Fix syntax highlight taking too long

Use Timeout to switch to plain rendering

1 files changed, 13 insertions, 1 deletions

diff --git a/lib/gitlab/highlight.rb b/lib/gitlab/highlight.rb
index 5408a1a6838..0b6cc893db1 100644
--- a/lib/gitlab/highlight.rb
+++ b/lib/gitlab/highlight.rb
@@ -1,5 +1,8 @@
 module Gitlab
   class Highlight
+    TIMEOUT_BACKGROUND = 30.seconds
+    TIMEOUT_FOREGROUND = 3.seconds
+
     def self.highlight(blob_name, blob_content, repository: nil, plain: false)
       new(blob_name, blob_content, repository: repository)
         .highlight(blob_content, continue: false, plain: plain)
@@ -51,11 +54,20 @@ module Gitlab
     end
 
     def highlight_rich(text, continue: true)
-      @formatter.format(lexer.lex(text, continue: continue), tag: lexer.tag).html_safe
+      tag = lexer.tag
+      tokens = lexer.lex(text, continue: continue)
+      Timeout.timeout(timeout_time) { @formatter.format(tokens, tag: tag).html_safe }
+    rescue Timeout::Error => e
+      Gitlab::Sentry.track_exception(e)
+      highlight_plain(text)
     rescue
       highlight_plain(text)
     end
 
+    def timeout_time
+      Sidekiq.server? ? TIMEOUT_BACKGROUND : TIMEOUT_FOREGROUND
+    end
+
     def link_dependencies(text, highlighted_text)
       Gitlab::DependencyLinker.link(blob_name, text, highlighted_text)
     end