[patch] Preload popup menus for the desktop (3.5)

[Scott Wheeler]

On Thursday 30 March 2006 10:04, David Faure wrote:
> I think the problem is either (or both)
> - service menus, which are .desktop files in a konq-specific directory so
> they are not pre-parsed by ksycoca
> - konqpopupmenu plugins, which are dlopened plugins (mostly from kdeaddons)
>
> I think pre-parsing the service menu files might be a good solution...
> ideally with a KDirWatch on the directories containing such files so that
> we notice when new files are added though.

Ok, I had some time to do some more profiling last night.  About 50-60% of the 
time is spent in KonqPopupMenu::addPlugins().  There the two expensive calls 
are:

About 15% of total popup creation:

plugin_offers = KTrader::self()->query( m_sMimeType.isNull() ? 
 QString::fromLatin1( "all/all" ) : m_sMimeType, "'KonqPopupMenu/Plugin' in  
 ServiceTypes");

About 35% of popup creation:

plugin = 
 KParts::ComponentFactory::createInstanceFromLibrary<KonqPopupMenuPlugin>(
  QFile::encodeName( (*iterator)->library() ), this,
  (*iterator)->name().latin1() );

The first is relatively easy to cache and doing so pretty quickly took it off 
of the profiling radar.  The latter was more problematic.

From what I saw tracing the calls from KParts and then to KLibLoader is that 
it was KLibLoader::createObject() which is using up most of the time.  Since 
that's just a virtual that's implemented in the plugs that's where I stopped 
and went back to caching.  The problem is that the second argument to the 
above call is a QObject (the parent), which in this case is the popup being 
created.  That naturally makes caching the call problematic.

There are a couple other areas that I could track down; I'm currently 
instrumenting the stuff by hand so I just know "20% of KonqPopupMenu::setup() 
is somewhere in this 20 line block of code and the other 30% is in that 
block."

At the moment, without changing the API, I don't see an obvious way to cache 
the createInstanceFromLibrary() call.  Thoughts?

-Scott
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