# Gustavo Widman

> Software engineer writing Rust for Azion's edge/CDN platform, based in São Paulo, Brazil. This site is his portfolio and blog: network stacks built from raw sockets up, a benchmarked reverse proxy, a bare-metal kernel, NixOS infrastructure, and research on autonomous coding agents.

Every page is available in English and Portuguese at the same URL (`?lang=en` or `?lang=pt`). Blog posts are available as markdown by appending `.mdx` to their URL; each one starts with a metadata header followed by the original source file.

## Blog

- [bringing cheap bluetooth leds into apple home](https://guswid.com/blog/iris.mdx): i wanted my existing led strip in apple home. that turned into a Matter bridge, a webcam experiment, and a very opinionated color correction.
- [i want to stop babysitting the loop](https://guswid.com/blog/autonomous-loops.mdx): FerriSync got me attached to an optimization problem. Volund got me thinking about what happens when trying the next hypothesis no longer needs me at the keyboard.
- [building a reverse proxy in rust: the "doing it properly" version](https://guswid.com/blog/upstreamer.mdx): what started as a quick weekend project turned into a reverse proxy that beats nginx, haproxy, caddy, and apache in both throughput and tail latency.
- [http from scratch, on top of a homemade tcp stack, in rust](https://guswid.com/blog/http-impl.mdx): i had a working tcp stack. the logical next step was to parse http by hand. this is how that went.
- [a billion rows later](https://guswid.com/blog/1brc.mdx): how a college assignment turned into a performance rabbit hole
- [tcp from scratch, over a tun device, in rust](https://guswid.com/blog/tcp-impl.mdx): i built a tcp stack without touching the socket api once. this is how it went, including the three bugs that almost made me quit.
- [homemade udp in rust](https://guswid.com/blog/udp-impl.mdx): college said "implement udp from scratch." i said "can i use rust?" it spiraled from there.
- [teaching rocks to fix themselves with hamming codes](https://guswid.com/blog/hamming-rust.mdx): i overengineered a university assignment in rust to understand how computers magically correct their own errors at the bit level.
- [overengineering the 'rinha de backend' with rust and sqlite](https://guswid.com/blog/rinha-de-backend.mdx): how i squeezed ~2900 rps out of a tiny rust api by dropping postgres and pushing sqlite to its limits.
- [getting rust to run on bare metal without hacks](https://guswid.com/blog/based-kernel.mdx): when a simple homework assignment spirals into writing raw assembly to flip cpu registers.
- [modernizing rsync for the multi-gigabit era](https://guswid.com/blog/modernizing-rsync.mdx): a thesis on why rsync's 1996 algorithm is cpu-bound on modern networks and how hardware optimizations might finally unlock our bandwidth.
- [escaping dependency hell with nix](https://guswid.com/blog/nix-intro.mdx): i spent 7 months building a nix infrastructure so i never have to run npm install again. here's why docker is overkill and how nix works under the hood.
- [i beat pytorch with a zero-dependency rnn in rust (kind of)](https://guswid.com/blog/rnn-rust.mdx): how i accidentally optimized a handmade rnn to be 60x faster than pytorch on small datasets.
- [automating terraria fishing with rust and memory manipulation](https://guswid.com/blog/terraria-autofish.mdx): how i went from failing with ocr to writing a performant cheat in rust using assembly pattern scanning and jit hooking.

## Optional

- [All posts in one file](https://guswid.com/llms-full.txt): every post above, concatenated
- [Blog index](https://guswid.com/llms.mdx/blog): titles, dates, tags and excerpts
- [Résumé (English)](https://guswid.com/resume-en.pdf)
- [Résumé (Portuguese)](https://guswid.com/resume-pt.pdf)
- [Source code](https://github.com/GustavoWidman/portfolio)