Project 4 - Multi-threaded Paxos-based Key-Value Store

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Project Overview

This project implements a distributed key-value store system using the Paxos consensus algorithm across five replicated servers. The system ensures data consistency and fault tolerance through Paxos consensus, featuring simulated random acceptor failures and recoveries.

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Key Features

Distributed Architecture

• 5 replicated server nodes
• Each node implements Proposer, Acceptor, and Learner roles
• Random acceptor failure simulation
• Automatic acceptor recovery mechanism

Paxos Consensus Implementation

• Complete Paxos protocol implementation:
  • Prepare phase (Phase 1)
  • Accept phase (Phase 2)
  • Learn phase (Phase 3)
• Majority-based consensus
• Failure handling and recovery

Key-Value Operations

• PUT(key, value): Store data with Paxos consensus
• GET(key): Retrieve data from any available node
• DELETE(key): Remove data with Paxos consensus

Fault Tolerance Features

• Random acceptor failures at 2-4 second intervals
• Automatic acceptor recovery after 2-4 seconds
• System continues functioning with majority of nodes available
• Consistent state maintenance across recoveries

Data Domain

• Pre-populated with fruit inventory data
  • Keys: Fruit names
  • Values: Fruit prices

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Usage - Two Execution Modes

1. Automated Testing Mode

```bash
# Clean up existing containers
docker-compose down -v

# Build fresh images
docker-compose build

# Start automated testing
docker-compose --profile automated up

2. Interactive Testing Mode

```bash
# Clean up existing containers
docker-compose down -v

# Build fresh images
docker-compose build

# Start in interactive mode
docker-compose --profile interactive up

# In a new terminal, attach to interact:
docker attach paxos-interactive-client
# then enter command in the format below:
Enter command (PUT/GET/DELETE:key:value[only with PUT] or 'exit'

Shutdown

• Automated Mode: Use Ctrl+C (Windows/Linux) or Cmd+C (Mac)
• Interactive Mode: Type exit in the client terminal
• Run docker-compose down to clean up containers

Output Demo

• Automated Mode

• Interactive Mode