KeyMesh

👀 High-performance distributed key-value store in C++

Overview

This project implements a distributed key-value store in C++ using TCP sockets and multithreading, mimicking a simplified Redis. Multiple nodes communicate to store, replicate, and retrieve key-value pairs.

Supports:

• SET <key> <value> → Save a key-value pair
• GET <key> → Retrieve value from key
• Replication across nodes
• Basic error handling and multithreaded client support

Motivation

Single server storage is risky due to failures. Distributing and replicating data across nodes enhances fault tolerance, scalability, and resilience. This project introduces concepts like TCP socket programming, multithreading, and replication in C++.

File Structure

.
├── main.cpp          # Entry point
├── server.cpp/.h     # TCP server & request handling
├── storage.cpp/.h    # In-memory key-value storage
├── replica.cpp/.h    # Replication logic
├── test.sh           # Automated test script
├── README.md         # This file

Build Instructions

Requires a C++11+ compiler with pthreads.

g++ main.cpp server.cpp storage.cpp replica.cpp -o kv_store -pthread -std=c++17

Running the System

In terminal 1:

./kv_store 9000

In terminal 2:

./kv_store 9001

Manual Testing

Use netcat (nc) to send commands:

nc localhost 9000
SET name john
OK
GET name
john

Automated Testing

chmod +x test.sh
./test.sh

Tests include:

• Basic set/get
• Replication between nodes
• Stress test with multiple keys
• Edge cases (missing keys)

Known Issues

• Replication is asynchronous, no retry on failure.
• Only supports two nodes (easy to expand).
• No persistence to disk.
• No conflict resolution for concurrent key sets.

Ideas for Improvement

• Add master node for coordination
• Implement consistency models (eventual, strong, quorum)
• Add hashing/sharding
• Add persistence (file or SQLite)
• Add CLI client

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