WebAssembly compiled module cache

Is your feature request related to a problem? Please describe.

Large WASM modules take a while to compile, impacting startup times. Browsers solve this problem by caching compiled module data.

WebAssembly is a promising media for software distribution. It makes sense to compile for WebAssembly once, instead of shipping multiple binaries for each supported CPU architecture / OS pair, doesn't it? There's a growing number of tools targeting this particular segment, e.g. https://wasmer.io.

Node.js has unique advantages as a WASM runner:

• WASI as a standardised interface for interfacing with the OS (e.g. accessing files, etc.) is insufficient for most practical needs. With Node, one can leverage a plethora of high quality battle-tested cross platform libraries.

• V8 is top notch! It beats competing WASM engines in terms of compile times, resource consumption and the footprint of compiled WASM files (a single data point: V8 produces 160MiB for a 50MiB WASM file, a competitor generates 1+GiB).

• NPM is super robust. Competitors have their own package managers but not particularly reliable ones.

The only component missing in Node.js is a compiled module cache.

It takes 47s to compile the previously mentioned 50MiB WASM file. With a cache POC, the startup time is reduced to under 1s.

Describe the solution you'd like

require('wasm/cache').loadFile('module.wasm')

as a cache-enabled moral equivalent of

WebAssembly.compile(require('fs').readFileSync('module.wasm'))

Cache files to be stored in OS-mandated cache directory, e.g. ~/.cache/node/wasm-cache on Linux.

Describe alternatives you've considered

It used to be possible to serialise a WebAssembly module to a file explicitly. #18265

It stopped working since Node.js 13 due to changes in V8 and there's no way to make it work again.

Instead of introducing a new API, it is possible to enhance WebAssembly.compile/WebAssembly.compileStreaming. Unfortunately, it's hard to come up with a good cache key. We could sha256 the data, but that's inefficient.

该 issue 未指定实现文件或测试；首先检查 WebAssembly.compile 和 WebAssembly.compileStreaming 入口点，以及 #18265 中的序列化历史。完成的标准是支持一种已编译模块缓存，能够从操作系统缓存目录加载 module.wasm，同时处理缓存键相关的问题和提议的 API 形式。