Add latest changes from gitlab-org/gitlab@master

2 files changed, 109 insertions, 0 deletions

diff --git a/lib/gitlab/pagination/base.rb b/lib/gitlab/pagination/base.rb
new file mode 100644
index 00000000000..90fa1f8d1ec
--- /dev/null
+++ b/lib/gitlab/pagination/base.rb
@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Pagination
+    class Base
+      private
+
+      def per_page
+        @per_page ||= params[:per_page]
+      end
+
+      def base_request_uri
+        @base_request_uri ||= URI.parse(request.url).tap do |uri|
+          uri.host = Gitlab.config.gitlab.host
+          uri.port = Gitlab.config.gitlab.port
+        end
+      end
+
+      def build_page_url(query_params:)
+        base_request_uri.tap do |uri|
+          uri.query = query_params
+        end.to_s
+      end
+
+      def page_href(next_page_params = {})
+        query_params = params.merge(**next_page_params, per_page: per_page).to_query
+
+        build_page_url(query_params: query_params)
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/pagination/offset_pagination.rb b/lib/gitlab/pagination/offset_pagination.rb
new file mode 100644
index 00000000000..bf31f252a6b
--- /dev/null
+++ b/lib/gitlab/pagination/offset_pagination.rb
@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Pagination
+    class OffsetPagination < Base
+      attr_reader :request_context
+      delegate :params, :header, :request, to: :request_context
+
+      def initialize(request_context)
+        @request_context = request_context
+      end
+
+      def paginate(relation)
+        paginate_with_limit_optimization(add_default_order(relation)).tap do |data|
+          add_pagination_headers(data)
+        end
+      end
+
+      private
+
+      def paginate_with_limit_optimization(relation)
+        pagination_data = relation.page(params[:page]).per(params[:per_page])
+        return pagination_data unless pagination_data.is_a?(ActiveRecord::Relation)
+        return pagination_data unless Feature.enabled?(:api_kaminari_count_with_limit)
+
+        limited_total_count = pagination_data.total_count_with_limit
+        if limited_total_count > Kaminari::ActiveRecordRelationMethods::MAX_COUNT_LIMIT
+          # The call to `total_count_with_limit` memoizes `@arel` because of a call to `references_eager_loaded_tables?`
+          # We need to call `reset` because `without_count` relies on `@arel` being unmemoized
+          pagination_data.reset.without_count
+        else
+          pagination_data
+        end
+      end
+
+      def add_default_order(relation)
+        if relation.is_a?(ActiveRecord::Relation) && relation.order_values.empty?
+          relation = relation.order(:id) # rubocop: disable CodeReuse/ActiveRecord
+        end
+
+        relation
+      end
+
+      def add_pagination_headers(paginated_data)
+        header 'X-Per-Page',    paginated_data.limit_value.to_s
+        header 'X-Page',        paginated_data.current_page.to_s
+        header 'X-Next-Page',   paginated_data.next_page.to_s
+        header 'X-Prev-Page',   paginated_data.prev_page.to_s
+        header 'Link',          pagination_links(paginated_data)
+
+        return if data_without_counts?(paginated_data)
+
+        header 'X-Total',       paginated_data.total_count.to_s
+        header 'X-Total-Pages', total_pages(paginated_data).to_s
+      end
+
+      def pagination_links(paginated_data)
+        [].tap do |links|
+          links << %(<#{page_href(page: paginated_data.prev_page)}>; rel="prev") if paginated_data.prev_page
+          links << %(<#{page_href(page: paginated_data.next_page)}>; rel="next") if paginated_data.next_page
+          links << %(<#{page_href(page: 1)}>; rel="first")
+
+          links << %(<#{page_href(page: total_pages(paginated_data))}>; rel="last") unless data_without_counts?(paginated_data)
+        end.join(', ')
+      end
+
+      def total_pages(paginated_data)
+        # Ensure there is in total at least 1 page
+        [paginated_data.total_pages, 1].max
+      end
+
+      def data_without_counts?(paginated_data)
+        paginated_data.is_a?(Kaminari::PaginatableWithoutCount)
+      end
+    end
+  end
+end