GSoC update

[Phalgun Guduthur]

On Fri, Jul 13, 2012 at 1:02 PM, Bart Cerneels <bart.cerneels at gmail.com>wrote:

> On Wed, Jul 4, 2012 at 4:37 PM, Phalgun Guduthur
> <phalgun.guduthur at gmail.com> wrote:
> > Hey All!
> >
> > An update on my GSoC project : Semantic Collection for Amarok
> >
> > I have figured out a way to reuse a lot of existing Amarok code. So it
> made
> > a part of the code I wrote till now redundant.
> >
> > I will be using MemoryCollection as other collections do. The Meta QMaps
> > will be constructed using queried results from Nepomuk. This will make
> all
> > the collections consistent and hopefully avoids a lot of bugs too.
> > Similarly, I will also be reusing the MemoryQueryMaker and the other
> support
> > classes that go with it.
> >
> > Right now, the Nepomuk Queries are taking too long. So I will have to run
> > them in the background using Threadweaver jobs.
> > Apart from this, the NepomukCollection looks complete with the Meta
> classes
> > implemented.
>
> This worries me a little bit. MemoryCollection obviously uses a lot of
> memory. Where possible we should avoid having to place the complete
> set of tracks in memory and rather rely on the design goals of
> QueryMaker to create them on demand. I would think Nepomuk is the
> perfectly suited for that. Can you explain what blocked you and
> decided to switch to MemoryCollection?
>
> Bart
>

Oh I haven't checked my memory usage when I ran Amarok Collection with
Nepomuk.
If all of the MetaMaps are being stored in memory, it should indeed eat up
a lot, if we consider collections of size more than 2000 tracks. But then,
wouldn't all the existing collections that use MemoryCollection also suffer
from the same problem? Say for example the iPodCollection.

I did speak to Edward (dr_lepper) on the possibility of caching resource
URI's (These are the unique identifiers of each resource in Nepomuk, just
strings) of each track so that they can be looked up quickly. But if this
caching is indeed required, I'll have to postpone it for now and work on
them after completing other milestones.

And as to why I wanted to reuse the MemoryCollection, I was going to
implement my NepomukQueryMaker on the same lines as MemoryQueryMaker,
including the *QueryMakerInternal and other intricacies. Then I realized I
could make use of MemoryCollection as other collections and maintain the
same consistency among the collections.

Now I do start to wonder if constructing tracks on demand, say when a user
clicks on the artist or a genre was indeed an option. Both approaches have
their pros and cons, 'cos the 'construct at beginning' approach causes a
lag only during the bootup of Amarok whereas the 'on demand' approach would
cause a lag every time a query is requested. ( time lag for the query to
run and enumerate )

Best,
Phalgun
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