[Freeswitch-users] Subscribing to events in managed C# / .NET

Josh Rivers josh at radianttiger.com
Tue Sep 8 22:46:48 PDT 2009


I confirmed that pop(1) works for me. since it's spinning in it's own
thread, that's probably the right solution. These are the relevant pieces of
core code, though:

APU_DECLARE(apr_status_t) apr_queue_trypop(apr_queue_t *queue, void **data)
{
    apr_status_t rv;

    if (queue->terminated) {
        return APR_EOF; /* no more elements ever again */
    }

    rv = apr_thread_mutex_lock(queue->one_big_mutex);
    if (rv != APR_SUCCESS) {
        return rv;
    }

    if (apr_queue_empty(queue)) {
        rv = apr_thread_mutex_unlock(queue->one_big_mutex);
        return APR_EAGAIN;
    }

    *data = queue->data[queue->out];
    queue->nelts--;

    queue->out = (queue->out + 1) % queue->bounds;
    if (queue->full_waiters) {
        Q_DBG("signal !full", queue);
        rv = apr_thread_cond_signal(queue->not_full);
        if (rv != APR_SUCCESS) {
            apr_thread_mutex_unlock(queue->one_big_mutex);
            return rv;
        }
    }

    rv = apr_thread_mutex_unlock(queue->one_big_mutex);
    return rv;
}

AND

APU_DECLARE(apr_status_t) apr_queue_pop(apr_queue_t *queue, void **data)
{
    apr_status_t rv;

    if (queue->terminated) {
        return APR_EOF; /* no more elements ever again */
    }

    rv = apr_thread_mutex_lock(queue->one_big_mutex);
    if (rv != APR_SUCCESS) {
        return rv;
    }

    /* Keep waiting until we wake up and find that the queue is not empty.
*/
    if (apr_queue_empty(queue)) {
        if (!queue->terminated) {
            queue->empty_waiters++;
            rv = apr_thread_cond_wait(queue->not_empty,
queue->one_big_mutex);
            queue->empty_waiters--;
            if (rv != APR_SUCCESS) {
                apr_thread_mutex_unlock(queue->one_big_mutex);
                return rv;
            }
        }
        /* If we wake up and it's still empty, then we were interrupted */
        if (apr_queue_empty(queue)) {
            Q_DBG("queue empty (intr)", queue);
            rv = apr_thread_mutex_unlock(queue->one_big_mutex);
            if (rv != APR_SUCCESS) {
                return rv;
            }
            if (queue->terminated) {
                return APR_EOF; /* no more elements ever again */
            }
            else {
                return APR_EINTR;
            }
        }
    }

    *data = queue->data[queue->out];
    queue->nelts--;

    queue->out = (queue->out + 1) % queue->bounds;
    if (queue->full_waiters) {
        Q_DBG("signal !full", queue);
        rv = apr_thread_cond_signal(queue->not_full);
        if (rv != APR_SUCCESS) {
            apr_thread_mutex_unlock(queue->one_big_mutex);
            return rv;
        }
    }

    rv = apr_thread_mutex_unlock(queue->one_big_mutex);
    return rv;
}

Is the trypop method returning without unlocking the mutex?

    rv = apr_thread_mutex_lock(queue->one_big_mutex);
    if (rv != APR_SUCCESS) {
        return rv;
    }

On Tue, Sep 8, 2009 at 7:06 PM, Michael Giagnocavo <mgg at giagnocavo.net>wrote:

>  I’m not sure how EventConsumer is supposed to work – maybe one of the
> real devs can explain how pop works and if it should fail on pop 0 or not.
>
>
>
> *From:* freeswitch-users-bounces at lists.freeswitch.org [mailto:
> freeswitch-users-bounces at lists.freeswitch.org] *On Behalf Of *Phillip
> Jones
> *Sent:* Tuesday, September 08, 2009 3:50 PM
>
> *To:* freeswitch-users at lists.freeswitch.org
> *Subject:* Re: [Freeswitch-users] Subscribing to events in managed C# /
> .NET
>
>
>
> I build this out.
>
> This seems to work fine:
>
> ThreadPool.QueueUserWorkItem((o) =>
>             {
>                 Log.WriteLine(LogLevel.Notice, "Thread Starting. ");
>                 EventConsumer con = new EventConsumer("all", "");
>                 while (true)
>                 {
>                    * Event ev = con.pop(1);*
>                     Log.WriteLine(LogLevel.Alert, "Event: " +
> ev.GetHeader("Event-Name"));
>                     //freeswitch.msleep(100);
>                 }
>             });
>
> With
>             Event ev = con.pop(0) however FS crashes with a
> System.NullReferenceException (attached)
>
>
>
>
>
>
>
>
>
>  On Tue, Sep 8, 2009 at 5:20 PM, Raffaele P. Guidi <
> raffaele.p.guidi at gmail.com> wrote:
>
> Oh, I see... all those years wasted doing java stuff! :D
>
>
>
> On Tue, Sep 8, 2009 at 22:46, Michael Giagnocavo <mgg at giagnocavo.net>
> wrote:
>
> “ ThreadPool.QueueUserWorkItem((o) =>”
>
> That starts a lambda, which is compiled to a delegate, same as anonymous
> methods.
>
> Guess I’ll wait for him to respond on the crash he gets.
>
>
>
>
>
> *From:* freeswitch-users-bounces at lists.freeswitch.org [mailto:
> freeswitch-users-bounces at lists.freeswitch.org] *On Behalf Of *Raffaele P.
> Guidi
> *Sent:* Tuesday, September 08, 2009 12:22 PM
>
>
> *To:* freeswitch-users at lists.freeswitch.org
> *Subject:* Re: [Freeswitch-users] Subscribing to events in managed C# /
> .NET
>
>
>
> Well, I can't see any delegate in josh sample, just a
> ThreadPool.QueueUserWorkItem. Here is an example that, at least on my
> system (I reached my home pc in the meanwhile), works fine.
>
>
>
>      public class LoadPluginDemo : ILoadNotificationPlugin {
>
>           delegate void Listener();
>
>           private void EventListener() {
>
>             EventConsumer con = new EventConsumer("all", null);
>
>             while (true){
>
>                  Event ev = con.pop(1);
>
>                  Log.WriteLine(LogLevel.Notice, "Got event " +
> ev.GetHeader("Event-Name"));
>
>             }
>
>           }
>
>         public bool Load() {
>
>             Log.WriteLine(LogLevel.Notice, "LoadDemo running.");
>
>             new Listener(EventListener).BeginInvoke(null,null);
>
>             return true;
>
>         }
>
>      }
>
>
>
>
>
>
>
> On Tue, Sep 8, 2009 at 18:43, Michael Giagnocavo <mgg at giagnocavo.net>
> wrote:
>
> That’s what his sample does, but he says it crashes.
>
>
>
> *From:* freeswitch-users-bounces at lists.freeswitch.org [mailto:
> freeswitch-users-bounces at lists.freeswitch.org] *On Behalf Of *Raffaele P.
> Guidi
> *Sent:* Tuesday, September 08, 2009 10:08 AM
>
>
> *To:* freeswitch-users at lists.freeswitch.org
> *Subject:* Re: [Freeswitch-users] Subscribing to events in managed C# /
> .NET
>
>
>
> Hi, you just have to use delegates to asynchronously call the function
> containing the loop and return back the control to the calling thread. Here
> an example (don't have my code at hand, hope it doesn't contain typos).
>
>
>
> Regards,
>
>    Raffaele
>
>
>
>    public class TestLoop : ILoadNotificationPlugin
>
>     {
>
>
>
>        Delegate void DoStuffDelegate();
>
>
>
>        public void doStuff()
>
>         {
>
>             EventConsumer con = new EventConsumer("all", "");
>
>             while (true)
>
>             {
>
>                 Event ev = con.pop(0);
>
>                 Log.WriteLine(LogLevel.Notice, "Event: " +
> ev.serialized_string);
>
>                 freeswitch.msleep(100);
>
>             }
>
>         }
>
>         public bool Load()
>
>         {
>
>             DoStuffDelegate dsdlg = new DoStuffDelegate(doStuff);
>
>             dsdlg.BeginInvoke();
>
>         }
>
>     }
>
> On Tue, Sep 8, 2009 at 08:21, Josh Rivers <josh at radianttiger.com> wrote:
>
> Thanks for the response!
>
>
>
> I have tried putting a long-running loop here, but then it blocks anything
> else managed from happening:
>
>
>
>    public class TestLoop : ILoadNotificationPlugin
>
>     {
>
>         public bool Load()
>
>         {
>
>             EventConsumer con = new EventConsumer("all", "");
>
>             while (true)
>
>             {
>
>                 Event ev = con.pop(0);
>
>                 Log.WriteLine(LogLevel.Notice, "Event: " +
> ev.serialized_string);
>
>                 freeswitch.msleep(100);
>
>             }
>
>         }
>
>     }
>
>
>
> However, if I fork off a thread here, freeswitch crashes:
>
>     public class TestLoop : ILoadNotificationPlugin
>
>     {
>
>         public bool Load()
>
>         {
>
>             ThreadPool.QueueUserWorkItem((o) =>
>
>             {
>
>                 Log.WriteLine(LogLevel.Notice, "Thread Starting. ");
>
>                 EventConsumer con = new EventConsumer("all", "");
>
>                 while (true)
>
>                 {
>
>                     Event ev = con.pop(0);
>
>                     Log.WriteLine(LogLevel.Notice, "Event: " +
> ev.serialized_string);
>
>                     freeswitch.msleep(100);
>
>                 }
>
>             });
>
>             return true;
>
>         }
>
>     }
>
>
>
> It doesn't look like this is a good place to start a long-running process?
>
>
>
> Thanks!
>
> Josh
>
>
>
> On Mon, Sep 7, 2009 at 11:05 PM, Raffaele P. Guidi <
> raffaele.p.guidi at gmail.com> wrote:
>
> Yes!
>
>
>
> public class LoadDemo : ILoadNotificationPlugin {
>
>     public bool Load() {
>
>         Log.WriteLine(LogLevel.Notice, "LoadDemo running.");
>
>         return true;
>
>     }
>
> }
>
>
>
> this example is from Michael Giagnocavo's Demo.csx which you can find into
> the mod_managed svn.
>
>
>
> And let me add that works like a charm :)
>
>
>
> Ciao,
>
>    Raffaele
>
>
>
> On Sun, Sep 6, 2009 at 22:50, Josh Rivers <josh at radianttiger.com> wrote:
>
>   Is there a way to start this when FreeSWITCH starts? The lua and perl
> modules have a 'startup-script' configuration preference. Is there something
> similar in mod_managed? Or is there a way to have an api command executed at
> a startup?
>
>
>
> <quote author="Phillip Jones">
>
> Exactly what I was after - thank you!
>
>
>
> On Thu, Sep 3, 2009 at 1:54 PM, Jeff Lenk <jlenk at frontiernet.net> wrote:
>
>
>
> >
>
> > try something like this
>
> >
>
> > EventConsumer con = new EventConsumer("all", "");
>
> > Event ev = con.pop(0);
>
> >
>
> > see lua sample -
>
> > http://wiki.freeswitch.org/wiki/Lua#freeswitch.EventConsumer
>
> >
>
> >
>
> > Phillip Jones-2 wrote:
>
> > >
>
> > > Hi there,
>
> > >
>
> > > mod_managed exposes EventReceivedFunction such that:
>
> > >
>
> > >  Session.EventReceivedFunction = (e) =>
>
> > >  {
>
> > >        Log.WriteLine(LogLevel.Alert, "Received Event {0}",
> e.ToString());
>
> > >        return "";
>
> > >  };
>
> > >
>
> > > should trap all events to which i subscribe.
>
> > >
>
> > >
>
> > > But how do I subscribe to events? What is the .NET / managed equivalent
>
> > > of:
>
> > >
>
> > > switch_event_bind(const char *id, switch_event_types_t event, const
> char
>
> > > *subclass_name, switch_event_callback_t callback, void *user_data);
>
> > >
>
> > >
>
> > >
>
> > > Thank you!
>
> > >
>
> > >
>
> > >
>
>
>
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