Add local markdown versionlocal-markdown-version

Cached markdown version is composed both from global and local
markdown version. This allows admins to bump version locally when
needed (e.g. when external URL is changed).

2 files changed, 28 insertions, 2 deletions

diff --git a/app/models/application_setting.rb b/app/models/application_setting.rb
index 88746375c67..c658211d12d 100644
--- a/app/models/application_setting.rb
+++ b/app/models/application_setting.rb
@@ -193,6 +193,10 @@ class ApplicationSetting < ActiveRecord::Base
             allow_nil: true,
             numericality: { only_integer: true, greater_than_or_equal_to: 1.day.seconds }
 
+  validates :local_markdown_version,
+            allow_nil: true,
+            numericality: { only_integer: true, greater_than_or_equal_to: 0, less_than: 65536 }
+
   SUPPORTED_KEY_TYPES.each do |type|
     validates :"#{type}_key_restriction", presence: true, key_restriction: { type: type }
   end
@@ -303,7 +307,8 @@ class ApplicationSetting < ActiveRecord::Base
       usage_stats_set_by_user_id: nil,
       diff_max_patch_bytes: Gitlab::Git::Diff::DEFAULT_MAX_PATCH_BYTES,
       commit_email_hostname: default_commit_email_hostname,
-      protected_ci_variables: false
+      protected_ci_variables: false,
+      local_markdown_version: 0
     }
   end
 
diff --git a/app/models/concerns/cache_markdown_field.rb b/app/models/concerns/cache_markdown_field.rb
index 5fa6f79bdaa..1a8570b80c3 100644
--- a/app/models/concerns/cache_markdown_field.rb
+++ b/app/models/concerns/cache_markdown_field.rb
@@ -115,7 +115,28 @@ module CacheMarkdownField
   end
 
   def latest_cached_markdown_version
-    CacheMarkdownField::CACHE_COMMONMARK_VERSION
+    @latest_cached_markdown_version ||= (CacheMarkdownField::CACHE_COMMONMARK_VERSION << 16) | local_version
+  end
+
+  def local_version
+    # because local_markdown_version is stored in application_settings which
+    # uses cached_markdown_version too, we check explicitly to avoid
+    # endless loop
+    return local_markdown_version if has_attribute?(:local_markdown_version)
+
+    settings = Gitlab::CurrentSettings.current_application_settings
+
+    # Following migrations are not properly isolated and
+    # use real models (by calling .ghost method), in these migrations
+    # local_markdown_version attribute doesn't exist yet, so we
+    # use a default value:
+    # db/migrate/20170825104051_migrate_issues_to_ghost_user.rb
+    # db/migrate/20171114150259_merge_requests_author_id_foreign_key.rb
+    if settings.respond_to?(:local_markdown_version)
+      settings.local_markdown_version
+    else
+      0
+    end
   end
 
   included do