perf(mdx-loader): cache mdx/remark compiler instances (#4997)

* (mdx-loader) only create mdx compiler once per webpack config

* type fixes

* fix path

* remove assertion

* docs: add missing Tab/TabItem imports

* fixup

Co-authored-by: slorber <lorber.sebastien@gmail.com>
Co-authored-by: Josh-Cena <sidachen2003@gmail.com>

packages/docusaurus-mdx-loader/src/deps.d.ts

@@ -10,8 +10,7 @@ declare module '@mdx-js/mdx' {
   import type {Processor} from 'unified';
   import type {RemarkOrRehypePlugin} from '@docusaurus/mdx-loader';
 
-  namespace mdx {
-    interface Options {
+  export interface Options {
     filepath?: string;
     skipExport?: boolean;
     wrapExport?: string;
@@ -19,10 +18,9 @@ declare module '@mdx-js/mdx' {
     rehypePlugins?: RemarkOrRehypePlugin[];
   }
 
-    function sync(content: string, options?: Options): string;
-    function createMdxAstCompiler(options?: Options): Processor;
-    function createCompiler(options?: Options): Processor;
-  }
+  export function sync(content: string, options?: Options): string;
+  export function createMdxAstCompiler(options?: Options): Processor;
+  export function createCompiler(options?: Options): Processor;
   export default function mdx(
     content: string,
     options?: mdx.Options,

packages/docusaurus-mdx-loader/src/index.ts

@@ -6,7 +6,7 @@
  */
 
 import fs from 'fs-extra';
-import mdx from '@mdx-js/mdx';
+import {createCompiler} from '@mdx-js/mdx';
 import logger from '@docusaurus/logger';
 import emoji from 'remark-emoji';
 import {
@@ -23,11 +23,18 @@ import transformImage from './remark/transformImage';
 import transformLinks from './remark/transformLinks';
 import type {MDXOptions} from '@docusaurus/mdx-loader';
 import type {LoaderContext} from 'webpack';
+import type {Processor} from 'unified';
 
 const {
   loaders: {inlineMarkdownImageFileLoader},
 } = getFileLoaderUtils();
 
+const pragma = `
+/* @jsxRuntime classic */
+/* @jsx mdx */
+/* @jsxFrag mdx.Fragment */
+`;
+
 const DEFAULT_OPTIONS: MDXOptions = {
   rehypePlugins: [],
   remarkPlugins: [unwrapMdxCodeBlocks, emoji, headings, toc],
@@ -35,6 +42,8 @@ const DEFAULT_OPTIONS: MDXOptions = {
   beforeDefaultRehypePlugins: [],
 };
 
+const compilerCache = new Map<string | Options, [Processor, Options]>();
+
 type Options = MDXOptions & {
   staticDirs: string[];
   siteDir: string;
@@ -124,6 +133,7 @@ export default async function mdxLoader(
 
   const hasFrontMatter = Object.keys(frontMatter).length > 0;
 
+  if (!compilerCache.has(this.query)) {
     const options: Options = {
       ...reqOptions,
       remarkPlugins: [
@@ -150,12 +160,20 @@ export default async function mdxLoader(
         ...DEFAULT_OPTIONS.rehypePlugins,
         ...(reqOptions.rehypePlugins ?? []),
       ],
-    filepath: filePath,
     };
+    compilerCache.set(this.query, [createCompiler(options), options]);
+  }
+
+  const [compiler, options] = compilerCache.get(this.query)!;
 
   let result: string;
   try {
-    result = await mdx(content, options);
+    result = await compiler
+      .process({
+        contents: content,
+        path: this.resourcePath,
+      })
+      .then((res) => res.toString());
   } catch (err) {
     return callback(err as Error);
   }
@@ -214,6 +232,7 @@ ${assets ? `export const assets = ${createAssetsExportCode(assets)};` : ''}
 `;
 
   const code = `
+${pragma}
 import React from 'react';
 import { mdx } from '@mdx-js/react';
 

packages/docusaurus-remark-plugin-npm2yarn/src/index.ts

@@ -6,7 +6,7 @@
  */
 
 import type {Code, Content, Literal} from 'mdast';
-import type {Plugin, Transformer} from 'unified';
+import type {Plugin} from 'unified';
 import type {Node, Parent} from 'unist';
 import visit from 'unist-util-visit';
 import npmToYarn from 'npm-to-yarn';
@@ -61,9 +61,9 @@ const nodeForImport: Literal = {
 
 const plugin: Plugin<[PluginOptions?]> = (options = {}) => {
   const {sync = false} = options;
+  return (root) => {
     let transformed = false;
     let alreadyImported = false;
-  const transformer: Transformer = (root) => {
     visit(root, (node: Node) => {
       if (isImport(node) && node.value.includes('@theme/Tabs')) {
         alreadyImported = true;
@@ -87,7 +87,6 @@ const plugin: Plugin<[PluginOptions?]> = (options = {}) => {
       (root as Parent).children.unshift(nodeForImport);
     }
   };
-  return transformer;
 };
 
 // To continue supporting `require('npm2yarn')` without the `.default` ㄟ(▔,▔)ㄏ