Increase the hard/soft limits for lines/files behind feature flag

Issue: gitlab.com/gitlab-org/gitlab/-/issues/219565
Merge Request: gitlab.com/gitlab-org/gitlab/-/merge_requests/40357

app/models/commit.rb

@@ -29,12 +29,6 @@ class Commit
   delegate :repository, to: :container
   delegate :project, to: :repository, allow_nil: true
 
-  DIFF_SAFE_LINES = Gitlab::Git::DiffCollection::DEFAULT_LIMITS[:max_lines]
-
-  # Commits above this size will not be rendered in HTML
-  DIFF_HARD_LIMIT_FILES = 1000
-  DIFF_HARD_LIMIT_LINES = 50000
-
   MIN_SHA_LENGTH = Gitlab::Git::Commit::MIN_SHA_LENGTH
   COMMIT_SHA_PATTERN = /\h{#{MIN_SHA_LENGTH},40}/.freeze
   EXACT_COMMIT_SHA_PATTERN = /\A#{COMMIT_SHA_PATTERN}\z/.freeze
@@ -80,10 +74,30 @@ class Commit
       sha[0..MIN_SHA_LENGTH]
     end
 
-    def max_diff_options
+    def diff_safe_lines
+      Gitlab::Git::DiffCollection.default_limits[:max_lines]
+    end
+
+    def diff_hard_limit_files(project: nil)
+      if Feature.enabled?(:increased_diff_limits, project)
+        2000
+      else
+        1000
+      end
+    end
+
+    def diff_hard_limit_lines(project: nil)
+      if Feature.enabled?(:increased_diff_limits, project)
+        75000
+      else
+        50000
+      end
+    end
+
+    def max_diff_options(project: nil)
       {
-        max_files: DIFF_HARD_LIMIT_FILES,
-        max_lines: DIFF_HARD_LIMIT_LINES
+        max_files: diff_hard_limit_files(project: project),
+        max_lines: diff_hard_limit_lines(project: project)
       }
     end
 

app/models/merge_request.rb

@@ -629,7 +629,7 @@ class MergeRequest < ApplicationRecord
   def diff_size
     # Calling `merge_request_diff.diffs.real_size` will also perform
     # highlighting, which we don't need here.
-    merge_request_diff&.real_size || diff_stats&.real_size || diffs.real_size
+    merge_request_diff&.real_size || diff_stats&.real_size(project: project) || diffs.real_size
   end
 
   def modified_paths(past_merge_request_diff: nil, fallback_on_overflow: false)

app/models/merge_request_diff.rb

@@ -651,7 +651,7 @@ class MergeRequestDiff < ApplicationRecord
     if compare.commits.empty?
       new_attributes[:state] = :empty
     else
-      diff_collection = compare.diffs(Commit.max_diff_options)
+      diff_collection = compare.diffs(Commit.max_diff_options(project: merge_request.project))
       new_attributes[:real_size] = diff_collection.real_size
 
       if diff_collection.any?

app/views/projects/diffs/_text_file.html.haml

-- too_big = diff_file.diff_lines.count > Commit::DIFF_SAFE_LINES
+- too_big = diff_file.diff_lines.count > Commit.diff_safe_lines
 - if too_big
   .suppressed-container
     %a.show-suppressed-diff.cursor-pointer.js-show-suppressed-diff= _("Changes suppressed. Click to show.")

config/feature_flags/development/increased_diff_limits.yml

+---
+name: increased_diff_limits
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/40357
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/241185
+group: group::source_code
+type: development
+default_enabled: false
\ No newline at end of file

lib/gitlab/diff/file_collection/merge_request_diff_base.rb

@@ -11,7 +11,7 @@ module Gitlab
 
           super(merge_request_diff,
             project: merge_request_diff.project,
-            diff_options: diff_options,
+            diff_options: merged_diff_options(diff_options),
             diff_refs: merge_request_diff.diff_refs,
             fallback_diff_refs: merge_request_diff.fallback_diff_refs)
         end
@@ -64,6 +64,11 @@ module Gitlab
             diff_stats_cache.read || super
           end
         end
+
+        def merged_diff_options(diff_options)
+          max_diff_options = ::Commit.max_diff_options(project: @merge_request_diff.project)
+          diff_options.present? ? diff_options.merge(max_diff_options) : max_diff_options
+        end
       end
     end
   end

lib/gitlab/git/diff_collection.rb

@@ -7,19 +7,23 @@ module Gitlab
     class DiffCollection
       include Enumerable
 
-      DEFAULT_LIMITS = { max_files: 100, max_lines: 5000 }.freeze
-
       attr_reader :limits
 
       delegate :max_files, :max_lines, :max_bytes, :safe_max_files, :safe_max_lines, :safe_max_bytes, to: :limits
 
+      def self.default_limits
+        { max_files: 100, max_lines: 5000 }
+      end
+
       def self.limits(options = {})
         limits = {}
-        limits[:max_files] = options.fetch(:max_files, DEFAULT_LIMITS[:max_files])
-        limits[:max_lines] = options.fetch(:max_lines, DEFAULT_LIMITS[:max_lines])
+        defaults = default_limits
+        limits[:max_files] = options.fetch(:max_files, defaults[:max_files])
+        limits[:max_lines] = options.fetch(:max_lines, defaults[:max_lines])
         limits[:max_bytes] = limits[:max_files] * 5.kilobytes # Average 5 KB per file
-        limits[:safe_max_files] = [limits[:max_files], DEFAULT_LIMITS[:max_files]].min
-        limits[:safe_max_lines] = [limits[:max_lines], DEFAULT_LIMITS[:max_lines]].min
+
+        limits[:safe_max_files] = [limits[:max_files], defaults[:max_files]].min
+        limits[:safe_max_lines] = [limits[:max_lines], defaults[:max_lines]].min
         limits[:safe_max_bytes] = limits[:safe_max_files] * 5.kilobytes # Average 5 KB per file
         limits[:max_patch_bytes] = Gitlab::Git::Diff.patch_hard_limit_bytes
 

lib/gitlab/git/diff_stats_collection.rb

@@ -22,8 +22,8 @@ module Gitlab
         @collection.map(&:path)
       end
 
-      def real_size
-        max_files = ::Commit.max_diff_options[:max_files]
+      def real_size(project: nil)
+        max_files = ::Commit.max_diff_options(project: project)[:max_files]
         if paths.size > max_files
           "#{max_files}+"
         else

spec/features/expand_collapse_diffs_spec.rb

@@ -7,6 +7,7 @@ RSpec.describe 'Expand and collapse diffs', :js do
   let(:project) { create(:project, :repository) }
 
   before do
+    stub_feature_flags(increased_diff_limits: false)
     sign_in(create(:admin))
 
     # Ensure that undiffable.md is in .gitattributes

spec/features/merge_request/user_expands_diff_spec.rb

@@ -7,6 +7,7 @@ RSpec.describe 'User expands diff', :js do
   let(:merge_request) { create(:merge_request, source_branch: 'expand-collapse-files', source_project: project, target_project: project) }
 
   before do
+    stub_feature_flags(increased_diff_limits: false)
     visit(diffs_project_merge_request_path(project, merge_request))
 
     wait_for_requests

spec/lib/gitlab/git/diff_collection_spec.rb

@@ -531,7 +531,9 @@ RSpec.describe Gitlab::Git::DiffCollection, :seed_helper do
           let(:iterator) { [fake_diff(1, 1)] * 4 }
 
           before do
-            stub_const('Gitlab::Git::DiffCollection::DEFAULT_LIMITS', { max_files: 2, max_lines: max_lines })
+            allow(Gitlab::Git::DiffCollection)
+              .to receive(:default_limits)
+              .and_return({ max_files: 2, max_lines: max_lines })
           end
 
           it 'prunes diffs by default even little ones' do
@@ -556,7 +558,9 @@ RSpec.describe Gitlab::Git::DiffCollection, :seed_helper do
           end
 
           before do
-            stub_const('Gitlab::Git::DiffCollection::DEFAULT_LIMITS', { max_files: max_files, max_lines: 80 })
+            allow(Gitlab::Git::DiffCollection)
+              .to receive(:default_limits)
+              .and_return({ max_files: max_files, max_lines: 80 })
           end
 
           it 'prunes diffs by default even little ones' do
@@ -581,7 +585,9 @@ RSpec.describe Gitlab::Git::DiffCollection, :seed_helper do
           end
 
           before do
-            stub_const('Gitlab::Git::DiffCollection::DEFAULT_LIMITS', { max_files: max_files, max_lines: 80 })
+            allow(Gitlab::Git::DiffCollection)
+              .to receive(:default_limits)
+              .and_return({ max_files: max_files, max_lines: 80 })
           end
 
           it 'prunes diffs by default even little ones' do
@@ -665,8 +671,9 @@ RSpec.describe Gitlab::Git::DiffCollection, :seed_helper do
         end
 
         before do
-          stub_const('Gitlab::Git::DiffCollection::DEFAULT_LIMITS',
-                     { max_files: max_files, max_lines: 80 })
+          allow(Gitlab::Git::DiffCollection)
+            .to receive(:default_limits)
+            .and_return({ max_files: max_files, max_lines: 80 })
         end
 
         it 'considers size of diffs before the offset for prunning' do

spec/lib/gitlab/gitaly_client/commit_service_spec.rb

@@ -13,6 +13,10 @@ RSpec.describe Gitlab::GitalyClient::CommitService do
   let(:client) { described_class.new(repository) }
 
   describe '#diff_from_parent' do
+    before do
+      stub_feature_flags(increased_diff_limits: false)
+    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(

spec/requests/api/merge_requests_spec.rb

@@ -1140,7 +1140,7 @@ RSpec.describe API::MergeRequests do
 
     context 'when a merge request has more than the changes limit' do
       it "returns a string indicating that more changes were made" do
-        stub_const('Commit::DIFF_HARD_LIMIT_FILES', 5)
+        allow(Commit).to receive(:diff_hard_limit_files).and_return(5)
 
         merge_request_overflow = create(:merge_request, :simple,
                                         author: user,

spec/requests/api/repositories_spec.rb

@@ -402,7 +402,9 @@ RSpec.describe API::Repositories do
       end
 
       it "returns an empty string when the diff overflows" do
-        stub_const('Gitlab::Git::DiffCollection::DEFAULT_LIMITS', { max_files: 2, max_lines: 2 })
+        allow(Gitlab::Git::DiffCollection)
+          .to receive(:default_limits)
+          .and_return({ max_files: 2, max_lines: 2 })
 
         get api(route, current_user), params: { from: 'master', to: 'feature' }