Go-Redis

A lightweight, concurrent in-memory key-value store built in Go, designed with a custom TCP server, interface-driven storage engines, TTL background expiration sweeps, and an interactive command-line experience.

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Overview

Go-Redis provides a thread-safe, Redis-inspired key-value store. It includes an interactive TCP socket interface that works directly with telnet, nc, or standard socket clients, alongside support for background janitor sweeps and one-off execution modes.

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Features

• Concurrent & Thread-Safe Engine: Backed by sync.RWMutex to ensure safe, concurrent reads and synchronized mutations across active client connections.
• TTL & Hybrid Eviction Strategy:
  • Active Janitor Sweep: An automated background routine (sync.WaitGroup + context.CancelFunc) continuously cleans stale keys at a configurable duration.
• Pluggable Storage Modes via IStore:
  • TTLStore: Background janitor-driven storage for ephemeral cache items.
  • Store: Persistent in-memory storage (with --no-ttl).
• Interactive Terminal REPL: Automatic terminal greeting, per-connection prompt (127.0.0.1:6379> ), and graceful session exits.

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Project Structure

go-redis/
├── stores/
│   ├── store_types.go     # IStore interface and TTL payload definitions
│   ├── store.go           # Thread-safe persistent in-memory store
│   ├── ttl_store.go       # TTL-aware store with background janitor cleaner
│   └── store_test.go      # Storage layer unit tests
├── cmd.go                 # Core command handlers (GET, SET, DELETE, etc.)
├── main.go                # TCP listener, REPL router, and CLI flag parser
└── go.mod                 # Go module definition

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Getting Started

Prerequisites

Ensure you have Go 1.20+ installed on your system.

Installation

Clone the repository and enter the directory:

git clone https://github.com/NooRMaseR/go-redis.git
cd go-redis

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Usage

1. Starting the Server

Run the server with the default configuration (binds to port 6379 with a 1s janitor interval):

go run .

Run in persistent mode (TTL janitor disabled):

go run . --no-ttl

Customize the janitor interval and port:

go run . --duration 500ms --port 6380

Available Flags

Flag	Type	Default	Description
-port	string	6379	TCP port to listen on or connect to
-no-ttl	bool	false	Disable TTL background sweeps and run in persistent mode
-duration	duration	1s	Janitor interval for expired key collection (e.g., 250ms, 2s)

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2. Interactive Terminal Connection

Connect via telnet or nc from any terminal:

telnet 127.0.0.1 6379

Once connected, execute commands directly inside the interactive session:

Connected to Go-Redis Server [127.0.0.1:6379]
Type 'HELP' or run commands directly.
127.0.0.1:6379> PING
PONG
127.0.0.1:6379> SET user "admin"
OK
127.0.0.1:6379> SET session "active" 5000
OK
127.0.0.1:6379> GET user
admin
127.0.0.1:6379> EXIST user
true
127.0.0.1:6379> LEN
2
127.0.0.1:6379> EXIT
Bye!

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Supported Commands

Command	Syntax	Description
SET	SET <key> <value> [ttl_ms]	Stores a key-value pair, with optional expiration in milliseconds.
GET	GET <key...>	Returns value for a single key or a formatted list for multiple keys.
DELETE	DELETE <key...>	Removes one or more keys from the store.
EXIST	EXIST <key...>	Checks existence of keys (true / false).
POP	POP <key...>	Atomically fetches and deletes key(s).
RENAME	RENAME <old> <new>	Renames an existing key, overwriting destination if present.
RENAMENX	RENAMENX <old> <new>	Renames an existing key only if destination key does not exist.
KEYS	KEYS	Returns all active keys in the database.
LEN	LEN	Returns the total count of active keys.
CLEAR	CLEAR	Flushes all entries from memory.
HELP	HELP	Prints available command signatures and descriptions.
EXIT	EXIT	Closes client connection gracefully.

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Architecture & Concurrency Model

• Connection Isolation: Every incoming client connection accepted via net.Listen is spawned into an independent goroutine (go handleConnection(conn, store)).
• Sequential In-Connection Processing: Individual multi-key operations process keys sequentially within the connection thread, eliminating redundant goroutine allocation overhead and avoiding lock thrashing across memory reads.
• Interface-Driven Decoupling: Storage implementations (Store and TTLStore) satisfy the unified stores.IStore contract, keeping TCP and command-line parsing code decoupled from storage logic.