gistfile1.rb

module Lock
  extend self
  delegate :connection, :to => ActiveRecord::Base

  def sync(*args)
    lock = Zlib.crc32 args.join
    obtain lock
    yield
  ensure
    release lock
  end

  private

  def obtain(key)
    connection.execute "SELECT pg_advisory_lock(#{key})"
  end

  def release(key)
    connection.execute "SELECT pg_advisory_unlock(#{key})"
  end
end