A persistent key-value store built from scratch in Rust. Implements a Log-Structured Merge-Tree with WAL, SSTables, compaction, and a TCP frontend. Built as a systems engineering learning project.

• LSM-tree: in-memory MemTable (HashMap) + disk-backed sorted SSTables.
• Write-Ahead Log: all writes are appended to a log before acknowledgement; on restart, the WAL is replayed to restore state.
• Compaction: merges and prunes tombstoned entries in memory.
• Bloom filters (optional): reduce unnecessary disk lookups.
• Concurrency: Arc<RwLock<T>> allows concurrent readers; writers take an exclusive lock.
• TCP server: accepts multiple connections and dispatches them to the parser + engine.

Measures sequential round-trips over a local TCP connection. Higher concurrency possible with thread-pooling, but not included in these numbers.

1. Network layer (server.rs) – raw TCP, thread per connection.
2. Parser (parser.rs) – zero-copy command parsing (SET, GET, DEL, COMPACT).
3. Engine (engine.rs) – MemTable + WAL + SSTable compaction.

• WAL replay on boot recovers all committed writes.
• Tombstone-based deletion avoids immediate disk rewrites.
• Graceful shutdown on SIGINT: flushes pending WAL, closes sockets cleanly.

git clone https://github.com/baltasarblanco/chronos_lsm.git
cd chronos_lsm

cargo run

Expected Output:

🚀 CHRONOS SERVER LISTO Y ESCUCHANDO EN TCP 127.0.0.1:8080

cargo run --bin client

chronos> SET user:101 {"name": "Venom", "role": "Symbiote"}
OK
chronos> GET user:101
{"name": "Venom", "role": "Symbiote"}
chronos> DEL user:101
OK_DELETED
chronos> COMPACT
OK_COMPACTED

MIT