deadlock.rb

class DeadlockRetry

DEADLOCK_ERROR_MESSAGES     = ["Deadlock found when trying to get lock", "Lock wait timeout exceeded"]
MAXIMUM_RETRIES_ON_DEADLOCK = 10

  class << self

    def deadlock_free(object, &block)
      retry_count = 0
      begin
        object.class.name.constantize.transaction do
#        raise ActiveRecord::StatementInvalid.new("Deadlock found when trying to get lock") 
          object.lock!
          block.call
        end
      rescue ActiveRecord::StatementInvalid => error
        if DEADLOCK_ERROR_MESSAGES.any? { |msg| error.message =~ /#{::Regexp.escape(msg)}/ }
          raise if retry_count >= MAXIMUM_RETRIES_ON_DEADLOCK
          # maybe some sleep in here ?
          retry_count += 1
          puts "Deadlock detected on retry #{retry_count}, restarting transaction"
          retry
        else
          raise
        end
      end
    end
  end
end