12 working implementations of consensus protocols, message brokers, and distributed data structures.
A tiny L7 request router with health checks, round-robin routing, least-connections routing, and forwarded request metadata.
A readable hash ring with virtual nodes and binary-search lookup, the core primitive behind cache and storage routing.
A compact membership filter that can reject misses cheaply while accepting a controlled false-positive rate.
A small inverted index with tokenization, posting lists, and a BM25-style ranking pass.
An in-memory limiter that stores recent request timestamps per key and computes allow, remaining, and retry-after decisions.
A lease-based leader election sketch with expiry and fencing tokens, showing the state transition behind one active worker.
A tiny durable key-value store that writes JSONL WAL records before applying in-memory state, then replays safe records after a crash.
A push-pull gossip simulation where nodes sample peers, exchange versioned records, and converge without broadcasting to everyone.
An in-memory TTL cache that stores absolute expiry timestamps, enforces lazy expiration on reads, and reclaims memory with active sweeps.
A small least-recently-used cache where reads refresh recency and full-capacity writes evict the oldest entry.
A compact Snowflake-style generator that packs timestamp, worker id, and per-millisecond sequence fields into one sortable integer.
An ordered in-memory dataset showing how cursor predicates resume after the last seen row while offset pagination can drift after inserts.