Cengiz Can cengiz-io

What is the Strict Aliasing Rule and Why do we care?

(OR Type Punning, Undefined Behavior and Alignment, Oh My!)

What is strict aliasing? First we will describe what is aliasing and then we can learn what being strict about it means.

In C and C++ aliasing has to do with what expression types we are allowed to access stored values through. In both C and C++ the standard specifies which expression types are allowed to alias which types. The compiler and optimizer are allowed to assume we follow the aliasing rules strictly, hence the term strict aliasing rule. If we attempt to access a value using a type not allowed it is classified as undefined behavior(UB). Once we have undefined behavior all bets are off, the results of our program are no longer reliable.

Unfortunately with strict aliasing violations, we will often obtain the results we expect, leaving the possibility the a future version of a compiler with a new optimization will break code we th

You will need nightly Rust

Install Rust, se rustup.sh curl -sSf https://static.rust-lang.org/rustup.sh | sh
Update installaion with: rustup self update rustup self update-data
Install nightly Rust: rustup toolchain install nightly
Default to nightly: rustup default nightly

Creating a redis Module in 15 lines of code!

A quick guide to write a very very simple "ECHO" style module to redis and load it. It's not really useful of course, but the idea is to illustrate how little boilerplate it takes.

Step 1: open your favorite editor and write/paste the following code in a file called module.c

#include "redismodule.h"
/* ECHO <string> - Echo back a string sent from the client */
int EchoCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {

Disabling GNOME Tracker and Other Info

GNOME's tracker is a CPU and privacy hog. There's a pretty good case as to why it's neither useful nor necessary here: http://lduros.net/posts/tracker-sucks-thanks-tracker/

After discovering it chowing 2 cores, I decided to go about disabling it.

Directories

Disable Secure Boot in BIOS, enable Boot of Ubuntu
Boot this ISO via USB stick: https://plus.google.com/+IanMORRISON/posts/igAkD5j3MAq
Use arch-bootstrap to install Arch Linux on the stick: https://github.com/tokland/arch-bootstrap
aloso install the wifi driver https://aur.archlinux.org/packages/rtl8723bs-dkms-git/
Copy Firmware rtl8723bs_nic.bin for Wifi from https://github.com/hadess/rtl8723bs
Update Compute Stick Firmware (to make headless work): https://communities.intel.com/message/347428#347428 https://downloadcenter.intel.com/download/25506
To boot headless: add kernel parameters text (maybe not needed anymore)

	lxc.net.0.type = veth
	lxc.net.0.link = lxcbr0
	lxc.net.0.flags = up
	lxc.net.0.hwaddr = 3e:3f:3a:3b:3c:3d

	lxc.idmap = u 0 100000 65536
	lxc.idmap = g 0 100000 65536

	---
	BasedOnStyle: LLVM
	Language: Cpp
	IndentWidth: 8
	UseTab: Always
	BreakBeforeBraces: Linux
	AlwaysBreakBeforeMultilineStrings: true
	AllowShortIfStatementsOnASingleLine: false
	AllowShortLoopsOnASingleLine: false
	AllowShortFunctionsOnASingleLine: false

	;;; ripgrep.el --- from end for ripgrep
	;;
	;; Copyright (C) 2016 Nicholas Matsakis
	;;
	;; Adapted from ack-and-a-half.el, which is licensed as follows:
	;;
	;; Copyright (C) 2011 Jacob Helwig
	;;
	;; Author: Jacob Helwig <jacob+ack * technosorcery.net>
	;; Version: 0.0.1

	match cache.entry(sql) {
	Occupied(entry) => Ok(entry.get().clone()),
	Vacant(entry) => {
	let statement = try!(Statement::prepare(&self.raw_connection, entry.key()));
	Ok(entry.insert(CachedStatement::new(statement)).clone())
	}
	}

	def foo[A](a: A)(implicit ma: HasSize[A]) = {
	ma.size(a)
	}

	def boo[A : HasSize](a: A) = {
	implicitly[HasSize[A]].size(a)
	}

	trait HasSize[-A] { def size(a: A): Int }