2026Systems
lithos
LSM-tree key-value storage engine in C++17, served through Rust.
An embeddable key-value database built around a Log-Structured Merge Tree. The engine is C++17, exposed through a Rust cxx FFI bridge and an Axum REST API, and monitored from a Next.js telemetry dashboard.
How it works
1
Write path
Every write hits a write-ahead log, then a skip-list memtable. Full memtables flush to sorted string tables at L0.
2
Background compaction
SSTables merge down through L0, L1 and L2, keeping reads bounded as data grows. Blocks are compressed on disk.
3
Bloom filters on reads
Each table carries a Bloom filter, so lookups skip files that cannot hold the key.
4
Rust around C++
A zero-cost cxx bridge exposes the engine to Rust safely; Axum serves it and the dashboard shows the engine live.
Built with
C++
Rust
Axum
Next.js
TypeScript