Merge branch 'finding-issues-by-labels-performance' into 'master'

Improve performance of finding issues with/without labels

The changes in this MR ultimately lead to finding issues with(out) labels being about 2x faster due to:

1. Newly added indexes on `issues.state` and `projects.visibility_level`
2. Adjusting the query so that finding issues for multiple projects is more efficient

See merge request !1787

1 files changed, 55 insertions, 0 deletions

diff --git a/spec/benchmarks/finders/issues_finder_spec.rb b/spec/benchmarks/finders/issues_finder_spec.rb
new file mode 100644
index 00000000000..b57a33004a4
--- /dev/null
+++ b/spec/benchmarks/finders/issues_finder_spec.rb
@@ -0,0 +1,55 @@
+require 'spec_helper'
+
+describe IssuesFinder, benchmark: true do
+  describe '#execute' do
+    let(:user) { create(:user) }
+    let(:project) { create(:project, :public) }
+
+    let(:label1) { create(:label, project: project, title: 'A') }
+    let(:label2) { create(:label, project: project, title: 'B') }
+
+    before do
+      10.times do |n|
+        issue = create(:issue, author: user, project: project)
+
+        if n > 4
+          create(:label_link, label: label1, target: issue)
+          create(:label_link, label: label2, target: issue)
+        end
+      end
+    end
+
+    describe 'retrieving issues without labels' do
+      let(:finder) do
+        IssuesFinder.new(user, scope: 'all', label_name: Label::None.title,
+                               state: 'opened')
+      end
+
+      benchmark_subject { finder.execute }
+
+      it { is_expected.to iterate_per_second(2000) }
+    end
+
+    describe 'retrieving issues with labels' do
+      let(:finder) do
+        IssuesFinder.new(user, scope: 'all', label_name: label1.title,
+                               state: 'opened')
+      end
+
+      benchmark_subject { finder.execute }
+
+      it { is_expected.to iterate_per_second(1000) }
+    end
+
+    describe 'retrieving issues for a single project' do
+      let(:finder) do
+        IssuesFinder.new(user, scope: 'all', label_name: Label::None.title,
+                               state: 'opened', project_id: project.id)
+      end
+
+      benchmark_subject { finder.execute }
+
+      it { is_expected.to iterate_per_second(2000) }
+    end
+  end
+end