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During the past few weeks I’ve built a basic key-value store that persists data to disk. It works, but only as a single node, so there is a fixed limit on the amount of data it can store, and the througput it can sustain. We can make the store scale horizontally in two ways: Replication , which keeps additional copies of the data in other nodes, improving throughput. Sharding , which…
This weekend I took a step back from working on my Key-Value store to make sure I understand the concurrency model of Eio, the OCaml 5 library that I’m using for concurrency and parallelism. I decided to turn my notes into a post to force myself to address any gaps in my understanding. I’m sure that there are several errors, or things to improve, so if you are reading this and find…
This weekend I decided to add some basic persistence to my Key-Value store . I considered going directly into B-Trees or LSM, but they are quite involved. Moving, forward I want to focus more on the distributed side of the store rather than low level storage details (saving those for later!), so for now I decided to implement something simpler, a basic Write Ahead Log (WAL, for short). What is a…
During the last couple of weeks I’ve gone on a completely different direction. I happened to hear a few people saying good things about OCaml, and I was kind of missing coding with strong types, so I decided to reimplement my basic key value store (see the post ), and see if it was fun to write. First of all, here is the result . The functionality is the same, a hash map over a network,…
2025-03-12 Update, as people on Twitter , Lobsters , and Reddit pointed out, I was missing a extern in the struct, see the last section! Last week I started playing with my own toy key-value store (see the previous post ). At the end I got to a hashtable exposed over the network, using a protocol based on S-Expressions. For the next steps, I have two alternatives, I can work on the low level…
This week I was looking for something new, and I realised that I’ve never tried to do any network programming using Common Lisp. Also, some time ago I came across the Build your own Redis book, but never tried to go through it. The project is perfect, it contains threading, networking, and even some async programming. I had no idea what the Common Lisp ecosystem for those things looks like,…
Looking for a first project to play with, I remembered CryptoPals . I did some of it several years ago, and it was fun, so I thought it could be a good way to get familiar with Common Lisp, at least the first set. With that in mind, I had a look, and hear we are! The very first challenge is about hex and base64 encoding. The first time around I just used available libraries for both (I used Rust…
During the past few years my work as a software engineer has involved less low level, algorithmic coding, and more high level strategy, architecture, dependency and team interactions. While that makes sense as careen progresion (I have more impact that way), the truth is that I miss coding things from scratch. Also, with the coming of our AI overlords, I keep on hearing that these skills, that…