Re-use issue/MR counts for the pagination systemmr-index-page-performance

This changes the issue and MR index pages so the pagination system
re-uses the output of the COUNT(*) query used to calculate the number of
rows per state (opened, closed, etc). This removes the need for an
additional COUNT(*) on both pages.

1 files changed, 82 insertions, 0 deletions

diff --git a/spec/controllers/concerns/issuable_collections_spec.rb b/spec/controllers/concerns/issuable_collections_spec.rb
new file mode 100644
index 00000000000..c9687af4dd2
--- /dev/null
+++ b/spec/controllers/concerns/issuable_collections_spec.rb
@@ -0,0 +1,82 @@
+require 'spec_helper'
+
+describe IssuableCollections do
+  let(:user) { create(:user) }
+
+  let(:controller) do
+    klass = Class.new do
+      def self.helper_method(name); end
+
+      include IssuableCollections
+    end
+
+    controller = klass.new
+
+    allow(controller).to receive(:params).and_return(state: 'opened')
+
+    controller
+  end
+
+  describe '#redirect_out_of_range' do
+    before do
+      allow(controller).to receive(:url_for)
+    end
+
+    it 'returns true and redirects if the offset is out of range' do
+      relation = double(:relation, current_page: 10)
+
+      expect(controller).to receive(:redirect_to)
+      expect(controller.send(:redirect_out_of_range, relation, 2)).to eq(true)
+    end
+
+    it 'returns false if the offset is not out of range' do
+      relation = double(:relation, current_page: 1)
+
+      expect(controller).not_to receive(:redirect_to)
+      expect(controller.send(:redirect_out_of_range, relation, 2)).to eq(false)
+    end
+  end
+
+  describe '#issues_page_count' do
+    it 'returns the number of issue pages' do
+      project = create(:project, :public)
+
+      create(:issue, project: project)
+
+      finder = IssuesFinder.new(user)
+      issues = finder.execute
+
+      allow(controller).to receive(:issues_finder)
+        .and_return(finder)
+
+      expect(controller.send(:issues_page_count, issues)).to eq(1)
+    end
+  end
+
+  describe '#merge_requests_page_count' do
+    it 'returns the number of merge request pages' do
+      project = create(:project, :public)
+
+      create(:merge_request, source_project: project, target_project: project)
+
+      finder = MergeRequestsFinder.new(user)
+      merge_requests = finder.execute
+
+      allow(controller).to receive(:merge_requests_finder)
+        .and_return(finder)
+
+      pages = controller.send(:merge_requests_page_count, merge_requests)
+
+      expect(pages).to eq(1)
+    end
+  end
+
+  describe '#page_count_for_relation' do
+    it 'returns the number of pages' do
+      relation = double(:relation, limit_value: 20)
+      pages = controller.send(:page_count_for_relation, relation, 28)
+
+      expect(pages).to eq(2)
+    end
+  end
+end