perf: reduce the number of traversals through posts (#5119)

lib/hexo/index.js

@@ -200,15 +200,9 @@ class Hexo extends EventEmitter {
  return db.model('Page').find(query);
  });
 
- locals.set('categories', () => {
- // Ignore categories with zero posts
- return db.model('Category').filter(category => category.length);
- });
+ locals.set('categories', () => db.model('Category'));
 
- locals.set('tags', () => {
- // Ignore tags with zero posts
- return db.model('Tag').filter(tag => tag.length);
- });
+ locals.set('tags', () => db.model('Tag'));
 
  locals.set('data', () => {
  const obj = {};

lib/models/category.js

@@ -52,7 +52,9 @@ module.exports = ctx => {
  });
 
  Category.virtual('length').get(function() {
- return this.posts.length;
+ const PostCategory = ctx.model('PostCategory');
+
+ return PostCategory.find({category_id: this._id}).length;
  });
 
  // Check whether a category exists

lib/models/post.js

@@ -71,7 +71,17 @@ module.exports = ctx => {
  return Tag.find({_id: {$in: ids}});
  });
 
+ Post.method('notPublished', function() {
+ // The same condition as ctx._bindLocals
+ return (!ctx.config.future && this.date > Date.now()) || (!ctx._showDrafts() && this.published === false);
+ });
+
  Post.method('setTags', function(tags) {
+ if (this.notPublished()) {
+ // Ignore tags of draft posts
+ // If the post is unpublished then the tag needs to be removed, thus the function cannot be returned early here
+ tags = [];
+ }
  tags = removeEmptyTag(tags);
 
  const PostTag = ctx.model('PostTag');
@@ -119,6 +129,9 @@ module.exports = ctx => {
  });
 
  Post.method('setCategories', function(cats) {
+ if (this.notPublished()) {
+ cats = [];
+ }
  // Remove empty categories, preserving hierarchies
  cats = cats.filter(cat => {
  return Array.isArray(cat) || (cat != null && cat !== '');

lib/models/tag.js

@@ -43,7 +43,11 @@ module.exports = ctx => {
  });
 
  Tag.virtual('length').get(function() {
- return this.posts.length;
+ // Note: this.posts.length is also working
+ // But it's slow because `find` has to iterate over all posts
+ const PostTag = ctx.model('PostTag');
+
+ return PostTag.find({tag_id: this._id}).length;
  });
 
  // Check whether a tag exists

lib/plugins/helper/list_categories.js

@@ -29,7 +29,7 @@ function listCategoriesHelper(categories, options) {
  query.parent = {$exists: false};
  }
 
- return categories.find(query).sort(orderby, order).filter(cat => cat.length);
+ return categories.find(query).sort(orderby, order);
  };
 
  const hierarchicalList = (level, parent) => {

lib/plugins/helper/list_tags.js

@@ -47,9 +47,6 @@ function listTagsHelper(tags, options) {
  // Sort the tags
  tags = tags.sort(orderby, order);
 
- // Ignore tags with zero posts
- tags = tags.filter(tag => tag.length);
-
  // Limit the number of tags
  if (options.amount) tags = tags.limit(options.amount);
 

test/scripts/models/category.js

@@ -191,6 +191,8 @@ describe('Category', () => {
 
  // draft on
  hexo.config.render_drafts = true;
+
+ await Promise.all(posts.map(post => post.setCategories(['foo'])));
  hexo.locals.invalidate();
  cat = Category.findOne({name: 'foo'});
  cat.posts.map(mapper).should.eql(posts.map(mapper));
@@ -227,6 +229,8 @@ describe('Category', () => {
 
  // future off
  hexo.config.future = false;
+
+ await Promise.all(posts.map(post => post.setCategories(['foo'])));
  hexo.locals.invalidate();
  cat = Category.findOne({name: 'foo'});
  cat.posts.eq(0)._id.should.eql(posts[0]._id);

test/scripts/models/tag.js

@@ -172,6 +172,7 @@ describe('Tag', () => {
 
  // draft on
  hexo.config.render_drafts = true;
+ await Promise.all(posts.map(post => post.setTags(['foo'])));
  tag = Tag.findOne({name: 'foo'});
  hexo.locals.invalidate();
  tag.posts.map(mapper).should.eql(posts.map(mapper));
@@ -206,6 +207,7 @@ describe('Tag', () => {
 
  // future off
  hexo.config.future = false;
+ await Promise.all(posts.map(post => post.setTags(['foo'])));
  hexo.locals.invalidate();
  tag = Tag.findOne({name: 'foo'});
  tag.posts.eq(0)._id.should.eql(posts[0]._id);