A very nice paper about fuzzing Rust compiler by generating custom MIR. Found some bugs in both rustc and LLVM, but notably not in Cranelift.

This is an opinionated essay about good and bad practices in data visualization. Examples and explanations are below.

How to spin before sleeping so that it actually helps and not harms?

Microbenchmark for futexes + spinlocks and some useful links at the bottom.

Because spin locks are so simple and fast, it seems to be a good idea to use them for short-lived critical sections. For example, if you only need to increment a couple of integers, should you really bother with complicated syscalls? In the worst case, the other thread will spin just for a couple of iterations…
Unfortunately, this logic is flawed! A thread can be preempted at any time, including during a short critical section. If it is preempted, that means that all other threads will need to spin until the original thread gets its share of CPU again. And, because a spinning thread looks like a good, busy thread to the OS, the other threads will spin until they exhaust their quants, preventing the unlucky thread from getting back on the processor!

Variables are the trickiest part of lambda calculus. And naming is the trickiest part of variables: the most complex code in our lambda evaluator is the part that renames variables to perform capture-avoiding substitutions.
Names are artificial tedious tags whose sole purpose is to aid human comprehension. Can we get rid of them? There ought to be a way to study computation without naming names.

This is the closing-file-handles-on-Windows post.

I'm titling this post Surprisingly Slow because the slowness was either surprising to me or the sub-optimal practices leading to slowness are prevalent enough that I think many programmers would be surprised by their existence.

The Go standard library’s net.IP type is problematic for a number of reasons. We wrote a new one.

This post explores some problems with Go’s “simplicity by design”: introducing a better IP type that’s also interoperable with the language proves to be a non-trivial challenge.

Distributed Proofreaders provides a web-based method to ease the conversion of Public Domain books into e-books. By dividing the workload into individual pages, many volunteers can work on a book at the same time.

The [board] game is about creating a small shellcode in memory by copying existing instructions and then exploiting a buffer overflow to jump into it, so that you can overwrite your opponent’s return address to force them to go to the game_over() function.There are other mechanics as well and more layers of strategy (like setting the exception handler or monkeypatching).

The book, focusing on Homo sapiens, surveys the history of humankind, starting from the Stone Age and going up to the twenty-first century. The account is situated within a framework that intersects the natural sciences with the social sciences.

Faster and simpler git rebase.

This blog post is one of those things that just blew up. From a tiny observation at work about odd behaviors of spinlocks I spent months trying to find good benchmarks, (still not entirely successful) writing my own spinlocks, mutexes and condition variables and even contributing a patch to the Linux kernel. The main thing I’ll try to answer is to give some more informed guidance on the endless discussion of mutex vs spinlock. Besides that I found that most mutex implementations are really good, that most spinlock implementations are pretty bad, and that the Linux scheduler is OK but far from ideal. The most popular replacement, the MuQSS scheduler has other problems instead. (the Windows scheduler is pretty good though)

The site contains all the lectures, project materials and tools necessary for building a general-purpose computer system and a modern software hierarchy from the ground up.

a whirlwind tour through the guts of the system

Dungeons and Dragons, but about philosophy.

Tutorial about building a self-hosting cargo-compatible build tool. I have many problems with cargo and was interested in nixifying our job builds for eternity, so maybe there’s something useful there.

What if all software suddenly disappeared? What's the minimum you'd need to bootstrap a practical system? I decided to start with a one sector (512-byte) seed and find out how far I can get.

A paper about message-passing memory allocator: could be useful for actor systems.

MLIR is an interesting LLVM compiler framework thingy that uses LLVM for multiple representations instead of just high-level assembly.

This tutorial runs through the implementation of a basic toy language on top of MLIR. The goal of this tutorial is to introduce the concepts of MLIR; in particular, how dialects can help easily support language specific constructs and transformations while still offering an easy path to lower to LLVM or other codegen infrastructure. This tutorial is based on the model of the LLVM Kaleidoscope Tutorial.

Detailed explanation of futexes, including some possible pitfalls.

Ruby tutorial with very unusual and interesting writing style.

Category Theory Illustrated is a primer in category theory and other mathematical theories that is made to be really accessible to people with no prior exposure to the subject, without being dumbed down, by utilizing visual explanations.

Up for a challenge and love programming? Well it seems that Bots Are Stupid might be a good fit for you. An ultra-precise platformer where you don't directly control things — what could possibly go wrong?

Book about proofs with Lean.

Paper about how IT in healthcare in general and IT security in particular is done by people who don’t actually use it, listing different problems and workarounds that end up being used in the field.

Sacrificing convenience for security leads you to having neither security nor convenience.

Niko’s post about using vectors (≈ arenas) instead of reference counters to model graphs. Explains how it relates to ownership and borrowing.

See also: Handles are the better pointers.

A blog post explaining the “single owner of data, everyone has indices instead of pointers” model. Not actually about Rust per se, just happens to be really useful for Rust.

See also: Modeling graphs in Rust using vector indices.

The paper’s claim:

False.

Compilers do optimize atomics, memory accesses around atomics, and utilize architecture-specific knowledge. This paper illustrates a few such optimizations, and discusses their implications.

Interestingly, none of the optimizations proposed in the paper actually work on GCC or Clang.

Push key blocks into their slots to gain control of the qwert. Regain Ctrl (and possible other keys) to get to the get through to the end. There are fourteen levels total. Can you get through them all?

You are a Wayfarer. Marked by a complete immunity to magic, Wayfarers travel the world, breaking curses, hunting monsters, and fighting magic when it spins out of control. Their Order, once a powerful presence in the world, is broken, leaving behind only a handful of warriors still bound by their creed.

Rediscover gravity and explore a beautiful Escher-esque world of impossible architecture. Geometry repeats infinitely in every direction, and falling down leads you back to where you started. Manipulate gravity to change your perspective and see the world in new ways. Master the rules of the universe and restore a barren world with vegetation and life.

A first (as far as I know) description of ringbuffer based on two mmaps. I hope to make a better one sometime, but for now this’ll the best explanation I have.

A fresh take on typesetting

When it comes to security, we care about limiting access of each entity of a system to as few other entities as possible. Network input, executables and users must be able to reach only those resources, which are necessary to perform the defined server tasks. Principle of least priviledge.

Generally, it's better to implement as many layers of security as possible. Although, there is no way to make a server 100% bullet proof - it's a huge endless topic, this article covers some feasible essential systemd tunables that give us a layer of protection.

Abstract: Polymorphic inline caches (PICs) provide a new way to reduce the overhead of polymorphic message sends by extending inline caches to include more than one cached lookup result per call site. For a set of typical object-oriented SELF programs, PICs achieve a median speedup of 11%.

Analyze how a Git repo grows over time

See how I use it:

• https://mycorrhiza.wiki/hypha/git_of_theseus

Introspectable and extensible IDEs with logic programming

In this blog post we explore how to write a type level contains operation for HList inspired type lists without running into overlapping trait implementations

Explanation of provenance, uninitialized memory and stuff like that. Useful as an entry point into realization that we don’t live in PDP-11 world anymore.

To Mock a Mockingbird and Other Logic Puzzles: Including an Amazing Adventure in Combinatory Logic is a book by the mathematician and logician Raymond Smullyan. It contains many nontrivial recreational puzzles of the sort for which Smullyan is well known. It is also a gentle and humorous introduction to combinatory logic and the associated metamathematics, built on an elaborate ornithological metaphor.

Life is hard. Some days are at the absolute limit of what we can manage. Some days are worse than that. Eating—picking a meal, making it, putting it into your facehole—can feel like an insurmountable challenge. We wrote this cookbook to share our coping strategies. It has recipes to make when you’ve worked a 16-hour day, when you can’t stop crying and you don’t know why, when you accidentally woke up an Eldritch abomination at the bottom of the ocean. But most of all, this cookbook exists to help Sad Bastards like us feel a little less alone at mealtimes.

tl;dr: /dev/random is obsolete and /dev/urandom is strictly better except in early boot.

Presented in an experimental mnemonic medium that makes it almost effortless to remember what you read

Colmena is a simple, stateless NixOS deployment tool modeled after NixOps and morph, written in Rust. It's a thin wrapper over Nix commands like nix-instantiate and nix-copy-closure, and supports parallel deployment.

Simple, fast, and green CI and caching for nix projects

It turns out that finite state machines are useful for things other than expressing computation. Finite state machines can also be used to compactly represent ordered sets or maps of strings that can be searched very quickly.