Serious side effect of #6299 (silencing salut so gabble can connect)
Jim Gettys
jg at laptop.org
Thu Feb 14 15:31:06 EST 2008
You may be correct; the one other issue we have to look at carefully is
Avahi (Salut's) behavior after resume. It is likely that all timeouts
have expired, and that as soon as you resume a system, it may be
immediately doing mdns traffic. If everyone opens up at the same time,
you'd have trouble.
In principle, Avahi isn't supposed to work this way, but right now,
there is no hook between power management and Avahi to prevent it.
- Jim
On Thu, 2008-02-14 at 17:56 -0200, Ricardo Carrano wrote:
> John,
>
> I am sure 20 laptops will melt down a channel currently. But in this
> case, the 20 are already turned on and running salut, right?
> My point is:
> If you turn on one laptop running salut (it is the only one turned on
> for a while) can it connect to a school server (even while running
> salut)? If so it can abandon mDNS in favor of XMPP after connected to
> gabble.
> The next laptop will do the same.
> If you don't turn many XOs on at the "same time", you won't have salut
> preventing gabble to work.
> My fear is that we are complicating things unnecessarily.
>
> On Thu, Feb 14, 2008 at 5:42 PM, John Watlington <wad at laptop.org>
> wrote:
>
> Ricardo,
> That is the current situation, and the chatter generated by
> Salut
> multiplied by mesh multicast
> really does prevent laptops from connecting through gabble.
> We did
> a recent test here where
> 20 laptops really melted down a single channel.
>
> wad
>
>
> On Feb 14, 2008, at 2:39 PM, Ricardo Carrano wrote:
>
> > I am not sure I was clear. I meant: maybe it is not
> necessary to
> > turn it (salut) off _while_ trying to connect to gabble. If
> > connected to gabble, then stop salut.
> > Wouldn't this simplify matters?
> >
> > On Thu, Feb 14, 2008 at 3:44 PM, Ricardo Carrano
> > <carrano at ricardocarrano.com> wrote:
> > (e) make salut less chatty during this period (instead of
> stopping
> > it).
> > But I don't know if this is possible or how to do it. So it
> maybe
> > not a valid suggestion.
> >
> > But ...
> >
> > I think we have a time sensitive problem. Salut clogs the
> network
> > if there are many XOs running it. So, if you think of a
> scenario
> > where many XOs are _not_ turned on at the same time (or
> within a
> > certain time window) each XO will have an opportunity to
> switch to
> > gabble without the need to turn salut off. The network will
> be
> > naturally salut free.
> >
> > Maybe we don't need to turn salut off while trying to
> connect to
> > gabble.
> >
> >
> >
> > On Thu, Feb 14, 2008 at 3:19 PM, John Watlington
> <wad at laptop.org>
> > wrote:
> >
> > On Feb 14, 2008, at 11:52 AM, Jim Gettys wrote:
> >
> > >
> > > On Thu, 2008-02-14 at 16:58 +0200, Morgan Collett wrote:
> > >> We're testing patches to Presence Service to not start
> salut (or
> > stop
> > >> it) for a while to give gabble a chance to connect to the
> > >> schoolserver.
> > >>
> > >> However, Daf came across what was a very minor problem
> which
> > becomes
> > >> more serious in light of this change.
> > >>
> > >> Many activities are calling PS get_preferred_connection()
> to
> > interact
> > >> directly with the appropriate Telepathy Connection
> Manager,
> > which was
> > >> required in the past before we expanded Presence
> Service's
> > >> management of
> > >> setting up channels for activities.
> > >>
> > >> However, during the period when we stop salut to let
> gabble try to
> > >> connect, this call fails as there is no running plugin in
> PS. If an
> > >> activity is launched during this time (and there's no
> particular
> > >> UI to
> > >> show this other than no buddies in mesh view) and it
> makes this
> > >> call in
> > >> __init__ as most of them do, then it will crash with a
> gray screen.
> > >>
> > >> This affects: Calculate, Chat, Pippy, Record, Web and
> Write (of the
> > >> activities we bundle) and potentially other non-bundled
> activities.
> > >
> > > Ouch...
> > >
> > > Seems like this is something we're going to have to fix
> pretty
> > quickly
> > > no matter what.
> > >
> > >>
> > >> Our options are:
> > >>
> > >> (a) Touch all these activities now and port them to the
> newer
> > cleaner
> > >> API offered by PS/Sugar
> > >
> > > How big are the diffs? Does this simplify the code?
> > >
> > >> (b) Don't do #6299 for Update.1, but do it and (a) for
> Update1.1
> > >
> > > This would be pretty much immediately, anyway.
> > >
> > >> (c) Find some way for the call to
> get_preferred_connection to fail
> > >> gracefully (We can't think of one so far)
> > >> (d) Make a UI change to let the children know not to
> launch
> > >> activities
> > >> during this time period\
> >
> > (d) might be the simplest to implement in the required time
> frame.
> >
> > > Let me ask a different question: what happens to
> activities already
> > > running which are running shared? Are they going to fail?
> > > Presumably,
> > > yes....
> >
> > It sounds like any activity trying to share until either
> gable
> > connect to a server
> > or gives up and starts salut is going to crash. This either
> happens
> > on boot or
> > when a user manually switches networks.
> >
> > wad
> >
> >
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> >
> >
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--
Jim Gettys
One Laptop Per Child
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