Added delayed_job as new background queue manager.

db/migrate/20120824114234_create_delayed_jobs.rb

@@ -0,0 +1,22 @@
+class CreateDelayedJobs < ActiveRecord::Migration
+  def self.up
+    create_table :delayed_jobs, :force => true do |table|
+      table.integer  :priority, :default => 0      # Allows some jobs to jump to the front of the queue
+      table.integer  :attempts, :default => 0      # Provides for retries, but still fail eventually.
+      table.text     :handler                      # YAML-encoded string of the object that will do work
+      table.text     :last_error                   # reason for last failure (See Note below)
+      table.datetime :run_at                       # When to run. Could be Time.zone.now for immediately, or sometime in the future.
+      table.datetime :locked_at                    # Set when a client is working on this object
+      table.datetime :failed_at                    # Set when all retries have failed (actually, by default, the record is deleted instead)
+      table.string   :locked_by                    # Who is working on this object (if locked)
+      table.string   :queue                        # The name of the queue this job is in
+      table.timestamps
+    end
+
+    add_index :delayed_jobs, [:priority, :run_at], :name => 'delayed_jobs_priority'
+  end
+
+  def self.down
+    drop_table :delayed_jobs
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20120622094337) do
+ActiveRecord::Schema.define(:version => 20120824114234) do
 
   create_table "article_categories", :force => true do |t|
     t.string "name",        :default => "", :null => false
@@ -78,6 +78,22 @@ ActiveRecord::Schema.define(:version => 20120622094337) do
 
   add_index "configurable_settings", ["name"], :name => "index_configurable_settings_on_name"
 
+  create_table "delayed_jobs", :force => true do |t|
+    t.integer  "priority",   :default => 0
+    t.integer  "attempts",   :default => 0
+    t.text     "handler"
+    t.text     "last_error"
+    t.datetime "run_at"
+    t.datetime "locked_at"
+    t.datetime "failed_at"
+    t.string   "locked_by"
+    t.string   "queue"
+    t.datetime "created_at"
+    t.datetime "updated_at"
+  end
+
+  add_index "delayed_jobs", ["priority", "run_at"], :name => "delayed_jobs_priority"
+
   create_table "deliveries", :force => true do |t|
     t.integer  "supplier_id"
     t.date     "delivered_on"