On 08/06/2013 02:54 PM, Tanu Kaskinen wrote: > On Tue, 2013-08-06 at 14:42 +0200, David Henningsson wrote: >> On 08/06/2013 02:30 PM, Tanu Kaskinen wrote: >>> On Tue, 2013-08-06 at 13:26 +0200, David Henningsson wrote: >>>> On 08/05/2013 01:37 PM, Tanu Kaskinen wrote: >>>>> On Wed, 2013-07-17 at 12:26 +0200, David Henningsson wrote: >>>>>> On 07/17/2013 11:22 AM, Tanu Kaskinen wrote: >>>>>>> On Wed, 2013-07-17 at 09:27 +0200, David Henningsson wrote: >>>>>>>> On 07/16/2013 03:20 PM, Tanu Kaskinen wrote: >>>>>>>>> What operations do you mean? Moving or removing a default connection is >>>>>>>>> not supported as such, but if the client tries that anyway, we can >>>>>>>>> implicitly convert the connection to an explicit one and disable default >>>>>>>>> connections, or we can require the client to do these operations >>>>>>>>> explicitly, but I think the latter would be too inconvenient for the >>>>>>>>> client. >>>>>>>> >>>>>>>> Ok, I think I didn't read the proposal well enough. Having done that, I >>>>>>>> understand that you're suggesting a global switch "default connections >>>>>>>> on/off" only. Or is it a per-node switch? >>>>>>> >>>>>>> It is a per-node switch. >>>>>>> >>>>>>>> I have another idea that might be worth considering: how about that the >>>>>>>> "explicit" layer can both enable and disable connections? So that there >>>>>>>> could be a default connection between A and B, but there is also some >>>>>>>> sort of explicit override that disables it. This would be more flexible >>>>>>>> than a more global on/off switch. >>>>>>> >>>>>>> I'm not sure what you mean. Do you perhaps mean that the default >>>>>>> connection on/off switch should be per-node (which it already is in my >>>>>>> proposal), or that it should be per-connection (so that if there are >>>>>>> multiple default from node A, it's possible to disable only a subset of >>>>>>> those)? >>>>>>> >>>>>>> I didn't make make it possible to disable individual default >>>>>>> connections, because I had a feeling that it would have very messy >>>>>>> semantics. If default connection from A to B is disabled, what is the >>>>>>> routing code supposed to do when conditions change and the default >>>>>>> routing is re-evaluated? Can it ever reactivate the connection between A >>>>>>> and B again? Is the per-connection disabling handled as a blacklist of >>>>>>> connections that must never be automatically activated? >>>>>> >>>>>> If the A -> B route is explicitly_disabled, that overrides any default >>>>>> connections the routing system tries to make. >>>>> >>>>> What is the use case for explicitly disabled connections? I'll assume >>>>> here that your idea was to allow moving a default connection elsewhere >>>>> (making the connection explicit in the process) without disabling all >>>>> default connections for the node. >>>>> >>>>> When the user moves a default connection, the routing system obviously >>>>> shouldn't immediately create another default connection elsewhere to >>>>> replace the disabled connection. >>>>> >>>>> On the other hand, if the routing system doesn't create replacement >>>>> connections, then that results in weird behaviour. Let's say that >>>>> there's a default connection A -> B, and the user moves the connection >>>>> to A -> C. Then B disappears. The routing changes its opinion of the >>>>> best available routing for A, which might be D. So removing node B >>>>> resulted in audio suddenly appearing in node D, even though nothing was >>>>> playing to B. >>>>> >>>> >>>> Assume your example of a default connection A -> B which the user >>>> changes into A -> C, by adding an explicit A -> C connection. Without >>>> some sort of explicitly_disabled blacklist that would then include A -> >>>> B, the routing system would be free to route A to *both* B and C. >>> >>> My solution is that the application disables the default routing >>> altogether for A, if it doesn't want to have the default connection A -> >>> B. It seems to me that this causes fewer surprises than the blacklisting >>> approach. >>> >>>> Whether this is implemented as a bool flag or as a separate blacklist is >>>> an implementation detail, but a bool flag just seemed simpler and faster >>>> to me, than having to look in several lists to figure out whether a >>>> connection exists or not. >>> >>> You don't need to look in several lists to figure out whether a >>> connection exists or not. If we have connection objects, which I think >>> we both want to have, it's enough to get the list all connections and >>> see whether a particular connection is included in that list. >>> >> >> Okay, so let me see if I understand this right. You propose that you can >> add explicit connections between two specified nodes, but blacklisting >> default connections have to be done on a node wide level (rather than >> per connection). >> >> That sounds interesting, as it would be more resilient towards nodes >> appearing and disappearing later on. >> I think that blacklisting would have to be two booleans per node though, >> one for outgoing connections and one for incoming. And a connection >> cannot exist if it is blocked on *either* side, rather than both sides. >> Does that make sense? > > My plan has so far been to only disable outgoing default connections, > but if there's need for it, I don't see any problem with adding another > bool for disabling incoming default connections. Do you have a use case? > Well, what's outgoing for playback is incoming for recording, so I think this would be the corresponding use case: assume a user changes from B -> A to C -> A, and that later on, a new source D appears. Then you would want to disable A on the incoming side to avoid a new D -> A connection? -- David Henningsson, Canonical Ltd. https://launchpad.net/~diwic
