Workhorse to send raw diff and patch for commits

Prior to this change, this was done through unicorn. In theory this
could time out. Workhorse has been sending these raw patches and diffs
for a long time and is stable in doing so.

Added bonus is the fact that `Commit#to_patch` can be removed.

`Commit#to_diff` too, which closes
https://gitlab.com/gitlab-org/gitaly/issues/324

Closes https://gitlab.com/gitlab-org/gitaly/issues/1196

6 files changed, 16 insertions, 70 deletions

diff --git a/app/controllers/projects/commit_controller.rb b/app/controllers/projects/commit_controller.rb
index b7f548e0e63..1d1184d46d1 100644
--- a/app/controllers/projects/commit_controller.rb
+++ b/app/controllers/projects/commit_controller.rb
@@ -23,8 +23,12 @@ class Projects::CommitController < Projects::ApplicationController
 
     respond_to do |format|
       format.html  { render }
-      format.diff  { render text: @commit.to_diff }
-      format.patch { render text: @commit.to_patch }
+      format.diff  do
+        send_git_diff(@project.repository, @commit.diff_refs)
+      end
+      format.patch do
+        send_git_patch(@project.repository, @commit.diff_refs)
+      end
     end
   end
 
diff --git a/changelogs/unreleased/zj-workhorse-commit-patch-diff.yml b/changelogs/unreleased/zj-workhorse-commit-patch-diff.yml
new file mode 100644
index 00000000000..bce68692d98
--- /dev/null
+++ b/changelogs/unreleased/zj-workhorse-commit-patch-diff.yml
@@ -0,0 +1,5 @@
+---
+title: Workhorse to send raw diff and patch for commits
+merge_request:
+author:
+type: other
diff --git a/lib/gitlab/git/commit.rb b/lib/gitlab/git/commit.rb
index fabcd46c8e9..d79a4dbeee4 100644
--- a/lib/gitlab/git/commit.rb
+++ b/lib/gitlab/git/commit.rb
@@ -342,21 +342,6 @@ module Gitlab
         parent_ids.first
       end
 
-      # Shows the diff between the commit's parent and the commit.
-      #
-      # Cuts out the header and stats from #to_patch and returns only the diff.
-      #
-      # Gitaly migration: https://gitlab.com/gitlab-org/gitaly/issues/324
-      def to_diff
-        Gitlab::GitalyClient.migrate(:commit_patch, status: Gitlab::GitalyClient::MigrationStatus::OPT_OUT) do |is_enabled|
-          if is_enabled
-            @repository.gitaly_commit_client.patch(id)
-          else
-            rugged_diff_from_parent.patch
-          end
-        end
-      end
-
       # Returns a diff object for the changes from this commit's first parent.
       # If there is no parent, then the diff is between this commit and an
       # empty repo. See Repository#diff for keys allowed in the +options+
@@ -432,16 +417,6 @@ module Gitlab
         Gitlab::Git::CommitStats.new(@repository, self)
       end
 
-      def to_patch(options = {})
-        begin
-          rugged_commit.to_mbox(options)
-        rescue Rugged::InvalidError => ex
-          if ex.message =~ /commit \w+ is a merge commit/i
-            'Patch format is not currently supported for merge commits.'
-          end
-        end
-      end
-
       # Get ref names collection
       #
       # Ex.
diff --git a/spec/controllers/projects/commit_controller_spec.rb b/spec/controllers/projects/commit_controller_spec.rb
index 694c64ae1ad..003fec8ac68 100644
--- a/spec/controllers/projects/commit_controller_spec.rb
+++ b/spec/controllers/projects/commit_controller_spec.rb
@@ -79,41 +79,18 @@ describe Projects::CommitController do
     end
 
     describe "as diff" do
-      include_examples "export as", :diff
-      let(:format) { :diff }
+      it "triggers workhorse to serve the request" do
+        go(id: commit.id, format: :diff)
 
-      it "should really only be a git diff" do
-        go(id: '66eceea0db202bb39c4e445e8ca28689645366c5', format: format)
-
-        expect(response.body).to start_with("diff --git")
-      end
-
-      it "is only be a git diff without whitespace changes" do
-        go(id: '66eceea0db202bb39c4e445e8ca28689645366c5', format: format, w: 1)
-
-        expect(response.body).to start_with("diff --git")
-
-        # without whitespace option, there are more than 2 diff_splits for other formats
-        diff_splits = assigns(:diffs).diff_files.first.diff.diff.split("\n")
-        expect(diff_splits.length).to be <= 2
+        expect(response.headers[Gitlab::Workhorse::SEND_DATA_HEADER]).to start_with("git-diff:")
       end
     end
 
     describe "as patch" do
-      include_examples "export as", :patch
-      let(:format) { :patch }
-      let(:commit2) { project.commit('498214de67004b1da3d820901307bed2a68a8ef6') }
-
-      it "is a git email patch" do
-        go(id: commit2.id, format: format)
-
-        expect(response.body).to start_with("From #{commit2.id}")
-      end
-
       it "contains a git diff" do
-        go(id: commit2.id, format: format)
+        go(id: commit.id, format: :patch)
 
-        expect(response.body).to match(/^diff --git/)
+        expect(response.headers[Gitlab::Workhorse::SEND_DATA_HEADER]).to start_with("git-format-patch:")
       end
     end
 
diff --git a/spec/lib/gitlab/git/commit_spec.rb b/spec/lib/gitlab/git/commit_spec.rb
index a05feaac1ca..2e068584c2e 100644
--- a/spec/lib/gitlab/git/commit_spec.rb
+++ b/spec/lib/gitlab/git/commit_spec.rb
@@ -554,24 +554,10 @@ describe Gitlab::Git::Commit, seed_helper: true do
     it_should_behave_like '#stats'
   end
 
-  describe '#to_diff' do
-    subject { commit.to_diff }
-
-    it { is_expected.not_to include "From #{SeedRepo::Commit::ID}" }
-    it { is_expected.to include 'diff --git a/files/ruby/popen.rb b/files/ruby/popen.rb'}
-  end
-
   describe '#has_zero_stats?' do
     it { expect(commit.has_zero_stats?).to eq(false) }
   end
 
-  describe '#to_patch' do
-    subject { commit.to_patch }
-
-    it { is_expected.to include "From #{SeedRepo::Commit::ID}" }
-    it { is_expected.to include 'diff --git a/files/ruby/popen.rb b/files/ruby/popen.rb'}
-  end
-
   describe '#to_hash' do
     let(:hash) { commit.to_hash }
     subject { hash }
diff --git a/spec/models/commit_spec.rb b/spec/models/commit_spec.rb
index 4e6b037a720..448b813c2e1 100644
--- a/spec/models/commit_spec.rb
+++ b/spec/models/commit_spec.rb
@@ -182,7 +182,6 @@ eos
     it { is_expected.to respond_to(:date) }
     it { is_expected.to respond_to(:diffs) }
     it { is_expected.to respond_to(:id) }
-    it { is_expected.to respond_to(:to_patch) }
   end
 
   describe '#closes_issues' do