From ff0cfca3cfe5cd62c480e8f11dc23aa19570cf3a Mon Sep 17 00:00:00 2001
From: Yuxin Wu <ppwwyyxxc@gmail.com>
Date: Tue, 29 Mar 2022 20:07:40 -0700
Subject: [PATCH] Async rendering of tags within a post

---
 lib/hexo/post.js          | 26 +++++++++++++++-----------
 package.json              |  1 +
 test/scripts/hexo/post.js |  4 ++--
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/lib/hexo/post.js b/lib/hexo/post.js
index 7f0db61bbe..817173041b 100644
--- a/lib/hexo/post.js
+++ b/lib/hexo/post.js
@@ -2,6 +2,7 @@
 
 const assert = require('assert');
 const moment = require('moment');
+const parse5 = require('parse5');
 const Promise = require('bluebird');
 const { join, extname, basename } = require('path');
 const { magenta } = require('picocolors');
@@ -414,18 +415,21 @@ class Post {
         text: data.content,
         path: source,
         engine: data.engine,
-        toString: true,
-        onRenderEnd(content) {
-          // Replace cache data with real contents
-          data.content = cacheObj.restoreAllSwigTags(content);
-
-          // Return content after replace the placeholders
-          if (disableNunjucks) return data.content;
-
-          // Render with Nunjucks
-          return tag.render(data.content, data);
-        }
+        toString: true
       }, options);
+    }).then(content => {
+      const doc = parse5.parseFragment(content);
+      // Indepedently render the tags in each top-level node
+      // asynchronously. This can significantly speed up rendering of slow tags
+      const results = doc.childNodes.map(async node => {
+        // Replace cache data with real contents
+        const content = cacheObj.restoreAllSwigTags(parse5.serializeOuter(node));
+        // If disabled, return content after replacing the placeholders
+        if (disableNunjucks) return content;
+        // Render with Nunjucks
+        return await tag.render(content, data);
+      });
+      return Promise.all(results).then(x => x.join(''));
     }).then(content => {
       data.content = cacheObj.restoreCodeBlocks(content);
 
diff --git a/package.json b/package.json
index f566b4e5e7..c0eca988fe 100644
--- a/package.json
+++ b/package.json
@@ -56,6 +56,7 @@
     "moment-timezone": "^0.5.34",
     "picocolors": "^1.0.0",
     "nunjucks": "^3.2.3",
+    "parse5": "^7.0.0",
     "pretty-hrtime": "^1.0.3",
     "resolve": "^1.22.0",
     "strip-ansi": "^6.0.0",
diff --git a/test/scripts/hexo/post.js b/test/scripts/hexo/post.js
index ccedb78a82..247204539d 100644
--- a/test/scripts/hexo/post.js
+++ b/test/scripts/hexo/post.js
@@ -3,7 +3,7 @@
 const { join } = require('path');
 const moment = require('moment');
 const { readFile, mkdirs, unlink, rmdir, writeFile, exists, stat, listDir } = require('hexo-fs');
-const { highlight, escapeHTML } = require('hexo-util');
+const { highlight } = require('hexo-util');
 const { spy, useFakeTimers } = require('sinon');
 const { parse: yfm } = require('hexo-front-matter');
 const fixture = require('../../fixtures/post_render');
@@ -1215,7 +1215,7 @@ describe('Post', () => {
       engine: 'markdown'
     });
 
-    data.content.trim().should.contains(`<pre><code class="sh">${escapeHTML('echo "Hi"')}\n</code></pre>`);
+    data.content.trim().should.contains('<pre><code class="sh">echo "Hi"\n</code></pre>');
     data.content.trim().should.contains('<script src="//gist.github.com/gist_id.js"></script>');
     data.content.trim().should.contains('<script src="//gist.github.com/gist_id_2.js"></script>');
   });