[patch] wireless network support

[David Zeuthen]

On Wed, 2004-05-26 at 11:28 +0200, Owen Fraser-Green wrote:
> > My only concern is that might cause a storm of D-BUS signal emissions
> > and callouts; Kay talked about adding attributes to properties so
> > perhaps one day we could say something like
> > 
> >  hal_property_set_attribute (d, "net.wireless.network0.noise", 
> >                              HAL_PROP_ATTR_NO_CALLOUT|
> >                              HAL_PROP_ATTR_NO_MASS_EMISSION);
> 
> I've thinking for a while that something like this will be necessary for
> some properties as there will inevitably be more such "continuous"
> properties. An alternative solution would be to make them more discrete
> by deciding only to send the value every few seconds for example but I
> don't think this would be very satisfactory. 
> 

Realistically we would have to poll for all but the most uninteresting
information and we probably only want to poll at the max every few
seconds to avoid that the HAL daemon is overeating (hey rml :-) the CPU.
Further, every property update invokes a dbus signal emission and that
means the system bus daemon will have to process a lot of rules for
every connected client for every signal emitted by the HAL daemon. Which
may also be a lot of work. So, I think it's not realistic to have
continuous properties like that.

> For quite a few of the continuous property use cases it would probably
> be nice, from the client's point of view, to only receive a signal when
> the value passes a certain threshold. The WLAN monitor applet could warn
> when the signal strength is too low, another applet could warn when disk
> space was too low (the property I was thinking of that got me started
> thinking about this subject) etc. But I don't really know how best to
> solve it...
> 

If we only have updates every few seconds it's probably not too bad to
have e.g. the WLAN monitor applet check threshold itself. It probably
wants to do fancy animations anyway so it for sure is swapped in :-)

Cheers,
David


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