Improve AutolinkFilter#text_parse performance

By using clever XPath queries we can quite significantly improve the performance of this method. The actual improvement depends a bit on the amount of links used but in my tests the new implementation is usually around 8 times faster than the old one. This was measured using the following benchmark: require 'benchmark/ips' text = '<p>' + Note.select("string_agg(note, '') AS note").limit(50).take[:note] + '</p>' document = Nokogiri::HTML.fragment(text) filter = Banzai::Filter::AutolinkFilter.new(document, autolink: true) puts "Input size: #{(text.bytesize.to_f / 1024 / 1024).round(2)} MB" filter.rinku_parse Benchmark.ips(time: 15) do |bench| bench.report 'text_parse' do filter.text_parse end bench.report 'text_parse_fast' do filter.text_parse_fast end bench.compare! end Here the "text_parse_fast" method is the new implementation and "text_parse" the old one. The input size was around 180 MB. Running this benchmark outputs the following: Input size: 181.16 MB Calculating ------------------------------------- text_parse 1.000 i/100ms text_parse_fast 9.000 i/100ms ------------------------------------------------- text_parse 13.021 (±15.4%) i/s - 188.000 text_parse_fast 112.741 (± 3.5%) i/s - 1.692k Comparison: text_parse_fast: 112.7 i/s text_parse: 13.0 i/s - 8.66x slower Again the production timings may (and most likely will) vary depending on the input being processed.

Improve AutolinkFilter#text_parse performance
dd35c3dd · Yorick Peterse · 73772eca · dd35c3dd · dd35c3dd
Unverified Commit dd35c3dd authored Aug 02, 2016 by Yorick Peterse
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Showing with 10 additions and 6 deletions

CHANGELOG CHANGELOG +1 -0

autolink_filter.rb lib/banzai/filter/autolink_filter.rb +9 -6

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--- a/CHANGELOG
+++ b/CHANGELOG
@@ -11,6 +11,7 @@ v 8.11.0 (unreleased)
  - Add support for using RequestStore within Sidekiq tasks via SIDEKIQ_REQUEST_STORE env variable
  - Optimize maximum user access level lookup in loading of notes
  - Add "No one can push" as an option for protected branches. !5081
+  - Improve performance of AutolinkFilter#text_parse by using XPath
  - Environments have an url to link to
  - Limit git rev-list output count to one in forced push check
  - Clean up unused routes (Josef Strzibny)

--- a/lib/banzai/filter/autolink_filter.rb
+++ b/lib/banzai/filter/autolink_filter.rb
@@ -31,6 +31,14 @@ module Banzai
      # Text matching LINK_PATTERN inside these elements will not be linked
      IGNORE_PARENTS = %w(a code kbd pre script style).to_set

+      # The XPath query to use for finding text nodes to parse.
+      TEXT_QUERY = %Q(descendant-or-self::text()[
+        not(#{IGNORE_PARENTS.map { |p| "ancestor::#{p}" }.join(' or ')})
+        and contains(., '://')
+        and not(starts-with(., 'http'))
+        and not(starts-with(., 'ftp'))
+      ])
+
      def call
        return doc if context[:autolink] == false

@@ -66,16 +74,11 @@ module Banzai
      # Autolinks any text matching LINK_PATTERN that Rinku didn't already
      # replace
      def text_parse
-        search_text_nodes(doc).each do |node|
+        doc.xpath(TEXT_QUERY).each do |node|
          content = node.to_html

-          next if has_ancestor?(node, IGNORE_PARENTS)
          next unless content.match(LINK_PATTERN)

-          # If Rinku didn't link this, there's probably a good reason, so we'll
-          # skip it too
-          next if content.start_with?(*%w(http https ftp))
-
          html = autolink_filter(content)

          next if html == content