Reconnect to Mysql 2 when server goes away

connection_fix.rb

# If your workers are inactive for a long period of time, they'll lose
# their MySQL connection.
#
# This hack ensures we re-connect whenever a connection is
# lost. Because, really. why not?
#
# Stick this in RAILS_ROOT/config/initializers/connection_fix.rb (or somewhere similar)
#
# Adapted from:
#   http://coderrr.wordpress.com/2009/01/08/activerecord-threading-issues-and-resolutions/
#
# The original version will retry the query. This does not do that. It simply reconnects 
# and throws the exception. This is more robust in case the connection is lost in the middle 
# of a transaction. This article explains the reason well: 
#   http://mysqlblog.fivefarmers.com/2010/07/05/do-you-really-want-autoreconnect-to-silently-reconnect/

module ActiveRecord::ConnectionAdapters
  class Mysql2Adapter
    alias_method :execute_without_retry, :execute

    def execute(*args)
      execute_without_retry(*args)
    rescue ActiveRecord::StatementInvalid => e
      if e.message =~ /server has gone away/i
        warn 'Server timed out, retrying'
        reconnect!
      end
      raise e
    end
  end
end