Single TCP connection with reusable buffers. The buffers are stored on the connection to avoid per-call allocations.

Handle for the background expiration sweeper. Call `stop` to signal shutdown and join the thread.

Synchronous client with connection pooling. This is a facade over the pool and RESP encoder/decoder. Each call acquires a connection, executes one co

Strategy pattern: defines the engine behavior surface for the server. Keys and values are treated as bulk strings (binary-safe) for Phase 1.

Fixed-bucket latency histogram. Uses a linear scan to pick buckets; this is O(buckets) but the list is small and stays hot in cache. If you need fast

Thread-safe metrics aggregator for the server. The struct is intentionally small and uses `AtomicU64` so record calls are zero-allocation and cheap.

RAII wrapper returning a connection to the pool on drop.