Merge branch 'sh-optimize-commit-stats' into 'master'

Speed up generation of commit stats by using Rugged native methods

See merge request gitlab-org/gitlab-ce!16186

changelogs/unreleased/sh-optimize-commit-stats.yml

+---
+title: Speed up generation of commit stats by using Rugged native methods
+merge_request:
+author:
+type: performance

lib/gitlab/git/commit_stats.rb

@@ -34,13 +34,8 @@ module Gitlab
 
       def rugged_stats(commit)
         diff = commit.rugged_diff_from_parent
-
-        diff.each_patch do |p|
-          # TODO: Use the new Rugged convenience methods when they're released
-          @additions += p.stat[0]
-          @deletions += p.stat[1]
-          @total += p.changes
-        end
+        _files_changed, @additions, @deletions = diff.stat
+        @total = @additions + @deletions
       end
     end
   end

spec/lib/gitlab/git/commit_spec.rb

@@ -428,6 +428,11 @@ describe Gitlab::Git::Commit, seed_helper: true do
       subject { super().deletions }
       it { is_expected.to eq(6) }
     end
+
+    describe '#total' do
+      subject { super().total }
+      it { is_expected.to eq(17) }
+    end
   end
 
   describe '#stats with gitaly on' do