roadmap

[David Stockwell]

Hello everyone,

From: "Colin Walters"


> On Wed, Aug 6, 2008 at 9:14 PM, Scott James Remnant 
> <scott at canonical.com> wrote:
>> On Wed, 2008-08-06 at 16:36 -0400, Colin Walters wrote:
>>
>>> That's about it, after that I think we can call it done.
>>>
>> I think that there's some interesting directions to take signals.
>>
>> Firstly having it such that an object is notified when somebody is
>> matching against its signals, and thus it can choose not to emit them
>> unless anybody's listening -- reducing bus wakeup, traffic, etc. 
>> This
>> could be handled entirely in bindings.
>
> Though before we do this, I think it'd be more valuable to go through
> the various bindings/apps and make sure they're using the existing
> detail match rule.  I remember discussion before about cases where
> bindings/apps were watching for NameOwnerChanged from the bus, without
> a match rule that means tons of processes wake up every time one
> leaves or joins the bus.
>
If I can chime in, I think it is useful to not care whether anyone is 
listening when emitting a signal.

Maybe there is some network and processing overhead in emitting a signal 
that noone cares about, but adding this notification would add 
complexity and overhead.

I can imagine putting in code that bypasses sending a signal when 
"nobody" is listening; but then having to add a callback when someone 
suddenly appears subscribing to a signal.  And then there is the 
possibility/probabability of race conditions, not emitting a signal when 
another process was "just about" to request the signal.

Anyway, just my opinion...

David Stockwell