Fix page_description helper performance

This helper is used for extracting part of the issue / MR / whatever
description for use in the description meta tag:

1. To do that, we look at the source of the Markdown description.
2. We then strip out all HTML tags.
3. And then take the first 30 words.

Doing that can be really slow - especially as Markdown is supposed to be
treated as plain text. There are many better ways to do this, but the
immediate performance fix is to swap steps 2 and 3. This does mean that
the description may be less than 30 words (or even empty), but it is
much faster when the description is very long.
This commit is contained in:
Sean McGivern 2019-05-22 15:30:10 +01:00
parent bc4a18ecb9
commit f9f9147290
3 changed files with 16 additions and 1 deletions

View file

@ -1,3 +1,4 @@
# coding: utf-8
# frozen_string_literal: true
module PageLayoutHelper
@ -36,7 +37,7 @@ module PageLayoutHelper
if description.present?
@page_description = description.squish
elsif @page_description.present?
sanitize(@page_description, tags: []).truncate_words(30)
sanitize(@page_description.truncate_words(30), tags: [])
end
end

View file

@ -0,0 +1,6 @@
---
title: Fix performance issue with large Markdown content in issue or merge request
description
merge_request: 28597
author:
type: performance

View file

@ -38,6 +38,14 @@ describe PageLayoutHelper do
expect(helper.page_description).to eq 'Bold Header'
end
it 'truncates before sanitizing' do
helper.page_description('<b>Bold</b> <img> <img> <img> <h1>Header</h1> ' * 10)
# 12 words because <img> was counted as a word
expect(helper.page_description)
.to eq('Bold Header Bold Header Bold Header Bold Header Bold Header Bold Header...')
end
end
describe 'page_image' do