Merge branch 'master' of github.com:rails/rails

8 files changed, 109 insertions, 2 deletions

diff --git a/railties/lib/rails.rb b/railties/lib/rails.rb
index 945063e55c..59c3c56e59 100644
--- a/railties/lib/rails.rb
+++ b/railties/lib/rails.rb
@@ -22,6 +22,7 @@ end
 module Rails
   autoload :Info, 'rails/info'
   autoload :InfoController, 'rails/info_controller'
+  autoload :Queueing, 'rails/queueing'
 
   class << self
     def application
@@ -37,6 +38,25 @@ module Rails
       application.config
     end
 
+    # Rails.queue is the application's queue. You can push a job onto
+    # the queue by:
+    #
+    #   Rails.queue.push job
+    #
+    # A job is an object that responds to +run+. Queue consumers will
+    # pop jobs off of the queue and invoke the queue's +run+ method.
+    #
+    # Note that depending on your queue implementation, jobs may not
+    # be executed in the same process as they were created in, and
+    # are never executed in the same thread as they were created in.
+    #
+    # If necessary, a queue implementation may need to serialize your
+    # job for distribution to another process. The documentation of
+    # your queue will specify the requirements for that serialization.
+    def queue
+      application.queue
+    end
+
     def initialize!
       application.initialize!
     end
diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index b063e7681d..6ab448910e 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -66,7 +66,7 @@ module Rails
       end
     end
 
-    attr_accessor :assets, :sandbox
+    attr_accessor :assets, :sandbox, :queue
     alias_method :sandbox?, :sandbox
     attr_reader :reloaders
 
@@ -199,6 +199,10 @@ module Rails
       @config ||= Application::Configuration.new(find_root_with_flag("config.ru", Dir.pwd))
     end
 
+    def queue #:nodoc:
+      @queue ||= config.queue.new
+    end
+
     def to_app
       self
     end
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 37297f0496..a36dad0e98 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -11,7 +11,7 @@ module Rails
                     :force_ssl, :helpers_paths, :logger, :log_formatter, :log_tags, :preload_frameworks,
                     :railties_order, :relative_url_root, :secret_token,
                     :serve_static_assets, :ssl_options, :static_cache_control, :session_options,
-                    :time_zone, :reload_classes_only_on_change, :use_schema_cache_dump
+                    :time_zone, :reload_classes_only_on_change, :use_schema_cache_dump, :queue
 
       attr_writer :log_level
       attr_reader :encoding
@@ -43,6 +43,7 @@ module Rails
         @autoflush_log                 = true
         @log_formatter                 = ActiveSupport::Logger::SimpleFormatter.new
         @use_schema_cache_dump         = true
+        @queue                         = Queue
 
         @assets = ActiveSupport::OrderedOptions.new
         @assets.enabled                  = false
diff --git a/railties/lib/rails/application/finisher.rb b/railties/lib/rails/application/finisher.rb
index 002c6026e4..6475b381f4 100644
--- a/railties/lib/rails/application/finisher.rb
+++ b/railties/lib/rails/application/finisher.rb
@@ -93,6 +93,13 @@ module Rails
           ActiveSupport::Dependencies.unhook!
         end
       end
+
+      initializer :activate_queue_consumer do |app|
+        if config.queue == Queue
+          consumer = Rails::Queueing::ThreadedConsumer.start(app.queue)
+          at_exit { consumer.shutdown }
+        end
+      end
     end
   end
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
index eb4dfa7c89..c486ae590e 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
@@ -35,4 +35,7 @@
   # Expands the lines which load the assets.
   config.assets.debug = true
   <%- end -%>
+
+  # In development, use an in-memory queue for queueing
+  config.queue = Queue
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
index 1c980e5ce6..854e6e95cd 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt
@@ -76,4 +76,8 @@
 
   # Use default logging formatter so that PID and timestamp are not suppressed
   config.log_formatter = ::Logger::Formatter.new
+
+  # Default the production mode queue to an in-memory queue. You will probably
+  # want to replace this with an out-of-process queueing solution
+  config.queue = Queue
 end
diff --git a/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
index b725dd19f6..b27b88a3c6 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt
@@ -33,4 +33,7 @@
 
   # Print deprecation notices to the stderr.
   config.active_support.deprecation = :stderr
+
+  # Use the testing queue
+  config.queue = Rails::Queueing::TestQueue
 end
diff --git a/railties/lib/rails/queueing.rb b/railties/lib/rails/queueing.rb
new file mode 100644
index 0000000000..b77940f821
--- /dev/null
+++ b/railties/lib/rails/queueing.rb
@@ -0,0 +1,65 @@
+module Rails
+  module Queueing
+    # In test mode, the Rails queue is backed by an Array so that assertions
+    # can be made about its contents. The test queue provides a +contents+
+    # method to make assertions about the queue's contents and a +drain+
+    # method to drain the queue and run the jobs.
+    #
+    # Jobs are run in a separate thread to catch mistakes where code
+    # assumes that the job is run in the same thread.
+    class TestQueue
+      attr_reader :contents
+
+      def initialize
+        @contents = []
+      end
+
+      def drain
+        # run the jobs in a separate thread so assumptions of synchronous
+        # jobs are caught in test mode.
+        t = Thread.new do
+          while job = @contents.pop
+            job.run
+          end
+        end
+        t.join
+      end
+
+      # implement the Queue API
+      def push(object)
+        @contents << object
+      end
+    end
+
+    # The threaded consumer will run jobs in a background thread in
+    # development mode or in a VM where running jobs on a thread in
+    # production mode makes sense.
+    #
+    # When the process exits, the consumer pushes a nil onto the
+    # queue and joins the thread, which will ensure that all jobs
+    # are executed before the process finally dies.
+    class ThreadedConsumer
+      def self.start(queue)
+        new(queue).start
+      end
+
+      def initialize(queue)
+        @queue = queue
+      end
+
+      def start
+        @thread = Thread.new do
+          while job = @queue.pop
+            job.run
+          end
+        end
+        self
+      end
+
+      def shutdown
+        @queue.push nil
+        @thread.join
+      end
+    end
+  end
+end