sql timeout

sql timeout

# ActiveRecord::Base.connection.timeout(20, []) do |connection|
#    worrisome sql
# end

module ActiveRecord
  class TimeoutError < ActiveRecordError    
    def initialize(message = nil)
      super(message)
    end
  end
  
  class ConnectionAdapters::MysqlAdapter
    # the on_fail parameter gets returned if the sql times out
    def timeout(time, on_fail = nil, &block)
      old_timeout = @config[:read_timeout]
      @config[:read_timeout] = (time / 3.0).ceil # read_timeout setting seems to be multiples of 3
      reconnect!
      connection_id = execute("select connection_id()").fetch_row.first
      begin 
        yield self
      rescue ActiveRecord::StatementInvalid
        if old_timeout
          @config[:read_timeout] = old_timeout
        else
          @config.delete(:read_timeout)
        end
        reconnect!
        execute("kill #{connection_id}")
        if on_fail
          return on_fail
        else
          raise TimeoutError
        end
      end
    end
  end
end