A high-performance, async key-value store written in Rust with Redis-compatible RESP protocol support.

Features

Core Commands

• GET key - Retrieve a value
• SET key value [EX seconds] - Store a value with optional TTL
• DEL key [key ...] - Delete one or more keys
• PING - Health check
• ECHO message - Echo a message Advanced Features
• TTL/Key Expiration - Automatic key expiration with SET key value EX seconds
• Async Architecture - Built with Tokio for high concurrency
• RESP Protocol - Redis-compatible serialization protocol for compatibility
• In-Memory Storage - Fast, thread-safe HashMap with RwLock
• Background Cleanup - Automatic expiration cleanup every 60 seconds

Building

cargo build --release

Running the Server

cargo run --release

The server listens on 127.0.0.1:6379 by default.

Usage Examples

Using the Included Test Client

cargo run --release --bin client

Using redis-cli

# Connect to kvstore
redis-cli -p 6379

# Basic commands
> PING
PONG

> SET mykey "Hello"
OK

> GET mykey
"Hello"

> SET mykey "World" EX 10
OK

> DEL mykey
(integer) 1

Using nc/telnet (raw RESP protocol)

# Connect and send PING
echo -ne "*1\r\n\$4\r\nPING\r\n" | nc localhost 6379

# SET key value
echo -ne "*3\r\n\$3\r\nSET\r\n\$3\r\nkey\r\n\$5\r\nvalue\r\n" | nc localhost 6379

# GET key
echo -ne "*2\r\n\$3\r\nGET\r\n\$3\r\nkey\r\n" | nc localhost 6379

Architecture

Core Components

1. KvStore - Thread-safe in-memory storage

   • Uses Arc<RwLock<HashMap>> for concurrent access
   • Stores values with optional expiration timestamps

2. RespCodec - RESP protocol parser/encoder

   • Parses Redis Serialization Protocol arrays
   • Encodes responses (simple strings, bulk strings, integers, errors, nil)

3. TCP Server - Async connection handler

   • Spawns new task per connection
   • Streams processed line-by-line
   • Graceful error handling

4. Cleanup Task - Background maintenance

   • Runs every 60 seconds
   • Removes expired keys from store

Performance Characteristics

• Read/Write: O(1) average case (HashMap operations)
• Expiration Check: O(1) per get, full scan every 60 seconds
• Concurrency: Unlimited concurrent connections via Tokio
• Memory: In-memory only (no persistence by default)

Future Enhancements

• Persistent storage (RocksDB/SQLite)
• TTL as a separate priority queue for immediate expiration
• Additional commands (INCR, APPEND, LPUSH, RPUSH, etc.)
• Pub/Sub support
• Cluster mode
• Replication