[Okular-devel] Dt. 6th August - status

Albert Astals Cid aacid at kde.org
Wed Aug 7 20:55:38 UTC 2013 

El Dijous, 8 d'agost de 2013, a les 01:36:12, Jaydeep Solanki va escriure:
> On Thu, Aug 8, 2013 at 1:21 AM, Albert Astals Cid <aacid at kde.org> wrote:
> > El Dijous, 8 d'agost de 2013, a les 01:09:27, Jaydeep Solanki va escriure:
> > > Yes I know I have not took care of it here, I just wanted to show you
> > > the
> > > approach. And I still have no clue on how to delete the static object.
> > > I tried QScopedPointer, it doesn't help
> > > 
> > > And what to do with the clone method, I mean it's not virtual, can't
> > > include EpubDocument because of circular dependency, then ?
> > > Those were the two I can think of.
> > 
> > Well, what's the point in fixing B if it needs A and you don't know how to
> > fix
> > A?
> 
> But don't you think both A and B in this case can be solved independently,
> because if I first fix threading and then fix the cloning issue, I just
> have to replace the name of the method.
> 
> For me it's totally okay, to fix resource loading issue first.
> 
> You have got any ideas, on how to avoid cyclic dependency and clone it ?

Why do you need to clone it, i'm still waiting for the answer to

"Why would the UI thread have to wait?"

Albert

> 
> > Please concentrate on doing first things first.
> > 
> > Cheers,
> > 
> >   Albert
> >   
> > > On Thu, Aug 8, 2013 at 12:57 AM, Albert Astals Cid <aacid at kde.org>
> > 
> > wrote:
> > > > El Dijous, 8 d'agost de 2013, a les 00:37:42, Jaydeep Solanki va
> > 
> > escriure:
> > > > > I tried a lot of approaches for TextDocument threading and finally I
> > > > > settled to a really simple approach (as it makes generator threaded
> > 
> > as
> > 
> > > > well
> > > > 
> > > > > as gives best performance), diff attached.
> > > > > I just want to ask, how to know when the document is closed and
> > 
> > delete
> > 
> > > > that
> > > > 
> > > > > pointer, because now if I close a document and open another document
> > > > 
> > > > images
> > > > 
> > > > > displayed are of the previous document.
> > > > 
> > > > How does this fix the incorrect loadResource being called?
> > > > 
> > > > Cheers,
> > > > 
> > > >   Albert
> > > >   
> > > > > On Wed, Aug 7, 2013 at 6:11 AM, Fabio D'Urso <fabiodurso at hotmail.it>
> > > > 
> > > > wrote:
> > > > > > Hi,
> > > > > > 
> > > > > > On Wednesday, August 07, 2013 12:31:41 AM Albert Astals Cid wrote:
> > > > > > > El Dimarts, 6 d'agost de 2013, a les 20:52:25, Jaydeep Solanki
> > > > > > > va
> > > > > > 
> > > > > > escriure:
> > > > > > > > Hi,
> > > > > > > > 
> > > > > > > > I have implemented a simple Qt Visibility support, which hides
> > > > 
> > > > text,
> > > > 
> > > > > > it's
> > > > > > 
> > > > > > > > doesn't hide the exact area of the text, because the way
> > > > 
> > > > QTextDocument
> > > > 
> > > > > > is
> > > > > > 
> > > > > > > > developed it is impossible to implement an approach that hides
> > > > 
> > > > only a
> > > > 
> > > > > > part
> > > > > > 
> > > > > > > > of line. Either we can hide a line or not hide it.
> > > > > > > > And implementing an approach in which incrementing the cursor
> > 
> > and
> > 
> > > > not
> > > > 
> > > > > > > > inserting the text was my idea, but it seems they are using
> > > > > > > > the
> > > > 
> > > > text
> > > > 
> > > > > > > > so
> > > > > > > > much that, I'm not able to get a way to exclude the text and
> > > > 
> > > > implement
> > > > 
> > > > > > > > visibility.
> > > > > > > 
> > > > > > > Before continuing to work on that, i think you should explore
> > 
> > with
> > 
> > > > the
> > > > 
> > > > > > > Qt
> > > > > > > guys how feasible is this work to be accepted upstream with the
> > > > > > > known
> > > > > > > limitations you mention, because if it's not going to be
> > 
> > accepted,
> > 
> > > > it's
> > > > 
> > > > > > not
> > > > > > 
> > > > > > > really useful for us since we can't expect people to patch their
> > 
> > Qt
> > 
> > > > for
> > > > 
> > > > > > us.
> > > > > > 
> > > > > > > > Regarding the threaded QTextDocument, I tried the approach you
> > > > 
> > > > said,
> > > > 
> > > > > > and
> > > > > > 
> > > > > > > > it
> > > > > > > > seems that it is also blocking UI, even more then single
> > 
> > threaded.
> > 
> > > > > > Suppose
> > > > > > 
> > > > > > > > I'm on a page and the next page is loading in other thread,
> > 
> > the UI
> > 
> > > > > > thread
> > > > > > 
> > > > > > > > will have to wait till the other thread finishes it's job
> > 
> > (because
> > 
> > > > of
> > > > 
> > > > > > > > locking), which takes a bit more time than usual because it is
> > > > > > 
> > > > > > generated
> > > > > > 
> > > > > > > > from a cloned QTextDocument.
> > > > > > > 
> > > > > > > Why would the UI thread have to wait?
> > > > > > 
> > > > > > Disclaimer: I haven't read the whole discussion, so this idea
> > > > > > might
> > > > 
> > > > not be
> > > > 
> > > > > > applicable. If I understood correctly, there's some object that
> > 
> > needs
> > 
> > > > to
> > > > 
> > > > > > be
> > > > > > cloned because its methods are not reentrant, but cloning is
> > > > > > expensive.
> > > > > > 
> > > > > > I was thinking about keeping a pool of clones, initially
> > > > > > containing
> > > > 
> > > > only
> > > > 
> > > > > > one
> > > > > > instance, and adding a new clone to the pool when an instance is
> > > > 
> > > > requested
> > > > 
> > > > > > and
> > > > > > there are no readily available ones.
> > > > > > 
> > > > > > Of course this approach, if feasible at all, will waste memory.
> > > > 
> > > > Depending
> > > > 
> > > > > > on
> > > > > > the size of the object it might pay or not.
> > > > > > 
> > > > > > > > Regarding the clone method overriding in EpubDocument, I'm
> > 
> > using a
> > 
> > > > > > dynamic
> > > > > > 
> > > > > > > > property, to store the name of the generator, and using it I
> > > > > > > > decide
> > > > > > 
> > > > > > which
> > > > > > 
> > > > > > > > method to call EpubDocument::myClone() or
> > 
> > QTextDocument::clone()
> > 
> > > > > > > > in
> > > > > > > > TextDocumentGenerator.
> > > > > > > 
> > > > > > > You can't call EpubDocument::myClone in TextDocumentGenerator,
> > 
> > that
> > 
> > > > > > > introduces a circular dependency.
> > > > > > > 
> > > > > > > > One more thing I noticed about Okular is it doesn't free up
> > > > > > > > memory,
> > > > > > 
> > > > > > after
> > > > > > 
> > > > > > > > the document is closed, it frees after Okular quits, so my
> > > > 
> > > > question is
> > > > 
> > > > > > > > does
> > > > > > > > it use the memory (cached pixmaps) when I load the same
> > 
> > document
> > 
> > > > again
> > > > 
> > > > > > ?
> > > > > > 
> > > > > > > Nope, it should free it, if it doesn't it's a bug that has to be
> > > > 
> > > > fixed.
> > > > 
> > > > > > I remember reading somewhere that most free() implementations
> > > > > > don't
> > > > > > actually
> > > > > > return the memory back to the OS, instead they keep free'd blocks
> > 
> > in a
> > 
> > > > > > internal pool for future reuse. Eventually, when the process dies,
> > 
> > all
> > 
> > > > of
> > > > 
> > > > > > its
> > > > > > memory is reclaimed back by the OS.
> > > > > > 
> > > > > > As Albert said, Okular does "free" pixmaps, but maybe you see that
> > > > > > behavior
> > > > > > for this reason.
> > > > > 
> > > > > Makes sense.
> > > > > 
> > > > > > > Cheers,
> > > > > > > 
> > > > > > >   Albert
> > > > > > >   
> > > > > > > > Cheers,
> > > > > > > > Jaydeep
> > > > > > > 
> > > > > > > _______________________________________________
> > > > > > > Okular-devel mailing list
> > > > > > > Okular-devel at kde.org
> > > > > > > https://mail.kde.org/mailman/listinfo/okular-devel
> > > > > > 
> > > > > > --
> > > > > > Fabio
> > > > > > 
> > > > > > _______________________________________________
> > > > > > Okular-devel mailing list
> > > > > > Okular-devel at kde.org
> > > > > > https://mail.kde.org/mailman/listinfo/okular-devel
> > > > 
> > > > _______________________________________________
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> > 
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