[digikam] [Bug 332665] New: Digikam should use Baloo for KDE 4.13

[Konrad Renner]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #18 from Konrad Renner <[hidden email]> ---
(In reply to comment #17)

> Hi Vishesh Handa,
>
> Can you give us a simple estimation of work to do about to port current
> digiKAm Nepomuk interface to use Baloo instead.
>
> All code relevant is here :
>
> https://projects.kde.org/projects/extragear/graphics/digikam/repository/
> revisions/master/show/utilities/nepomuk
>
> Also, please take a look of analysis from Veaceslav in comments #13 and #15
> to see if all is fine...
>
> Thanks in advance
>
> Gilles Caulier

Hi,

Vishesh has posted about tagging and baloo:
http://vhanda.in/blog/2014/07/tagging-your-files/ , does this help?

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[Vishesh Handa]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #19 from Vishesh Handa <[hidden email]> ---
Sorry about the delay. I finally looked at the code.

With Baloo, we have tried to keep Baloo just as a file indexer for searching.
Everything else which Nepomuk used to do have either been thrown away or put in
other places. In the case of tags, ratings and comments, they are stored in the
extended attributes.

So, if you guys want, you can skip depending on Baloo completely. Lets talk
about the code -

dknepomukwrap.cpp - This can be converted into reading and writing the extended
attributes.
dknepomukquery.cpp - This is something you can use Baloo for if you want. Or
you can scan the files yourself. If you want to use Baloo, I can help with the
query. Baloo would just be giving you a list of files which have the xattrs
set.
dknepomukwatcher.cpp - Baloo can inform you when a file changes. Or you can use
KDirWatch and listen for changes yourself. It's up to you.

On a separate note, one of the things I hated about Nepomuk was the need for
these "synchornization agents" to be always running. We had those in PIM and in
digikam. Perhaps, now would be a good time to revise that? I'm not aware of the
digikam code base, but it might be simpler to just read and write tags from the
file system directly.

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[Vishesh Handa]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #22 from Vishesh Handa <[hidden email]> ---
(In reply to comment #21)
> (In reply to comment #20)
> > We have our own database so the demon is needed to sync to the digikam
> > database when digikam is not running, and a file is changed.
> > Hm, is the modification date touched when the xattr is edited?
>
> Hi, I edited xattr (user.xdg.comment and user.baloo.rating) with the
> setfattr command and with a little java app. Result: The modification date
> is not touched.

The mtime does not change, but the ctime does -

vlap:~ $ touch fook
vlap:~ $ stat fook
  File: ‘fook’
  Size: 0               Blocks: 0          IO Block: 4096   regular empty file
Device: 12h/18d Inode: 13395683    Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/ vishesh)   Gid: ( 1000/ vishesh)
Access: 2014-07-11 13:36:24.339823962 +0200
Modify: 2014-07-11 13:36:24.339823962 +0200
Change: 2014-07-11 13:36:24.339823962 +0200
 Birth: -
vlap:~ $
vlap:~ $ setfattr -n "user.baloo.rating" -v "4" fook
vlap:~ $ stat fook
  File: ‘fook’
  Size: 0               Blocks: 0          IO Block: 4096   regular empty file
Device: 12h/18d Inode: 13395683    Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/ vishesh)   Gid: ( 1000/ vishesh)
Access: 2014-07-11 13:36:24.339823962 +0200
Modify: 2014-07-11 13:36:24.339823962 +0200
Change: 2014-07-11 13:36:41.619823391 +0200
 Birth: -

I think you can use QFileInfo::created() to access it.

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[Veaceslav Munteanu-2]

https://bugs.kde.org/show_bug.cgi?id=332665

Veaceslav Munteanu <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |CONFIRMED

--- Comment #23 from Veaceslav Munteanu <[hidden email]> ---
I decided to simplify a little the entire nepomuk/baloo thing.

Since digiKam database and metadata can be out of sync, I suggest to extend
read/write metadata options to also read and write using Baloo.

This will reduce the need of having a Nepomuk service and would be much easier
to maintain.

But currently I have 2 problems:
1. digiKam image scanner do not detect changes when I add tag with Dolphin
2. I'm still looking for a tutorial for get/set with Ballo, CMake rules and API
(I don't know, google does not return relevant searches for Baloo API or
tutorial)

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #24 from Gilles Caulier <[hidden email]> ---
Veaceslav,

>digiKam image scanner do not detect changes when I add tag with Dolphin

Image scanner must be triggered by media change notifier at least. Do you see
this kind of information printed on the console when you tag file with Dolphin.

If yes, image scanner must be not able yet to see Baloo event. But are you sure
that Dolphin write tags in image metadata when Baloo info are changed ?

>I'm still looking for a tutorial for get/set with Ballo, CMake rules and API (I >don't know, google does not return relevant searches for Baloo API or tutorial)

If Dolphin is already ported to Baloo, you can find probably all relevant info
in Dolphin code :

https://projects.kde.org/projects/kde/applications/kde-baseapps/repository/revisions/5707e1e92c9c6ad320dbce5f9eeecb637f3e3312

Gilles Caulier

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[Konrad Renner]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #25 from Konrad Renner <[hidden email]> ---
(In reply to Veaceslav Munteanu from comment #23)

> 2. I'm still looking for a tutorial for get/set with Ballo, CMake rules and
> API (I don't know, google does not return relevant searches for Baloo API or
> tutorial)

Hi,

you don't need baloo for setting or getting the attributes from a file. The
important part is, that the attributes are stored in a namespace as defined
here: http://www.freedesktop.org/wiki/CommonExtendedAttributes/

baloo uses the following namespaces for attributes:
 - user.xdg.comment
 - user.xdg.tags => tags are separated with ,
 - user.baloo.ratig => rating range is from 0 to 10 (9 is displayed as 4.5
Stars in dolphin)

In "the near future" baloo will detect changes on this attributes on its own,
see Bug 337602 for more information.

I think the real cool part is, that every application which uses the
freedesktop defined namespaces will be able to interpret those attributes and
is not depened to another software or library.

I don't know how to set the attributes with C/C++ but I have found these:
 -
http://stackoverflow.com/questions/9979864/system-file-read-write-o-create-custom-metadata-or-attributes-extended
 - http://www.lesbonscomptes.com/pxattr/

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[Vishesh Handa]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #26 from Vishesh Handa <[hidden email]> ---
I have to agree with Konrad Renner. As a previously said, it might be best NOT
to use Baloo. Diadvantages -

* Using Baloo introduces a large number of dependencies
* The API still does not guarantee source compatibility in KF5

The whole point of moving to xattr was also so that other applications can use
tags/ratings/comments without having to use Baloo. The primary AIM of Baloo is
just to be a good file indexer + searching frameworking.

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[Veaceslav Munteanu-2]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #27 from Veaceslav Munteanu <[hidden email]> ---
wait... what?

I already ported both sync digiKam->Baloo and Baloo -> digiKam for
tags/comment/rating

This means I must one more time drop everything to trash?

Do Baloo have any signals which tells if an image is updated?(I need this to
tell digiKam to rescan metadata...)

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[Vishesh Handa]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #28 from Vishesh Handa <[hidden email]> ---
On Sat, Aug 9, 2014 at 8:28 PM, Veaceslav Munteanu <
[hidden email]> wrote:

>   *Comment # 27 <https://bugs.kde.org/show_bug.cgi?id=332665#c27> on bug
> 332665 <https://bugs.kde.org/show_bug.cgi?id=332665> from Veaceslav
> Munteanu <[hidden email]> *
>
> wait... what?
>
> I already ported both sync digiKam->Baloo and Baloo -> digiKam for
> tags/comment/rating
>
> This means I must one more time drop everything to trash?
>
>

No. Definitely not. I just meant that there may be some *minor* changes to
the API. Minor.


> Do Baloo have any signals which tells if an image is updated?(I need this to
> tell digiKam to rescan metadata...)
>
> When someone changes the tag/rating/comment? We have a file monitor.

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[Veaceslav Munteanu-2]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #29 from Veaceslav Munteanu <[hidden email]> ---
File monitor is not quite flexible. In old nepomuk implementation we could
register a listener for tags, comments and rating and images.

Adding few thousand of urls in filemonitor at each digiKam start-up will not
scale at all...

Marcel, Gilles, I sucessfully integrated read/write with metadatahub and
imagescanner, but I don't know how to keep baloo <-> digiKam in sync when is
off... even when It is on, might be a problem if I don't find a way to get an
universal signal...

Should I let the user to sync manually through read/write metadata?

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[Veaceslav Munteanu-2]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #30 from Veaceslav Munteanu <[hidden email]> ---
I already implemented read/write and all necessary switches in digiKam.

But extended atributes are very volatile. If I disable write support, each
metadata update simply destroy all existing extended attributes...

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[Vishesh Handa]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #31 from Vishesh Handa <[hidden email]> ---
(In reply to Veaceslav Munteanu from comment #30)
> I already implemented read/write and all necessary switches in digiKam.
>
> But extended atributes are very volatile. If I disable write support, each
> metadata update simply destroy all existing extended attributes...

Could you please elaborate? The metadata update destroys all existing extended
attributes?

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[Veaceslav Munteanu-2]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #32 from Veaceslav Munteanu <[hidden email]> ---
yes, when I enable write to baloo, tags, comments and rating is updated. If I
disable it, and trigger write metadata, the image is empty: no rating, no
comment, no tags..

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #33 from Gilles Caulier <[hidden email]> ---
Vishesh,

Any progress here to help Veaceslav to complete Baloo digiKam interface ?

Thanks in advance

Gilles Caulier

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[Vishesh Handa]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #34 from Vishesh Handa <[hidden email]> ---
@Veaceslav: Could you give me a specific test case for me to reproduce it and
fix it. Perhaps it would be simpler to just look at the code? The code is in
baloo/src/file/lib/filemodifyjobtest.cpp. The code is *quite* simple. I'll be
happy to answer any questions.

Is there anything else you require? We do not plan to add more facilities in
the file monitor for informing clients about what exactly changed. It's too
expensive.

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[nucleo]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #35 from nucleo <[hidden email]> ---
Is this bug figed in 4.3.0?

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[nucleo]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #36 from nucleo <[hidden email]> ---
Here message when compiling 4.3.0:

--  Baloo libraries found.................... YES (optional)

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #37 from Gilles Caulier <[hidden email]> ---
Partially.

See Veaceslav comments for details. It still some work to do i think...

Gilles Caulier

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[nucleo]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #38 from nucleo <[hidden email]> ---
So, can it be already enabled at comile time or better to disable baloo in
4.3.0?

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[Veaceslav Munteanu-2]

https://bugs.kde.org/show_bug.cgi?id=332665

--- Comment #39 from Veaceslav Munteanu <[hidden email]> ---
@Vishesh, in older Nepomuk Api, I was able to register in ResourceMonitor which
type of resource I want to monitor.

I used to register: comments, tags, ratings and images.

what I really need from Baloo is signalFileMetadatachanged(Kurl file), so I can
also trigger it in digiKam.

At least, if filemodifyjob could register a folder path, that would be much
better.

If it's to expensive to fire a signal when Baloo register a change.... well
there is nothing more I can do to integrate better with digiKam except basic
read/write on request.

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