# LDN Talks January, 2020 ## Chris Whealy on Pororus\_Absorber * Speaker - [Chris Whealy](http://whealy.com/) * He is a drummer and home practice is what motivated him to build an acoustic environment * Project - [Pororus\_Absorber](https://github.com/ChrisWhealy/porous_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](https://uk.linkedin.com/in/andriusaucinas) 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 - * Project - * 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 - , ```rust #![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](https://guava.dev/releases/24.0-jre/api/docs/com/google/common/net/InternetDomainName.html), 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.