Redis-lite

A Redis-compatible TCP server built from scratch in TypeScript/Node.js.
Implements the RESP protocol, key-value storage with expiry, and RDB file loading.

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Run

npm run dev
# or with RDB persistence
npm run dev -- --dir /path/to/rdb --dbfilename dump.rdb

Listens on 127.0.0.1:6379 by default.

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Supported Commands

Command	Example	Response
PING	PING	+PONG
ECHO	ECHO hello	"hello"
SET	SET key value	+OK
SET with expiry	SET key value EX 10	+OK
SET with ms expiry	SET key value PX 500	+OK
GET	GET key	"value" or nil
KEYS	KEYS *	array of all live keys
CONFIG GET	CONFIG GET dir	array reply

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Architecture

TCP socket (net)
    │
    ▼
parser.ts       — RESP protocol parser
                  handles: + - : $ * types, pipelining, nested arrays
    │
    ▼
server.ts       — command dispatcher
                  reads args[], routes to handlers
    │
    ▼
store.ts        — in-memory key-value store
                  Map<string, { value, expiresAt }>
                  lazy expiry: keys evicted on read
    ▲
    │
rdb.ts          — RDB file loader (read-only)
                  runs once at startup before first client connects

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RDB Loading

Pass --dir and --dbfilename at startup to load an existing RDB snapshot:

npm run dev -- --dir /var/lib/redis --dbfilename dump.rdb

Supported RDB opcodes: 0xFE (DB select), 0xFB (resize DB), 0xFC (expiry ms), 0xFD (expiry sec), 0x00 (string value), 0xFF (EOF).
Keys already expired at load time are silently skipped.

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Test

# connect interactively
redis-cli -p 6379

# raw wire format (shows actual RESP bytes)
printf "*2\r\n\$4\r\nECHO\r\n\$5\r\nhello\r\n" | nc 127.0.0.1 6379

# stress test — 20 concurrent clients
npx tsx src/stress-test.ts