LDN Talks January, 2020

Chris Whealy on Pororus_Absorber

• Speaker - Chris Whealy https://twitter.com/LogaRhythm

  • He is a drummer and home practice is what motivated him to build an acoustic environment

• Project - Pororus_Absorber

  • App is designed to assist acousticians when designing environments such as home cinemas

  • It calculates the acoustic absorption curve of a variety of absorption devices mounted against a rigid backing such as a brick wall

  • This is a Rust-WASM project which is a port of an Excel sheet he wrote about 15 years ago using VBScript!

• This was his first Rust WASM project and due to that it took about three months for this project.

• Maths for acoustic calculations were not new to him and they were basically ports from Excel to Rust.

• If done again, he mentioned that he would be able to do the project in a couple of weeks now.

• Some design decisions, such as using JavaScript for event handling could be revisited if reimplemented from scratch.

  • Since WASM allows capturing the DOM at the start, even handling can be done completely within Rust-WASM.

  • For some functions he is passing simply JSObjects, which can stand for anything - this is something he found that he preferred from experience given that obscure error messages one gets if type conversions fail w.r.t. more specific parameters.

Andrius Aucinas on Brave adblock improvements with Rust

• Andrius Aucinas is a performance researcher at Brave and was previously the Head of Engineering at HAT (Hub of All Things), which he co-founded.

• Andrius' Twitter - https://twitter.com/AndriusAuc

• Project - https://github.com/brave/adblock-rust

• He is part of the team responsible for porting Brave Browser's AdBlock engine over from C++ to Rust, he'll be sharing some insights and experiences of that development process.

• Pointers from the talk

  • Used Apple Instruments for profiling

  • Algorithmic improvements were far more important than the optimisation potential of Rust vs C++

  • Blocking alogorithm is now close to uBlock's implementation

  • Brave does uBlock like filtering but also some fingerprinting protectoin which uBlock cannot do since it is not as integrated to the core

  • Brave and other vendors fund the Easylist maintainer which is an open source collaborative effort

  • Thanks to really optimised libraries (which does use unsafe for performance reasons) this new code did not have to use unsafe

    • Rust unsafe code can be disabled by setting following macro - https://doc.rust-lang.org/nomicon/safe-unsafe-meaning.html,

      #![forbid(unsafe_code)]

  • One of the surprising speedups was using ASCII for string processing, instead of UTF when it was possible to. This is something I have also observed even in Java code. It is a known optimisation in InternetDomainName, for example, to use Ascii internally, when possible.

  • Even though not used by this specific code, SMID optimisations used by the libraries make a huge difference.