add lock_version to context module progressions

preparation for rework of the context module progression evaluation

test plan:
 * automated tests pass

refs CNVS-11818

Change-Id: I10618e576c7b44aebce0a9803876b8f543d9b61b
Reviewed-on: https://gerrit.instructure.com/32904
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Matt Fairbourn <mfairbourn@instructure.com>
Product-Review: Mark Severson <markse@instructure.com>

app/models/context_module_progression.rb

@@ -274,6 +274,12 @@ class ContextModuleProgression < ActiveRecord::Base
     end
   end
 
+  # This prevents active record using optimistic locking, until the data migration is complete
+  # (once the data migration is complete, this method can simply be removed)
+  def locking_enabled?
+    false
+  end
+
   def trigger_completion_events
     if workflow_state_changed? && completed?
       context_module.completion_event_callbacks.each do |event|

db/migrate/20140314220629_add_lock_version_on_context_module_progressions.rb

@@ -0,0 +1,12 @@
+class AddLockVersionOnContextModuleProgressions < ActiveRecord::Migration
+  tag :predeploy
+
+  def self.up
+    add_column :context_module_progressions, :lock_version, :integer
+    change_column_default :context_module_progressions, :lock_version, 0
+  end
+
+  def self.down
+    remove_column :context_module_progressions, :lock_version
+  end
+end

db/migrate/20140314220630_populate_lock_version_on_context_module_progressions.rb

@@ -0,0 +1,7 @@
+class PopulateLockVersionOnContextModuleProgressions < ActiveRecord::Migration
+  tag :postdeploy
+
+  def up
+    DataFixup::PopulateLockVersionOnContextModuleProgressions.send_later_if_production_enqueue_args(:run, :priority => Delayed::LOW_PRIORITY, :max_attempts => 1)
+  end
+end

lib/data_fixup/populate_lock_version_on_context_module_progressions.rb

@@ -0,0 +1,7 @@
+module DataFixup::PopulateLockVersionOnContextModuleProgressions
+  def self.run
+    ContextModuleProgression.where(lock_version: nil).find_ids_in_ranges do |min_id, max_id|
+      ContextModuleProgression.where(id: min_id..max_id, lock_version: nil).update_all(lock_version: 0)
+    end
+  end
+end