I'm David Llewellyn-Jones and this is my homepage. I'm a software engineer at Jolla, who's also interested in programming, security, privacy and graphics. I occasionally crave adventure and a good thunderstorm. You might be interested in my software, my research or my random musings.

Want to know more about me? Here's a personality sketch written by a psychologist when I was in school.

“David is of high intelligence, although lacking in true creativity. He has a need for order and clarity, and for neat and tidy systems in which every detail finds its appropriate place. His writing is rather dull and mechanical, occasionally enlivened by somewhat corny puns and by flashes of imagination of the sci-fi type. He has a strong drive for competence. He seems to have little feel and little sympathy for other people and does not enjoy interacting with others. Self-centered, he nonetheless has a deep moral sense.”

Wow. Harsh. But disturbingly accurate.

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24 Oct 2020 : Waste data dump #
My fortnightly(-ish) waste data dump has just gone up. The daily average is 161g/day, which is pretty good for me. What's more, the largest category is compost, which I suspect is the least environmentally damaging out of them all. In related news I've taken the luxury of getting a couple more bins (paper and plastic) to help with this process. So I'm pretty happy with things this weekend.
10 Oct 2020 : Waste data dump #
It's been a good fortnight on the waste front, probably due to the fact I'm now spending my daytimes in the office rather than at home (although, looking at the trends, I may have to change back to home-working in the not-too-distant future). My daily average over the last 13 days has been 120g/day, which is less than half my 300g daily target. I can't say I'm not pleased. Having said that, looking at the details more closely reveals a more regressive trend. The big shift has been a decrease in compostable waste, while my general waste actually increased slightly on my previous readings. General waste being the most damaging, that's not such a good shift. The numbers that make the difference aren't huge, so it's probably just a fluctuation, but maybe I should be thinking more about category-specific targets in future, rather than combined targets.
9 Oct 2020 : Test CWA-server shutdown #
Today I terminated my test cwa-server AWS instance. That means any old versions of Contrac will start generating errors if they try to download diagnosis keys. Hopefully that'll encourage anyone still on an old version to move over to the latest using the corona-warn-app production servers.
8 Oct 2020 : Contrac 0.7.4 released #
Hot on the heals of 0.7.3 comes Contrac 0.7.4. This continues in the same spirit as the previous version, but fixing restarting of BLE scanning on Xperia X phones.
8 Oct 2020 : Contrac 0.7.3 released #
A small update to Contrac to bring it to version 0.7.3. This will hopefully fix an issue that prevented the daemon from shuting down the BLE scanning properly on Xperia X devices.