Only cache highlight results for latest MR diffs

Previously, we kept them all in the cache. We don't need the highlight results
for older diffs - if someone does view that (which is rare), we can do the
highlighting on the fly.

1 files changed, 8 insertions, 4 deletions

diff --git a/lib/gitlab/diff/file_collection/merge_request_diff.rb b/lib/gitlab/diff/file_collection/merge_request_diff.rb
index ff68bc7303a..9c1f85c70d6 100644
--- a/lib/gitlab/diff/file_collection/merge_request_diff.rb
+++ b/lib/gitlab/diff/file_collection/merge_request_diff.rb
@@ -29,6 +29,14 @@ module Gitlab
           @merge_request_diff.real_size
         end
 
+        def clear_cache!
+          Rails.cache.delete(cache_key)
+        end
+
+        def cache_key
+          [@merge_request_diff, 'highlighted-diff-files', diff_options]
+        end
+
         private
 
         def highlight_diff_file_from_cache!(diff_file, cache_diff_lines)
@@ -70,10 +78,6 @@ module Gitlab
         def cacheable?(diff_file)
           @merge_request_diff.present? && diff_file.text? && diff_file.diffable?
         end
-
-        def cache_key
-          [@merge_request_diff, 'highlighted-diff-files', diff_options]
-        end
       end
     end
   end