[Kde-pim] Nepomuk Feeder Improvements

[Vishesh Handa]

On Sun, Oct 28, 2012 at 10:05 PM, Christian Mollekopf
<chrigi_1 at fastmail.fm>wrote:

>
>
> On Sun, Oct 28, 2012, at 02:31 PM, Vishesh Handa wrote:
> > On Sun, Oct 28, 2012 at 2:34 PM, Andras Mantia <amantia at kde.org> wrote:
> >
> > > Hi,
> > >
> > >  I have a question about caching. Do you mean that the feeder should
> cache
> > > in memory all contacts and especially all headers for every mail?
> > >
> >
> > Nope. When a contact is stored in Nepomuk, it is given a unique
> > identifier
> > of the form 'nepomuk:/res/some-uuid'. I would like to cache this uri for
> > certain regularly used contacts, and headers.
> >
> > Each header is a separate object in Nepomuk, and has its own identifier.
> > When pushing common headers such as 'Mailing List', it makes sense the
> > cache the last 10 mailing lists identifiers pushed. That way Nepomuk has
> > to
> > avoid the job of querying the database to see if an object exists and
> > with
> > the corresponding information, and finding its identifier.
> >
> > I hope this makes it clearer.
> >
>
> Hey,
>
> I understand the intentions and how it's supposed to work, it's not
> entirely trivial though and I'm wondering if we wouldn't be better off
> implementing the same feature inside nepomuk.
>

I cannot do that cause I have no knowledge about the data being pushed.
StoreResources has to be generic. The only way I can identify the resources
is based on its properties.

You on the other hand know exactly what data you're pushing. I think it
would be trivial to map a Mbox to a QUrl.

Since the cache would grow endlessly, we'd have to expire it's values
> based on access, size and maybe also time, given the same data is
> available in nepomuk,


Use QCache, and cache the last 20-30 elements. Shouldn't consume too much
memory.


> I think we could also implement the feature there.
> Of course, by implementing the feature in the feeder we'd have some
> additional information, such as which resource we actually want to try
> caching, but given the level of intelligence the cache needs anyways I
> think the cache would achieve about the same performance boost by just
> caching everything (or a defined set of resources).
>

Possibly. Though I'm not sure how to do it.

>
> Do you think this cache could also be useful to other nepomuk clients or
> is a very feeder specific solution?
>

Well, the file indexer doesn't need the cache, and telepathy already has
one.


>
> Cheers,
> Christian
>
> > If yes, that is probably not good, it would use a lot of memory.
> > >
> > > Andras
> > > _______________________________________________
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> > >
> >
> >
> >
> > --
> > Vishesh Handa
> > _______________________________________________
> > KDE PIM mailing list kde-pim at kde.org
> > https://mail.kde.org/mailman/listinfo/kde-pim
> > KDE PIM home page at http://pim.kde.org/
>
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