fix export performance of CI builds

app/models/ci/build.rb

@@ -451,6 +451,10 @@ module Ci
       trace
     end
 
+    def serializable_hash(options = {})
+      super(options.merge(when: read_attribute(:when)))
+    end
+
     private
 
     def update_artifacts_size

lib/gitlab/import_export/import_export.yml

@@ -116,6 +116,7 @@ excluded_attributes:
   statuses:
     - :trace
     - :token
+    - :when
   push_event_payload:
     - :event_id
 

lib/gitlab/import_export/reader.rb

@@ -18,9 +18,7 @@ module Gitlab
         attributes = @attributes_finder.find(:project)
         project_attributes = attributes.is_a?(Hash) ? attributes[:project] : {}
 
-        build_hash(@tree).each do |sub_hash|
-          yield(project_attributes.merge(include: sub_hash))
-        end
+        project_attributes.merge(include: build_hash(@tree))
       rescue => e
         @shared.error(e)
         false

spec/lib/gitlab/import_export/project_tree_saver_spec.rb

@@ -117,6 +117,13 @@ describe Gitlab::ImportExport::ProjectTreeSaver do
         expect(saved_project_json['pipelines'].first['statuses'].count { |hash| hash['type'] == 'Ci::Build' }).to eq(1)
       end
 
+      it 'builds do not call the attributes for retrieving when' do
+        allow_any_instance_of(Ci::Pipeline).to receive(:ci_yaml_file).and_return(File.read(Rails.root.join('spec/support/gitlab_stubs/gitlab_ci.yml')))
+        expect_any_instance_of(Ci::GitlabCiYamlProcessor).not_to receive(:build_attributes)
+
+        saved_project_json
+      end
+
       it 'has pipeline commits' do
         expect(saved_project_json['pipelines']).not_to be_empty
       end
@@ -251,15 +258,11 @@ describe Gitlab::ImportExport::ProjectTreeSaver do
     create(:label_priority, label: group_label, priority: 1)
     milestone = create(:milestone, project: project)
     merge_request = create(:merge_request, source_project: project, milestone: milestone)
-    commit_status = create(:commit_status, project: project)
 
-    ci_pipeline = create(:ci_pipeline,
-                         project: project,
-                         sha: merge_request.diff_head_sha,
-                         ref: merge_request.source_branch,
-                         statuses: [commit_status])
+    ci_build = create(:ci_build, project: project, when: nil)
+    ci_build.pipeline.update(project: project)
+    commit_status = create(:commit_status, project: project, pipeline: ci_build.pipeline)
 
-    create(:ci_build, pipeline: ci_pipeline, project: project)
     create(:milestone, project: project)
     create(:note, noteable: issue, project: project)
     create(:note, noteable: merge_request, project: project)
@@ -267,7 +270,7 @@ describe Gitlab::ImportExport::ProjectTreeSaver do
     create(:note_on_commit,
            author: user,
            project: project,
-           commit_id: ci_pipeline.sha)
+           commit_id: ci_build.pipeline.sha)
 
     create(:event, :created, target: milestone, project: project, author: user)
     create(:service, project: project, type: 'CustomIssueTrackerService', category: 'issue_tracker')