Detailed KDirModel problems (was: Re: KFileTreeView almost fixed - STRANGE STUFF)

[Rafael Fernández López]

Hi all,

I am leaving right now, and I haven't got time to try to fix it, but I will 
try tonight. Meanwhile I'd like to share with you what I've found, since I 
consider this a clear showstopper for KDE 4.0.

If we recapitulate, what we had is a KFileTreeView class that is not able to 
sort. I added a KDirSortFilterProxyModel to fix that problem, and suddenly 
strange things started to happen to the tree. This is directly related to 
KDirModel.

Now, all you need to test the problem is to run the test:

kdelibs/kfile/tests/kfiletreeviewtest

Let's try to reproduce the problem:

First, apply the attached patch.

For example, my home folder is located at /home/ereslibre. If we run the 
kfiletreeviewtest the tree is located at /. Nice.

Navigate through the tree and expand /home, now collapse it (or leave it as 
expanded). Now click on "Home" button. It worked nice. It seems like the 
contents of "/home" were cached and when clicking "Home" (that calls to 
setCurrentUrl(), that calls to KDirModel::expandToUrl(), that calls to 
KDirModel::nodeForUrl()) they were retrieved and the index was found 
successfully.

Now, reopen the test.

Click directly on "Home" button... OMG, now you have a nice assertion failure.

Basically:

kfiletreeviewtest(4660)/kio (KDirModel) KDirModelPrivate::nodeForUrl: 
CURRENTLY AT  "file:///home"  WITH  0  ELEMENTS
ASSERT: "it != end" in 
file /home/ereslibre/kdesvn/kdelibs/kio/kio/kdirmodel.cpp, line 180

If you comment out the assert [the Q_ASSERT(it != end) on KDirModel], you will 
see that if you click the "Home" 
button directly when running the test, the view won't move to your "Home" 
folder. That is because of the next:

We get for example this output:
KDirModelPrivate::nodeForUrl: What we want is:  KUrl("file:///")
KDirModelPrivate::_k_slotNewItems: 20  in  KUrl("file:///")  index= "[invalid 
index, i.e. root]"  newRowCount= 20
KDirModelPrivate::nodeForUrl: What we want is:  KUrl("file:///home/ereslibre")
KDirModelPrivate::nodeForUrl: Trying with  "file:///lost+found"
KDirModelPrivate::nodeForUrl: Trying with  "file:///boot"
KDirModelPrivate::nodeForUrl: Trying with  "file:///bin"
KDirModelPrivate::nodeForUrl: Trying with  "file:///dev"
KDirModelPrivate::nodeForUrl: Trying with  "file:///etc"
KDirModelPrivate::nodeForUrl: Trying with  "file:///home"
KDirModelPrivate::nodeForUrl: going into  "file:///home/"
KDirModelPrivate::nodeForUrl:   KUrl("file:///home")
KDirModelPrivate::nodeForUrl: CURRENTLY AT  "file:///home"  WITH  0  ELEMENTS
KDirModelPrivate::nodeForUrl: child equal or starting with  
KUrl("file:///home/ereslibre")  not found

That shows in a very clear way that somehow "/home" hasn't been "cached" 
or "explored". Therefore, "/home/ereslibre" can never be found.

Remember that if you manually expand the /home node, and then you click on 
the "Home" button you will be driven to that node without problems.

Now, try to comment out the checks I added for "result.first == -1" on 
KDirModel. What you will see is blank nodes on the "/home" folder. That was 
the problem I was trying to solve. If you only apply the 
KDirSortFilterProxyModel for sorting the folders, you get blank nodes (that 
is what I posted on the previous thread).

It is important to note that you get as much as blank nodes as warnings 
printed through the console: kDebug(7008) << "child equal or starting with " 
<< url << " not found";.

As I haven't got more time right now, and I have to leave, I will try to find 
a solution tonight, or till the weekend, but I really hope David could give a 
hand here :)


Bye and thanks, 
Rafael Fernández López

GPG Fingerprint: B9F4 4730 43F8 FFDD CC5E BA8E 724E 406E 3F01 D070
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