Backpedal from class-oriented config.queue. Set an actual queue instance.

activesupport/lib/active_support/queueing.rb

@@ -64,10 +64,6 @@ module ActiveSupport
   # queue and joins the thread, which will ensure that all jobs
   # are executed before the process finally dies.
   class ThreadedQueueConsumer
-    def self.start(*args)
-      new(*args).start
-    end
-
     def initialize(queue, options = {})
       @queue = queue
       @logger = options[:logger]

guides/source/4_0_release_notes.md

@@ -95,9 +95,9 @@ Railties
 
 *   Load all environments available in `config.paths["config/environments"]`.
 
-*   Add `config.queue_consumer` to allow the default consumer to be configurable.
+*   Add `config.queue_consumer` to change the job queue consumer from the default `ActiveSupport::ThreadedQueueConsumer`.
 
-*   Add `Rails.queue` as an interface with a default implementation that consumes jobs in a separate thread.
+*   Add `Rails.queue` for processing jobs in the background.
 
 *   Remove `Rack::SSL` in favour of `ActionDispatch::SSL`.
 

guides/source/configuring.md

@@ -115,9 +115,9 @@ NOTE. The `config.asset_path` configuration is ignored if the asset pipeline is
 
 * `config.middleware` allows you to configure the application's middleware. This is covered in depth in the [Configuring Middleware](#configuring-middleware) section below.
 
-* `config.queue` configures a different queue implementation for the application. Defaults to `ActiveSupport::SynchronousQueue`. Note that, if the default queue is changed, the default `queue_consumer` is not going to be initialized, it is up to the new queue implementation to handle starting and shutting down its own consumer(s).
+* `config.queue` configures the default job queue for the application. Defaults to `ActiveSupport::Queue.new` which processes jobs in a background thread. If you change the queue, you're responsible for running the jobs as well.
 
-* `config.queue_consumer` configures a different consumer implementation for the default queue. Defaults to `ActiveSupport::ThreadedQueueConsumer`.
+* `config.queue_consumer` configures a different job consumer for the default queue. Defaults to `ActiveSupport::ThreadedQueueConsumer`. The job consumer must respond to `start`.
 
 * `config.reload_classes_only_on_change` enables or disables reloading of classes only when tracked files change. By default tracks everything on autoload paths and is set to true. If `config.cache_classes` is true, this option is ignored.
 

railties/CHANGELOG.md

@@ -81,9 +81,9 @@
 
 *   Load all environments available in `config.paths["config/environments"]`. *Piotr Sarnacki*
 
-*   Add `config.queue_consumer` to allow the default consumer to be configurable. *Carlos Antonio da Silva*
+*   Add `config.queue_consumer` to change the job queue consumer from the default `ActiveSupport::ThreadedQueueConsumer`. *Carlos Antonio da Silva*
 
-*   Add Rails.queue as an interface with a default implementation that consumes jobs in a separate thread. *Yehuda Katz*
+*   Add `Rails.queue` for processing jobs in the background. *Yehuda Katz*
 
 *   Remove Rack::SSL in favour of ActionDispatch::SSL. *Rafael Mendonça França*
 

railties/lib/rails/application/configuration.rb

@@ -43,7 +43,7 @@ module Rails
         @exceptions_app                = nil
         @autoflush_log                 = true
         @log_formatter                 = ActiveSupport::Logger::SimpleFormatter.new
-        @queue                         = ActiveSupport::SynchronousQueue
+        @queue                         = ActiveSupport::SynchronousQueue.new
         @queue_consumer                = ActiveSupport::ThreadedQueueConsumer
         @eager_load                    = nil
 

railties/lib/rails/application/finisher.rb

@@ -97,8 +97,8 @@ module Rails
       end
 
       initializer :activate_queue_consumer do |app|
-        if config.queue == ActiveSupport::Queue
-          app.queue_consumer = config.queue_consumer.start(app.queue, {logger: Rails.logger})
+        if config.queue.class == ActiveSupport::Queue
+          app.queue_consumer = config.queue_consumer.start
           at_exit { app.queue_consumer.shutdown }
         end
       end

railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt

@@ -88,5 +88,5 @@
 
   # Default the production mode queue to an synchronous queue. You will probably
   # want to replace this with an out-of-process queueing solution.
-  # config.queue = ActiveSupport::SynchronousQueue
+  # config.queue = ActiveSupport::SynchronousQueue.new
 end

railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt

@@ -35,5 +35,5 @@
   config.active_support.deprecation = :stderr
 
   # Use the synchronous queue to run jobs immediately.
-  config.queue = ActiveSupport::SynchronousQueue
+  config.queue = ActiveSupport::SynchronousQueue.new
 end

railties/test/application/configuration_test.rb

@@ -56,14 +56,6 @@ module ApplicationTests
       assert_match "ActiveRecord::PendingMigrationError", last_response.body
     end
 
-    test "multiple queue construction is possible" do
-      require 'rails'
-      require "#{app_path}/config/environment"
-      mail_queue             = Rails.application.build_queue
-      image_processing_queue = Rails.application.build_queue
-      assert_not_equal mail_queue, image_processing_queue
-    end
-
     test "Rails.groups returns available groups" do
       require "rails"
 

railties/test/application/queue_test.rb

@@ -113,12 +113,12 @@ module ApplicationTests
     test "a custom consumer implementation can be provided" do
       add_to_env_config "production", <<-RUBY
         require "my_queue_consumer"
-        config.queue = ActiveSupport::Queue
-        config.queue_consumer = MyQueueConsumer
+        config.queue = ActiveSupport::Queue.new
+        config.queue_consumer = MyQueueConsumer.new
       RUBY
 
       app_file "lib/my_queue_consumer.rb", <<-RUBY
-        class MyQueueConsumer < ActiveSupport::ThreadedQueueConsumer
+        class MyQueueConsumer
           attr_reader :started
 
           def start