Migrate Gitlab::Git::Wiki#file to Gitaly

Closes gitaly#689

lib/gitlab/git/wiki.rb

@@ -68,11 +68,13 @@ module Gitlab
       end
 
       def file(name, version)
-        version ||= self.class.default_ref
-        gollum_file = gollum_wiki.file(name, version)
-        return unless gollum_file
-
-        Gitlab::Git::WikiFile.new(gollum_file)
+        @repository.gitaly_migrate(:wiki_find_file) do |is_enabled|
+          if is_enabled
+            gitaly_find_file(name, version)
+          else
+            gollum_find_file(name, version)
+          end
+        end
       end
 
       def page_versions(page_path)
@@ -156,6 +158,14 @@ module Gitlab
         new_page(gollum_page)
       end
 
+      def gollum_find_file(name, version)
+        version ||= self.class.default_ref
+        gollum_file = gollum_wiki.file(name, version)
+        return unless gollum_file
+
+        Gitlab::Git::WikiFile.new(gollum_file)
+      end
+
       def gitaly_write_page(name, format, content, commit_details)
         gitaly_wiki_client.write_page(name, format, content, commit_details)
       end
@@ -170,6 +180,13 @@ module Gitlab
 
         Gitlab::Git::WikiPage.new(wiki_page, version)
       end
+
+      def gitaly_find_file(name, version)
+        wiki_file = gitaly_wiki_client.find_file(name, version)
+        return unless wiki_file
+
+        Gitlab::Git::WikiFile.new(wiki_file)
+      end
     end
   end
 end

lib/gitlab/gitaly_client/wiki_file.rb

+module Gitlab
+  module GitalyClient
+    class WikiFile
+      FIELDS = %i(name mime_type path raw_data).freeze
+
+      attr_accessor(*FIELDS)
+
+      def initialize(params)
+        params = params.with_indifferent_access
+
+        FIELDS.each do |field|
+          instance_variable_set("@#{field}", params[field])
+        end
+      end
+    end
+  end
+end

lib/gitlab/gitaly_client/wiki_service.rb

@@ -80,6 +80,32 @@ module Gitlab
         [wiki_page, version]
       end
 
+      def find_file(name, revision)
+        request = Gitaly::WikiFindFileRequest.new(
+          repository: @gitaly_repo,
+          name: GitalyClient.encode(name),
+          revision: GitalyClient.encode(revision)
+        )
+
+        response = GitalyClient.call(@repository.storage, :wiki_service, :wiki_find_file, request)
+        wiki_file = nil
+
+        response.each do |message|
+          next unless message.name.present?
+
+          if wiki_file
+            wiki_file.raw_data << message.raw_data
+          else
+            wiki_file = GitalyClient::WikiFile.new(message.to_h)
+            # All gRPC strings in a response are frozen, so we get
+            # an unfrozen version here so appending in the else clause below doesn't blow up.
+            wiki_file.raw_data = wiki_file.raw_data.dup
+          end
+        end
+
+        wiki_file
+      end
+
       private
 
       def gitaly_commit_details(commit_details)

spec/features/projects/wiki/user_views_wiki_page_spec.rb

@@ -81,10 +81,15 @@ describe 'User views a wiki page' do
     end
 
     it 'shows a file stored in a page' do
-      file = Gollum::File.new(project.wiki)
-
-      allow_any_instance_of(Gollum::Wiki).to receive(:file).with('image.jpg', 'master').and_return(file)
-      allow_any_instance_of(Gollum::File).to receive(:mime_type).and_return('image/jpeg')
+      gollum_file_double = double('Gollum::File',
+                                  mime_type: 'image/jpeg',
+                                  name: 'images/image.jpg',
+                                  path: 'images/image.jpg',
+                                  raw_data: '')
+      wiki_file = Gitlab::Git::WikiFile.new(gollum_file_double)
+
+      allow(wiki_file).to receive(:mime_type).and_return('image/jpeg')
+      allow_any_instance_of(ProjectWiki).to receive(:find_file).with('image.jpg', nil).and_return(wiki_file)
 
       expect(page).to have_xpath('//img[@data-src="image.jpg"]')
       expect(page).to have_link('image', href: "#{project.wiki.wiki_base_path}/image.jpg")

spec/models/project_wiki_spec.rb

@@ -156,27 +156,17 @@ describe ProjectWiki do
   end
 
   describe '#find_file' do
+    shared_examples 'finding a wiki file' do
       before do
-      file = Gollum::File.new(subject.wiki)
-      allow_any_instance_of(Gollum::Wiki)
-                   .to receive(:file).with('image.jpg', 'master')
-                   .and_return(file)
-      allow_any_instance_of(Gollum::File)
-                   .to receive(:mime_type)
-                   .and_return('image/jpeg')
-      allow_any_instance_of(Gollum::Wiki)
-                   .to receive(:file).with('non-existant', 'master')
-                   .and_return(nil)
-    end
+        file = File.open(Rails.root.join('spec', 'fixtures', 'dk.png'))
+        subject.wiki # Make sure the wiki repo exists
 
-    after do
-      allow_any_instance_of(Gollum::Wiki).to receive(:file).and_call_original
-      allow_any_instance_of(Gollum::File).to receive(:mime_type).and_call_original
+        BareRepoOperations.new(subject.repository.path_to_repo).commit_file(file, 'image.png')
       end
 
       it 'returns the latest version of the file if it exists' do
-      file = subject.find_file('image.jpg')
-      expect(file.mime_type).to eq('image/jpeg')
+        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
@@ -184,11 +174,20 @@ describe ProjectWiki do
       end
 
       it 'returns a Gitlab::Git::WikiFile instance' do
-      file = subject.find_file('image.jpg')
+        file = subject.find_file('image.png')
         expect(file).to be_a Gitlab::Git::WikiFile
       end
     end
 
+    context 'when Gitaly wiki_find_file is enabled' do
+      it_behaves_like 'finding a wiki file'
+    end
+
+    context 'when Gitaly wiki_find_file is disabled', :skip_gitaly_mock do
+      it_behaves_like 'finding a wiki file'
+    end
+  end
+
   describe "#create_page" do
     shared_examples 'creating a wiki page' do
       after do

spec/support/bare_repo_operations.rb

+require 'zlib'
+
+class BareRepoOperations
+  # The ID of empty tree.
+  # See http://stackoverflow.com/a/40884093/1856239 and https://github.com/git/git/blob/3ad8b5bf26362ac67c9020bf8c30eee54a84f56d/cache.h#L1011-L1012
+  EMPTY_TREE_ID = '4b825dc642cb6eb9a060e54bf8d69288fbee4904'.freeze
+
+  include Gitlab::Popen
+
+  def initialize(path_to_repo)
+    @path_to_repo = path_to_repo
+  end
+
+  # Based on https://stackoverflow.com/a/25556917/1856239
+  def commit_file(file, dst_path, branch = 'master')
+    head_id = execute(['show', '--format=format:%H', '--no-patch', branch], allow_failure: true)[0] || EMPTY_TREE_ID
+
+    execute(['read-tree', '--empty'])
+    execute(['read-tree', head_id])
+
+    blob_id = execute(['hash-object', '--stdin', '-w']) do |stdin|
+      stdin.write(file.read)
+    end
+
+    execute(['update-index', '--add', '--cacheinfo', '100644', blob_id[0], dst_path])
+
+    tree_id = execute(['write-tree'])
+
+    commit_tree_args = ['commit-tree', tree_id[0], '-m', "Add #{dst_path}"]
+    commit_tree_args += ['-p', head_id] unless head_id == EMPTY_TREE_ID
+    commit_id = execute(commit_tree_args)
+
+    execute(['update-ref', "refs/heads/#{branch}", commit_id[0]])
+  end
+
+  private
+
+  def execute(args, allow_failure: false)
+    output, status = popen(base_args + args, nil) do |stdin|
+      yield stdin if block_given?
+    end
+
+    unless status.zero?
+      if allow_failure
+        return []
+      else
+        raise "Got a non-zero exit code while calling out `#{args.join(' ')}`: #{output}"
+      end
+    end
+
+    output.split("\n")
+  end
+
+  def base_args
+    [
+      Gitlab.config.git.bin_path,
+      "--git-dir=#{@path_to_repo}"
+    ]
+  end
+end