Merge branch 'sidekiq-job-throttling' into 'master'

Allow certain Sidekiq jobs to be throttled

## What does this MR do?

Allows certain slow running Sidekiq jobs to be throttled. It is disabled by default and can be enabled via the Application Settings. 

![Screen_Shot_2016-11-04_at_4.51.24_PM](/uploads/a1f1d24c693fcdb278602765cd404d94/Screen_Shot_2016-11-04_at_4.51.24_PM.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG.md) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing

## What are the relevant issue numbers?

Related to #23352

See merge request !7292

1 files changed, 28 insertions, 0 deletions

diff --git a/spec/lib/gitlab/sidekiq_throttler_spec.rb b/spec/lib/gitlab/sidekiq_throttler_spec.rb
new file mode 100644
index 00000000000..ff32e0e699d
--- /dev/null
+++ b/spec/lib/gitlab/sidekiq_throttler_spec.rb
@@ -0,0 +1,28 @@
+require 'spec_helper'
+
+describe Gitlab::SidekiqThrottler do
+  before do
+    Sidekiq.options[:concurrency] = 35
+
+    stub_application_setting(
+      sidekiq_throttling_enabled: true,
+      sidekiq_throttling_factor: 0.1,
+      sidekiq_throttling_queues: %w[build project_cache]
+    )
+  end
+
+  describe '#execute!' do
+    it 'sets limits on the selected queues' do
+      Gitlab::SidekiqThrottler.execute!
+
+      expect(Sidekiq::Queue['build'].limit).to eq 4
+      expect(Sidekiq::Queue['project_cache'].limit).to eq 4
+    end
+
+    it 'does not set limits on other queues' do
+      Gitlab::SidekiqThrottler.execute!
+
+      expect(Sidekiq::Queue['merge'].limit).to be_nil
+    end
+  end
+end