My C++ Redis Server

A lightweight Redis-compatible in-memory data store written in C++. Supports strings, lists, and hashes with full Redis Serialization Protocol (RESP) parsing, multi-client concurrency, and periodic disk persistence.

Features

• Redis-Compatible Protocol: Full RESP parsing support
• Multi-Client Concurrency: Each client handled in separate threads
• Data Types: Strings, Lists, and Hashes
• Persistence: Automatic disk dumps every 5 minutes and on shutdown
• TTL Support: Key expiration with lazy eviction
• Thread-Safe: Mutex-protected data stores

Quick Start

Prerequisites

• C++17 (or later) compiler
• POSIX-compatible system (Linux, macOS)
• Make (optional)

Build

# Using Makefile (recommended)
make

# Or compile manually
g++ -std=c++17 -pthread -Iinclude src/*.cpp -o my_redis_server

Run

# Default port (6379)
./my_redis_server

# Custom port
./my_redis_server 6380

Connect

# Using redis-cli
redis-cli -p 6379

# Example commands
127.0.0.1:6379> PING
PONG
127.0.0.1:6379> SET mykey "Hello World"
OK
127.0.0.1:6379> GET mykey
"Hello World"

Supported Commands

General Commands

• PING - Test server connectivity
• ECHO <message> - Echo a message
• FLUSHALL - Clear all data

String Operations

• SET <key> <value> - Store a string value
• GET <key> - Retrieve a string value
• DEL <key> / UNLINK <key> - Delete a key
• KEYS * - List all keys
• TYPE <key> - Get the data type of a key
• EXPIRE <key> <seconds> - Set key expiration
• RENAME <oldkey> <newkey> - Rename a key

List Operations

• LGET <key> - Get all elements from a list
• LLEN <key> - Get list length
• LPUSH <key> <value1> [value2 ...] - Push to list head
• RPUSH <key> <value1> [value2 ...] - Push to list tail
• LPOP <key> - Pop from list head
• RPOP <key> - Pop from list tail
• LINDEX <key> <index> - Get element at index
• LSET <key> <index> <value> - Set element at index
• LREM <key> <count> <value> - Remove elements

Hash Operations

• HSET <key> <field> <value> - Set hash field
• HGET <key> <field> - Get hash field value
• HEXISTS <key> <field> - Check if field exists
• HDEL <key> <field> - Delete hash field
• HLEN <key> - Get number of fields
• HKEYS <key> - Get all field names
• HVALS <key> - Get all field values
• HGETALL <key> - Get all field-value pairs
• HMSET <key> <field1> <value1> [field2 value2 ...] - Set multiple fields

Architecture

Core Components

• RedisServer: TCP socket handling and client management
• RedisDatabase: Thread-safe data storage (singleton pattern)
• RedisCommandHandler: RESP protocol parsing and command execution

Data Storage

• String Store: unordered_map<string, string>
• List Store: unordered_map<string, vector<string>>
• Hash Store: unordered_map<string, unordered_map<string, string>>
• Expiry Map: TTL tracking for automatic key expiration

Concurrency Model

• One thread per client connection
• Single global mutex (db_mutex) protecting all data stores
• Lazy expiration on key access

Persistence

The server automatically saves data to dump.my_rdb:

• Every 300 seconds (5 minutes) via background thread
• On graceful shutdown (Ctrl+C)
• Loads existing dump file on startup

Project Structure

├── include/                     # Header files
│   ├── RedisCommandHandler.h
│   ├── RedisDatabase.h
│   └── RedisServer.h
├── src/                         # Implementation files
│   ├── RedisCommandHandler.cpp
│   ├── RedisDatabase.cpp
│   ├── RedisServer.cpp
│   └── main.cpp
├── Makefile                     # Build configuration
├── README.md                    # This file
├── Concepts,UseCases&Tests.md   # Design documentation
└── test_all.sh                  # Test script

Development

Building from Source

1. Clone the repository
2. Navigate to project directory
3. Run make to build
4. Run make clean to clean build artifacts

Testing

Run the provided test script:

./test_all.sh

Or test manually with redis-cli or any RESP-compatible client.

Configuration

• Default Port: 6379
• Persistence File: dump.my_rdb
• Auto-save Interval: 300 seconds
• Protocol: Redis RESP (REdis Serialization Protocol)

Limitations

• Single-threaded command execution (per client)
• Text-based persistence format (simplified RDB)
• Memory-only storage (no disk-based datasets)
• Subset of Redis commands implemented

Server Name: my_redis_server
Default Port: 6379
Protocol: Redis RESP