From 997d76fe94f9e2548b2e30b51c1c44f58bbf2aa4 Mon Sep 17 00:00:00 2001
From: Peter Leitzen <pl@neopoly.de>
Date: Sat, 7 Jul 2018 13:53:45 +0200
Subject: [PATCH 1/2] Improve render performance of large wiki pages

Compile often used regexps only once outside of the loop.

This commit improves the performance of large wiki pages with many, many references.
---
 lib/banzai/filter/abstract_reference_filter.rb | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/banzai/filter/abstract_reference_filter.rb b/lib/banzai/filter/abstract_reference_filter.rb
index 60a12dca9d3..b39b11009b3 100644
--- a/lib/banzai/filter/abstract_reference_filter.rb
+++ b/lib/banzai/filter/abstract_reference_filter.rb
@@ -100,6 +100,11 @@ module Banzai
         ref_pattern = object_class.reference_pattern
         link_pattern = object_class.link_reference_pattern
 
+        # Compile often used regexps only once outside of the loop
+        ref_pattern_anchor = /\A#{ref_pattern}\z/
+        link_pattern_start = /\A#{link_pattern}/
+        link_pattern_anchor = /\A#{link_pattern}\z/
+
         nodes.each do |node|
           if text_node?(node) && ref_pattern
             replace_text_when_pattern_matches(node, ref_pattern) do |content|
@@ -108,7 +113,7 @@ module Banzai
 
           elsif element_node?(node)
             yield_valid_link(node) do |link, inner_html|
-              if ref_pattern && link =~ /\A#{ref_pattern}\z/
+              if ref_pattern && link =~ ref_pattern_anchor
                 replace_link_node_with_href(node, link) do
                   object_link_filter(link, ref_pattern, link_content: inner_html)
                 end
@@ -118,7 +123,7 @@ module Banzai
 
               next unless link_pattern
 
-              if link == inner_html && inner_html =~ /\A#{link_pattern}/
+              if link == inner_html && inner_html =~ link_pattern_start
                 replace_link_node_with_text(node, link) do
                   object_link_filter(inner_html, link_pattern, link_reference: true)
                 end
@@ -126,7 +131,7 @@ module Banzai
                 next
               end
 
-              if link =~ /\A#{link_pattern}\z/
+              if link =~ link_pattern_anchor
                 replace_link_node_with_href(node, link) do
                   object_link_filter(link, link_pattern, link_content: inner_html, link_reference: true)
                 end

From 4a7af8074957d5e001d7e28c963209182f85fcc9 Mon Sep 17 00:00:00 2001
From: Peter Leitzen <pl@neopoly.de>
Date: Sat, 7 Jul 2018 14:57:13 +0200
Subject: [PATCH 2/2] Add changelog entry for !20465

[ci skip]
---
 changelogs/unreleased/perf-wiki-pattern-once.yml | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 changelogs/unreleased/perf-wiki-pattern-once.yml

diff --git a/changelogs/unreleased/perf-wiki-pattern-once.yml b/changelogs/unreleased/perf-wiki-pattern-once.yml
new file mode 100644
index 00000000000..fb4085a06ae
--- /dev/null
+++ b/changelogs/unreleased/perf-wiki-pattern-once.yml
@@ -0,0 +1,5 @@
+---
+title: Improve render performance of large wiki pages
+merge_request: 20465
+author: Peter Leitzen
+type: performance