1 files changed, 63 insertions, 0 deletions
diff --git a/lib/gitlab/markdown_cache/redis/extension.rb b/lib/gitlab/markdown_cache/redis/extension.rb
new file mode 100644
index 00000000000..97fc23343b4
--- /dev/null
+++ b/lib/gitlab/markdown_cache/redis/extension.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module MarkdownCache
+    module Redis
+      module Extension
+        extend ActiveSupport::Concern
+
+        attr_reader :cached_markdown_version
+
+        class_methods do
+          def cache_markdown_field(markdown_field, context = {})
+            super
+
+            # define the `[field]_html` accessor
+            html_field = cached_markdown_fields.html_field(markdown_field)
+            define_method(html_field) do
+              load_cached_markdown unless markdown_data_loaded?
+
+              instance_variable_get("@#{html_field}")
+            end
+          end
+        end
+
+        private
+
+        def save_markdown(updates)
+          markdown_store.save(updates)
+        end
+
+        def write_markdown_field(field_name, value)
+          instance_variable_set("@#{field_name}", value)
+        end
+
+        def markdown_field_changed?(field_name)
+          false
+        end
+
+        def changed_markdown_fields
+          []
+        end
+
+        def cached_markdown
+          @cached_data ||= markdown_store.read
+        end
+
+        def load_cached_markdown
+          cached_markdown.each do |field_name, value|
+            write_markdown_field(field_name, value)
+          end
+        end
+
+        def markdown_data_loaded?
+          cached_markdown_version.present? || markdown_store.loaded?
+        end
+
+        def markdown_store
+          @store ||= Gitlab::MarkdownCache::Redis::Store.new(self)
+        end
+      end
+    end
+  end
+end