Let’s go for my web review for the week 2024-34.

Unbundling Profile: MIT Libraries - SPARC

Tags: research, copyright, open-access

It’s good to see major institutions like this get out of contracts with scientific publishing companies. Those unfortunately became mostly parasitic. Open access should be the norm for research.

https://sparcopen.org/our-work/big-deal-knowledge-base/unbundling-profiles/mit-libraries/

Make Firefox Private Again

Tags: tech, mozilla, privacy

Since they unfortunately turned on private attribution by default (why? Mozilla, why?). Here is an easy automated way to turn it off.

https://make-firefox-private-again.com/

Being on The Semantic Web is easy, and, frankly, well worth the bother

Tags: tech, web, semantic

With all those bots and scripts crawling the Web, some of the semantic web vision got silently implemented.

https://csvbase.com/blog/13

Markov chains are funnier than LLMs

Tags: tech, ai, machine-learning, gpt, markov-chains, funny

Interesting musing. The predictability in tone doesn’t make for very funny content indeed. Also as a side-effect this might help people remember that Markov chain are a thing and much less expensive.

https://emnudge.dev/blog/markov-chains-are-funny/

ugh. I picked up a shitty NUC from ewaste…

Tags: tech, security

Scary thread… developers should know better than do this and ship it on devices around the world. Their data is now anyone for the taking and users’ privacy can’t be ensured.

https://digipres.club/@foone/112990331505043510

NetAlert X

Tags: tech, networking, security, tools

Looks like a nice tool to monitor your network.

https://netalertx.com/

Free, OpenSource IPv6 Textbook

Tags: tech, book, ip, networking

Looks like an interesting resource to learn about IPv6.

https://ipv6textbook.com/

Andries Brouwer on the OOM killer

Tags: tech, linux, kernel, memory

Funny musing about the OOM killer. With nice pointers if you want to dive further into the topic.

https://quuxplusone.github.io/blog/2024/08/22/overcommit/

The Closed-Loop Benchmark Trap

Tags: tech, benchmarking

Be sure to pick the right behavior model when you make a benchmark. Otherwise you might just measure the wrong thing.

https://buttondown.com/jaffray/archive/the-closed-loop-benchmark-trap/

What is std::ref?

Tags: tech, c++

A little refresher about std::ref and std::cref. They come in handy sometimes, but also if you don’t realize you need them you’ll generate more copies than necessary.

https://www.sandordargo.com/blog/2024/08/21/std-ref

SIMD Matters :: Box2D

Tags: tech, cpu, simd, performance, physics, simulation

SIMD is hard to use, not all problems can apply to it. But when they can, the performance gain can be great.

https://box2d.org/posts/2024/08/simd-matters/

uv: Unified Python packaging

Tags: tech, python, tools

Looks like there’s another contender for package management for Python. This is sooo fragmented now… this one is compelling though.

https://astral.sh/blog/uv-unified-python-packaging

Common Causes of Memory Leaks in JavaScript

Tags: tech, javascript, memory, leak

There are many ways to create a memory leak in Javascript. Here is a good list of the things to pay attention to.

https://www.trevorlasn.com/blog/common-causes-of-memory-leaks-in-javascript

Toasts are Bad UX – Max Schmitt

Tags: tech, web, frontend, ux

It’s better than no feedback. It’s a bit lazy and far from perfect though.

https://maxschmitt.me/posts/toasts-bad-ux

Reckoning

Tags: tech, web, frontend, ux, criticism

Interesting series about the rise of the javascript frontend framework, the bad practices which came with them and the very real impacts on the users. There are indeed better ways.

https://infrequently.org/series/reckoning/

Don’t Repeat Yourself and the Strong Law of Small Numbers - iRi

Tags: tech, design, programming

This is a good point. The DRY principle has value but the trick is finding the right time to apply it.

https://jerf.org/iri/post/2024/dry_strong/

Code review antipatterns

Tags: tech, codereview

Starts like a satire, but there’s a serious conclusion in the end. Indeed, mind the power dynamics in code reviews. Be nice, steer away from those antipatterns, especially since you might be on the receiving end the next time.

https://www.chiark.greenend.org.uk/~sgtatham/quasiblog/code-review-antipatterns/

Interview with Ron Jeffries

Tags: tech, agile, history, criticism

Very nice interview. This is an interesting reflection on the past 20+ years of Agile Software Development.

https://ronjeffries.com/articles/-x024/-v04/8/

Decision Logs

Tags: tech, product-management

Nice way to keep in check how and why behavior changes as the requests from various stakeholders come in.

https://buttondown.com/j2kun/archive/decision-logs/

Bug squash: An underrated interview question

Tags: tech, hr, interviews, debugging

This is indeed a nice way to approach technical interviews. Unfortunately it requires quite some effort to setup and maintain. You also have to find the right bugs to put in the interview and this is a rarity.

https://blog.jez.io/bugsquash/

Bye for now!

Since Plasma 5.18, nearly five years ago, Plasma has shipped with a "telemetry" system. It’s opt-in, allowing users to send a small amount of data back to us.

Was it useful or worth it? It's a question that comes up occasionally, and the answer is mixed. I believe it showed real potential, though the reality of our implementation was somewhat underwhelming and didn't really deliver. There are many lessons learned that are worth sharing with other projects that might face similar endeavours.

The good bits

Where we had data available for topics being discussed it worked. To give two concrete examples from memory:

• A developer claimed, "No one is using a screen smaller than 1024x768," while bumping the minimum size of a window. This was proved wrong; the number of users at 800x600 or even 640x480 is surprisingly high. Still low as an overall percentage, but higher than you would ever intuitively think. Presumably, it's the default for a lot of virtual machines.

• Four years ago, a developer claimed, "No one still uses only OpenGL2; we can change the code to do XYZ." A check of our user base showed it would have affected nearly 5% of our users, so the change was abandoned.

Interestingly, this last topic came up again very recently, as it held back colour management improvements, but in a narrower Wayland-only path and with a fallback. After checking metrics again, the usage was below 1%, so we went ahead with that merge request.

So, are metrics worth it just to stop developers and designers from making nonsense claims out of thin air? Absolutely! 90% of stats are just made up on the spot. Metrics are just as much about preventing changes as it is about sparking changes.

Indirect impact

The other important part is having a more general sense of the landscape. Currently, we have a lot of hard conversations about how quickly we push the move to Wayland. We have voices wanting to maintain support, and we have voices wanting to push quicker. These decisions shouldn't be made just by who can be the loudest. For every individual topic that came up in those discussions, I would always have in mind our current adoption value at the time.

Should we care about Nvidia? Knowing they make up about 25% of our user base makes the decision for us. I ran with an Nvidia card in one machine because of this, implementing Nvidia context loss handling and doing what we could during the Wayland transition
We don't test BSD while developing Plasma, but we also let it hold us back. Should we care about it more or less? My opinion matches exactly what the metrics say.

Some stats and graphs:

Another role of metrics is being a conversation starter—people will fawn over a graph. More topics on Reddit will be about our Wayland usage rather than the topic I'm trying to discuss. I'll focus on Wayland examples beacuse that's a topic close to me.

Wayland adoption over time

I keep tabs on what our metrics show here. We can see the slow increase from under 20% to around 45% over time, showing the progress as both we and the Wayland ecosystem evolved. At Plasma 6, we switched the defaults a small bump in the graph can be seen. but 45% still seemed rather disappointing.

Filtering on just Plasma 6 reveals the true story:

There's still 20% of users switching away, or using a distro with a different default, or having carried over presets, but it's more promising. Interestingly, we can see that the GPU vendor distribution differs between X11 and Wayland.

Problems and lessons learned

Ultimately, despite the positive parts it would be hard to call our telemetry a staggering success. For the handful of examples above, there are a hundreds of cases where we had no data to back anything up. The range of data points was pitiful and it wasn't often used

The viewing tool is really, really important!

Data collection without viewing it is meaningless. As shown above, we often need to drill down and cross-reference filters to extract conclusions.

The original plan was to use the existing UI provided by kuserfeedback, which did not scale at all and quickly fell over. It was designed for high-fidelity data for a small number of users, not what we had.

In a rush, we pivoted to using Grafana because there was already a setup hosted.

It worked—ish, but it’s not designed for this, especially combined with our data structure, which was a manual NoSQL in normal SQL. Every graph needed to be written by hand, and it felt very much like fighting the system rather than working with it. Combined with the limited access permissions granted, it wasn't used by many people.

It being used is the number one indicator of its usefulness!

We need to find a tool specifically designed for visualization and querying datasets (maybe Apache Superset?).

Time-based data just makes noise

Our system sent updates every N days with basically the same data every time. This made writing queries way messier than it should have been. It never added any value; I would always be interested in what the current stats are. As described in the Wayland usage graphs above, if I'm making a Wayland decision, it doesn't matter what most people are using; it matters what people on the latest release are using. We always ended up having to add filters to focus on just the latest version.

The upgrade story needs planning in advance

The amount of data we collected was tiny—some GPU information, screen information, language, and a few other fragments. The plan was to slowly add more and more stats over time, but we hit a wall. Our UX involved the user selecting to enable metrics and it being a fire-and-forget operation.

What do we do when we want to add more data? For example, whether you use an analog or digital clock. We would need to prompt the user and reset their settings in the meantime, which is at odds with it being a setting. The whole thing became such an ordeal that made it not worthwhile.

Wrap up

The project didn't fail, when we had data and it was used it worked, but overall our implementation falls short. I would like to open a discussion at Akademy on how we move forward with our current system potentially starting from scratch treating it more like a survey that we prompt to auto populate and submit each year.

Hello everyone! Time flies and now we’re already in the final week of GSoC. In this blog post I’ll be sharing the progress I’ve made since my last update, focusing primarily on subtitle styling.

Subtitle Editor

The first thing I did was to enhance the existing subtitle editor. The updated editor now serves as an interface for editing ASS events, which include various components. With the new subtitle editor, we can easily modify elements such as the event’s layer, style, margins, and more. I’ve also simplified the effects section, allowing us to control subtitle scrolling by simply adjusting checkboxes and combo boxes for speed, direction, and range.

However, the most significant change is the text field and the buttons above it. To better understand these changes, it’s important to first introduce the relationship between ASS styles and events. In ASS files, each event must be assigned a valid style that applies to the entire event text. Additionally, ASS override tags are special text blocks within events that allow precise control over the styles of different parts of the text, rather than the entire text. (There are some exceptions, like “Set Position.”)

The text field has been enhanced to assist users in inputting ASS override tags using the provided buttons. For instance, when a user clicks the “Toggle Bold” button, tags are automatically inserted or adjusted to toggle the bold style for either the selected text or the text following the cursor if nothing is selected. Additionally, the text field features a highlighter that renders different parts of the tags in distinct styles, making them more distinguishable, and an auto-completer that lists all valid presets as we start typing a tag name.

For those who prefer the previous subtitle editor, which only displays the rendered text, a “Simple Editor” is also available. This editor syncs with the normal editor but displays only the text without tags while rendering some basic tag effects. However, due to the complexities of ASS tag rules, style editing in the Simple Editor can sometimes behave unpredictably. So it’s best suited for simpler use cases before or after editing styles.

Subtitle Manager

Continuing from the previous improvements, the Subtitle Manager is now integrated with style management and has been divided into four sections: File, Event, Style, and Info, which correspond to the four main components of ASS subtitles. Each section, except for the File section, includes a sidebar for switching between different subtitle files. Additionally, when in the Style section, we can drag and drop a style item onto a subtitle file name in the sidebar to efficiently move or copy styles between files. The same functionality is available in the Event section, where we can move or copy an entire layer to another file.

Misc

Style Editor

A new widget, the Style Editor, was created to edit styles and provide a preview.

Convert Old Global Style

Old styles will now be automatically converted to the “Default” style in the new project. Font size, outline, and shadow will be scaled to maintain the original effects.

Different Default Styles for Layers

Now, we can assign different default styles to each layer, which will automatically be applied to a subtitle event when it’s created on the corresponding layer. This feature is especially useful for quickly building a subtitle file with multiple speakers, allowing each speaker to have a distinct style.

Summary

It has been a wonderful summer getting involved in the KDE community and contributing to Kdenlive! I may not be the best at coding, but I’ve learned a lot throughout this journey. Thanks for everyone who has gave me guidence — Eugen Mohr, Farid Abdelnour, and especially my mentor, Jean-Baptiste Mardelle. While GSoC is coming to an end, my journey with KDE is just beginning. After these updates, I plan to continue improving subtitle functions, including making it easier for users to input more ASS override tags and refining the UI and user experience. See you in my next blog :)

Implementing an Audio Mixer, Part 1

Image Source: Wikipedia

Description from Wikipedia: Sampling and quantization of a signal (red) for 4-bit LPCM over a time domain at specific frequency.

Image Source: Wikimedia Commons

Description from Wikimedia Commons: Image of a discrete time sinusoid

qint16 combineSamples(qint32 samp1, qint32 samp2)
{
    const auto sum = samp1 + samp2;

    if (std::numeric_limits<qint16>::max() < sum)
        return std::numeric_limits<qint16>::max();

    if (std::numeric_limits<qint16>::min() > sum)
        return std::numeric_limits<qint16>::min();

    return sum;
}

qint16 accumulatedSum = 0;

for (auto *stream : mStreams)
{
    // call stream->read(char *, qint64)
    // to read a sample from the stream into streamSample
    qint16 streamSample;
    stream->read(reinterpret_cast<char *>(&streamSample), sizeof(qint16)));

    // accumulate
    accumulatedSum = combineSamples(sample, accumulatedSum);
}

void readData(char *data, qint64 maxSize);

constexpr qint16 bitDepth = sizeof(qint16);

const qint16 numSamples = maxSize / bitDepth;

void readData(char *data, qint64 maxSize)
{
    // start with 0 in the buffer
    memset(data, 0, maxSize);

    constexpr qint16 bitDepth = sizeof(qint16);
    const qint16 numSamples = maxSize / bitDepth;

    for (auto *stream : mStreams)
    {
        // this pointer will be incremented across the buffer
        auto *cursor = reinterpret_cast<qint16 *>(data);
        qint16 sample;

        for (int i = 0; i < numSamples; ++i, ++cursor)
            if (stream->read(reinterpret_cast<char *>(&sample), bitDepth))
                *cursor = combineSamples(sample, *cursor);
    }
}

The post Implementing an Audio Mixer, Part 1 appeared first on KDAB.

A while ago a colleague of mine asked about our crash infrastructure in Plasma and whether I could give some overview on it. This seems very useful to others as well, I thought. Here I am, telling you all about it!

Our crash infrastructure is comprised of a number of different components.

• KCrash: a KDE Framework performing crash interception and prepartion for handover to…
• coredumpd: a systemd component performing process core collection and handover to…
• DrKonqi: a GUI for crashes sending data to…
• Sentry: a web service and UI for tracing and presenting crashes for developers

We will look at them in turn. This post introduces KCrash.

KCrash

KCrash, as the name suggests, is our KDE framework for crash handling. While it is a mid-tier framework and could be used by outside projects, it mostly doesn’t make sense to, because some behavior is very KDE-specific.

It installs POSIX signal handlers to intercept crash signals and then prepares the crashed process for handover to coredumpd and DrKonqi. More on these two in another post. Once prepared it sends the crash signal into the next higher level crash handler until the signal eventually reaches the default handler and cause the kernel to invoke the core pattern.

Before that can happen, a bunch of work needs doing inside KCrash. Most of it quite boring, but also somewhat challenging.

You see, when handling a signal you need to only use signal-safe functions. The manpage explains very well why. This proves quite challenging at the level we usually are at (i.e. Qt) because it is entirely unclear what is and isn’t ultimately signal-safe under the hood. Additionally, since we are dealing with crash scenarios, we must not trigger new memory allocation, because the heap management may have had an accident.

To that end, KCrash has to use fairy low-level API. To make that easier to work with, there are actually two parts to KCrash:

• The Initialization Stage
• The Crash Stage

The Initialization Stage

Initialization is generally triggered by calling KCrash::initialize. You may already wonder what kind of initialization KCrash could possibly need. Well, the obvious one is setting up the signal handling. But beyond that the init stage is also used to prepare us for the crash stage. I’ve already mentioned the serious constraints we will encounter once the signal hits, so we had best be prepared for that. In particular we’ll do as much of the work as possible during initialization. This most important includes copying QString content into pre-allocated char * instances such that we later only need to read existing memory. The second most important aspect is the metadata file preparation for use in…

The Crash Stage

Once initialization has happened, we are ready for crashes. Ideally the application doesn’t crash, of course. 😉

But if it does the biggest task is rescuing our data!

Metadata

Inside KCrash we have the concept of Metadata: everything we know about the crashed application: the signal, process ID, executable, used graphics device… and so on and so forth. All this data is collected into a metadata file on-disk in ~/.cache/kcrash-metadata at the time of crash.

Here’s an example file:

[KCrash]
exe=/usr/bin/kwin_wayland
glrenderer=
platform=wayland
appname=kwin_wayland
apppath=/usr/bin
signal=11
pid=1353
appversion=6.1.80
programname=KWin
bugaddress=submit@bugs.kde.org

The actual fields vary depending on what is available for any given application, but it’s generally more or less what is shown in the example.

This metadata file will later be consumed by DrKonqi in an effort to obtain information that only existed at runtime inside the application - such as the version that was running, or whether it was running in legacy X11 mode.

Handoff

Once the metadata is safely saved to disk, KCrash simply calls raise(). This re-raises the signal into the default handler, and through that causes a core dump.

What happens next is up to the system configuration as per the core manpage.

The recommended setup for distributions is that a crash handler be configured as core_pattern and that this handler consumes the crash. We recommend an implementation of the coredumpd and journald interfaces as that will then allow our crash handler to come in and log the crash with KDE.

So that was KCrash, the first in our four-step crash-handling pipeline. In the next blog post I’ll tell you all about the next one: coredumpd.

A new Craft cache has just been published. The update is already available for KDE's CD, CI will follow in the next hours or days.

Please note that this only applies to the Qt6 cache. The Qt5 cache is in LTS mode since April 2024 and does not recieve major updates anymore.

Changes (highlights)

• Qt 6.7.2
• FFmpeg 7.0.1
• llvm 18.1.8
• boost 1.86.0
• OpenSSL 3.3.1 (for Android too, which was still on 1.1.1v until recently)
• CMake 3.30.0
• Ninja 1.12.1
• Removed qt-installer-framework (Windows)

About KDE Craft

KDE Craft is an open source meta-build system and package manager. It manages dependencies and builds libraries and applications from source on Windows, macOS, Linux, FreeBSD and Android.

Learn more on https://community.kde.org/Craft or join the Matrix room #kde-craft:kde.org

It's been more than three weeks since the midterm summary, and the project is now nearing completion.

Currently, all the original features of Blinken have been fully implemented in the QML version. The remaining tasks involve UI adjustments, testing, and fixing potential bugs.

Over the past few weeks, I’ve been working on the following:

Integrating Blinken's Logic

The game logic of Blinken is handled by the BlinkenGame class from the original Blinken. The original code design is quite good, with most of the game logic encapsulated in this one class. The separation between the logic and the UI rendering is well done, so all I needed to do was connect the signals from this class in QML.

As for the audio playback in Blinken, the original code used the Phonon library, which is also open-source but does not support Android. Therefore, I replaced it with the QtMultimedia library, which provides cross-platform audio playback functionality.

Android Build for KF6 Applications

Some features of Blinken rely on libraries provided by the KF6 framework, such as KF6I18n and KF6Config. When cross-compiling to the Android platform, it's necessary to use the aarch64-linux versions of these libraries. If these libraries are not available on your system, you will encounter the following errors during compilation:

ld.lld: error: /usr/lib64/libKF6XmlGui.so.6.4.0 is incompatible with aarch64linux ld.lld: error: /usr/lib64/libKF6ConfigWidgets.so.6.4.0 is incompatible with aarch64linux 
……

However, the package manager on my Fedora distribution does not provide these versions. Compiling and installing them one by one from source is too cumbersome. On the advice of the community, I used Craft to handle cross-compilation.

For reference, here is the Craft tutorial: Craft - KDE Community Wiki

Important note: If you encounter installation failures, make sure to clear all contents under craft-kde-android before trying again, as leftover files may cause the installation to fail.

When installing, choose the Arm64 target architecture. If there are remnants from a previous failed installation, it may prevent the option to select the ARM64 architecture.

If you encounter issues like "Permission denied," you’ll need to disable SELinux:

sudo apt-get install selinux-utils 
sudo setenforce 0

Additionally, note that in the virtual machine invent-registry.kde.org/sysadmin/ci-images/android-qt67 provided by the community, the Java version is outdated, preventing the use of Gradle 8.6. You can either manually update the Java version in the docker or use an older version of Gradle.

To use Craft for building applications, you need to write a script called a Blueprint, which describes the libraries your application depends on. These scripts are relatively easy to write, and you can quickly get started by following the community documentation: Craft/Blueprints - KDE Community Wiki.

Using KF6 Framework Libraries

Some of the libraries originally used by Blinken are compatible with the Android platform, while others are not. By referring to the API Documentation, you can check which libraries are supported on Android. In Blinken, the following libraries are Android-compatible:

• CoreAddons
• GuiAddons
• I18n
• XmlGui

I needed to use these libraries in the QML version of Blinken.

The KF6 framework provides a convenient internationalization API, and the usage in QML is almost the same as in QWidget, which allowed me to directly reuse Blinken’s original multi-language support, saving a lot of time.

KConfig is used in Blinken to store high score information and settings. For the high scores, I needed to extract the HighScoreManager class from the original HighScoreDialog file, make some modifications, and then create a new high score interface in QML that connects the signals and slots of HighScoreManager. For the settings functionality, it’s as simple as registering a KConfig singleton in QML :

`qmlRegisterSingletonInstance<blinkenSettings>("org.kde.blinken", 1, 0, "BlinkenSettings", blinkenSettings::self());

KF6XmlGui was used in the original Blinken to create the About Blinken Page, About KDE Page, and Handbook Page. Although this library is Android-compatible, it is based on QWidget, while the main interface of Blinken is built with QML. Bringing in QWidget just for these pages didn't seem like a good idea. Luckily, for the Android platform, kirigami-addons provides this functionality. By incorporating it, I also brought in Kirigami, which helps optimize the UI.

After adding new dependencies, it’s important to modify the .kde-ci.yml file to support CI/CD. For more information: Infrastructure/Continuous Integration System - KDE Community Wiki.

Let’s go for my web review for the week 2024-33.

Why We Picked AGPL - ParadeDB

Tags: tech, foss, business

I wish more product companies would pick this license. Going for AGPL with a support and/or double license offering is a strong model in my opinion.

https://blog.paradedb.com/pages/agpl

Fellowship for Maintainers | Sovereign Tech Fund

Tags: tech, foss, economics

Interesting initiative. I’m looking forward to the results of this first pilot.

https://www.sovereigntechfund.de/programs/fellowship

Breaking Up Google

Tags: tech, google, monopoly, law, economics

Of course it sounds complicated to break Google up… but that’s not the point. It’s about avoiding its monopolistic position, the fact that it’s complicated is just another symptom.

https://micro.webology.dev/2024/08/14/breaking-up-google.html

The Dying Web

Tags: tech, google, browser, web, standard

Yes, please let’s increase the market share of non-Chromium based browsers.

https://endler.dev/2024/the-dying-web/

Hacking the Scammers

Tags: tech, security, hacking

Someone was about to get revenge, this gives an interesting exploration.

https://blog.smithsecurity.biz/hacking-the-scammers

‘Sinkclose’ Flaw in Hundreds of Millions of AMD Chips Allows Deep, Virtually Unfixable Infections | WIRED

Tags: tech, cpu, amd, security

Luckily this kind of very low level vulnerabilities are not too common and difficult to exploit. But when they get exploited all things break loose and you can’t trust your hardware anymore.

https://www.wired.com/story/amd-chip-sinkclose-flaw/

Why exploits prefer memory corruption

Tags: tech, security, memory

Interesting take, those bugs are more convenient to exploit. Logic bugs are too specific to easily exploit at scale.

https://pacibsp.github.io/2024/why-exploits-prefer-memory-corruption.html

Some thoughts on OpenSSH 9.8’s PerSourcePenalties feature

Tags: tech, security, ssh

Clearly a new OpenSSH feature to keep an eye on. This should improved security of the server by default. That said, it needs to be a bit more in the wild before knowing how to best tune it.

https://utcc.utoronto.ca/~cks/space/blog/sysadmin/OpenSSHPerSourcePenaltiesThings

slow TCP connect on Windows

Tags: tech, windows, networking

This is indeed surprising behavior and specific to Windows. If you wonder why TCP connect is slow and you got IPv6 support active this might be why.

https://daniel.haxx.se/blog/2024/08/14/slow-tcp-connect-on-windows/

Recent Performance Improvements in Function Calls in CPython

Tags: tech, python, performance

Interesting dive into some of the performance improvements introduced into recent CPython releases.

https://blog.codingconfessions.com/p/are-function-calls-still-slow-in-python

Approximating sum types in Python with Pydantic

Tags: tech, python, type-systems

Here is an interesting use of Pydantic to properly model inputs.

https://blog.yossarian.net/2024/08/12/Approximating-sum-types-in-Python-with-Pydantic

Reflection-based JSON in C++ at Gigabytes per Second – Daniel Lemire’s blog

Tags: tech, c++, reflection, type-systems, performance

Compile time reflection in C++ will indeed be a big deal.

https://lemire.me/blog/2024/08/13/reflection-based-json-in-c-at-gigabytes-per-second/

High-precision date/time in SQLite

Tags: tech, time, databases, sqlite

Looks like a neat extension which can come in handy.

https://antonz.org/sqlean-time/

PostgreSQL masking and obfuscation tool

Tags: tech, databases, postgresql, tools

Looks like an interesting tool for creating anonymized pre-production environments.

https://greenmask.io/latest/

The fastest way to copy data between Postgres tables

Tags: tech, databases, postgresql

Need to duplicate data in Postgres? Several options are on the table.

https://ongres.com/blog/fastest_way_copy_data_between_postgres_tables/

blocking=render: Why would you do that?!

Tags: tech, web, browser, frontend, html

A new HTML attribute to keep an eye on. I can expect people to abuse it with hard to debug problems in the frontend if you don’t know it is there.

https://csswizardry.com/2024/08/blocking-render-why-whould-you-do-that/

Garbage Collection and Metastability - Marc’s Blog

Tags: tech, garbage-collector, performance, safety, memory

Interesting, it confirms garbage collectors can be the source of unrecoverable performance degradation in request based systems.

https://brooker.co.za/blog/2024/08/14/gc-metastable.html

Good Retry, Bad Retry: An Incident Story

Tags: tech, distributed, failure, recovery

Retries are becoming common place to deal with transient errors. That said, they can be a problem with recovery of longer failures due to amplification. There are options on the table to solve this though.

https://medium.com/yandex/good-retry-bad-retry-an-incident-story-648072d3cee6

The Perils of Future-Coding

Tags: tech, design, complexity, performance

Or why anticipating too much is merely a gamble. You can be lucky, but how often will you be? Also I agree that in such cases the performance will be impacted longer term leading to a death by thousands of paper cuts.

https://www.sebastiansylvan.com/post/the-perils-of-future-coding/

How we deleted 4195 code files in 9 hours - by Anton Zaides

Tags: tech, technical-debt, organization, leadership, funny

I’m not sure the incentives are right… it’s better to clean up as you go. Still some places would benefit from such an event from time to time and even if you clean up as you go missed opportunities happen.

https://zaidesanton.substack.com/p/organizing-the-best-cleanathon-your

Stop Team Topologies. Reevaluating Team Topologies

Tags: tech, organization

Surprisingly, I bumped into this article as I’m wrapping up reading the Team Topologies book. This highlight fairly well some of the concerns I have with it and where it shines. I think it’s right to turn to the principles it’s built on rather than use the model it proposes as a blueprint.

https://martyoo.medium.com/stop-team-topologies-fd954ea26eca

How to build a strategy

Tags: business, organization, management, strategy

It’s bloody hard to build a strategy. This article is full of good wisdom to make one. This won’t make it really easier, but at least you won’t start in the wrong direction and will be able to know if what you produce is any good.

https://www.cultivatedmanagement.com/how-to-build-a-strategy/

Anime girl breaking the fourth wall

Tags: tech, blender, 3d, funny

Funny short video, I guess it has also some tutorial value to know what you can do with Blender? (and no, you can’t break the fourth wall with it)

https://www.youtube.com/watch?v=gTi_-HGtsDY

Bye for now!

This will be a guide on how to generate Python bindings for your C++ library using Shiboken. Shiboken is a tool specifically created to build PySide, so it supports Qt code perfectly fine.

The steps described here require at least KDE Frameworks 6.8. I’ll use KUnitConversion as example, because it’s a small library.

We’ll start adding the building instructions. This part is mostly boilerplate code as it’s the same for any library (except for the obvious thing of changing the library name):

 1set(bindings_library "KUnitConversion")
 2
 3set(wrapped_header ${CMAKE_SOURCE_DIR}/python/bindings.h)
 4set(typesystem_file ${CMAKE_SOURCE_DIR}/python/bindings.xml)
 5
 6set(generated_sources
 7    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_module_wrapper.cpp
 8    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_wrapper.cpp
 9    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_converter_wrapper.cpp
10    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_unit_wrapper.cpp
11    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_unitcategory_wrapper.cpp
12    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_updatejob_wrapper.cpp
13    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_value_wrapper.cpp)
14
15ecm_generate_python_bindings(
16    PACKAGE_NAME ${bindings_library}
17    VERSION ${KF_VERSION}
18    WRAPPED_HEADER ${wrapped_header}
19    TYPESYSTEM ${typesystem_file}
20    GENERATED_SOURCES ${generated_sources}
21    DEPENDENCIES KF6::UnitConversion
22    QT_VERSION ${REQUIRED_QT_VERSION}
23    HOMEPAGE_URL "https://invent.kde.org/frameworks/kunitconversion"
24    ISSUES_URL "https://bugs.kde.org/describecomponents.cgi?product=frameworks-kunitconversion"
25    AUTHOR "The KDE Community"
26    README ../README.md
27)
28
29target_link_libraries(${bindings_library} PRIVATE KF6UnitConversion)
30install(TARGETS ${bindings_library} LIBRARY DESTINATION "${KDE_INSTALL_LIBDIR}/python-kf6")

Let’s see what each part does.

 1set(bindings_library "KUnitConversion")
 2
 3set(wrapped_header ${CMAKE_SOURCE_DIR}/python/bindings.h)
 4set(typesystem_file ${CMAKE_SOURCE_DIR}/python/bindings.xml)
 5
 6set(generated_sources
 7    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_module_wrapper.cpp
 8    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_wrapper.cpp
 9    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_converter_wrapper.cpp
10    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_unit_wrapper.cpp
11    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_unitcategory_wrapper.cpp
12    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_updatejob_wrapper.cpp
13    ${CMAKE_CURRENT_BINARY_DIR}/KUnitConversion/kunitconversion_value_wrapper.cpp)

The first line just defines the name of the Python library we’ll build later. Then we set the header file that includes all the necessary headers of the library. We’ll see that file later. The generated sources list is a bit more complicated, as you need to guess the names of the files generated by Shiboken. Fortunately, you can probably guess the pattern from the example above: the first two files are always the same (the name of the library + _module_wrapper or _wrapper) and the rest is the list of classes defined in your XML file (more about it later). The qt_libs variable just contains a list of the Qt modules that our library requires. You should list all of them, even if one depends on another, because otherwise Shiboken won’t be able to find the include directories.

15ecm_generate_python_bindings(
16    PACKAGE_NAME ${bindings_library}
17    VERSION ${KF_VERSION}
18    WRAPPED_HEADER ${wrapped_header}
19    TYPESYSTEM ${typesystem_file}
20    GENERATED_SOURCES ${generated_sources}
21    DEPENDENCIES KF6::UnitConversion
22    QT_VERSION ${REQUIRED_QT_VERSION}
23    HOMEPAGE_URL "https://invent.kde.org/frameworks/kunitconversion"
24    ISSUES_URL "https://bugs.kde.org/describecomponents.cgi?product=frameworks-kunitconversion"
25    AUTHOR "The KDE Community"
26    README ../README.md
27)

This is the magic part. The ecm_generate_python_bindings function takes care of running Shiboken with all the required arguments, building the Python library and a wheel file to publish it on the Python Package Index (pypi.org). It has the following arguments:

• PACKAGE_NAME: Name of the Python library.
• VERSION: Version of the resulting library.
• WRAPPED_HEADER: The header file we talked about above.
• TYPESYSTEM: XML file with the type system information.
• GENERATED_SOURCES: The list of files that Shiboken will generate.
• DEPENDENCIES: A list of libraries that the bindings require, typically the library we’re building the bindings of.
• QT_VERSION: The minimum required Qt version.
• HOMEPAGE_URL: A URL to the homepage of the project.
• ISSUES_URL: A URL where users can report bugs.
• AUTHOR: The author of the library.
• README: The README file for the Python library.

29target_link_libraries(${bindings_library} PRIVATE KF6UnitConversion)
30install(TARGETS ${bindings_library} LIBRARY DESTINATION "${KDE_INSTALL_LIBDIR}/python-kf6")

The last part links the C++ library with the Python bindings and installs it. Now let’s take a look at the header file:

1#pragma once
2
3// Make "signals:", "slots:" visible as access specifiers
4#define QT_ANNOTATE_ACCESS_SPECIFIER(a) __attribute__((annotate(#a)))
5
6#include <KUnitConversion/Converter>
7#include <KUnitConversion/Unit>
8#include <KUnitConversion/UnitCategory>
9#include <KUnitConversion/Value>

Nothing exciting there, just the list of includes (and some Qt thing that I don’t understand).

The last file you need is the typesystem definition, where you tell Shiboken which things (classes, structs, enums, namespaces…) you want to include in your bindings and how it should interpret them. You can delete or rename functions, change the return type, modify the input parameters and many other things. You may want to take a look at the documentation because the list of posible options is very large.

 1<?xml version="1.0"?>
 2<typesystem package="KUnitConversion">
 3    <load-typesystem name="typesystem_core.xml" generate="no" />
 4
 5    <namespace-type name="KUnitConversion">
 6        <enum-type name="CategoryId" />
 7        <object-type name="Converter" />
 8        <object-type name="Unit" />
 9        <object-type name="UnitCategory" />
10        <enum-type name="UnitId" />
11        <object-type name="UpdateJob" />
12        <object-type name="Value" />
13    </namespace-type>
14</typesystem>

You need to load the typesystems of the Qt libraries that you are using so Shiboken can understand what your code is referring to. They come included with PySide.

That’s all you need to generate the Python bindings for your library. The last step is building the project as you usually do.

After a long wait, Plasma Dialer 24.08 is finally out. This released is based on Qt6 and contains 17 months of bug fixing as well as small improvements all other the place.

Packager Section

You can find the package on download.kde.org and it has been signed with my Carl's GPG key.