#83 ✓invalid

It is difficult to process events in order

Reported by dimas | September 14th, 2009 @ 07:45 AM

i'm writign standalone Ruby application which hooks into AMI event stream and reacts to some events. The application does something like:

require 'adhearsion/events_support'
  Adhearsion::Events.register_callback %w[asterisk manager_interface] do |event|
    puts event.inspect

except that it does some real processing instead of "puts event.inspect"

The problem is that sometimes I receive events in wrong order. To my understanding this happens because the Theatre created by events_support is initialized with default 6 thread count so if events come in fast but processing of some of them takes time, another event will can be pulled by another thread and processed first.

Putting critical section/monitor/whatever inside my event processing loop does not help because the Theatre can still dequeue event in one thread, then context switch occurs and another thread dequeues and processes another event. Some sort of race conditions.

What could help me is to tell Theatre to use only one thread. However I can not do that because Theatre initialization is controlled by events_support which does not let specifying thread count...

Comments and changes to this ticket

  • dimas

    dimas November 14th, 2009 @ 06:17 PM

    In 0.8.3 I saw

            # TODO: Extract number of threads to use from AHN_CONFIG
            @@framework_theatre = Theatre::Theatre.new

    which looks like a Good Thing :)
    However if the whole config stuff needs to be designed first (soeey I'm not aware of what is there already), it can take very long time.

    How about adding theatre_thread_count static (class) variable to Adhearsion::Events which defaults to nil but calling code can change its value. If value is not nil it is passed to Theatre.new.
    Later when config is added, you can extend the check like:
    1. if theatre_thread_count is not nil - use it
    2. if theatre_thread_count is not overriden load a value from config.
    3. if config does not specify value, use default.

    This way you can quickly add ability to specify number of threads while still allow doing the same with config when it is ready.

  • Jay Phillips

    Jay Phillips November 14th, 2009 @ 08:19 PM

    • State changed from “new” to “open”

    If you're using this in a standalone Ruby process and want only to capture events in order, I'd probably recommend subclassing ManagerInterface and overriding event_message_received():

    class MyManager < Adhearsion::VoIP::Asterisk::Manager::ManagerInterface
      def event_message_received(event)
        p event
    # Connect MyManager to Asterisk...
    MyManager.connect ........ # normal args here
  • dimas

    dimas November 14th, 2009 @ 08:45 PM

    Hmmm... how stupid of me.
    Yeah I guess it will work and it probably much more clean approach than trying to tune Theatre for my needs.

    I believe this one can be closed.

  • Ben Klang

    Ben Klang August 2nd, 2010 @ 02:38 PM

    • State changed from “open” to “invalid”
    • Milestone order changed from “0” to “0”

    Closing per reporter.

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