Created attachment 36465 [details]
First version of a provider selection algorith.

I've been playing a bit with the Master provider and i noticed that the
providers selection algorithm is still unimplemented. Currently, if i've
understood the code, the first available provider is always selected:

/* TODO: currently returning even providers that are worse than
priv->min_accuracy, if nothing else is available */ 
if (gc_master_provider_get_status (provider) ==GEOCLUE_STATUS_AVAILABLE)
{ 
        /* unsubscribe from all providers worse than this */
        gc_master_client_unsubscribe_providers (client,l->next,iface);  
        return provider;
}

I think this shouldn't be a problem, but if im not wrong, it always
selects the manual provider, which is always available. I guess it would
depend on the order of the providers list reading operation, but i've
experimented that most of times the manual provider is selected, even if
the Localnet, for instance, is also available.

I've implemented a patch, not very tested yet, trying to face this
problem. I would like to get some feedback about this issue, since i
guess is a well known problem and perhaps you already had some
alternative approaches.