Use standalone diff stats RPC on every comparison view

5 files changed, 46 insertions, 7 deletions

diff --git a/lib/gitlab/diff/file.rb b/lib/gitlab/diff/file.rb
index d2ca7a070fa..fb117baca9e 100644
--- a/lib/gitlab/diff/file.rb
+++ b/lib/gitlab/diff/file.rb
@@ -20,8 +20,9 @@ module Gitlab
         DiffViewer::Image
       ].sort_by { |v| v.binary? ? 0 : 1 }.freeze
 
-      def initialize(diff, repository:, diff_refs: nil, fallback_diff_refs: nil)
+      def initialize(diff, repository:, diff_refs: nil, fallback_diff_refs: nil, stats: nil)
         @diff = diff
+        @stats = stats
         @repository = repository
         @diff_refs = diff_refs
         @fallback_diff_refs = fallback_diff_refs
@@ -165,11 +166,11 @@ module Gitlab
       end
 
       def added_lines
-        diff_lines.count(&:added?)
+        @stats&.additions || diff_lines.count(&:added?)
       end
 
       def removed_lines
-        diff_lines.count(&:removed?)
+        @stats&.deletions || diff_lines.count(&:removed?)
       end
 
       def file_identifier
diff --git a/lib/gitlab/diff/file_collection/base.rb b/lib/gitlab/diff/file_collection/base.rb
index 2acb0e43b69..b79ff771a2b 100644
--- a/lib/gitlab/diff/file_collection/base.rb
+++ b/lib/gitlab/diff/file_collection/base.rb
@@ -2,23 +2,27 @@ module Gitlab
   module Diff
     module FileCollection
       class Base
+        include Gitlab::Utils::StrongMemoize
+
         attr_reader :project, :diff_options, :diff_refs, :fallback_diff_refs, :diffable
 
         delegate :count, :size, :real_size, to: :diff_files
 
         def self.default_options
-          ::Commit.max_diff_options.merge(ignore_whitespace_change: false, expanded: false)
+          ::Commit.max_diff_options.merge(ignore_whitespace_change: false, expanded: false, include_stats: true)
         end
 
         def initialize(diffable, project:, diff_options: nil, diff_refs: nil, fallback_diff_refs: nil)
           diff_options = self.class.default_options.merge(diff_options || {})
 
           @diffable = diffable
+          @include_stats = diff_options.delete(:include_stats)
           @diffs = diffable.raw_diffs(diff_options)
           @project = project
           @diff_options = diff_options
           @diff_refs = diff_refs
           @fallback_diff_refs = fallback_diff_refs
+          @repository = project.repository
         end
 
         def diff_files
@@ -43,10 +47,27 @@ module Gitlab
 
         private
 
+        def diff_stats_collection
+          strong_memoize(:diff_stats) do
+            # There are scenarios where we don't need to request Diff Stats,
+            # when caching for instance.
+            next unless @include_stats
+            next unless diff_refs
+
+            @repository.diff_stats(diff_refs.base_sha, diff_refs.head_sha)
+          end
+        end
+
         def decorate_diff!(diff)
           return diff if diff.is_a?(File)
 
-          Gitlab::Diff::File.new(diff, repository: project.repository, diff_refs: diff_refs, fallback_diff_refs: fallback_diff_refs)
+          stats = diff_stats_collection&.find_by_path(diff.new_path)
+
+          Gitlab::Diff::File.new(diff,
+                                 repository: project.repository,
+                                 diff_refs: diff_refs,
+                                 fallback_diff_refs: fallback_diff_refs,
+                                 stats: stats)
         end
       end
     end
diff --git a/lib/gitlab/diff/position.rb b/lib/gitlab/diff/position.rb
index 978962ab2eb..4b6016e00bc 100644
--- a/lib/gitlab/diff/position.rb
+++ b/lib/gitlab/diff/position.rb
@@ -116,6 +116,10 @@ module Gitlab
         end
       end
 
+      def diff_options
+        { paths: paths, expanded: true, include_stats: false }
+      end
+
       def diff_line(repository)
         @diff_line ||= diff_file(repository)&.line_for_position(self)
       end
@@ -130,7 +134,7 @@ module Gitlab
         return unless diff_refs.complete?
         return unless comparison = diff_refs.compare_in(repository.project)
 
-        comparison.diffs(paths: paths, expanded: true).diff_files.first
+        comparison.diffs(diff_options).diff_files.first
       end
 
       def get_formatter_class(type)
diff --git a/lib/gitlab/git/diff_stats_collection.rb b/lib/gitlab/git/diff_stats_collection.rb
index 84d9e46f98e..d4033f56387 100644
--- a/lib/gitlab/git/diff_stats_collection.rb
+++ b/lib/gitlab/git/diff_stats_collection.rb
@@ -3,6 +3,7 @@
 module Gitlab
   module Git
     class DiffStatsCollection
+      include Gitlab::Utils::StrongMemoize
       include Enumerable
 
       def initialize(diff_stats)
@@ -12,6 +13,18 @@ module Gitlab
       def each(&block)
         @collection.each(&block)
       end
+
+      def find_by_path(path)
+        indexed_by_path[path]
+      end
+
+      private
+
+      def indexed_by_path
+        strong_memoize(:indexed_by_path) do
+          index_by { |stats| stats.path }
+        end
+      end
     end
   end
 end
diff --git a/lib/gitlab/git/repository.rb b/lib/gitlab/git/repository.rb
index fa22294ac51..3d5a63bdbac 100644
--- a/lib/gitlab/git/repository.rb
+++ b/lib/gitlab/git/repository.rb
@@ -444,7 +444,7 @@ module Gitlab
         end
 
         Gitlab::Git::DiffStatsCollection.new(stats)
-      rescue CommandError
+      rescue CommandError, TypeError
         Gitlab::Git::DiffStatsCollection.new([])
       end