Replace wiki#find_file RPC with Gitaly call

In this commit we introduce a feature flag that will toggle
using the RPC or the new Gitaly method.

app/models/wiki.rb

@@ -159,8 +159,17 @@ def find_sidebar(version = nil)
     find_page(SIDEBAR, version)
   end
-  def find_file(name, version = 'HEAD')
-    wiki.file(name, version)
+  def find_file(name, version = 'HEAD', load_content: true)
+    if Feature.enabled?(:gitaly_find_file, user, default_enabled: :yaml)
+      data_limit = load_content ? -1 : 0
+      blobs = repository.blobs_at([[version, name]], blob_size_limit: data_limit)
+
+      return if blobs.empty?
+
+      Gitlab::Git::WikiFile.from_blob(blobs.first)
+    else
+      wiki.file(name, version)
+    end
   end
   def create_page(title, content, format = :markdown, message = nil)

config/feature_flags/development/gitaly_find_file.yml

+---
+name: gitaly_find_file
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/56321
+rollout_issue_url:
+milestone: '13.10'
+type: development
+group: group::editor
+default_enabled: false

lib/banzai/filter/gollum_tags_filter.rb

@@ -100,7 +100,7 @@ def process_image_tag(parts)
         if url?(content)
           path = content
-        elsif file = wiki.find_file(content)
+        elsif file = wiki.find_file(content, load_content: false)
           path = ::File.join(wiki_base_path, file.path)
         end

lib/gitlab/git/wiki_file.rb

@@ -12,6 +12,19 @@ def initialize(gitaly_file)
         @name = gitaly_file.name
         @path = gitaly_file.path
       end
+
+      def self.from_blob(blob)
+        hash = {
+          name: File.basename(blob.name),
+          mime_type: blob.mime_type,
+          path: blob.path,
+          raw_data: blob.data
+        }
+
+        gitaly_file = Gitlab::GitalyClient::WikiFile.new(hash)
+
+        Gitlab::Git::WikiFile.new(gitaly_file)
+      end
     end
   end
 end

spec/benchmarks/banzai_benchmark.rb

@@ -56,7 +56,7 @@
     it 'benchmarks several pipelines' do
       path = 'images/example.jpg'
       gitaly_wiki_file = Gitlab::GitalyClient::WikiFile.new(path: path)
-      allow(wiki).to receive(:find_file).with(path).and_return(Gitlab::Git::WikiFile.new(gitaly_wiki_file))
+      allow(wiki).to receive(:find_file).with(path, load_content: false).and_return(Gitlab::Git::WikiFile.new(gitaly_wiki_file))
       allow(wiki).to receive(:wiki_base_path) { '/namespace1/gitlabhq/wikis' }
       puts "\n--> Benchmarking Full, Wiki, and Plain pipelines\n"

spec/features/markdown/markdown_spec.rb

@@ -290,7 +290,7 @@ def doc(html = @html)
       path = 'images/example.jpg'
       gitaly_wiki_file = Gitlab::GitalyClient::WikiFile.new(path: path)
-      expect(@wiki).to receive(:find_file).with(path).and_return(Gitlab::Git::WikiFile.new(gitaly_wiki_file))
+      expect(@wiki).to receive(:find_file).with(path, load_content: false).and_return(Gitlab::Git::WikiFile.new(gitaly_wiki_file))
       allow(@wiki).to receive(:wiki_base_path) { '/namespace1/gitlabhq/wikis' }
       @html = markdown(@feat.raw_markdown, { pipeline: :wiki, wiki: @wiki, page_slug: @wiki_page.slug })

spec/lib/banzai/filter/gollum_tags_filter_spec.rb

@@ -22,7 +22,7 @@
                                   path: 'images/image.jpg',
                                   raw_data: '')
       wiki_file = Gitlab::Git::WikiFile.new(gollum_file_double)
-      expect(wiki).to receive(:find_file).with('images/image.jpg').and_return(wiki_file)
+      expect(wiki).to receive(:find_file).with('images/image.jpg', load_content: false).and_return(wiki_file)
       tag = '[[images/image.jpg]]'
       doc = filter("See #{tag}", wiki: wiki)
@@ -31,7 +31,7 @@
     end
     it 'does not creates img tag if image does not exist' do
-      expect(wiki).to receive(:find_file).with('images/image.jpg').and_return(nil)
+      expect(wiki).to receive(:find_file).with('images/image.jpg', load_content: false).and_return(nil)
       tag = '[[images/image.jpg]]'
       doc = filter("See #{tag}", wiki: wiki)

spec/support/shared_examples/models/wiki_shared_examples.rb

@@ -354,27 +354,47 @@ def total_pages(entries)
       subject.repository.create_file(user, 'image.png', image, branch_name: subject.default_branch, message: 'add image')
     end
-    it 'returns the latest version of the file if it exists' do
-      file = subject.find_file('image.png')
-      expect(file.mime_type).to eq('image/png')
-    end
-    it 'returns nil if the page does not exist' do
-      expect(subject.find_file('non-existent')).to eq(nil)
+    shared_examples 'find_file results' do
+      it 'returns the latest version of the file if it exists' do
+        file = subject.find_file('image.png')
+        expect(file.mime_type).to eq('image/png')
+      end
+
+      it 'returns nil if the page does not exist' do
+        expect(subject.find_file('non-existent')).to eq(nil)
+      end
+
+      it 'returns a Gitlab::Git::WikiFile instance' do
+        file = subject.find_file('image.png')
+
+        expect(file).to be_a Gitlab::Git::WikiFile
+      end
+      it 'returns the whole file' do
+        file = subject.find_file('image.png')
+        image.rewind
+
+        expect(file.raw_data.b).to eq(image.read.b)
+      end
     end
-    it 'returns a Gitlab::Git::WikiFile instance' do
-      file = subject.find_file('image.png')
-      expect(file).to be_a Gitlab::Git::WikiFile
+    it_behaves_like 'find_file results'
+
+    context 'when load_content is disabled' do
+      it 'includes the file data in the Gitlab::Git::WikiFile' do
+        file = subject.find_file('image.png', load_content: false)
+        expect(file.raw_data).to be_empty
+      end
     end
-    it 'returns the whole file' do
-      file = subject.find_file('image.png')
-      image.rewind
-      expect(file.raw_data.b).to eq(image.read.b)
+    context 'when feature flag :gitaly_find_file is disabled' do
+      before do
+        stub_feature_flags(gitaly_find_file: false)
+      end
+      it_behaves_like 'find_file results'
     end
   end