Entries Tagged 'General' ↓

What is it?
In short it is a replacement for tracker-search-tool. I know the name is a tad lame, but I used that for lack of a better alternative at this point.

Why?
We have quite a few people asking for things which are simply not available in tracker-search-tool and I wanted a good excuse to learn Vala. So, tracker-needle was born out of my desire to learn Vala.

Where?
Currently, it lives in a branch on GNOME’s Tracker GIT repository. I am hoping we can merge this to master before we start doing stable releases (which is going to be quite soon).

What next?
Well, right now, it is fairly basic and I plan to add more polish and more “views”. I have in mind to add some sort of photo/icon view for images only and perhaps also some sort of category chooser type view. Possibly some way of displaying and setting tags nicely would be good too. Any ideas appreciated. Note, the idea here isn’t to replace Nautilus or Zeitgeist, this is purely a tool for users to try Tracker with and use occasionally. Ultimately many of the Tracker team believe Tracker should be integrated with applications, not a separate application to search and I tend to agree.

Video?
Eye candy for anyone interested

A while back we had this bug from Bastien: 613255 – “Read-only, non-DBus, store access”. For the past 5 or 6 weeks we have been working on this. Initially the idea was just to do direct access, but once we got started, we realised that the libtracker-client API wasn’t really good enough and we would like to extend it. But we didn’t want the old API there either, so we came up with this new library to supersede libtracker-client. For now we package both, but all functions in libtracker-client are marked as deprecated at this point.

So what do we have now? Fundamentally we have ONE API for different backends using different technologies. To summarise:

1. D-Bus (libtracker-bus, backend)
2. Direct Access (libtracker-direct, backend)

D-Bus – Read/Write Access
Depending on the version, we either use FD passing (requires > 1.3.1) to avoid copious memory copies OR we use D-Bus glib marshalling which represents the worst performance you can get from Tracker (though it is still usable).

Direct Access – Read Only Access
This is based on a library we had internally in Tracker called libtracker-data. We merged some things to make this happen (like libtracker-db) but generally, we sit on top of this library in libtracker-direct.

Plugins?
The backends are dynamically loaded at run time depending on the client’s needs (i.e. if you only ever do SELECT type queries, you’ll use the direct-access backend).

How does the API look for libtracker-sparql?
The idea here was to facilitate all the old API needs and some new ones. What we wanted was less API bloat and to incorporate some of the things we had in the code base all spread out in multiple libraries into this libtracker-sparql. These things include:

• Connections – used in libtracker-client, we wanted some common way to get a connection to Tracker regardless of what backend was in use.
• Cursors – used in libtracker-db and wanted as a public API for some time, but not possible without WAL (Write Ahead Logging) in SQLite 3.7. Now we share the same API internally and externally.
• Builder – used in tracker-extract for building SPARQL queries for selecting/inserting data.
• Utilities – used in tracker-extract, the miners, etc. for escaping text used in SPARQL queries and some other common functionality.

Example
So this is what you might expect with the new API:

TrackerSparqlConnection *connection;
GError *error = NULL;
const gchar *query = "SELECT ?class WHERE { ?class tracker:writeback true }";

connection = tracker_sparql_connection_get (&error);

if (!connection) {
	g_printerr ("%s: %s\n", _("Could not establish a connection to Tracker"), error ? error->message : _("No error given"));
	g_clear_error (&error);
	return;
}

/* The NULL below is the GCancellable */
cursor = tracker_sparql_connection_query (connection, query, NULL, &error);

if (error) {
	g_printerr ("%s, %s\n", _("Could not query classes"), error->message);
	g_error_free (error);
	g_object_unref (connection);
	return;
}

if (!cursor) {
	g_print ("%s\n", _("No classes were found"));
} else {
	while (tracker_sparql_cursor_next (cursor, NULL, NULL)) {
		g_print ("%s\n", tracker_sparql_cursor_get_string (cursor, 1, NULL));
	}

	g_object_unref (cursor);
}

g_object_unref (connection);

So, now we have direct access. I have ported my tracker-needle experimental application to it and it seems faster than tracker-search-tool (which it aims to supersede). I will blog about tracker-needle later, but for now, direct-access is available in master for anyone interested to try it out! This has been a huge team effort with Jürg, Philip and Aleksander Morgado and myself involved. Try it out, any comments about the API are appreciated and it is documented quite nicely too.

Recently, there has been so much work going into Tracker master. For a while now we have been averaging between 1 and 2 branches a week being merged into master. So I thought I would highlight some of the sweet work going into Tracker at the moment:

Dropping libinotify
For some years, we have been using an imported version of libinotify in our source tree to do the things not available in GIO’s monitoring API. One of the main reasons we didn’t move to GIO’s API was that the model we were using didn’t fit the model GIO used. In Tracker, if you monitored a directory and it moved to another location, we moved the monitor to that location. With GIO, if you monitor a directory it doesn’t move, which makes sense. Thanks to Aleksander Morgado, we have now merged his drop-inotify branch into master. It is so nice to be able to remove that imported library now.

D-Bus with file descriptors
We are always trying to reduce the memory footprint of Tracker. Recently Adrien Bustany finished implementing support for DBUS_TYPE_UNIX_FD in Tracker. The nice thing about this, is that we now don’t copy masses of memory from one place to another just for pushing the data between two processes. Adrien and Philip have previously blogged about this, but more recently, Adrien finished support for this by also implementing this for the tracker-miner-fs and tracker-extract communication. Effectively the same data is transported between those as tracker-miner-fs and tracker-store, with the difference that tracker-store also receives file specific information appended to the SPARQL message (like size, modified dates, etc).

To use this you need D-Bus 1.3.1, it is nice to see these sort of performance improvements in Tracker. Great work Adrien thanks!

Direct access
Bastien reported a bug not so long ago about adding support for direct access to the databases via a library API. This week, we started a branch to get this work under way. While we do this, we are considering re-writing the libtracker-client API using Vala and improving the old API substantially.

Git branch management
Due to the high number of branches we create, I decided to do some sort of clean up. I created a script to list all the branches and relevant information about them to be able to email the mailing list and check if everyone was happy with removing old branches. I thought this might be useful to other projects. Here is the script I used:

#!/bin/sh

if ! git rev-parse --git-dir > /dev/null; then
        echo "This is not a git directory"
        exit 1
fi

if test $# -lt 1; then
        remote=origin
else
        remote=$1
fi

git ls-remote $remote | while read LINE; do
        commit=`echo $LINE | sed 's/ .*//'`
        name=`echo $LINE | sed 's/.* //'`

        if [ -z $name ]; then
                continue;
        fi

        case $name in
        refs/heads/master)
                continue
                ;;
        refs/heads/*)
                shortname=`echo $name | sed 's@.*/@@'`
                if ! git log --max-count=1 --pretty=format:"Branch '$shortname' -- last commit was %ar by %an (%h)" $commit 2>/dev/null; then
                        echo
                        echo "Your checkout doesn't contain commit `echo $commit | sed 's/^\(.......\).*/\1/'` for branch $shortname"
                        echo
                        exit 1
                fi
                ;;
        esac
done

This produces output like:

Branch 'album-art-to-libtracker-extract' -- last commit was 3 months ago by Martyn Russell (d1f1384)
Branch 'albumart-quill' -- last commit was 8 months ago by Philip Van Hoof (a397a0f)
Branch 'anonymous-file-nodes' -- last commit was 5 months ago by Carlos Garnacho (60658be)
Branch 'async-queries' -- last commit was 2 months ago by Carlos Garnacho (88358dd)
Branch 'async-queries-due' -- last commit was 10 weeks ago by Jürg Billeter (52634ce)
...

Thanks to Sven Herzberg for some of the improvements to the original script. Most importantly, the use of git ls-remote. This makes sure that local branches are not used which may have been removed in the origin repository.

This year Lanedo are proud to be silver sponsors of GUADEC 2010. If you’re interested in sponsoring and want to know how you can, the details are available here

For GUADEC this year, Lanedo have 3 talks accepted:

• Best Practices in Maintaining Vendor Specific GTK+ Branches
  Submitted by Kris.
• Multitouching your apps
  Submitted by Carlos (based on the new X input 2 work he has been doing for GTK+).
• Tracker’s place in the GNOME platform
  Submitted by me.

Looking forward to seeing you all there!

So we now have our first stable release of Tracker for a long time! Here is the announcement.

Thanks to everyone that has contributed, tested and been part of making this happen, especially the core team Jürg, Philip, Ivan, Mikael and Carlos.

0.7.28
Today we released 0.7.28. We are considering this our last unstable release for 0.7 before we do 0.8. So long as there are no major regressions, this time next week, we hope to have our first stable release with the super shiny stuff we have been working on for over 6 months.

Using tracker-sparql
Recently I added support to list classes which we notify of changes in the database. This is generally quite useful and a common question on IRC:

$ tracker-sparql --list-notifies
Notifies: 23
   Continue reading →

We at Lanedo are currently looking at hiring people with development experience around GNOME and GTK+ related technologies again.

If you have this and are interested in working for us, please send your CV to jobs at lanedo.com.

Managed to get 0.7.20 out of the door. Not long now before we start 0.8 releases. I want to start doing this within the next few weeks if possible.

Tracker is looking great right now though. The core team has been exemplary in recent weeks.

Roll on 0.8

This year we are sending everyone in Lanedo over to Brussels for FOSDEM. Looking forward to meeting up with old friends. It has been a few years since I last made the trip.

Most of us will be there by Friday evening in time to attend the beer event. We hope to see you there, should be good fun!