#dom #web #api-bindings

macro sledgehammer_bindgen_macro

Fast batched js bindings

3 unstable releases

new 0.5.1 Jul 8, 2024
0.5.0 Mar 14, 2024
0.4.0 Feb 27, 2024

#1275 in WebAssembly

Download history 497/week @ 2024-03-14 677/week @ 2024-03-21 1271/week @ 2024-03-28 1366/week @ 2024-04-04 1740/week @ 2024-04-11 1538/week @ 2024-04-18 2048/week @ 2024-04-25 2819/week @ 2024-05-02 2955/week @ 2024-05-09 3370/week @ 2024-05-16 3057/week @ 2024-05-23 3320/week @ 2024-05-30 3001/week @ 2024-06-06 3187/week @ 2024-06-13 3376/week @ 2024-06-20 2417/week @ 2024-06-27

12,661 downloads per month
Used in 14 crates (via sledgehammer_bindgen)

MIT license


sledgehammer bindgen

What is Sledgehammer Bindgen?

Sledgehammer bindgen provides faster rust batched bindings for js code.

How does this compare to wasm-bindgen:

  • wasm-bindgen is a lot more general it allows returning values and passing around a lot more different types of values. For most users wasm-bindgen is a better choice. Sledgehammer is specifically designed for web frameworks that want low-level, fast access to the dom.

  • You can use sledgehammer bindgen with wasm-bindgen. See the docs and examples for more information.

Why is it fast?

String decoding

  • Strings are expensive to decode, but the cost doesn't change much with the size of the string. Wasm-bindgen calls TextDecoder.decode for every string. Sledgehammer only calls TextEncoder.decode once per batch.

  • If the string is small, it is faster to decode the string in javascript to avoid the constant overhead of TextDecoder.decode

  • See this benchmark: https://jsbench.me/4vl97c05lb/5

String Caching

  • You can cache strings in javascript to avoid decoding the same string multiple times.
  • If the string is static sledgehammer will hash by pointer instead of by value.

Byte encoded operations

  • In sledgehammer every operation is encoded as a sequence of bytes packed into an array. Every operation takes 1 byte plus whatever data is required for it.

  • Each operation is encoded in a batch of four as a u32. Getting a number from an array buffer has a high constant cost, but getting a u32 instead of a u8 is not more expensive. Sledgehammer bindgen reads the u32 and then splits it into the 4 individual bytes. It will shuffle and pack the bytes into as few buckets as possible and try to inline reads into js.

  • See this benchmark: https://jsbench.me/csl9lfauwi/2


~18K SLoC