Port C Module

2. Define A Porting Plan

Create a $ARGUMENTS_plan.md file to outline the steps and decisions for porting the module. Determine if the C code should be modified, at this stage, to ease the porting process. For example:

• Introduce getters and setters to avoid exposing inner fields of data structures defined in this module.
• Split the module into smaller, more manageable parts.

3. Create the Rust Crate

cd src/redisearch_rs
cargo new $ARGUMENTS --lib

4. Implement Pure Rust Logic

• Create idiomatic Rust code
• Add comprehensive tests
  • Ensure that all C/C++ tests have equivalent Rust tests
• Document public APIs with doc comments
• For performance sensitive code, create microbenchmarks using criterion
• Use proptest for property-based testing where appropriate
• Testing code should be written with the same care reserved to production code

5. Compare Rust API with C API

• Review the public API of the new Rust module against the C API in the header file
• Ensure that differences can be bridged by adding appropriate wrappers or adapters
• Go back to step 1 if discovered differences cannot be bridged without a re-design

6. Create FFI Wrapper

Create an FFI crate to expose the new Rust module to the C codebase:

cd src/redisearch_rs/c_entrypoint
cargo new ${ARGUMENTS}_ffi --lib

FFI crate should:

• Expose #[unsafe(no_mangle)] pub extern "C" fn functions
• Handle null pointers and error cases
• Convert between C and Rust types safely
• Document all unsafe blocks with // SAFETY: comments

7. Wire Up C Code

• Delete the C header file and its implementation
• Update the rest of the C codebase to import the new Rust header wherever the old C header was used

C header files for Rust FFI crates are auto-generated. No need to use their full path in imports, use just their name (e.g. #include $ARGUMENTS.h; for ${ARGUMENTS}_ffi)

8. Test The Integration

./build.sh RUN_UNIT_TESTS               # C/C++ unit tests
./build.sh RUN_PYTEST                   # Integration tests

Example: Well-Ported Module

See src/redisearch_rs/trie_rs/ for a high-quality example:

• Pure Rust implementation with comprehensive docs
• Extensive test coverage
• Clean FFI boundary in c_entrypoint/trie_ffi/