The last few months I've been dedicating most of my (very little) free time to a new project: speculo, a library which implements IPC (Inter-Process Communication) on top of shared memory. Since developers appreciate conciseness and minimalism, here's a description of speculo in a few bullet points:

• written in C
• POSIX (tested in Linux and FreeBSD)
• small (~850 LOC)
• well commented (~400 lines)
• good test coverage
• zerocopy
• lockless
• one writer, many readers
• data is written and read in chunks of arbitrary size
• a data chunk becomes visible to the readers as soon as the writer commits it
• data chunks can have an expiration time
• data chunks can be obsoleted by a newer copy
• garbage collector
• no file descriptors are permanently kept open
• no change notification

But here I probably need to write some paragraphs to explain a couple of points.  Except for a few memory addresses which hold the state of the memory area and which are atomically updated and guarded with memory barriers, all the data written to the shared memory object is immutable. This in particular guarantees that readers have a consistent access to the data, which will not change under their eyes. Data chunks are only appended, which means that the shared memory object can only grow. However, data chunks can be marked as expired (if they have an expiration time associated with them) or obsoleted (if a new chunk is said to replace their contents), which means that not all of the data which is written in the SHM object is actually valid. The readers' functions know this, and skip over the invalid data.
At some point the garbage collector will kick in, when the conditions specified by the writer are met or when the SHM area is completely full. All the chunks which are still valid will be copied over to a new SHM object, and then the SHM objects will be atomically switched. Readers will be able to complete their ongoing reads, and transparently move on to the new SHM object as they request to read a new data chunk.

Mappero has always been distributed under a GPL licence. However, since when I started selling Mappero Geotagger (which is built from the same source), I decided not to publish the source code in a public repository, but only to provide it to those who made an explicit request to obtain it.

I spent some time reconsidering the matter, and I've finally decided to let the source code live in a public repository. I also setup a mailing list for it. And indeed I welcome code contributions, however there's a small catch: a CLA. While Mappero is distributed under the GPLv3 licence, I request that all contributors send me an e-mail in which they give me the right to re-licence their contribution under any licence published by the Free Software Foundation.

Since I believe that the busiest time for my involvement with speculo has passed, I expect to be able to spend some more time developing Mappero. The qt5 port is more or less working, but most of the cool features are missing, so it's little more than a map viewer at the moment (Mappero Geotagger, however, is fully working under Qt5!).

Here you can see Mappero running on an Ubuntu Touch powered Nexus 4. Pinch zooming and GPS are not yet working, but I promise they'll be there in less than a week. Also I found a nasty bug which can cause the application to crash when downloading map tiles, and I'll fix it ASAP (I'm mentioning it just so that I won't be flooded with identical bug reports now :-) ).

With all the talk about debian choosing a default init system (link, link), I've decided to share with the world a little project I've been working on to help me understand /sbin/init aka. PID 1. In this blog post I will go step by step showing what an init system must do to be functional. … Continue reading Demystifying the init system (PID 1)

I've just release a new version of Tirelire 1.1.0. This minor release add a settings page, so you ll be able to set the currency symbol for the money you use.

Overview

Eyrie is a music identification program that I originally created for the Nokia N9 but which I’ve now also ported to Ubuntu Touch. It works in a similar way to commercial applications like Shazam and SoundHound, listening to music through the phone’s microphone and then generating an acoustic fingerprint using the open source EchoPrint algorithm. Currently the EchoPrint database isn’t anywhere near as large as the various commercial offerings, so it won’t recognise everything, but it has reasonable coverage.

Video

Video of Eyrie running on Ubuntu Touch

Installation

To install Eyrie on Ubuntu Touch simply search for “Eyrie” on your phone and it should appear.

About four years ago I created the first code for AGTL. It was built on previous experience I made with a very simple geocaching application for Android. Ever since, I kept AGTL running, first on the Openmoko Freerunner, then on the Nokia N900 (still a great phone!) and finally on the Nokia N9. And ever since, I had less time than I wanted to fix bugs, create new features and to stay in contact with you, the community.

A few days ago, I switched from the Nokia N9 to the Dark Side, a.k.a., Android (Nexus 5). With this switch I lost the ability to test new version of AGTL on the N9 and to use the software for myself (still the best method for finding bugs). Therefore, I decided to lay the responsibility for AGTL into the hands of somebody else. I decided to name Aapo Rantalainen as the new maintainer for AGTL. He caught my attention with many helpful bug reports and patches for AGTL, so I decided to pass the torch to him. Apparently, this has already paid off: Aapo made a lot of commits during the last days, fixing bugs and applying patches that I didn't have time for.

I hope to be able to help here and there with AGTL, and to stay up-to-date on its further development. New versions will be announced on this website.

Thanks to Aapo for taking the responsibility and to all the other people that provided me with bug reports, feature suggestions and (sometimes also monetary) input during the last years! It was definitely a great time and its not over yet!

About four years ago I created the first code for AGTL. It was built on previous experience I made with a very simple geocaching application for Android. Ever since, I kept AGTL running, first on the Openmoko Freerunner, then on the Nokia N900 (still a great phone!) and finally on the Nokia N9. And ever since, I had less time than I wanted to fix bugs, create new features and to stay in contact with you, the community. A few days ago, I switched from the Nokia N9 to the Dark Side, a.k.a., Andr...

Firefox for Mobile A good time to try Firefox for Metro - http://limpet.net/mbrubec... November 10, 2013 from Matt Brubeck - Comment - Like

Firefox for Mobile Better automated detection of Firefox performance regressions - http://limpet.net/mbrubec... November 10, 2013 from Matt Brubeck - Comment - Like

Belatedly I have realized that going along with big old WordPress for this intermittent blog of mine was probably a mistake.

I use about 1% of its wealth of functionality, and not often enough to become proficient at it. It’s also slow as molasses on this cheap host I’ve been using.

Moving to a better host (for many other reasons) also made me aware of the hassle involved in carrying over database contents for such apps.

So instead I painstakingly extracted my posts from WordPress and ported them to a much simpler, lighter and database-less blog app called PluXml.

There will be a post with actual content appearing shortly on this new media, which makes it two posts this year, a huge improvement on the previous ones :-)

The new IBTC is at http://w4.monbo.net/blog/ and the old one will probably disappear shortly.

 

In my ongoing uphill battle to maintain at least one meaningful post per year in this solitary monologue, here is the new entry I announced earlier today.

I must warn Planet Maemo purists (if there are still any) that it is not, stricto sensu, Maemo-related.

It is, however, a follow-up on previous posts dating back to 2009, so it is arguably not completely off-topic either :-)

You can read it on my new host & blog:

w4.monbo.net/blog/index.php?article33/a-foolish-consistency-is-the-hobgoblin-of-little-minds

 

Overview

CuteSpotify makes it possible to listen to your Spotify songs on Ubuntu Touch. It’s based on MeeSpot (a MeeGo Spotify client), which I’ve updated to make use of Qt5 and Ubuntu’s QML components. It’s still a little rough around the edges but most of the core functionality is in place now.

One particular problem to look out for is that because of the way Ubuntu Touch currently handles applications CuteSpotify has to be kept in the foreground and the phone has to be kept switched on for music to play (otherwise the application gets suspended). Approaches for handling applications that need to keep running are currently being debated, so hopefully that won’t be the case in future version of Ubuntu Touch.

As a temporary workaround, if your phone is in developer mode (achieved by connecting it up to the Ubuntu SDK) you can run “sudo service powerd stop” (default password is phablet) to stop the phone from going to sleep while you’re listening to music, then “sudo service powerd start” to resume normal power management when you’re done. (See popey’s comment for an alternative method).

Video

Video of CuteSpotify running on Ubuntu Touch

Installation

To install CuteSpotify on Ubuntu Touch simply search for “CuteSpotify” on your phone and it should appear.

Source

The source code for CuteSpotify can be found here: https://github.com/Elleo/cutespotify