GSoC Status Update – Week 8

13 Aug 2013

This is a status update for my Google Summer of Code 2013 project - implementing advanced statistics importers for Amarok. Please read the first post if you would like to know more about the project.

My GSoC project is done!

Alright, not really. But, I already reached my hard goals and am well on the way to finishing up on soft goals as written in my proposal: tests and two-way synchronization. Reaching all the hard goals is something to celebrate!

Amarok 2.x importer

The Amarok 2.x importer is up and running, and it supports both kinds of Amarok database: external and embedded. The external one is pretty much your standard SQL-based importer. The embedded one is much more fun.

Obviously there's no daemon running when dealing with embedded Amarok database; yet we have to start a MySQL server because data-mining its files is a particularly bad idea. The most straightforward approach would be to simply run an embedded MySQL server, but due to technical reasons we are limited to one embedded server per process. This means that if current Amarok process stores its collection in an embedded database - which is the default - we're quite out of luck.

The solution I opted for is not perfect, but better than any other I could come up with: start a server as a sub-process. The child is fed delicious arguments, making it suitable to run in a multi-server environment, and under typical desktop user's privileges. We then connect to the server and treat it in the same way as external one: that's exactly what it is. The code is written in a way that starts the server on demand and shuts it down after a period of inactivity. Neat.

There are several drawbacks to this approach, the most obvious one being that mysqld binary has to be present on the system. A less obvious one, but which proved to be most troublesome, is lack of answer to a simple question: has the server started up yet? We can't poll the output for equivalent of "ready to serve" message, as it can be written in any language... or can it? There may be another way to determine if the server is fully started, but I haven't found one yet. So for now, after mysqld process starts, it's given a small time window to get ready.

The future

In addition to things outlined in previous posts, I've got a few small tasks on my to-do list - just some overall edge-rounding and a little problem-solving. The process-handling part of Amarok 2.x importer will also be receiving a bit more love, and hopefully I'll find a better solution to the problem mentioned above. I'll also be looking into implementing Banshee importer.

As always, you can check out my progress on my public Amarok clone. The branch is named gsoc-importers.

Thanks for reading!