kalle (jag) applejag

Installation of NixOS with encrypted root

These are my notes on instaling NixOS 16.03 on a Lenovo ThinkPad X1 Carbon (4th generation) with an encrypted root file system using UEFI.

Most of this is scrambled from the following pages:

Code is clean if it can be understood easily – by everyone on the team. Clean code can be read and enhanced by a developer other than its original author. With understandability comes readability, changeability, extensibility and maintainability.

General rules

Follow standard conventions.
Keep it simple stupid. Simpler is always better. Reduce complexity as much as possible.
Boy scout rule. Leave the campground cleaner than you found it.
Always find root cause. Always look for the root cause of a problem.

Design rules

Increasing replication factor for a topic

Create a custom reassignment plan (see attached file inc-replication-factor.json). In this case we are going from replication factor of 1 to 3.

Run Kafka partition reassignment script:

kafka-reassign-partitions --zookeeper $ZOOKEEPER_CONNECT \
    --reassignment-json-file /home/liquidnt/inc-replication-factor.json  \
    --execute

Verify if the assignment was successful

Install virtualbox repo

cd /etc/yum.repos.d/
wget http://download.virtualbox.org/virtualbox/rpm/fedora/virtualbox.repo

Edit virtualbox repo
```
nano /etc/yum.repos.d/virtualbox.repo
```

The goal of this exercise is to get pitch shifting (changing the pitch of music up or down) working with Spotify on Windows 10 using WSL2. Technically this solution is really not dependent on WSL2 at all, but it does require you to have a Linux system running somewhere, whether virtual or physical, with extremely low latency and high throughput networking available to your Windows box.

For this solution, the actual sound playback will be occurring on your Windows PC using your soundcard, but there are other components of the solution that do some audio processing. I'll explain each.

Requirements

A Spotify Premium account
Windows build supporting WSL2; as of December 2019 that'd be the Insider Preview Slow or Fast Ring. This can also be done with Linux in VirtualBox, VMware, or Hyper-V, but I've not tested it.
(Windows PulseAudio From Source method only) A recent Fedora-based distribution of Linux
A modern distribution of Linux that can run a recent Rust toolchain; e.g. Debian Testing, l

Filling an array or slice with a repeated pattern

Looking for an efficient pure GO approach to copy repeating patterns into a slice, for a toy project, I ran a few tests and discovered a neat approach to significantly improve performance. For the toy project, I am using this to fill a background buffer with a specific RGB color pattern, so improving this performance significantly improved my acheivable framerate.

All the test were run with a buffer of 73437 bytes, allocated as follows

var bigSlice = make([]byte, 73437, 73437)

	let toMap dictionary =
	(dictionary :> seq<_>)
	\|> Seq.map (\|KeyValue\|)
	\|> Map.ofSeq

	//Dr. Seuss once wrote, "IF." He meant, "If you give a fuck, maybe,
	//JUST MAYBE, you can change this shitty world in some small way for
	//the better." I might've been an writer of children's books someday,
	//but instead, I decided to make this. So in lieu of The Lorax,
	//let's call this The Dragon, and have my word be, "DON'T." As in,
	//"Don't do something stupid like this the way I did, you jackass."
	//But the truth is humans are very stubborn creatures. You probably
	//won't listen to my advice and, chances are, neither will I.

	open System

	// helper function to set the console collor and automatically set it back when disposed
	let consoleColor (fc : ConsoleColor) =
	let current = Console.ForegroundColor
	Console.ForegroundColor <- fc
	{ new IDisposable with
	member x.Dispose() = Console.ForegroundColor <- current }

	// printf statements that allow user to specify output color

	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
	<title>Sanitize HTML with jQuery</title>
	</head>
	<body>
	<h1>Sanitize HTML with jQuery</h1>
	<h2>HTML Code</h2>