Redis Java Implementation

A comprehensive Redis server implementation written in Java, featuring full Redis protocol support, master-slave replication, and persistent storage capabilities.

This project implements a fully functional Redis-compatible server that handles the complete Redis protocol (RESP) and supports advanced features including replication, persistence, and concurrent client handling.

Features

Redis Commands Supported

• PING - Test server connectivity
• SET/GET - Basic key-value operations with expiration support
• ECHO - Echo back the provided message
• CONFIG - Server configuration management (GET operations)
• KEYS - Pattern-based key listing
• INFO - Server information and statistics

Advanced Features

• Master-Slave Replication - Full Redis replication protocol with PSYNC and REPLCONF
• RDB File Support - Read and parse Redis database files
• Key Expiration - TTL support with automatic cleanup
• Multi-threading - Concurrent client handling with thread pool
• RESP Protocol - Complete Redis Serialization Protocol implementation
• Persistent Storage - Database persistence with RDB format support

Architecture

• Master Server - Primary Redis server with replication capabilities
• Replica Server - Slave server that syncs with master
• Protocol Parser - Handles complete RESP protocol parsing
• Database Engine - Thread-safe in-memory storage with expiration
• Configuration System - Flexible server configuration management

Requirements

• Java 17 or higher
• Maven 3.6+

Installation & Usage

Building the Project

mvn clean package

Running the Server

Master Server (Default)

# Run on default port 6379
./your_program.sh

# Run on custom port
./your_program.sh --port 6380

# Run with custom database directory and filename
./your_program.sh --port 6379 --dir /path/to/db --dbfilename dump.rdb

Replica Server

# Run as replica connecting to master
./your_program.sh --port 6380 --replicaof localhost 6379

Connecting to the Server

You can connect using any Redis client or telnet:

# Using telnet
telnet localhost 6379

# Example commands
PING
SET mykey "Hello World"
GET mykey
CONFIG GET port
KEYS *
INFO replication

Example Usage

# Terminal 1: Start master server
./your_program.sh --port 6379

# Terminal 2: Start replica server  
./your_program.sh --port 6380 --replicaof localhost 6379

# Terminal 3: Connect and test
telnet localhost 6379
> SET test "value"
> GET test
> PING

Development

Project Structure

src/main/java/
├── Main.java              # Application entry point
├── Master.java            # Master server implementation
├── Replica.java           # Replica server implementation
├── ProtocolParser.java    # RESP protocol parser
├── Database.java          # In-memory database engine
├── RDBReader.java         # RDB file parser
├── ClientHandler.java     # Client connection handler
├── core/
│   └── ServerConfig.java  # Configuration management
├── utils/
│   └── Command.java       # Supported commands enum
└── RESP/
    └── RESPEncoder.java   # RESP protocol encoder

Key Components

• Main.java - Parses arguments and starts appropriate server type
• Master.java - Implements master server with replication support
• Replica.java - Implements replica server with master synchronization
• ProtocolParser.java - Handles all Redis command parsing and execution
• Database.java - Thread-safe singleton database with TTL support

Contributing

This project implements the complete Redis protocol and advanced features. When contributing:

1. Ensure thread safety for all database operations
2. Follow RESP protocol specifications
3. Add comprehensive logging for debugging
4. Test both master and replica functionality
5. Validate RDB file compatibility

License

This project was originally developed as part of the CodeCrafters Redis challenge but has evolved into a full-featured Redis implementation.