rust-hmr-experiment

Rust Web Dev; Proof of Concept for HMR (Hot Module Replacement) using WASM modules.

File tree

./hmr-server
- It does:
  - compilation & modification of host-wasm
  - compilation & modification of mod1.wasm
  - serves to localhost:3000
./wasm-project
- It is the sample project that will be compiled into wasm
- contains lib.rs and mod1.rs

cd hmr-server
cargo run

compile whole cargo project into WASM (main module)
modify the main wasm so it exports all the library functions
- e.g. alloc::alloc::handle_alloc_error
Compile a single rust file into a separate WASM file (component module)
Load the component WASM module (mod1.wasm) from main WASM module
- Import object: __wbindgen_placeholder__, __wbindgen_externref_xform__ fields
- Use of Proxy in JS to flexibly resolve the importObject for WASM instanciation
- Compile mod1.rs into object file with --emit obj flag in rustc
  - mod1.wasm will be minimal and imports all library functions at runtime
  - also imports memory from outside
- Modify the wasm binary with Walrus
  - add exports
    - parse Custom Linking section of wasm binary and obtain name map of functions
  - demangle import & func names
- pass in the host's memory & imports to instanciate mod1.wasm
Error: accessing thread_local! value from mod1.wasm fails; accessing to wrong memory address
- Hmmmm
- Try: Override thread_local crate for the compilation
  - Try it in the host module compilation first
Modify the source code and pass to the compiling process
- Idea: Virtual sandboxed filesystem that returns processed file content
  - Similar idea as using Proxy in JS but for filesystems
- substitute crate::mod with proj_name::mod only in the module compilation
rust source modifier plugin (for activating HMR thru plugin interface)