Use Gitaly for CommitController#show

Gemfile

@@ -352,4 +352,4 @@ gem 'vmstat', '~> 2.3.0'
 gem 'sys-filesystem', '~> 1.1.6'
 
 # Gitaly GRPC client
-gem 'gitaly', '~> 0.2.1'
+gem 'gitaly', '~> 0.3.0'

Gemfile.lock

@@ -250,7 +250,7 @@ GEM
       json
     get_process_mem (0.2.0)
     gherkin-ruby (0.3.2)
-    gitaly (0.2.1)
+    gitaly (0.3.0)
       google-protobuf (~> 3.1)
       grpc (~> 1.0)
     github-linguist (4.7.6)
@@ -896,7 +896,7 @@ DEPENDENCIES
   fuubar (~> 2.0.0)
   gemnasium-gitlab-service (~> 0.2)
   gemojione (~> 3.0)
-  gitaly (~> 0.2.1)
+  gitaly (~> 0.3.0)
   github-linguist (~> 4.7.0)
   gitlab-flowdock-git-hook (~> 1.0.1)
   gitlab-markup (~> 1.5.1)

app/models/commit.rb

@@ -317,7 +317,14 @@ class Commit
   end
 
   def raw_diffs(*args)
-    raw.diffs(*args)
+    use_gitaly = Gitlab::GitalyClient.feature_enabled?(:commit_raw_diffs)
+    deltas_only = args.last.is_a?(Hash) && args.last[:deltas_only]
+
+    if use_gitaly && !deltas_only
+      Gitlab::GitalyClient::Commit.diff_from_parent(self, *args)
+    else
+      raw.diffs(*args)
+    end
   end
 
   def diffs(diff_options = nil)

changelogs/unreleased/feature-use-gitaly-for-commit-show.yml

@@ -0,0 +1,4 @@
+---
+title: Use Gitaly for CommitController#show
+merge_request: 9629
+author:

lib/gitlab/git/diff.rb

@@ -176,9 +176,13 @@ module Gitlab
       def initialize(raw_diff, collapse: false)
         case raw_diff
         when Hash
-          init_from_hash(raw_diff, collapse: collapse)
+          init_from_hash(raw_diff)
+          prune_diff_if_eligible(collapse)
         when Rugged::Patch, Rugged::Diff::Delta
           init_from_rugged(raw_diff, collapse: collapse)
+        when Gitaly::CommitDiffResponse
+          init_from_gitaly(raw_diff)
+          prune_diff_if_eligible(collapse)
         when nil
           raise "Nil as raw diff passed"
         else
@@ -266,13 +270,26 @@ module Gitlab
         @diff = encode!(strip_diff_headers(patch.to_s))
       end
 
-      def init_from_hash(hash, collapse: false)
+      def init_from_hash(hash)
         raw_diff = hash.symbolize_keys
 
         serialize_keys.each do |key|
           send(:"#{key}=", raw_diff[key.to_sym])
         end
+      end
 
+      def init_from_gitaly(diff_msg)
+        @diff = diff_msg.raw_chunks.join
+        @new_path = encode!(diff_msg.to_path.dup)
+        @old_path = encode!(diff_msg.from_path.dup)
+        @a_mode = diff_msg.old_mode.to_s(8)
+        @b_mode = diff_msg.new_mode.to_s(8)
+        @new_file = diff_msg.from_id == BLANK_SHA
+        @renamed_file = diff_msg.from_path != diff_msg.to_path
+        @deleted_file = diff_msg.to_id == BLANK_SHA
+      end
+
+      def prune_diff_if_eligible(collapse = false)
         prune_large_diff! if too_large?
         prune_collapsed_diff! if collapse && collapsible?
       end

lib/gitlab/git/diff_collection.rb

@@ -30,7 +30,9 @@ module Gitlab
         elsif @deltas_only
           each_delta(&block)
         else
-          each_patch(&block)
+          Gitlab::GitalyClient.migrate(:commit_raw_diffs) do
+            each_patch(&block)
+          end
         end
       end
 

lib/gitlab/gitaly_client.rb

@@ -25,5 +25,19 @@ module Gitlab
     def self.enabled?
       gitaly_address.present?
     end
+
+    def self.feature_enabled?(feature)
+      enabled? && ENV["GITALY_#{feature.upcase}"] == '1'
+    end
+
+    def self.migrate(feature)
+      is_enabled  = feature_enabled?(feature)
+      metric_name = feature.to_s
+      metric_name += "_gitaly" if is_enabled
+
+      Gitlab::Metrics.measure(metric_name) do
+        yield is_enabled
+      end
+    end
   end
 end

lib/gitlab/gitaly_client/commit.rb

@@ -0,0 +1,25 @@
+module Gitlab
+  module GitalyClient
+    class Commit
+      # 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
+
+      class << self
+        def diff_from_parent(commit, options = {})
+          stub      = Gitaly::Diff::Stub.new(nil, nil, channel_override: GitalyClient.channel)
+          repo      = Gitaly::Repository.new(path: commit.project.repository.path_to_repo)
+          parent    = commit.parents[0]
+          parent_id = parent ? parent.id : EMPTY_TREE_ID
+          request   = Gitaly::CommitDiffRequest.new(
+            repository: repo,
+            left_commit_id: parent_id,
+            right_commit_id: commit.id
+          )
+
+          Gitlab::Git::DiffCollection.new(stub.commit_diff(request), options)
+        end
+      end
+    end
+  end
+end

spec/lib/gitlab/git/diff_spec.rb

@@ -109,6 +109,43 @@ EOT
         end
       end
     end
+
+    context 'using a Gitaly::CommitDiffResponse' do
+      let(:diff) do
+        described_class.new(
+          Gitaly::CommitDiffResponse.new(
+            to_path: ".gitmodules",
+            from_path: ".gitmodules",
+            old_mode: 0100644,
+            new_mode: 0100644,
+            from_id: '357406f3075a57708d0163752905cc1576fceacc',
+            to_id: '8e5177d718c561d36efde08bad36b43687ee6bf0',
+            raw_chunks: raw_chunks,
+          )
+        )
+      end
+
+      context 'with a small diff' do
+        let(:raw_chunks) { [@raw_diff_hash[:diff]] }
+
+        it 'initializes the diff' do
+          expect(diff.to_hash).to eq(@raw_diff_hash)
+        end
+
+        it 'does not prune the diff' do
+          expect(diff).not_to be_too_large
+        end
+      end
+
+      context 'using a diff that is too large' do
+        let(:raw_chunks) { ['a' * 204800] }
+
+        it 'prunes the diff' do
+          expect(diff.diff).to be_empty
+          expect(diff).to be_too_large
+        end
+      end
+    end
   end
 
   describe 'straight diffs' do

spec/lib/gitlab/gitaly_client/commit_spec.rb

@@ -0,0 +1,58 @@
+require 'spec_helper'
+
+describe Gitlab::GitalyClient::Commit do
+  describe '.diff_from_parent' do
+    let(:diff_stub) { double('Gitaly::Diff::Stub') }
+    let(:project) { create(:project, :repository) }
+    let(:repository_message) { Gitaly::Repository.new(path: project.repository.path) }
+    let(:commit) { project.commit('913c66a37b4a45b9769037c55c2d238bd0942d2e') }
+
+    before do
+      allow(Gitaly::Diff::Stub).to receive(:new).and_return(diff_stub)
+      allow(diff_stub).to receive(:commit_diff).and_return([])
+    end
+
+    context 'when a commit has a parent' do
+      it 'sends an RPC request with the parent ID as left commit' do
+        request = Gitaly::CommitDiffRequest.new(
+          repository: repository_message,
+          left_commit_id: 'cfe32cf61b73a0d5e9f13e774abde7ff789b1660',
+          right_commit_id: commit.id,
+        )
+
+        expect(diff_stub).to receive(:commit_diff).with(request)
+
+        described_class.diff_from_parent(commit)
+      end
+    end
+
+    context 'when a commit does not have a parent' do
+      it 'sends an RPC request with empty tree ref as left commit' do
+        initial_commit = project.commit('1a0b36b3cdad1d2ee32457c102a8c0b7056fa863')
+        request        = Gitaly::CommitDiffRequest.new(
+          repository: repository_message,
+          left_commit_id: '4b825dc642cb6eb9a060e54bf8d69288fbee4904',
+          right_commit_id: initial_commit.id,
+        )
+
+        expect(diff_stub).to receive(:commit_diff).with(request)
+
+        described_class.diff_from_parent(initial_commit)
+      end
+    end
+
+    it 'returns a Gitlab::Git::DiffCollection' do
+      ret = described_class.diff_from_parent(commit)
+
+      expect(ret).to be_kind_of(Gitlab::Git::DiffCollection)
+    end
+
+    it 'passes options to Gitlab::Git::DiffCollection' do
+      options = { max_files: 31, max_lines: 13 }
+
+      expect(Gitlab::Git::DiffCollection).to receive(:new).with([], options)
+
+      described_class.diff_from_parent(commit, options)
+    end
+  end
+end

spec/models/commit_spec.rb

@@ -369,4 +369,32 @@ eos
       expect(described_class.valid_hash?('a' * 41)).to be false
     end
   end
+
+  describe '#raw_diffs' do
+    context 'Gitaly commit_raw_diffs feature enabled' do
+      before do
+        allow(Gitlab::GitalyClient).to receive(:feature_enabled?).with(:commit_raw_diffs).and_return(true)
+      end
+
+      context 'when a truthy deltas_only is not passed to args' do
+        it 'fetches diffs from Gitaly server' do
+          expect(Gitlab::GitalyClient::Commit).to receive(:diff_from_parent).
+            with(commit)
+
+          commit.raw_diffs
+        end
+      end
+
+      context 'when a truthy deltas_only is passed to args' do
+        it 'fetches diffs using Rugged' do
+          opts = { deltas_only: true }
+
+          expect(Gitlab::GitalyClient::Commit).not_to receive(:diff_from_parent)
+          expect(commit.raw).to receive(:diffs).with(opts)
+
+          commit.raw_diffs(opts)
+        end
+      end
+    end
+  end
 end