Re-organize queues to use for Sidekiq

Dumping too many jobs in the same queue (e.g. the "default" queue) is a
dangerous setup. Jobs that take a long time to process can effectively
block any other work from being performed given there are enough of
these jobs.

Furthermore it becomes harder to monitor the jobs as a single queue
could contain jobs for different workers. In such a setup the only
reliable way of getting counts per job is to iterate over all jobs in a
queue, which is a rather time consuming process.

By using separate queues for various workers we have better control over
throughput, we can add weight to queues, and we can monitor queues
better. Some workers still use the same queue whenever their work is
related. For example, the various CI pipeline workers use the same
"pipeline" queue.

This commit includes a Rails migration that moves Sidekiq jobs from the
old queues to the new ones. This migration also takes care of doing the
inverse if ever needed. This does require downtime as otherwise new jobs
could be scheduled in the old queues after this migration completes.

This commit also includes an RSpec test that blacklists the use of the
"default" queue and ensures cron workers use the "cronjob" queue.

Fixes gitlab-org/gitlab-ce#23370

CHANGELOG.md

@@ -2,6 +2,9 @@ Please view this file on the master branch, on stable branches it's out of date.
 ## 8.13.0 (2016-10-22)
+  - Fix save button on project pipeline settings page. (!6955)
+  - All Sidekiq workers now use their own queue
+  - Avoid race condition when asynchronously removing expired artifacts. (!6881)
   - Improve Merge When Build Succeeds triggers and execute on pipeline success. (!6675)
   - Respond with 404 Not Found for non-existent tags (Linus Thiel)
   - Truncate long labels with ellipsis in labels page

app/workers/admin_email_worker.rb

 class AdminEmailWorker
   include Sidekiq::Worker
-
-  sidekiq_options retry: false # this job auto-repeats via sidekiq-cron
+  include CronjobQueue
   def perform
     repository_check_failed_count = Project.where(last_repository_check_failed: true).count

app/workers/build_coverage_worker.rb

 class BuildCoverageWorker
   include Sidekiq::Worker
-  sidekiq_options queue: :default
+  include BuildQueue
   def perform(build_id)
     Ci::Build.find_by(id: build_id)

app/workers/build_email_worker.rb

 class BuildEmailWorker
   include Sidekiq::Worker
+  include BuildQueue
   def perform(build_id, recipients, push_data)
     recipients.each do |recipient|

app/workers/build_finished_worker.rb

 class BuildFinishedWorker
   include Sidekiq::Worker
+  include BuildQueue
   def perform(build_id)
     Ci::Build.find_by(id: build_id).try do |build|

app/workers/build_hooks_worker.rb

 class BuildHooksWorker
   include Sidekiq::Worker
-  sidekiq_options queue: :default
+  include BuildQueue
   def perform(build_id)
     Ci::Build.find_by(id: build_id)

app/workers/build_success_worker.rb

 class BuildSuccessWorker
   include Sidekiq::Worker
-  sidekiq_options queue: :default
+  include BuildQueue
   def perform(build_id)
     Ci::Build.find_by(id: build_id).try do |build|

app/workers/clear_database_cache_worker.rb

 # This worker clears all cache fields in the database, working in batches.
 class ClearDatabaseCacheWorker
   include Sidekiq::Worker
+  include DedicatedSidekiqQueue
   BATCH_SIZE = 1000

app/workers/concerns/build_queue.rb

+# Concern for setting Sidekiq settings for the various CI build workers.
+module BuildQueue
+  extend ActiveSupport::Concern
+
+  included do
+    sidekiq_options queue: :build
+  end
+end

app/workers/concerns/cronjob_queue.rb

+# Concern that sets various Sidekiq settings for workers executed using a
+# cronjob.
+module CronjobQueue
+  extend ActiveSupport::Concern
+
+  included do
+    sidekiq_options queue: :cronjob, retry: false
+  end
+end

app/workers/concerns/dedicated_sidekiq_queue.rb

+# Concern that sets the queue of a Sidekiq worker based on the worker's class
+# name/namespace.
+module DedicatedSidekiqQueue
+  extend ActiveSupport::Concern
+
+  included do
+    sidekiq_options queue: name.sub(/Worker\z/, '').underscore.tr('/', '_')
+  end
+end

app/workers/concerns/pipeline_queue.rb

+# Concern for setting Sidekiq settings for the various CI pipeline workers.
+module PipelineQueue
+  extend ActiveSupport::Concern
+
+  included do
+    sidekiq_options queue: :pipeline
+  end
+end

app/workers/concerns/repository_check_queue.rb

+# Concern for setting Sidekiq settings for the various repository check workers.
+module RepositoryCheckQueue
+  extend ActiveSupport::Concern
+
+  included do
+    sidekiq_options queue: :repository_check, retry: false
+  end
+end

app/workers/delete_user_worker.rb

 class DeleteUserWorker
   include Sidekiq::Worker
+  include DedicatedSidekiqQueue
   def perform(current_user_id, delete_user_id, options = {})
     delete_user  = User.find(delete_user_id)

app/workers/email_receiver_worker.rb

 class EmailReceiverWorker
   include Sidekiq::Worker
-
-  sidekiq_options queue: :incoming_email
+  include DedicatedSidekiqQueue
   def perform(raw)
     return unless Gitlab::IncomingEmail.enabled?

app/workers/emails_on_push_worker.rb

 class EmailsOnPushWorker
   include Sidekiq::Worker
-  sidekiq_options queue: :mailers
+  include DedicatedSidekiqQueue
   attr_reader :email, :skip_premailer
   def perform(project_id, recipients, push_data, options = {})

app/workers/expire_build_artifacts_worker.rb

 class ExpireBuildArtifactsWorker
   include Sidekiq::Worker
+  include CronjobQueue
   def perform
     Rails.logger.info 'Scheduling removal of build artifacts'

app/workers/expire_build_instance_artifacts_worker.rb

 class ExpireBuildInstanceArtifactsWorker
   include Sidekiq::Worker
+  include DedicatedSidekiqQueue
   def perform(build_id)
     build = Ci::Build.with_expired_artifacts.reorder(nil).find_by(id: build_id)

app/workers/git_garbage_collect_worker.rb

 class GitGarbageCollectWorker
   include Sidekiq::Worker
   include Gitlab::ShellAdapter
-  sidekiq_options queue: :gitlab_shell, retry: false
+  include DedicatedSidekiqQueue
+  sidekiq_options retry: false
   def perform(project_id)
     project = Project.find(project_id)

app/workers/gitlab_shell_worker.rb

 class GitlabShellWorker
   include Sidekiq::Worker
   include Gitlab::ShellAdapter
-
-  sidekiq_options queue: :gitlab_shell
+  include DedicatedSidekiqQueue
   def perform(action, *arg)
     gitlab_shell.send(action, *arg)