Wrap mysql2 deadlocks in an ActiveRecord exception

gistfile1.rb

# This core extension aims to manage Deadlocks
# with a proper ActiveRecord exception.
#
# It only works for mysql2
#
# Example:
# 
# MyModel.transaction do
#   begin
#     record1 = MyModel.find(:id, lock: true)
#     record2 = MyModel.find(:id2, lock: true)
#   rescue ActiveRecord::Deadlock => e
#     retry
#   end
# end
#
# Author: Bastien Gysler <www.bastiengysler.com>
module ActiveRecord
  class Deadlock < WrappedDatabaseException
  end
 
  module ConnectionAdapters
    class Mysql2Adapter < AbstractMysqlAdapter
 
      alias :core_translate_exception :translate_exception
      def translate_exception(exception, message)
        if (message =~ /Deadlock/)
          Deadlock.new(message, exception)
        else
          core_translate_exception(exception, message)
        end
      end
    end
  end
end

What exactly was the usecase? You needed to catch a Deadlock in your application code? Can you write an executable test-case to reproduce the behavior: https://github.com/rails/rails/blob/master/guides/bug_report_templates/active_record_master.rb ?

Yes I need to catch deadlocks. Do you want a test that cause a deadlock?

@basgys yea. If we introduce such an exception we should see if we can get it working with other db adapters.