Rukuzu: Porting a 200,000 Line C++ Graph Database to Rust with Systematic Testing

Porting Strategy for Large C++ Codebases to Rust

The Rukuzu project addresses a common systems software challenge: porting a mature 200,000-line C++ codebase (kuzu, an embedded graph database) to a pure Rust implementation. The motivation wasn't that the C++ code was problematic, but rather environmental constraints: mobile devices, edge deployments where C++ toolchains aren't available, FFI boundaries create debugging difficulties, and where a single statically-linked binary is valuable.

Systematic Porting Workflow

The team developed a workflow encoded as a Claude Code custom command that enables:

• Keeping the C++ version operational while building the Rust version
• Testing both implementations against each other
• Verifying at every step that the Rust port produces identical results to the original C++

Implementation Details

The workflow emerged from practical experience with:

• 15 ported crates
• 2,700+ tests
• Lessons about what translates mechanically versus what requires human judgment

The DEALER project (a fuzzy OWLv2 EL++ Description Logic reasoner) consumes both backends through a pluggable architecture, providing a production-grade testbed for correctness and performance comparison.