[avahi] Mono apps don't get notified of ClientState.Running

[Trent Lloyd]

What do the other examples do, not bother to check?

Trent

On Mon, May 01, 2006 at 04:47:38AM +0100, Celso Pinto wrote:
> Hi again guys,
> 
> the Connect() method doesn't work because the Client.OnClientCallback 
> method is invoked while avahi_client_new, which means that the Client 
> object still has an invalid Handle and Avahi.EntryGroup barfs on it.
> 
> I'm attaching the patch if you care to take a look (it prints a couple 
> of debug messages to stdout).
> 
> You'll see that the output "OnClientCallback invoked for state Running" 
> is printed before the "Got handle" message.
> 
> Any ideas?
> 
> Cheers,
> Celso
> 
> Celso Pinto wrote:
> >Hi everyone,
> >
> >I'm programming an application that uses Avahi's Mono bindings and I 
> >think I found an ugly problem: when a Mono app creates an instance of 
> >Avahi.Client, the constructor of this class invokes the native 
> >avahi_client_new method, which receives a parameter for the client_state 
> >callback.
> >
> >While still in construction, the Avahi.Client class gets notified that 
> >the ClientState is now Running, so the Client.OnClientCallback method is 
> >invoked but the StateChanged event still doesn't contain any Handlers 
> >because this is all happening during construction of the Avahi.Client 
> >object.
> >
> >This means that applications, like my own, that are waiting on the 
> >StateChanged event with a ClientState.Running value to start publishing 
> >their services never get notified, therefore never get to publish anything.
> >
> >The only way to fix this problem is to create a Client.Connect() method. 
> >This allows us to first create an instance of Avahi.Client, then add a 
> >delegate to the StateChanged event and finally call the 
> >Avahi.Client.Connect() method. Only then our callbacks get notified of 
> >the running state.
> >
> >The big question is: because this will break the current behaviour of 
> >the Avahi.Client class (meaning that the client connects to the daemon 
> >during construction), will you guys make the necessary changes?
> >
> >Cheers,
> >Celso
> >_______________________________________________
> >avahi mailing list
> >avahi at lists.freedesktop.org
> >http://lists.freedesktop.org/mailman/listinfo/avahi
> >

> --- Client.cs.old	2006-05-01 03:59:28.000000000 +0100
> +++ Client.cs	2006-05-01 04:44:05.000000000 +0100
> @@ -117,6 +117,7 @@
>          private ClientCallback cb;
>          private PollCallback pollcb;
>          private IntPtr spoll;
> +        private ClientFlags cflags;
>  
>          private Thread thread;
>  
> @@ -251,6 +252,16 @@
>  
>          public Client (ClientFlags flags)
>          {
> +            cflags = flags;
> +        }
> +
> +        public Client () : this (ClientFlags.None) {
> +        }
> +
> +        public void Connect()
> +        {
> +            if (handle != IntPtr.Zero) return;
> +
>              spoll = avahi_simple_poll_new ();
>  
>              pollcb = OnPollCallback;
> @@ -259,18 +270,22 @@
>              cb = OnClientCallback;
>  
>              int error;
> -            handle = avahi_client_new (poll, flags, cb, IntPtr.Zero, out error);
> +            handle = avahi_client_new (poll, cflags, cb, IntPtr.Zero, out error);
> +            Console.WriteLine("Got handle");
>              if (error != 0)
> -                throw new ClientException (error);
> +            {
> +                avahi_simple_poll_quit (spoll);
> +                avahi_simple_poll_free (spoll);
> +                handle = IntPtr.Zero;
>  
> +                throw new ClientException (error);
> +            }
> +            
>              thread = new Thread (PollLoop);
>              thread.IsBackground = true;
>              thread.Start ();
>          }
> -
> -        public Client () : this (ClientFlags.None) {
> -        }
> -
> +        
>          ~Client ()
>          {
>              Dispose ();
> @@ -348,6 +363,7 @@
>          
>          private void OnClientCallback (IntPtr client, ClientState state, IntPtr userData)
>          {
> +            Console.WriteLine("OnClientCallback invoked for state {0}",state);
>              if (StateChanged != null)
>                  StateChanged (this, new ClientStateArgs (state));
>          }

> _______________________________________________
> avahi mailing list
> avahi at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/avahi


-- 
Trent Lloyd <lathiat at bur.st>
Bur.st Networking Inc.