Rails - Mar 2012 - Not sure about event machine workings

I found this example of using faye for a chatroom type app as I am
trying to get a feel for push servers:

http://net.tutsplus.com/tutorials/ruby/how-to-use-faye-as-a-real-time-push-server-in-rails/

 I got some of that to work, although multiuser from the same browser
doesn''t exactly make sense.
I then tried to look into a server side client. I am using a windows
laptop for everything.

I have the following code below which publishes a message to the
chatroom fine, but it never really exits.
The last statement "puts ''end''" is never reached. If
I put EM.stop or
an exit statement inside the event machine block, then the messages
don''t make it to the chat room.

 The other thin I noticed is if I have a loop that puts say 5 messages
to the chat room, but sleeps for several seconds between each. They
don''t show up until they have all been published. It''s like it
needs
to reach the bottom of the block, but once there it never exits the
block.



require ''eventmachine''

require ''faye''



client = Faye::Client.new(''http://localhost:9292/faye'')

EM.run {

  client.subscribe(''/messages/public'') do |message|
    puts message.inspect
  end


  client.publish(''/messages/public'',
''username'' => ''Joe'',
                   ''msg'' => "hey there again")

}

puts ''end''

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When you enter a eventmachine block it never return control to your app.
You have to turn it on but dont stay inside the evented block.

Use this method before initializing comunication to faye

def self.ensure_reactor_running
        Thread.new { EM.run } unless EM.reactor_running?
        sleep 0.1 until EM.reactor_running?
  end

this will start eventmachine in a thread that is not the one your rails app
is running if not already running.

Just call

ensure_reactor_running

before subscribing

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Your post has been very helpful, I tried something like what you
posted, but it didn''t
quite make sense to me.

 If you look at what I have currently below, I have to have this
sleep(30) at the bottom which is not optimal.
a join on the thread doesn''t work.

 I also tried run_block() instead of run() with no luck.

 I guess if I do everything inside of a EM that doesn''t take too long,
it wouldn''t matter, but I am trying to get an idea of
how this sort of thing should work

#########################


require ''eventmachine''

require ''faye''



client = Faye::Client.new(''http://localhost:9292/faye'')

thr = nil

if !EM.reactor_running?
    thr = Thread.new do
      EM.run do

        puts ''in ev machine''
        client.subscribe(''/messages/public'') do |message|
          puts message.inspect
        end

        puts ''1''

        client.publish(''/messages/public'',
''username'' => ''Joe'',
                      ''msg'' => "hey there
againzoggle")
        sleep 10
        puts ''2''

        client.publish(''/messages/public'',
''username'' => ''Joe'',
                      ''msg'' => "hey there again")
        puts ''end of ev machine block''
      end
    end

  end

puts ''wait for running''
sleep 0.1 until EM.reactor_running?

sleep 30

puts ''end of client''

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On Thu, Mar 29, 2012 at 7:28 PM,
wbsurfver-/E1597aS9LQAvxtiuMwx3w@public.gmane.org
<wbsurfver-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>wrote:
> Your post has been very helpful, I tried something like what you
> posted, but it didn''t
> quite make sense to me.
>
>  If you look at what I have currently below, I have to have this
> sleep(30) at the bottom which is not optimal.
> a join on the thread doesn''t work.
>
>  I also tried run_block() instead of run() with no luck.
>
>  I guess if I do everything inside of a EM that doesn''t take too
long,
> it wouldn''t matter, but I am trying to get an idea of
> how this sort of thing should work
>
> #########################
>
>
> require ''eventmachine''
>
> require ''faye''
>
>
>
> client = Faye::Client.new(''http://localhost:9292/faye'')
>
> thr = nil
>
> if !EM.reactor_running?
>    thr = Thread.new do
>      EM.run do
>
>        puts ''in ev machine''
>         client.subscribe(''/messages/public'') do |message|
>          puts message.inspect
>        end
>
>         puts ''1''
>
>        client.publish(''/messages/public'',
''username'' => ''Joe'',
>                       ''msg'' => "hey there
againzoggle")
>        sleep 10
>        puts ''2''
>
>        client.publish(''/messages/public'',
''username'' => ''Joe'',
>                      ''msg'' => "hey there
again")
>         puts ''end of ev machine block''
>      end
>    end
>
>  end
>
> puts ''wait for running''
> sleep 0.1 until EM.reactor_running?
>
> sleep 30
>
> puts ''end of client''

Ok, Rails is a single threaded application, once you start event machine
inside the application flow, control is lost until a event triggers a
return somehow.
Do not put your code inside the EM block.

This is how i do it


class CommBridge

  def self.set_connection
    ensure_reactor_running
    @@client ||= self.set
    @@client
  end

private

   def self.set
     client =   Faye::Client.new("http://localhost:9292/faye",
{timeout:
20})
     client.add_extension(ClientAuth.new)
     return client
   end

  def self.ensure_reactor_running
        Thread.new { EM.run } unless EM.reactor_running?
        sleep 0.1 until EM.reactor_running?
  end



end

class ClientAuth
  def outgoing(message, callback)
    if message[''channel''] !~ %r{^/meta/}
      message[''ext''] ||= {}
        message[''ext''][''authToken''] =
"#{FAYE_TOKEN}"
  end
  callback.call(message)
  end
end

This calls takes care of creating a client fot he rails server.

Then anywhere in your app

client = CommBridge.set_connection
client.publish("/user/#{channel}",msg.to_json)

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