built into a .md.js file following
       // the path conversion scheme.
-      // /foo/bar.html -> /js/foo_bar.md.js
-      const useLeanBuild = isInitialPageLoad || initialPath === pagePath
-      pagePath =
-        (inBrowser ? __BASE__ + '_assets/' : './') +
-        pagePath.slice(inBrowser ? __BASE__.length : 1).replace(/\//g, '_') +
-        (useLeanBuild ? '.md.lean.js' : '.md.js')
+      // /foo/bar.html -> ./foo_bar.md
+
+      if (inBrowser) {
+        pagePath = pagePath.slice(__BASE__.length).replace(/\//g, '_') + '.md'
+        // client production build needs to account for page hash, which is
+        // injected directly in the page's html
+        const pageHash = __VP_HASH_MAP__[pagePath]
+        // use lean build if this is the initial page load or navigating back
+        // to the initial loaded path (the static vnodes already adopted the
+        // static content on that load so no need to re-fetch the page)
+        const ext =
+          isInitialPageLoad || initialPath === pagePath ? 'lean.js' : 'js'
+        pagePath = `${__BASE__}_assets/${pagePath}.${pageHash}.${ext}`
+      } else {
+        // ssr build uses much simpler name mapping
+        pagePath = `./${pagePath.slice(1).replace(/\//g, '_')}.md.js`
+      }
     }
 
     if (inBrowser) {
diff --git a/lib/shim.d.ts b/lib/shim.d.ts
index 52bc0549..aadea8a8 100644
--- a/lib/shim.d.ts
+++ b/lib/shim.d.ts
@@ -1,5 +1,6 @@
 declare const __DEV__: boolean
 declare const __BASE__: string
+declare const __VP_HASH_MAP__: Record<string, string>
 
 declare module '*.vue' {
   import { ComponentOptions } from 'vue'
diff --git a/src/build/build.ts b/src/build/build.ts
index 00610b9b..4a5828fb 100644
--- a/src/build/build.ts
+++ b/src/build/build.ts
@@ -3,6 +3,7 @@ import { bundle } from './bundle'
 import { BuildConfig as ViteBuildOptions } from 'vite'
 import { resolveConfig } from '../config'
 import { renderPage } from './render'
+import { OutputChunk } from 'rollup'
 
 export type BuildOptions = Pick<
   ViteBuildOptions,
@@ -17,10 +18,32 @@ export const ASSETS_DIR = '_assets/'
 export async function build(buildOptions: BuildOptions = {}) {
   const siteConfig = await resolveConfig(buildOptions.root)
   try {
-    const [clientResult] = await bundle(siteConfig, buildOptions)
+    const [clientResult, , pageToHashMap] = await bundle(
+      siteConfig,
+      buildOptions
+    )
     console.log('rendering pages...')
+
+    const indexChunk = clientResult.assets.find(
+      (chunk) =>
+        chunk.type === 'chunk' && chunk.fileName.match(/^index\.\w+\.js$/)
+    ) as OutputChunk
+
+    // We embed the hash map string into each page directly so that it doesn't
+    // alter the main chunk's hash on every build. It's also embedded as a
+    // string and JSON.parsed from the client because it's faster than embedding
+    // as JS object literal.
+    const hashMapStirng = JSON.stringify(JSON.stringify(pageToHashMap))
+
     for (const page of siteConfig.pages) {
-      await renderPage(siteConfig, page, clientResult)
+      await renderPage(
+        siteConfig,
+        page,
+        clientResult,
+        indexChunk,
+        pageToHashMap,
+        hashMapStirng
+      )
     }
   } finally {
     await fs.remove(siteConfig.tempDir)
diff --git a/src/build/bundle.ts b/src/build/bundle.ts
index b0102f5d..558a2a47 100644
--- a/src/build/bundle.ts
+++ b/src/build/bundle.ts
@@ -31,12 +31,13 @@ const isPageChunk = (
 export async function bundle(
   config: SiteConfig,
   options: BuildOptions
-): Promise<BuildResult[]> {
+): Promise<[BuildResult, BuildResult, Record<string, string>]> {
   const root = config.root
   const resolver = createResolver(config.themeDir)
   const markdownToVue = createMarkdownToVueRenderFn(root)
 
   let isClientBuild = true
+  const pageToHashMap = Object.create(null)
 
   const VitePressPlugin: Plugin = {
     name: 'vitepress',
@@ -82,13 +83,18 @@ export async function bundle(
         const chunk = bundle[name]
         if (isPageChunk(chunk)) {
           // foo/bar.md -> foo_bar.md.js
-          chunk.fileName =
-            slash(path.relative(root, chunk.facadeModuleId)).replace(
-              /\//g,
-              '_'
-            ) + '.js'
+          const hash = isClientBuild
+            ? chunk.fileName.match(/\.(\w+)\.js$/)![1]
+            : ``
+          const pageName = slash(
+            path.relative(root, chunk.facadeModuleId)
+          ).replace(/\//g, '_')
+          chunk.fileName = `${pageName}${hash ? `.${hash}` : ``}.js`
 
           if (isClientBuild) {
+            // record page -> hash relations
+            pageToHashMap[pageName] = hash
+
             // inject another chunk with the content stripped
             bundle[name + '-lean'] = {
               ...chunk,
@@ -131,13 +137,22 @@ export async function bundle(
       preserveEntrySignatures: 'allow-extension',
       plugins: [VitePressPlugin, ...(rollupInputOptions.plugins || [])]
     },
-    rollupOutputOptions,
+    rollupOutputOptions: {
+      ...rollupOutputOptions,
+      chunkFileNames: `common-[hash].js`
+    },
     silent: !process.env.DEBUG,
     minify: !process.env.DEBUG
   }
 
   console.log('building client bundle...')
-  const clientResult = await build(viteOptions)
+  const clientResult = await build({
+    ...viteOptions,
+    rollupOutputOptions: {
+      ...viteOptions.rollupOutputOptions,
+      entryFileNames: `[name].[hash].js`
+    }
+  })
 
   console.log('building server bundle...')
   isClientBuild = false
@@ -146,5 +161,5 @@ export async function bundle(
     outDir: config.tempDir
   })
 
-  return [clientResult, serverResult]
+  return [clientResult, serverResult, pageToHashMap]
 }
diff --git a/src/build/render.ts b/src/build/render.ts
index b4c830e5..e9a643e1 100644
--- a/src/build/render.ts
+++ b/src/build/render.ts
@@ -11,7 +11,10 @@ const escape = require('escape-html')
 export async function renderPage(
   config: SiteConfig,
   page: string, // foo.md
-  result: BuildResult
+  result: BuildResult,
+  indexChunk: OutputChunk,
+  pageToHashMap: Record<string, string>,
+  hashMapStirng: string
 ) {
   const { createApp } = require(path.join(
     config.tempDir,
@@ -23,27 +26,30 @@ export async function renderPage(
   router.go(routePath)
   const content = await renderToString(app)
 
-  const pageJsFileName = page.replace(/\//g, '_') + '.js'
+  const pageName = page.replace(/\//g, '_')
+  // server build doesn't need hash
+  const pageServerJsFileName = pageName + '.js'
+  // for any initial page load, we only need the lean version of the page js
+  // since the static content is already on the page!
+  const pageHash = pageToHashMap[pageName]
+  const pageClientJsFileName = pageName + `.` + pageHash + '.lean.js'
 
   // resolve page data so we can render head tags
   const { __pageData } = require(path.join(
     config.tempDir,
     ASSETS_DIR,
-    pageJsFileName
+    pageServerJsFileName
   ))
   const pageData = JSON.parse(__pageData)
 
   const assetPath = `${config.site.base}${ASSETS_DIR}`
-
   const preloadLinks = [
     // resolve imports for index.js + page.md.js and inject script tags for
     // them as well so we fetch everything as early as possible without having
     // to wait for entry chunks to parse
-    ...resolvePageImports(config, page, result),
-    // for any initial page load, we only need the lean version of the page js
-    // since the static content is already on the page!
-    pageJsFileName.replace(/\.js$/, '.lean.js'),
-    'index.js'
+    ...resolvePageImports(config, page, result, indexChunk),
+    pageClientJsFileName,
+    indexChunk.fileName
   ]
     .map((file) => {
       return `<link rel="modulepreload" href="${assetPath}${file}">`
@@ -64,7 +70,10 @@ export async function renderPage(
   </head>
   <body>
     <div id="app">${content}</div>
-    <script type="module" async src="${assetPath}index.js"></script>
+    <script>__VP_HASH_MAP__ = JSON.parse(${hashMapStirng})</script>
+    <script type="module" async src="${assetPath}${
+    indexChunk.fileName
+  }"></script>
   </body>
 </html>`.trim()
   const htmlFileName = path.join(config.outDir, page.replace(/\.md$/, '.html'))
@@ -75,13 +84,12 @@ export async function renderPage(
 function resolvePageImports(
   config: SiteConfig,
   page: string,
-  result: BuildResult
+  result: BuildResult,
+  indexChunk: OutputChunk
 ) {
   // find the page's js chunk and inject script tags for its imports so that
   // they are start fetching as early as possible
-  const indexChunk = result.assets.find(
-    (chunk) => chunk.type === 'chunk' && chunk.fileName === `index.js`
-  ) as OutputChunk
+
   const srcPath = path.join(config.root, page)
   const pageChunk = result.assets.find(
     (chunk) => chunk.type === 'chunk' && chunk.facadeModuleId === srcPath