From kde-devel  Wed May 04 06:32:05 2011
From: Kevin Krammer <kevin.krammer () gmx ! at>
Date: Wed, 04 May 2011 06:32:05 +0000
To: kde-devel
Subject: Re: KJob: chaining and synchronizing jobs
Message-Id: <201105040832.05567.kevin.krammer () gmx ! at>
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On Sunday, 2011-05-01, Michael Schuerig wrote:
> I have several KJob jobs, some of which may run in parallel, some depend
> on the results of one or more others, and all of them are fallible. The
> context is Akonadi, but I think my question is generic.
>=20
> I want to retrieve items from several Akonadi collections and act on
> them. By the nature of the (prefered) interface, the individual steps
> executed asynchronously as KJobs.
>=20
> The parts are these:
>=20
> I launch several retrieval jobs and want to know when all of them have
> finished. If one of them fails, all others are killed and failure is
> signaled.
>=20
> As far as I can tell, there's no pre-build way to group jobs in such a
> way as to be notified when all of them have finished. Therefore,
> apparently I need to do the synchronization myself, possibly by
> connecting to each jobs result signal and keeping track of how many are
> still active.
>=20
> For chaining jobs, I need to glue them together so that the result of
> one is passed as an argument to the next. Of course, if an error occurs,
> the chain ought to be broken.
>=20
> For all this I can write very specific code -- and do it again the next
> time I want to do something similar. I'd rather not do that. Instead,
> I'd like to connect independent pieces that are ignorant of each other.

=46or passing one job's result as a parameter to new job you'll need some p=
lace=20
that knows the API of both, gets the data from the finished job and creates=
=20
the new job.

Maybe using KCompositeJob and reimplementing  slotResult()?

Cheers,
Kevin
=2D-=20
Kevin Krammer, KDE developer, xdg-utils developer
KDE user support, developer mentoring

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