Eventmachine talk - May 2007 - Redefining receive_data using define_method

Hi,
In a vanilla ruby class and module I can define and redefine an
instance method using define_method.

However in EventMachine the redefinition does not ''take'' _and_
no
exception is thrown.  I am ''run''ing EventMachine in a thread,
and this
might have side effects?

Specifically:
 - I define receive_data  at the end of post_init
 - I redefine receive_data at the end of connection_completed

I only see the first definition ''at work''

Should this be possible with EventMachine?  Can anyone hint at a work around?
I include a working example below

Regards
Mark

require ''thread''
require ''rubygems''
require ''eventmachine''

class EchoServer < EventMachine::Connection
   def post_init
     puts "Received a new connection"
     @data_received = ""
     @line_count = 0
     self.class.send(:define_method, "receive_data" ){ |data|
                        receive_handshake_data( data ) }
  end

  def connection_completed
    puts "connection completed... #{self.class.name}"
#   EchoServer.remove_method( :receive_data )
   self.class.send(:define_method, "receive_data" ){ |data|
                        receive_regular_data( data ) }
  end

  def receive_handshake_data( data )
    puts ''receive_data for connection handshake data.''
    send_data ">> #{data}"
    puts "The server received: #{data} \nThen the server sent: >>
#{data}"
    close_connection if data =~ /quit/i
  end

  def receive_regular_data( data )
    puts ''receive_data for regular data.''
    send_data ">> #{data}"
    puts "The server received: #{data} \nThen the server sent: >>
#{data}"
    close_connection if data =~ /quit/i
  end

end

class Echo < EventMachine::Connection

  @@conn_list = []

  def self.print_connections
   @@conn_list.each {|conn|
        puts conn.inspect
        }
  end

  def initialize *args
    super
    @@conn_list << self
  end

  def post_init
    # your normal processing
  end
  def connection_completed
    puts "connection completed... #{self.class.name}"
  end
  def receive_data data
    # your normal processing
    puts "The client received: #{data}"
    # puts Echo.print_connections
  end

  def client_send_data data
    puts "The client is sending: #{data}"
    send_data data
  end

  def unbind
    @@conn_list.delete self
  end

end

host,port = "192.168.1.1", 8090
Thread.abort_on_exception = true

begin
    @my_em_run_thread = Thread.new do
          EventMachine::run {
                Thread.current[:server] = EventMachine::start_server
host, port, EchoServer
                puts "Now accepting connections on address #{host},
port #{port}..."
                Thread.current[:client_1] = EventMachine::connect
host, port, Echo
                Thread.current[:client_2] = EventMachine::connect
host, port, Echo
                Thread.current[:client_3] = EventMachine::connect
host, port, Echo
                Thread.current[:client_4] = EventMachine::connect
host, port, Echo
#                EventMachine::add_periodic_timer( 10 ) {
#                            $stderr.write "*...\n"
#                            Echo.print_connections
#                            }
         } # EventMachine::run
    end # Thread.new
rescue => err

  puts err

end # begin

#
# Using one connection
#
puts @my_em_run_thread.status
@my_em_run_thread[:client_1].client_send_data "On client_1 connection,
we should see this text... first \n"
@my_em_run_thread[:client_1].client_send_data "On client_1 connection,
we should see this text... second \n"

sleep(1)
@my_em_run_thread[:client_1].client_send_data "On client_1 connection,
we should see this text... third \n"

sleep(1)
@my_em_run_thread[:client_1].client_send_data "On client_1 connection,
we should see this text... last! \n"

#
# Using all connections
#
@my_em_run_thread[:client_4].client_send_data "On client_4 connection,
we _should_ see this text... out of order \n"
@my_em_run_thread[:client_3].client_send_data "On client_3 connection,
we _should_ see this text... out of order \n"

sleep(1)
@my_em_run_thread[:client_2].client_send_data "On client_2 connection,
we should see this text... third \n"

sleep(1)
@my_em_run_thread[:client_1].client_send_data "On client_1 connection,
we should see this text... last! \n"

puts @my_em_run_thread.status

On 5/11/07, Mark Van De Vyver <mvyver at gmail.com>
wrote:
>
> Hi,
> In a vanilla ruby class and module I can define and redefine an
> instance method using define_method.
>
> However in EventMachine the redefinition does not ''take''
_and_ no
> exception is thrown.  I am ''run''ing EventMachine in a
thread, and this
> might have side effects?
>
> Specifically:
> - I define receive_data  at the end of post_init
> - I redefine receive_data at the end of connection_completed
>
> I only see the first definition ''at work''
>
> Should this be possible with EventMachine?  Can anyone hint at a work
> around?
> I include a working example below
>
> Regards
> Mark


I didn''t take the time to read your code in great detail but it appears
that
you''re trying to do the method redefinition in connection_completed.
However, this event is NOT delivered to TCP servers, only to TCP clients.
Does this shed any light on your problem? If so, then write back here and
I''ll explain the semantics of connection_completed if they are not
clear.
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