KegDB

KegDB is a Java implementation of a key-value store based on the Bitcask paper (Bitcask: A Log-Structured Hash Table for Fast Key/Value Data). It implements a Redis-compatible protocol (RESP) for client communication.

Features

• Redis-compatible protocol (RESP)
• Persistent storage using log-structured file format
• Concurrent access support
• Data integrity verification using checksums
• Configurable settings via properties file

Supported Commands

• PING - Test server connectivity
• GET key - Retrieve a value by key
• SET key value - Store a key-value pair
• DEL key OR DELETE key - Delete a key-value pair

Configuration

Configuration is managed through src/main/resources/db.properties:

port=6379 # Server port (default: 6379)
thread_pool_size=10 # Number of worker threads
data_directory=./db # Data storage directory
max_file_size=10000000 # Maximum size for data files (10MB)

Building and Running

Prerequisites

• Java 17 or higher
• Maven

Build

mvn clean package

Run

java -jar target/kegdb.jar

Implementation Details

KegDB implements the Bitcask design with the following components:

• KeyDir: In-memory hash table mapping keys to file locations
• Data Files: Append-only log files storing the actual data
• RESP Protocol: Redis-compatible communication protocol
• Concurrent Access: Thread-safe operations using read-write locks