Eventmachine talk - May 2007 - send_data using multiple connections from

Hi,
To understand EM a little better I''ve merged a couple of examples. One
from Francis (the conn_list) and the other from Eloy Duran (the
threading idea)
I''m interested in being able to create several connections, and
sending/receiving data on them.  I''d also appreciate any tips on a
better way to achieve the same effect.

If I comment out the Thread related code (including the very last
command) things seem to run, in that I see:

*...
Now accepting connections on address 192.168.1.1, port 8090...
Received a new connection
connection completed... Echo
[#<Echo:0xb792888c
@signature="1ba0acb0aa0debe146bf4a2f566ef6183">]
*...
[#<Echo:0xb792888c
@signature="1ba0acb0aa0debe146bf4a2f566ef6183">]

Hoverver, if I run the code as it is below, I see:

Now accepting connections on address 192.168.1.1, port 8090...
The client is sending: We should see this text...


The problem seems to be related to the use of threads.  There are no
exceptions thrown, and it seems that client and server instances are
not created.

I appreciate if anyone can point out where I have gone wrong.

Thanks in advance
Mark

# Example code below

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

module EchoServer
   def post_init
     puts "Received a new connection"
     @data_received = ""
     @line_count = 0
   end

  def receive_data data
    send_data ">> #{data}"
    puts "The server received: #{data} \nThen sent: >> #{data}"
    close_connection if data =~ /quit/i
  end
end

class Echo < EventMachine::Connection

  @@conn_list = []

  def self.print_connections
    p @@conn_list
  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 self.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

begin
    @my_conn_threads = Thread.new do
          t = Thread.current
          host,port = "192.168.1.1", 8090
          EventMachine::run {
          t[:server] = EventMachine::start_server host, port, EchoServer
          puts "Now accepting connections on address #{host}, port
#{port}..."
          t[:client] = EventMachine::connect host, port, Echo
          EventMachine::add_periodic_timer( 2 ) {
                      $stderr.write "*...\n"
                      Echo.print_connections
                      }
          }
      end
rescue => err

  puts err

end

@my_conn_threads[:client].client_send_data "We should see this text...
\n"

Hi,
I have managed to get this example working,,, !
I''m going to top post since this replaces my earlier email.

There was one gotcha that I really don''t understand the reason for:

In the Echo#receive_data( data ) method, the line:
   puts self.print_connections
should be
   puts Echo.print_connections

If you examine the output carefully you''ll notice a
''nil'' is printed
to the screen after the connections list is printed.....
I have no idea where that is coming from, and it quite possibly is a
symptom of a serious or trivial problem - use at your own risk :)

Apart from that the code of Francis and Eloy is pretty much as is.

I hope this helps someone else understand/appreciate how great the
work of the EventMachine developers is!

Thanks again
Mark


#!/usr/bin/ruby
require ''thread''
require ''rubygems''
require ''eventmachine''

module EchoServer
   def post_init
     puts "Received a new connection"
     @data_received = ""
     @line_count = 0
   end

  def receive_data 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
    p @@conn_list
  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

@my_em_run_thread.join # Force a wait here indefinitely


On 5/9/07, Mark Van De Vyver <mvyver at gmail.com>
wrote:
> Hi,
> To understand EM a little better I''ve merged a couple of examples.
One
> from Francis (the conn_list) and the other from Eloy Duran (the
> threading idea)
> I''m interested in being able to create several connections, and
> sending/receiving data on them.  I''d also appreciate any tips on a
> better way to achieve the same effect.
>
> If I comment out the Thread related code (including the very last
> command) things seem to run, in that I see:
>
> *...
> Now accepting connections on address 192.168.1.1, port 8090...
> Received a new connection
> connection completed... Echo
> [#<Echo:0xb792888c
@signature="1ba0acb0aa0debe146bf4a2f566ef6183">]
> *...
> [#<Echo:0xb792888c
@signature="1ba0acb0aa0debe146bf4a2f566ef6183">]
>
> Hoverver, if I run the code as it is below, I see:
>
> Now accepting connections on address 192.168.1.1, port 8090...
> The client is sending: We should see this text...
>
>
> The problem seems to be related to the use of threads.  There are no
> exceptions thrown, and it seems that client and server instances are
> not created.
>
> I appreciate if anyone can point out where I have gone wrong.
>
> Thanks in advance
> Mark
>
> # Example code below
>
> require ''rubygems''
> require ''eventmachine''
>
> module EchoServer
>    def post_init
>      puts "Received a new connection"
>      @data_received = ""
>      @line_count = 0
>    end
>
>   def receive_data data
>     send_data ">> #{data}"
>     puts "The server received: #{data} \nThen sent: >>
#{data}"
>     close_connection if data =~ /quit/i
>   end
> end
>
> class Echo < EventMachine::Connection
>
>   @@conn_list = []
>
>   def self.print_connections
>     p @@conn_list
>   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 self.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
>
> begin
>     @my_conn_threads = Thread.new do
>           t = Thread.current
>           host,port = "192.168.1.1", 8090
>           EventMachine::run {
>           t[:server] = EventMachine::start_server host, port, EchoServer
>           puts "Now accepting connections on address #{host}, port
#{port}..."
>           t[:client] = EventMachine::connect host, port, Echo
>           EventMachine::add_periodic_timer( 2 ) {
>                       $stderr.write "*...\n"
>                       Echo.print_connections
>                       }
>           }
>       end
> rescue => err
>
>   puts err
>
> end
>
> @my_conn_threads[:client].client_send_data "We should see this text...
\n"
>