[avahi] when can avahi_entry_group_commit return "Bad state" ?

[Julien PUYDT]

Lennart Poettering a écrit :
> On Tue, 02.09.08 19:00, Julien PUYDT (julien.puydt at laposte.net) wrote:
> 
>>>> I have a bug where I get published correctly at first, but don't manage 
>>>> to update my information later : avahi_entry_group_commit returns "Bad 
>>>> state"...
>>>>
>>>> What should I do after/before 
>>>> avahi_entry_group_update_service_txt_strlst so that my data is updated?
>>> the Avahi client will return AVAHI_ERR_BAD_STATE if you commit an
>>> entry group whose connection to the server is dead.
>> Hmmm... and how do I know if the connection to the server is dead? 
>> Shouldn't I know from the callback client?
> 
> You can find that out with avahi_client_get_state(). If the state is
> any of AVAHI_CLIENT_S_REGISTERING, AVAHI_CLIENT_S_COLLISION and
> AVAHI_CLIENT_S_RUNNING a connection tot he Avahi daemon is available.
> 
> If the state is AVAHI_CLIENT_S_RUNNING the host name is well
> established and you may install entry groups which refer to the host
> name. If the state leaves AVAHI_CLIENT_S_RUNNING you should remove
> your entry groups since the hostname they internally might refer to is
> no longer established.
> 
> Browsers/resolvers may be kept during the whole time we are in one of
> the aforementioned AVAHI_CLIENT_S_xxx states.
> 
> This is documented on http://avahi.org/download/doxygen/main.html
> under "How to Register Services".
>

Registering services is ok, precisely because it's well documented.

Updating services isn't that well ; I'm trying to use the 
avahi_entry_group_update_service_txt function:
http://avahi.org/download/doxygen/publish_8h.html#9f805d25a03009baf606c14a4d7cb3dc

And I don't manage to get it to work ; I added g_print statements to 
follow the client and entry group state change, and to my functions 
which deal with empty group ; here is what it prints :

AVAHI_CLIENT_S_RUNNING
AVAHI_ENTRY_GROUP_UNCOMMITED
avahi_entry_group_add_service_strlst: OK
avahi_entry_group_add_service_strlst: OK
avahi_entry_group_commit: OK
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_commit: Bad state
AVAHI_ENTRY_GROUP_REGISTERING
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_commit: Bad state
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_commit: Bad state
AVAHI_ENTRY_GROUP_ESTABLISHED
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_commit: Bad state

 From this I gather :
(1) that whenever my updating function gets called, it triggers the 
display of :
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_update_service_txt_strlst: OK
avahi_entry_group_commit: Bad state

FIX: I certainly call it too soon, and should guard against calling it 
before AVAHI_ENTRY_GROUP_ESTABLISHED is obtained (using 
avahi_entry_group_get_state)

(2) after AVAHI_ENTRY_GROUP_ESTABLISHED is obtained, I don't get why I 
still have problems.

Snark