Re: Doubts about GPeriodic

[Simon McVittie <simon mcvittie collabora co uk>]

On Fri, 22 Oct 2010 at 16:48:34 -0400, Owen Taylor wrote:
> I suppose you could tag D-Bus methods in some fashion, and have the
> D-Bus client library reorder the messages. But again, that depends on
> the user recognizing where compression is useful.

Some D-Bus APIs rely on method replies and signals arriving in the order
they were sent; various bits of Telepathy want this, for instance. Otherwise,
you can end up with situations where a receipient has to process a message
without having received the necessary information to process it correctly.

(Obviously, if the process or client library or whatever has opted-in to
re-ordering, that's fine.)

In Telepathy, our usual approach to this sort of compression is to
aggregate things at the D-Bus level - for instance, methods that get
information about contacts act on a *list* of contacts (on the Nokia 770
this apparently reduced the join time for a pathologically busy IRC channel
like #ubuntu from minutes to seconds!). This also reduces process wakeups,
context switches and other per-message overhead.

    S