Added RDoc for each Active Job adapter

13 files changed, 187 insertions, 36 deletions

diff --git a/activejob/README.md b/activejob/README.md
index 5734ca413e..b5d27272b1 100644
--- a/activejob/README.md
+++ b/activejob/README.md
@@ -24,9 +24,9 @@ Set the queue adapter for Active Job:
 
 ``` ruby
 ActiveJob::Base.queue_adapter = :inline # default queue adapter
-# Adapters currently supported: :backburner, :delayed_job, :qu, :que, :queue_classic,
-#                               :resque, :sidekiq, :sneakers, :sucker_punch
 ```
+Note: To learn how to use your preferred queueing backend see its adapter
+documentation at ActiveJob::QueueAdapters.
 
 Declare a job like so:
 
@@ -88,18 +88,9 @@ by default has been mixed into Active Record classes.
 
 ## Supported queueing systems
 
-We currently have adapters for:
-
-* [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)
-* [QueueClassic](https://github.com/ryandotsmith/queue_classic)
-* [Resque 1.x](https://github.com/resque/resque)
-* [Sidekiq](https://github.com/mperham/sidekiq)
-* [Sneakers](https://github.com/jondot/sneakers)
-* [Sucker Punch](https://github.com/brandonhilkert/sucker_punch)
-
+Active Job has built-in adapters for multiple queueing backends (Sidekiq,
+Resque, Delayed Job and others). To get an up-to-date list of the adapters
+see the API Documentation for [ActiveJob::QueueAdapters](http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html).
 
 ## Auxiliary gems
 
diff --git a/activejob/lib/active_job/queue_adapters.rb b/activejob/lib/active_job/queue_adapters.rb
index 345b01ef00..e865c901ce 100644
--- a/activejob/lib/active_job/queue_adapters.rb
+++ b/activejob/lib/active_job/queue_adapters.rb
@@ -1,4 +1,38 @@
 module ActiveJob
+  # == Active Job adapters
+  #
+  # Active Job has adapters for the following queueing backends:
+  #
+  # * {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]
+  # * {QueueClassic 2.x}[https://github.com/ryandotsmith/queue_classic/tree/v2.2.3]
+  # * {Resque 1.x}[https://github.com/resque/resque/tree/1-x-stable]
+  # * {Sidekiq}[http://sidekiq.org]
+  # * {Sneakers}[https://github.com/jondot/sneakers]
+  # * {Sucker Punch}[https://github.com/brandonhilkert/sucker_punch]
+  #
+  # #### Backends Features
+  #
+  #   |                   | Async | Queues | Delayed   | Priorities | Timeout | Retries |
+  #   |-------------------|-------|--------|-----------|------------|---------|---------|
+  #   | Backburner        | Yes   | Yes    | Yes       | Yes        | Job     | Global  |
+  #   | Delayed Job       | Yes   | Yes    | Yes       | Job        | Global  | Global  |
+  #   | Que               | Yes   | Yes    | Yes       | Job        | No      | Job     |
+  #   | Queue Classic     | Yes   | Yes    | No*       | No         | No      | No      |
+  #   | Resque            | Yes   | Yes    | Yes (Gem) | Queue      | Global  | Yes     |
+  #   | Sidekiq           | Yes   | Yes    | Yes       | Queue      | No      | Job     |
+  #   | Sneakers          | Yes   | Yes    | No        | Queue      | Queue   | No      |
+  #   | Sucker Punch      | Yes   | Yes    | No        | No         | No      | No      |
+  #   | Active Job Inline | No    | Yes    | N/A       | N/A        | N/A     | N/A     |
+  #   | Active Job        | Yes   | Yes    | Yes       | No         | No      | No      |
+  #
+  # NOTE:
+  # Queue Classic does not support Job scheduling. However you can implement this
+  # yourself or you can use the queue_classic-later gem. See the documentation for
+  # ActiveJob::QueueAdapters::QueueClassicAdapter.
+  #
   module QueueAdapters
     extend ActiveSupport::Autoload
 
diff --git a/activejob/lib/active_job/queue_adapters/backburner_adapter.rb b/activejob/lib/active_job/queue_adapters/backburner_adapter.rb
index a07a6fc223..2453d065de 100644
--- a/activejob/lib/active_job/queue_adapters/backburner_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/backburner_adapter.rb
@@ -2,13 +2,23 @@ require 'backburner'
 
 module ActiveJob
   module QueueAdapters
+    # == Backburner adapter for Active Job
+    #
+    # Backburner is a beanstalkd-powered job queue that can handle a very
+    # high volume of jobs. You create background jobs and place them on
+    # multiple work queues to be processed later. Read more about
+    # Backburner {here}[https://github.com/nesquena/backburner].
+    #
+    # To use Backburner set the queue_adapter config to +:backburner+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :backburner
     class BackburnerAdapter
       class << self
-        def enqueue(job)
+        def enqueue(job) #:nodoc:
           Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name
         end
 
-        def enqueue_at(job, timestamp)
+        def enqueue_at(job, timestamp) #:nodoc:
           delay = timestamp - Time.current.to_f
           Backburner::Worker.enqueue JobWrapper, [ job.serialize ], queue: job.queue_name, delay: delay
         end
diff --git a/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb b/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb
index 30c535f3b4..370a1fc01f 100644
--- a/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/delayed_job_adapter.rb
@@ -2,13 +2,23 @@ require 'delayed_job'
 
 module ActiveJob
   module QueueAdapters
+    # == Delayed Job adapter for Active Job
+    #
+    # Delayed::Job (or DJ) encapsulates the common pattern of asynchronously
+    # executing longer tasks in the background. Although DJ can have many
+    # storage backends one of the most used is based on Active Record.
+    # Read more about Delayed Job {here}[https://github.com/collectiveidea/delayed_job].
+    #
+    # To use Delayed Job set the queue_adapter config to +:delayed_job+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :delayed_job
     class DelayedJobAdapter
       class << self
-        def enqueue(job)
+        def enqueue(job) #:nodoc:
           JobWrapper.new.delay(queue: job.queue_name).perform(job.serialize)
         end
 
-        def enqueue_at(job, timestamp)
+        def enqueue_at(job, timestamp) #:nodoc:
           JobWrapper.new.delay(queue: job.queue_name, run_at: Time.at(timestamp)).perform(job.serialize)
         end
       end
diff --git a/activejob/lib/active_job/queue_adapters/inline_adapter.rb b/activejob/lib/active_job/queue_adapters/inline_adapter.rb
index fdefa38d5e..e498454909 100644
--- a/activejob/lib/active_job/queue_adapters/inline_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/inline_adapter.rb
@@ -1,12 +1,20 @@
 module ActiveJob
   module QueueAdapters
+    # == Active Job Inline adapter
+    #
+    # When enqueueing jobs with the Inline adapter the job will be executed
+    # immediately.
+    #
+    # To use the Inline set the queue_adapter config to +:inline+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :inline
     class InlineAdapter
       class << self
-        def enqueue(job)
+        def enqueue(job) #:nodoc:
           Base.execute(job.serialize)
         end
 
-        def enqueue_at(*)
+        def enqueue_at(*) #:nodoc:
           raise NotImplementedError.new("Use a queueing backend to enqueue jobs in the future. Read more at https://github.com/rails/activejob")
         end
       end
diff --git a/activejob/lib/active_job/queue_adapters/qu_adapter.rb b/activejob/lib/active_job/queue_adapters/qu_adapter.rb
index 5485f20689..7cdefefc02 100644
--- a/activejob/lib/active_job/queue_adapters/qu_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/qu_adapter.rb
@@ -2,15 +2,28 @@ 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 that we experienced.
+    # The advantages of Qu are: Multiple backends (redis, mongo), jobs are
+    # requeued when worker is killed, resque-like API.
+    #
+    # Read more about Que {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
       class << self
-        def enqueue(job, *args)
+        def enqueue(job, *args) #:nodoc:
           Qu::Payload.new(klass: JobWrapper, args: [job.serialize]).tap do |payload|
             payload.instance_variable_set(:@queue, job.queue_name)
           end.push
         end
 
-        def enqueue_at(job, timestamp, *args)
+        def enqueue_at(job, timestamp, *args) #:nodoc:
           raise NotImplementedError
         end
       end
diff --git a/activejob/lib/active_job/queue_adapters/que_adapter.rb b/activejob/lib/active_job/queue_adapters/que_adapter.rb
index 2e8a64aa87..e501fe0368 100644
--- a/activejob/lib/active_job/queue_adapters/que_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/que_adapter.rb
@@ -2,13 +2,25 @@ require 'que'
 
 module ActiveJob
   module QueueAdapters
+    # == Que adapter for Active Job
+    #
+    # Que is a high-performance alternative to DelayedJob or QueueClassic that
+    # improves the reliability of your application by protecting your jobs with
+    # the same ACID guarantees as the rest of your data. Que is a queue for
+    # Ruby and PostgreSQL that manages jobs using advisory locks.
+    #
+    # Read more about Que {here}[https://github.com/chanks/que].
+    #
+    # To use Que set the queue_adapter config to +:que+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :que
     class QueAdapter
       class << self
-        def enqueue(job)
+        def enqueue(job) #:nodoc:
           JobWrapper.enqueue job.serialize, queue: job.queue_name
         end
 
-        def enqueue_at(job, timestamp)
+        def enqueue_at(job, timestamp) #:nodoc:
           JobWrapper.enqueue job.serialize, queue: job.queue_name, run_at: Time.at(timestamp)
         end
       end
diff --git a/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb b/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb
index e8452938b8..bde20e037e 100644
--- a/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/queue_classic_adapter.rb
@@ -2,13 +2,27 @@ require 'queue_classic'
 
 module ActiveJob
   module QueueAdapters
+    # == Queue Classic adapter for Active Job
+    #
+    # queue_classic provides a simple interface to a PostgreSQL-backed message
+    # queue. queue_classic specializes in concurrent locking and minimizing
+    # database load while providing a simple, intuitive developer experience.
+    # queue_classic assumes that you are already using PostgreSQL in your
+    # production environment and that adding another dependency (e.g. redis,
+    # beanstalkd, 0mq) is undesirable.
+    #
+    # Read more about Queue Classic {here}[https://github.com/ryandotsmith/queue_classic].
+    #
+    # To use Queue Classic set the queue_adapter config to +:queue_classic+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :queue_classic
     class QueueClassicAdapter
       class << self
-        def enqueue(job)
+        def enqueue(job) #:nodoc:
           build_queue(job.queue_name).enqueue("#{JobWrapper.name}.perform", job.serialize)
         end
 
-        def enqueue_at(job, timestamp)
+        def enqueue_at(job, timestamp) #:nodoc:
           queue = build_queue(job.queue_name)
           unless queue.respond_to?(:enqueue_at)
             raise NotImplementedError, 'To be able to schedule jobs with Queue Classic ' \
diff --git a/activejob/lib/active_job/queue_adapters/resque_adapter.rb b/activejob/lib/active_job/queue_adapters/resque_adapter.rb
index b1bc2f15ee..88c6b48fef 100644
--- a/activejob/lib/active_job/queue_adapters/resque_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/resque_adapter.rb
@@ -14,13 +14,24 @@ end
 
 module ActiveJob
   module QueueAdapters
+    # == Resque adapter for Active Job
+    #
+    # Resque (pronounced like "rescue") is a Redis-backed library for creating
+    # background jobs, placing those jobs on multiple queues, and processing
+    # them later.
+    #
+    # Read more about Resque {here}[https://github.com/resque/resque].
+    #
+    # To use Resque set the queue_adapter config to +:resque+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :resque
     class ResqueAdapter
       class << self
-        def enqueue(job)
+        def enqueue(job) #:nodoc:
           Resque.enqueue_to job.queue_name, JobWrapper, job.serialize
         end
 
-        def enqueue_at(job, timestamp)
+        def enqueue_at(job, timestamp) #:nodoc:
           unless Resque.respond_to?(:enqueue_at_with_queue)
             raise NotImplementedError, "To be able to schedule jobs with Resque you need the " \
               "resque-scheduler gem. Please add it to your Gemfile and run bundle install"
diff --git a/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb b/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb
index 6d351172de..74655cf0ca 100644
--- a/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/sidekiq_adapter.rb
@@ -2,9 +2,21 @@ require 'sidekiq'
 
 module ActiveJob
   module QueueAdapters
+    # == Sidekiq adapter for Active Job
+    #
+    # Simple, efficient background processing for Ruby. Sidekiq uses threads to
+    # handle many jobs at the same time in the same process. It does not
+    # require Rails but will integrate tightly with Rails 3/4 to make
+    # background processing dead simple.
+    #
+    # Read more about Sidekiq {here}[http://sidekiq.org].
+    #
+    # To use Sidekiq set the queue_adapter config to +:sidekiq+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :sidekiq
     class SidekiqAdapter
       class << self
-        def enqueue(job)
+        def enqueue(job) #:nodoc:
           #Sidekiq::Client does not support symbols as keys
           Sidekiq::Client.push \
             'class' => JobWrapper,
@@ -13,7 +25,7 @@ module ActiveJob
             'retry' => true
         end
 
-        def enqueue_at(job, timestamp)
+        def enqueue_at(job, timestamp) #:nodoc:
           Sidekiq::Client.push \
             'class' => JobWrapper,
             'queue' => job.queue_name,
diff --git a/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb b/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb
index 91658e08f0..6d60a2f303 100644
--- a/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/sneakers_adapter.rb
@@ -3,18 +3,30 @@ require 'thread'
 
 module ActiveJob
   module QueueAdapters
+    # == Sneakers adapter for Active Job
+    #
+    # A high-performance RabbitMQ background processing framework for Ruby.
+    # Sneakers is being used in production for both I/O and CPU intensive
+    # workloads, and have achieved the goals of high-performance and
+    # 0-maintenance, as designed.
+    #
+    # Read more about Sneakers {here}[https://github.com/jondot/sneakers].
+    #
+    # To use Sneakers set the queue_adapter config to +:sneakers+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :sneakers
     class SneakersAdapter
       @monitor = Monitor.new
 
       class << self
-        def enqueue(job)
+        def enqueue(job) #:nodoc:
           @monitor.synchronize do
             JobWrapper.from_queue job.queue_name
             JobWrapper.enqueue ActiveSupport::JSON.encode(job.serialize)
           end
         end
 
-        def enqueue_at(job, timestamp)
+        def enqueue_at(job, timestamp) #:nodoc:
           raise NotImplementedError
         end
       end
diff --git a/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb b/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb
index 68aa58cadb..be9e7fd03a 100644
--- a/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb
@@ -2,13 +2,28 @@ require 'sucker_punch'
 
 module ActiveJob
   module QueueAdapters
+    # == Sucker Punch adapter for Active Job
+    #
+    # Sucker Punch is a single-process Ruby asynchronous processing library.
+    # It's girl_friday and DSL sugar on top of Celluloid. With Celluloid's
+    # actor pattern, we can do asynchronous processing within a single process.
+    # This reduces costs of hosting on a service like Heroku along with the
+    # memory footprint of having to maintain additional jobs if hosting on
+    # a dedicated server. All queues can run within a single Rails/Sinatra
+    # process.
+    #
+    # Read more about Sucker Punch {here}[https://github.com/brandonhilkert/sucker_punch].
+    #
+    # To use Sucker Punch set the queue_adapter config to +:sucker_punch+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :sucker_punch
     class SuckerPunchAdapter
       class << self
-        def enqueue(job)
+        def enqueue(job) #:nodoc:
           JobWrapper.new.async.perform job.serialize
         end
 
-        def enqueue_at(job, timestamp)
+        def enqueue_at(job, timestamp) #:nodoc:
           raise NotImplementedError
         end
       end
diff --git a/activejob/lib/active_job/queue_adapters/test_adapter.rb b/activejob/lib/active_job/queue_adapters/test_adapter.rb
index 12ef72310d..e4fdf60008 100644
--- a/activejob/lib/active_job/queue_adapters/test_adapter.rb
+++ b/activejob/lib/active_job/queue_adapters/test_adapter.rb
@@ -1,5 +1,14 @@
 module ActiveJob
   module QueueAdapters
+    # == Test adapter for Active Job
+    #
+    # The test adapter should be used only in testing. Along with
+    # <tt>ActiveJob::TestCase</tt> and <tt>ActiveJob::TestHelper</tt>
+    # it makes a great tool to test your Rails application.
+    #
+    # To use the test adapter set queue_adapter config to +:test+.
+    #
+    #   Rails.application.config.active_job.queue_adapter = :test
     class TestAdapter
       delegate :name, to: :class
       attr_accessor(:perform_enqueued_jobs, :perform_enqueued_at_jobs)
@@ -15,7 +24,7 @@ module ActiveJob
         @performed_jobs ||= []
       end
 
-      def enqueue(job)
+      def enqueue(job) #:nodoc:
         if perform_enqueued_jobs
           performed_jobs << {job: job.class, args: job.arguments, queue: job.queue_name}
           job.perform_now
@@ -24,7 +33,7 @@ module ActiveJob
         end
       end
 
-      def enqueue_at(job, timestamp)
+      def enqueue_at(job, timestamp) #:nodoc:
         if perform_enqueued_at_jobs
           performed_jobs << {job: job.class, args: job.arguments, queue: job.queue_name, at: timestamp}
           job.perform_now