module ActiveRecord::Locking::Optimistic::ClassMethods

def column_defaults 

def column_defaults
  @column_defaults ||= begin
    defaults = super
    if defaults.key?(locking_column) && lock_optimistically
      defaults[locking_column] ||= 0
    end
    defaults
  end
end

def locking_column

The version column used for optimistic locking. Defaults to +lock_version+. 
def locking_column
  reset_locking_column unless defined?(@locking_column)
  @locking_column
end

def locking_column=(value)

Set the column to use for optimistic locking. Defaults to +lock_version+. 
def locking_column=(value)
  @locking_column = value.to_s
end

def locking_enabled?

+locking_column+ column (defaults to +lock_version+).
(which it is, by default) and the table includes the
Returns true if the +lock_optimistically+ flag is set to true 
def locking_enabled?
  lock_optimistically && columns_hash[locking_column]
end

def quoted_locking_column

Quote the column name used for optimistic locking. 
def quoted_locking_column
  connection.quote_column_name(locking_column)
end

def reset_locking_column

Reset the column used for optimistic locking back to the +lock_version+ default. 
def reset_locking_column
  self.locking_column = DEFAULT_LOCKING_COLUMN
end

def update_counters(id, counters)

updated.
Make sure the lock version column gets updated when counters are 
def update_counters(id, counters)
  counters = counters.merge(locking_column => 1) if locking_enabled?
  super
end