Jellyfish

          .-""-.
        /       \
       |  O   O  |
        \  ___  /
    .-"""-'   '-"""-.
   /  /\    ^    /\  \
  |  | .\  /_\  /. |  |
   \  \/  /   \  \/  /
    '-.__/     \__.-'
      |  \     /  |
      |   |   |   |
       \  |   |  /
        '-'   '-'

Jellyfish is an in-memory key-value store that speaks the Redis protocol. It supports strings, hash maps, TTLs, transactions (MULTI/EXEC), and vector storage with cosine similarity search.

Everything is built from scratch in Go with zero external dependencies.

Getting started

Build and run:

go build -o jellyfish .
./jellyfish

Or just:

go run .

The server starts on port 6379. You can talk to it with redis-cli or any Redis client:

redis-cli

Commands

Key-value basics:

SET mykey hello
GET mykey          # "hello"
DEL mykey
EXPIRE mykey 60    # expire in 60 seconds
TTL mykey          # seconds remaining (-1 = no expiry, -2 = doesn't exist)

Transactions:

MULTI              # start a transaction
SET a 1
SET b 2
EXEC               # execute atomically

Use DISCARD to cancel a transaction. Transactions are per-connection and execute atomically at EXEC. There is no isolation across clients between MULTI and EXEC.

Vector storage and search:

TSET vec1 0.1 0.2 0.3
TSET vec2 0.4 0.5 0.6
TGET vec1                # [0.1, 0.2, 0.3]
VSEARCH 0.1 0.2 0.3 2   # find 2 nearest vectors by cosine distance

Hash maps:

HSET user name Alice age 30   # set fields (returns number of new fields added)
HGET user name                # "Alice"
HGETALL user                  # ["name", "Alice", "age", "30"]
HEXISTS user name             # 1
HLEN user                     # 2
HDEL user age                 # 1

Misc:

PING               # PONG
ECHO hello         # hello

Protocol

Jellyfish expects RESP arrays of bulk strings for requests. Null bulk values ($-1) are accepted.

Persistence

Write operations are logged to an append-only file (database.aof). When the server restarts, it replays the log to restore state. If an AOF write fails, the command returns an error. There is no fsync policy yet, so recent writes may be lost on crash.

Running tests

go test ./... -v