Migrate fetching wiki page formatted content to Gitaly

Closes gitaly#958

GITALY_SERVER_VERSION

-0.74.0
+0.75.0

Gemfile

@@ -406,7 +406,7 @@ group :ed25519 do
 end
 
 # Gitaly GRPC client
-gem 'gitaly-proto', '~> 0.78.0', require: 'gitaly'
+gem 'gitaly-proto', '~> 0.82.0', require: 'gitaly'
 
 gem 'toml-rb', '~> 0.3.15', require: false
 

Gemfile.lock

@@ -285,7 +285,7 @@ GEM
       po_to_json (>= 1.0.0)
       rails (>= 3.2.0)
     gherkin-ruby (0.3.2)
-    gitaly-proto (0.78.0)
+    gitaly-proto (0.82.0)
       google-protobuf (~> 3.1)
       grpc (~> 1.0)
     github-linguist (4.7.6)
@@ -1056,7 +1056,7 @@ DEPENDENCIES
   gettext (~> 3.2.2)
   gettext_i18n_rails (~> 1.8.0)
   gettext_i18n_rails_js (~> 1.2.0)
-  gitaly-proto (~> 0.78.0)
+  gitaly-proto (~> 0.82.0)
   github-linguist (~> 4.7.0)
   gitlab-flowdock-git-hook (~> 1.0.1)
   gitlab-markup (~> 1.6.2)

app/models/project_wiki.rb

@@ -124,6 +124,12 @@ class ProjectWiki
     update_project_activity
   end
 
+  def page_formatted_data(page)
+    page_title, page_dir = page_title_and_dir(page.title)
+
+    wiki.page_formatted_data(title: page_title, dir: page_dir, version: page.version)
+  end
+
   def page_title_and_dir(title)
     title_array = title.split("/")
     title = title_array.pop

app/models/wiki_page.rb

@@ -107,7 +107,10 @@ class WikiPage
 
   # The processed/formatted content of this page.
   def formatted_content
-    @attributes[:formatted_content] ||= @page&.formatted_data
+    # Assuming @page exists, nil formatted_data means we didn't load it
+    # before hand (i.e. page was fetched by Gitaly), so we fetch it separately.
+    # If the page was fetched by Gollum, formatted_data would've been a String.
+    @attributes[:formatted_content] ||= @page&.formatted_data || @wiki.page_formatted_data(@page)
   end
 
   # The markup format for the page.

lib/gitlab/git/wiki.rb

@@ -117,6 +117,20 @@ module Gitlab
         page.url_path
       end
 
+      def page_formatted_data(title:, dir: nil, version: nil)
+        version = version&.id
+
+        @repository.gitaly_migrate(:wiki_page_formatted_data) do |is_enabled|
+          if is_enabled
+            gitaly_wiki_client.get_formatted_data(title: title, dir: dir, version: version)
+          else
+            # We don't use #page because if wiki_find_page feature is enabled, we would
+            # get a page without formatted_data.
+            gollum_find_page(title: title, dir: dir, version: version)&.formatted_data
+          end
+        end
+      end
+
       private
 
       # options:

lib/gitlab/gitaly_client/wiki_service.rb

@@ -127,6 +127,18 @@ module Gitlab
         wiki_file
       end
 
+      def get_formatted_data(title:, dir: nil, version: nil)
+        request = Gitaly::WikiGetFormattedDataRequest.new(
+          repository: @gitaly_repo,
+          title: encode_binary(title),
+          revision: encode_binary(version),
+          directory: encode_binary(dir)
+        )
+
+        response = GitalyClient.call(@repository.storage, :wiki_service, :wiki_get_formatted_data, request)
+        response.reduce("") { |memo, msg| memo << msg.data }
+      end
+
       private
 
       # If a block is given and the yielded value is true, iteration will be

spec/models/wiki_page_spec.rb

@@ -387,7 +387,8 @@ describe WikiPage do
   end
 
   describe '#formatted_content' do
-    it 'returns processed content of the page', :disable_gitaly do
+    shared_examples 'fetching page formatted content' do
+      it 'returns processed content of the page' do
         subject.create({ title: "RDoc", content: "*bold*", format: "rdoc" })
         page = wiki.find_page('RDoc')
 
@@ -397,6 +398,15 @@ describe WikiPage do
       end
     end
 
+    context 'when Gitaly wiki_page_formatted_data is enabled' do
+      it_behaves_like 'fetching page formatted content'
+    end
+
+    context 'when Gitaly wiki_page_formatted_data is disabled', :disable_gitaly do
+      it_behaves_like 'fetching page formatted content'
+    end
+  end
+
   private
 
   def remove_temp_repo(path)