[avahi] browsing without event loop ?

[Lennart Poettering]

On Mon, 03.09.07 16:57, Ludovic Courtès (ludovic.courtes at laas.fr) wrote:


Hi!

> > Why would you want to avoid running an event loop anyway?
> 
> My guess is that it's because it's cumbersome.
> 
> Sometimes, you'd like to write something like:
> 
>   for machine in services(type=_workstation._tcp)
>   do
>     shutdown $machine
>   done
> 
> Using the call-back API makes it hard to express such simple things.

You're welcome to run the Avahi event loop only until a certain
condition holds. i.e.:

while (avahi_client_get_state(client) != AVAHI_CLIENT_FAILURE) {
    if (avahi_simple_poll_iterate(p, NULL) != 0)
        break;       
}

Then, in your event callback just run avai_simple_poll_quit() and this
loop will exit, because avahi_simple_poll_iterate() will return
1. A good candidate for calling that function at would be
ALL_FOR_NOW.

> FWIW, I'm planning to add a "threaded" API to Guile-Avahi, whereby the
> event loop would be run in a separate thread.  User threads would send
> requests such as "list all services of a given type" to the
> event-processing thread and would block until the event-processing
> thread is done (e.g., until "ALL_FOR_NOW" or an error is caught).

You are aware of AvahiThreadedPoll which does exactly this in C and
has been part of Avahi since 0.6.3?

See http://avahi.org/wiki/RunningAvahiClientAsThread for more
information.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
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