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

Jaydeep Solanki jaydp17 at gmail.com
Thu Aug 8 20:32:49 UTC 2013 

On Fri, Aug 9, 2013 at 1:44 AM, Albert Astals Cid <aacid at kde.org> wrote:

> El Divendres, 9 d'agost de 2013, a les 01:36:18, Jaydeep Solanki va
> escriure:
> > yes it won't wait
>
> So the UI thread won't block, right? Because you said it would.
>
yes, if there are two QTextDocuments one used in UI thread and other in
non-UI thread, and considering all the rendering is taking place in non-UI
thread then there is no reason that will block the UI thread

>
> Cheers,
>   Albert
>
> >
> > On Fri, Aug 9, 2013 at 1:33 AM, Albert Astals Cid <aacid at kde.org> wrote:
> > > El Divendres, 9 d'agost de 2013, a les 01:11:25, Jaydeep Solanki va
> > >
> > > escriure:
> > > > On Thu, Aug 8, 2013 at 2:25 AM, Albert Astals Cid <aacid at kde.org>
> wrote:
> > > > > 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 clone because I read it
> > > > here<
> > >
> > >
> http://qt-project.org/doc/qt-4.8/threads-modules.html#threads-and-rich->
> > > text-processing> .
> > >
> > > Ok, that's most probably a non issue nowadays when a QPixmap is
> basically
> > > thread friendly in almost most platforms, but ok.
> > >
> > > > > , i'm still waiting for the answer to
> > > > >
> > > > > "Why would the UI thread have to wait?"
> > > >
> > > > it wouldn't have to wait if two different mutexes are used.
> > >
> > > If all the rendering is done in the second thread, why is the UI thread
> > > waiting for a mutex at all?
> > >
> > > Cheers,
> > >
> > >   Albert
> > >
> > > > > 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
> > > > > > > > >
> > > > > > > > > _______________________________________________
> > > > > > > > > Okular-devel mailing list
> > > > > > > > > Okular-devel at kde.org
> > > > > > > > > https://mail.kde.org/mailman/listinfo/okular-devel
> > > > > > >
> > > > > > > _______________________________________________
> > > > > > > Okular-devel mailing list
> > > > > > > Okular-devel at kde.org
> > > > > > > https://mail.kde.org/mailman/listinfo/okular-devel
> > > > >
> > > > > _______________________________________________
> > > > > Okular-devel mailing list
> > > > > Okular-devel at kde.org
> > > > > https://mail.kde.org/mailman/listinfo/okular-devel
> > >
> > > _______________________________________________
> > > 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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