Remove support for Qu gem.

Reasons are that the Qu gem wasn't compatible since Rails 5.1,
gem development was stopped in 2014 and maintainers have
confirmed its demise. See issue #32273

Gemfile

@@ -64,9 +64,6 @@ group :job do
   gem "sneakers", require: false
   gem "que", require: false
   gem "backburner", require: false
-  # TODO: add qu after it support Rails 5.1
-  # gem 'qu-rails', github: "bkeepers/qu", branch: "master", require: false
-  # gem "qu-redis", require: false
   gem "delayed_job_active_record", require: false
   gem "sequel", require: false
 end

activejob/CHANGELOG.md

+*   Remove support for Qu gem.
+
+    Reasons are that the Qu gem wasn't compatible since Rails 5.1,
+    gem development was stopped in 2014 and maintainers have
+    confirmed its demise. See issue #32273
+
+    *Alberto Almagro*
+
 *   Add support for timezones to Active Job.
 
     Record what was the current timezone in effect when the job was

activejob/Rakefile

@@ -2,7 +2,6 @@
 
 require "rake/testtask"
 
-# TODO: add qu back to the list after it support Rails 5.1
 ACTIVEJOB_ADAPTERS = %w(async inline delayed_job que queue_classic resque sidekiq sneakers sucker_punch backburner test)
 ACTIVEJOB_ADAPTERS.delete("queue_classic") if defined?(JRUBY_VERSION)
 

activejob/lib/active_job/queue_adapters.rb

@@ -7,7 +7,6 @@ module ActiveJob
   #
   # * {Backburner}[https://github.com/nesquena/backburner]
   # * {Delayed Job}[https://github.com/collectiveidea/delayed_job]
-  # * {Qu}[https://github.com/bkeepers/qu]
   # * {Que}[https://github.com/chanks/que]
   # * {queue_classic}[https://github.com/QueueClassic/queue_classic]
   # * {Resque}[https://github.com/resque/resque]
@@ -24,7 +23,6 @@ module ActiveJob
   #   |-------------------|-------|--------|------------|------------|---------|---------|
   #   | Backburner        | Yes   | Yes    | Yes        | Yes        | Job     | Global  |
   #   | Delayed Job       | Yes   | Yes    | Yes        | Job        | Global  | Global  |
-  #   | Qu                | Yes   | Yes    | No         | No         | No      | Global  |
   #   | Que               | Yes   | Yes    | Yes        | Job        | No      | Job     |
   #   | queue_classic     | Yes   | Yes    | Yes*       | No         | No      | No      |
   #   | Resque            | Yes   | Yes    | Yes (Gem)  | Queue      | Global  | Yes     |
@@ -115,7 +113,6 @@ module QueueAdapters
     autoload :InlineAdapter
     autoload :BackburnerAdapter
     autoload :DelayedJobAdapter
-    autoload :QuAdapter
     autoload :QueAdapter
     autoload :QueueClassicAdapter
     autoload :ResqueAdapter

activejob/lib/active_job/queue_adapters/qu_adapter.rb

-# frozen_string_literal: true
-
-require "qu"
-
-module ActiveJob
-  module QueueAdapters
-    # == Qu adapter for Active Job
-    #
-    # Qu is a Ruby library for queuing and processing background jobs. It is
-    # heavily inspired by delayed_job and Resque. Qu was created to overcome
-    # some shortcomings in the existing queuing libraries.
-    # The advantages of Qu are: Multiple backends (redis, mongo), jobs are
-    # requeued when worker is killed, resque-like API.
-    #
-    # Read more about Qu {here}[https://github.com/bkeepers/qu].
-    #
-    # To use Qu set the queue_adapter config to +:qu+.
-    #
-    #   Rails.application.config.active_job.queue_adapter = :qu
-    class QuAdapter
-      def enqueue(job, *args) #:nodoc:
-        qu_job = Qu::Payload.new(klass: JobWrapper, args: [job.serialize]).tap do |payload|
-          payload.instance_variable_set(:@queue, job.queue_name)
-        end.push
-
-        # qu_job can be nil depending on the configured backend
-        job.provider_job_id = qu_job.id unless qu_job.nil?
-        qu_job
-      end
-
-      def enqueue_at(job, timestamp, *args) #:nodoc:
-        raise NotImplementedError, "This queueing backend does not support scheduling jobs. To see what features are supported go to http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html"
-      end
-
-      class JobWrapper < Qu::Job #:nodoc:
-        def initialize(job_data)
-          @job_data = job_data
-        end
-
-        def perform
-          Base.execute @job_data
-        end
-      end
-    end
-  end
-end

activejob/test/adapters/qu.rb

-# frozen_string_literal: true
-
-require "qu-immediate"
-
-ActiveJob::Base.queue_adapter = :qu

activejob/test/integration/queuing_test.rb

@@ -82,7 +82,7 @@ class QueuingTest < ActiveSupport::TestCase
   end
 
   test "should supply a provider_job_id when available for immediate jobs" do
-    skip unless adapter_is?(:async, :delayed_job, :sidekiq, :qu, :que, :queue_classic)
+    skip unless adapter_is?(:async, :delayed_job, :sidekiq, :que, :queue_classic)
     test_job = TestJob.perform_later @id
     assert test_job.provider_job_id, "Provider job id should be set by provider"
   end

activejob/test/support/integration/adapters/qu.rb

-# frozen_string_literal: true
-
-module QuJobsManager
-  def setup
-    require "qu-rails"
-    require "qu-redis"
-    ActiveJob::Base.queue_adapter = :qu
-    ENV["REDISTOGO_URL"] = "redis://127.0.0.1:6379/12"
-    backend = Qu::Backend::Redis.new
-    backend.namespace = "active_jobs_int_test"
-    Qu.backend  = backend
-    Qu.logger   = Rails.logger
-    Qu.interval = 0.5
-    unless can_run?
-      puts "Cannot run integration tests for qu. To be able to run integration tests for qu you need to install and start redis.\n"
-      exit
-    end
-  end
-
-  def clear_jobs
-    Qu.clear "integration_tests"
-  end
-
-  def start_workers
-    @thread = Thread.new { Qu::Worker.new("integration_tests").start }
-  end
-
-  def stop_workers
-    @thread.kill
-  end
-
-  def can_run?
-    begin
-      Qu.backend.connection.client.connect
-    rescue
-      return false
-    end
-    true
-  end
-end